Tribute to Lansing-Heritage-Forum and DIY 2405 & 2446 & E145 build

[Dr.db]

Hey guys,


I have been a member in this forum for a couple of years now and have benefited from a lot of whisdom and help on this board.
My journey started about 10 years ago with a pair of 2470 drivers and from that moment on I had been infected with the JBL-Virus. I started collecting vintage JBL speakers and building enclosures for them. But unfortunatelly I´m not a professional, so I was depending on your advices many times.

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:applaud: This thread is dedicated to all the members that had been a big help for me over the years! :applaud:
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.
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After all I think I owe you guys at least a report about my final build.
So I have taken the time to document this during my build by taking pictures. I will post these gradually as I´m making progress in my build.

My setup consists of the following drivers:
JBL 2405
JBL 2446 (JBL 2441 dia´s)
JBL E-145

The bass cabinet will obtain a volume of 7,5 cubic ft and be vented with 2 ducts.
The midrange horn will be a westlake copy.
Crossovers will be passive.

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Thanks again for your sustained help over the years, I hope you will enjoy the pictures. :)

[Dr.db]

It all starts with a big slab of walnut hardwood for the wooden westlake-horns.

[Ed Zeppeli]

Nice! Looking forward to the progress.

[Dr.db]

Some more wood for the horn-vanes.
73397

Finishing the vanes.
73398

Walnut vanes for the midrange-horns.
73399

[JeffW]

Man, those are some slabs o' wood you got there!

[Dr.db]

Indeed. It had been air dryed over 10years and didn`t had much tension when sawing it. :)
It was very easy to work with...

[NVGrampy]

I have a project where large slabs of hardwood would be a big boost. If you are willing to discuss it with me, even if you are not interested, please respond by email to [email protected] Thank you. Les Orr

[berga12]

interested to follow :)

[svollmer]

I'll look forward to following your progress and pictures too. I love watching what talented people can do with beautiful wood.

[Dr.db]

The horns have been finished :)

73605

73606

.

Top-side:

73607

Bottom-side:

73608

[Ed Zeppeli]

That grain!

[srm51555]

Those look great, nice work!

[Dr.db]

Thanks a lot :)
Here are some more....


Front-view:
73609


Back-view:
73610

[JeffW]

How about a close up of the insignia?

[Dr.db]

How about a close up of the insignia?


Shure!
Allthough this photos were taken on a different speaker-project of mine, because right now I´m not in the joinery and cannot take new pictures of the horns...

Best regards,
Olaf

73611

73612

[gdmoore28]

What beautiful work! Will be eagerly following your progress.

GeeDeeEmm

[Dr.db]

Thank you! :)

BTW, this is a sketch of what it is supposed to look like when finished :bouncy:

73620

[dkalsi]

Although I am super impressed with your work, I do wish you post more pictures from the build.

I don't know about others, but I absolutely love looking through project build pictures. Gets me motivated to start my own project.

Great work and can't wait to see more.

Cheers,
D

[srm51555]

I don't know about others, but I absolutely love looking through project build pictures.
Great work and can't wait to see more.

Always!


Gets me motivated to start my own project.
Maybe:p

[Dr.db]

Although I am super impressed with your work, I do wish you post more pictures from the build.




I will try, but most of the time I´m alone at work and have no one around to take pictures during the process.
But if you have specific questions about the build, please feel free to ask ;)

[berga12]

Are you still in time to round better the inner of the horn mouth? I see a "sharp" edge, the sound will not be so happy as the Quality of the construction is....;)

[Dr.db]

Do you mean the transition to the ~45° bevel ?

[berga12]

Do you mean the transition to the ~45° bevel ?


yes this one

[Jennifer]

Indeed. It had been air dryed over 10years and didn`t had much tension when sawing it. :)
It was very easy to work with...

Yes indeed, one rarely gets to see wood like that! In Portland Oregon we have Gilmer Wood, a place of woodworker dreams, but the prices are what they need to be for rare and exotic, so projects such as yours with such nice materials remain elusive for many... 10 year dry and stable has to be a dream to work with... and so nice on the eye!

[Dr.db]

I have choosen 1inch thick birch plywood for the cabinets.
I ordered a total of 18 square meters. That´s quit a lot, but I will brace the enclosures heavily ;)

So far I have glued solid walnut strips to all edges. This is a lot of work, but I absolutly hate fringed edges and these enclosures shall last decades.

73638

In the back you can see the veneer.
It is 2mm thick walnut veneer for the outside, and 2mm mahogany for the inside to function as back pull, so the boards will remain flat without twisting.

73639

[Dr.db]

Boards have been veenered on this pics....

Frontbaffel is aprox. 2 inch thick.

73640


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73642

[ARMED]

thats a lot of wood!!!









































thats what she said!

[mortron]

Beauty build so far. Love seeing slabs of wood become functional pieces of art. Even the tree would be honoured.

I am curious why you chose the bass drivers you did? Will you be augmenting them with subwoofers or anything?

[Dr.db]

Thanks, very kind of you!

I choosed the E-145, because it has been the most accurate bass-driver I have listened to so far. The 2235 for example had less slam and didn`t thrill me at all.
But I have to admit, the E-145 is a bit reserved in the very low end.

I will propably rise the bass response by 2-3db by using an active highpass-filter with a 2db-gain around the tuning-freq. with a q-factor of aprox. q=1,3....
My intention is to use this without subwoofers and to achieve relatively flat response to 40hz in listening room.

[Dr.db]

One thing I have always disliked with end-consumer speakers was the small stiffness of their enclosures. Their certainly are manufacturers that build sophisticated enclosures besides just looking good, but they are very few....

Im aware that every box will vibrate at some point no matter how much bracing had been used. But I believe it still is a good start to keep the enclosure as stiff as possible.

73857

I sawed these squares (braces) out of 1inch thick birch plywood.
I have placed these in such way, that there isn`t more than 8 inch of enclosure wall without a brace.
Besides the achieved stiffness, it actually doesn`t need that much capacity....


I have to admit, it really was hard work to assemble all the parts. :blink:
Their where plenty of joints I had to glue.
To avoid drying of the glue at the first coated parts before finishing the assemble, I did split this process in 3 steps.
I glued all the braces together in 2 steps.
To enshure a good fit later on, I used the enclosure walls as a template while glueing the braces.

73856

This is what the bracing workpiece looks like after glueing.
Quite peculiar, right!? :bouncy:

73859

In the last step I joined the braces and the enclosure walls.
Likely we had plenty of strong clamps around, this made a good fit a lot easier...

73858

[maxserg]

suscribed:)

[dkalsi]

Awesome! Thanks for posting pictures :-)

[Dr.db]

The tuning for the 7,5cubic feet enclosure will be aprox. 40hz, similar to the Everest DD55000...
To achieve this, the ports have to be about 3,5" long and 4" in diameter.
I don´t like the plastic-ports so I milled some solid walnut ports out of some well dried slabs.

73902

The ports have to be glued together out of to slices, as these are only 2" thick each...

73901

Mounted in the enclosure it looks like this:

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[Odd]

Amazing wood work

[dkalsi]

Amazing wood work

Ditto

[grumpy]

Has an interesting Aquarius II-vintage vibe going on... :)

[Dr.db]

Has an interesting Aquarius II-vintage vibe going on... :)

Actually I haven´t been aware of these speakers at all, but I totally have to agree with you!
Funny, I thought I had a glorious idea to make a big speaker look more slender, but I´m decades too late with my idea :D

[gdmoore28]

Wow, Doc! Those walnut vents just look FANTASTIC! Great work, my friend.

GeeDeeEmm

[Dr.db]

I will build the passive crossovers for the 2405 & 2446 (2441 diaphragm) compressiondrivers according to the 3155 equivalent crossover network.
It has the required xover frequencies of 1,2khz and 10khz and is highly regarded on this board.

It had been puplished by 4313B .
http://www.audioheritage.org/vbulletin/showthread.php?27199-DIY-quot-4345-quot-Project&p=292188&viewfull=1#post292188
74085


The crossover for the E-145 will be similar to the JBL 3120 network.
http://www.jblproservice.com/navigation/Network%20Schematics.html

The coils are pure copper AWG 6 (3,9mm) air-core-inductors.
They are 1,5mh (milli-henry) and weight several pounds :blink:
74086

[Dr.db]

This is the lowpass crossover for the E-145.
Don´t be confused, the big inductor/coil is mounted seperatly due to the high weight!

74091

The circuit board is based on epoxy and very resistant and none fragile.
All screws are pure brass and non magnetic or inductiv.
Capacitors are Mundorf MCap and MCap ZN.
Resistors are non magnetic and non inductiv from Mills.

[1audiohack]

This whole project is amazing. Art from end to end.

Thank you for taking the additional time to share with us.

Barry.

[srm51555]

This whole project is amazing. Art from end to end.

Thank you for taking the additional time to share with us.

Barry.

No kidding!! Great work.

[Dr.db]

I´m glad you guys enjoy it, thanks a lot for your kind compliments!

[cooky1257]

I´m glad you guys enjoy it, thanks a lot for your kind compliments!

Is it possible to fall in love with speaker ports? Amazing, best I've seen anywhere.:applaud::applaud::applaud:

[berga12]

Hi,
I Only do not agree to run the midrange at 1,2Khz as high pass.

this is a 3 way, why you want to run the E145 till 1-1,2Khz??? This make no sense.

You have the opportunity with your horn and 2446 to go down to 400-500hz and let the voice not to be in the Really critical "1Khz zone" where the final result will be a Giant and not realistic voice.

You have not a 4 way with a midrange..........so use as much as you can the Compression Driver from 400 to 10khz. (I'm telling that to you because before I had a similar system with my 2441).

[audiomagnate]

Is it possible to fall in love with speaker ports?...

As long as you keep it platonic I think you'll be OK.

[Dr.db]

Hi,
I Only do not agree to run the midrange at 1,2Khz as high pass.


Appropriate note I have to admit!
I have thought quit a while about the correct crossover between the E-145 and 2441 and did several listening tests.

1,2khz is very high for a 15" cone, but it works. I´m shure it´s not the most audiophile solution for the E-145, but it was the best compromise in my opinion.
The E-145 sounds very clean in the upper frequency range besides a nasty resonance at about 1,6khz.
It does get more beamy than a JBL 2123 up there though...

But the JBL 2397 / westlake midrange-horn hasn´t got a large hornmouth area and sounds rather thin below 1khz.
Moreover I have made the experience, that crossing compressiondrivers (too) low results in a stressed and distorted sound. I like to keep the crossover well above the actual cut-off freq. of the horn...
Maybe a Yuichi or TAD horn would have been a better match with the E-145 due to its ability to really reproduce sound from ~600hz upwards.

[Mr. Widget]

Appropriate note I have to admit!
I have thought quit a while about the correct crossover between the E-145 and 2241 and did several listening tests.

1,2khz is very high for a 15" cone, but it works. I´m shure it´s not the most audiophile solution for the E-145, but it was the best compromise in my opinion.
The E-145 sounds very clean in the upper frequency range besides a nasty resonance at about 1,6khz.
It does get more beamy than a JBL 2123 up there though...

But the JBL 2397 / westlake midrange-horn hasn´t got a large hornmouth area and sounds rather thin below 1khz.
Moreover I have made the experience, that crossing compressiondrivers (too) low results in a stressed and distorted sound. I like to keep the crossover well above the actual cut-off freq. of the horn...
Maybe a Yuichi or TAD horn would have been a better match with the E-145 due to its ability to really reproduce sound from ~600hz upwards.Agreed 100%... might consider a 1000Hz crossover as a "better" compromise, but one would want to built the variants and compare them.

I do think a larger horn and a 700-800Hz crossover would be better still... not so sure about dropping the crossover to 400-500Hz.


Widget

[Dr.db]

These are the midrange circuit boards for the 2446 (2441 dia):

74101


This is one of the high-freq. circuit board for the 2405:

74102

[Dr.db]

All circuit boards together.
(...missing the 1,5mh inductor on this pic)

74103

[berga12]

My intention was not to argue :) , of course if you had already experimented with your components that's fine!

Maybe the E145 have a better midrange response compared to other 15" (for example also the D130 was historically used in a 2 way).

on the distortion at 400-500hz it depends also on the power you are going to use, if you drive the mid high with a nice 2-3Watt tube amplifier there are no problem about distortion, important is always to be 2xFc of the horn.

Nevetheless, amazing work, I'm also using Mundorf components, on the modern ages, those are the best no-compromise and they have many price range for every poket.

[Dr.db]

My intention was not to argue :) , of course if you had already experimented with your components that's fine!

No worries!
This is a forum and open to any opinion. I would say a good discussion is always welcome and important!

[ivica]

No worries!
This is a forum and open to any opinion. I would say a good discussion is always welcome and important!

Hi Dr.db,

Your work is really astonishing.
One question, why not make Yuich-A290 horn like, instead of 2397 like, and use it from about 1000Hz (may be even 800Hz)
I believe that A290 would make better driver LF frequency horn loading then 2397.

regards
ivica

[Ruediger]

... JBL recommends baffling for the 2397. See the data sheet. This has nothing to do with the 1 kHz xover frequency but it may influence your diy design.

Ruediger

[Dr.db]

@ivica:

Actually the only horn of these two I have personally listened to has been the 2397. So I did choose the "safe" way and build the horn I knew...

The yuichi looks very tempting but without having listened to one I didn`t want to base my project on one of these...
Maybe I´ll build one of them in the future and change the horns, but so far I really like the 2397.
Besides that, I have never seen a detailed plan of these horns including all flares and angles....


@Rüdiger

Thanks a lot for your hint!
I believe that is because of pattern control, right?

Unfortunatelly I didn`t know about this circumstance and havn´t included these aspects in my project.
The horn will be mounted on top of the bass-enclosures. It is too late to integrate them in the baffle as the bass enclosures habe been finished.
Besides that, I think it is much better looking this way! Allthough I´m a fan of the mantra "form follows function", aesthetics do matter a lot and with such big boxes in the room they simply have to look good.
But everyone´s taste is different.

[Dr.db]

There are 3 pairs of binding posts in total.
One is for amplifier input.
The other two are for the high and mid output of the internal crossovers.
The high and midrange horn are mounted separatly on top, that is why there are crossover outputs on the back.

74222


Here are my individual signboards out of solid brass. It is in german but I´m shure you guys will know what it says! ;)

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Here is another close-up.
The brass is about 3mm thick. The engraving is reasonable deep but still clean sight. The brass has been lacquered to avoid eventual oxidation.

74224

[Ed Zeppeli]

What, were they out of gold?

[Odd]

Again fantastic work.

The project has been ongoing for some time?
"Anno 2007"?

[ivica]

@ivica:

Actually the only horn of these two I have personally listened to has been the 2397. So I did choose the "safe" way and build the horn I knew...

The yuichi looks very tempting but without having listened to one I didn`t want to base my project on one of these...
Maybe I´ll build one of them in the future and change the horns, but so far I really like the 2397.
Besides that, I have never seen a detailed plan of these horns including all flares and angles....




Hi Dr.db,
May one day these attached data would be useful.

All the best

ivica

[Dr.db]

@Ed Zeppeli: Only brass....

@Odd: I started woodworking in 2007, not this project ;)

@ivica: Thanks a lot, that are some very useful plans!! Are these horns identical with the TAD horns ?

[Ed Zeppeli]

@Ed Zeppeli: Only brass....

I'm glad you took my comment the right way. It was meant as a testament to the quality of your project.

[Dr.db]

Thanks a lot for you nice compliment! :)

[ivica]

t ;)

@ivica: Thanks a lot, that are some very useful plans!! Are these horns identical with the TAD horns ?

Hi Dr.db,
I do not know, but a way of calculation have been shown,so I believe A290 is very similar to the mentioned TAD horn. But as can be seen, all the calculation has benn done applying horn theory.
Regards
Ivica

[Dr.db]

Hey guys,

I need your advice today! :dont-know:

I just received new JBL diaphragms for the 2405 and 2441.
One of the D16R2405 diaphragms looks a bit faulty.
The wire on the voicecoil protrudes about 1mm at one spot!
It looks like there has been some dirt on the voicecoil before the wire has been wound on it. Now the wire sticks out at this spot for 1mm....

Im not shure if this will affect the function in any way!?
But I do not know how tight the magnet gap is and if the voicecoil will scrape in it.

74263

[grumpy]

If it's just the coating, it can be reduced in height. I've had a few diaphragms with that issue. Looked worse than it was.

You may also want to see about a return if it's new and don't want to potentially void any warranty you may have.

[more10]

What a beautiful speaker! And well documented.

[Dr.db]

If it's just the coating, it can be reduced in height.

No, actually there is one winding of the wire on top of that bulge.

If it was coating I would use sandpaper and wouldn´t worry.... ;)

[Dr.db]

74319

74320

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[maxserg]

Magnifique! :eek::applaud::applaud::applaud:

[NWCgrad]

Mighty impressive build! If they sound as great as they look you have a great pair of speakers.

[JeffW]

Those turned out nice, all the details give a very professional look.

[Mr. Widget]

Nicely done. Congratulations and thank you for sharing your journey.


Widget

[Dr.db]

Thanks a lot, I really do appreciate your guys feedback! :)

[srm51555]

Great work!

[wsilva]

VERY very nice :)

Your speakers came out gorgeous!

Mad skills to carry out a project like that.

[Titanium Dome]

"A thing of beauty is a joy forever..."

---–John Keats

Splendid work! Well done.

[gibber]

36 Inch Big Smith Horns Custom Made To Order


Sure sounds interesting, always thought a larger version of the 2397 would have given Bob H. Smith more deserved exposure than he's had with his '53 paper on 'plugs.

--
Ralph

[gdmoore28]

Dr.dB - You've built one of the nicest JBL interpretations I've seen so far. It's just beautiful, with an appropriate nod to the old school guys who placed so much emphasis on producing a speaker that sounded marvelous to the ear, and looked great to the eye! I love your attention to detail in the crossover builds, too.

May I suggest one finishing touch? One hundred years from now somebody - maybe one of your grand children - will develop an interest is audio, but will be unable to find the story behind your fine speakers. I'd suggest writing a one-page summary of the speakers, what they are built from, and the fine components contained inside. Along with a graph or two. And, of course, a short devotion to the builder - you. Glue the paper inside the cabinet with contact cement and you will have done somebody a great service downline.

Can't wait to see your next project!

[rusty jefferson]

.......Can't wait to see your next project!
Hopefully, matching subwoofer(s) ;)

[Dr.db]

@gdmoore28:

Thanks a lot for the honor!!
It sounds like a very nice idea, I will do so :)


@rusty jefferson:

Subwoofers will follow, but I think I won´t have time for that until 2018....

[maxserg]

So how do they sound? I imagine that they are very dynamic :)

[Dr.db]

Describing sound is allways subjective, but I´ll try ;)

To my ears they sound very detailed and controlled. The sound is very dynamic, but the midrange horn tames it a little bit. I would say other JBL horns are more straight forward e.g. right in your face.
The 2397 e.g. westlake horn sounds a bit softer, more hifi-like...
I think this mates very well with the 2405 slot driver, as this sounds softer than the 2402 bullet for example...
I´ve owned many horns and driver and allways liked the 2402 and big radial horns for a short thrill. But in the long term, the 2397 and 2405 are a little less dynamic but sound much more realistic.
The low-mid and lows are really transparent I have to say! Listening to a contrabass is a pleashure and it is easy to distinguish the different sounds. The punch has endless energy, but the low end is still weak in these big enclosures.
I would say it looses gradually efficiency below 100hz and sounds a bit thin. Yet it does reproduce 35-40hz nicely.

[Dr.db]

The punch has endless energy, but the low end is still weak in these big enclosures.
I would say it looses gradually efficiency below 100hz and sounds a bit thin. Yet it does reproduce 35-40hz nicely.

I´ve had these enclosure in my living room for a couple of weeks now.
As some may have noticed in my other thread (musically sub), I´m not satisfied with the low end.
I hoped the E-145 would reach down low in these huge enclosures, but unfortunatelly they have rather lost efficiency in the low end.

My idea would be, to reduce the internal volume from 8ft³ to 5-6ft³ and change the ports from 38hz tuning to aprox. 50hz. This smaller enclosure should gain 2-3db between 50-100hz and give me the punch I´m looking for.
Below 50hz I would use a dedicated sub.

What do you guys think of this idea :confused:
I think the only way to reduce the internal volume of this enclosure would be to put some bags filled with pebbles inside...

[grumpy]

1/2 of a 2" thk 4x8' dow building insulation sheet (blue styrofoam) ?
it'd be a lot lighter than 3ft3 of pebbles :)

[Dr.db]

Does the styrofoam really hinder the sound waves from penetrating it ?

I would think it is some kind of foam and wouldn´t really take away any volume, as sound waves would penetrate it....

[berga12]

I´ve had these enclosure in my living room for a couple of weeks now.
As some may have noticed in my other thread (musically sub), I´m not satisfied with the low end.
I hoped the E-145 would reach down low in these huge enclosures, but unfortunatelly they have rather lost efficiency in the low end.

My idea would be, to reduce the internal volume from 8ft³ to 5-6ft³ and change the ports from 38hz tuning to aprox. 50hz. This smaller enclosure should gain 2-3db between 50-100hz and give me the punch I´m looking for.
Below 50hz I would use a dedicated sub.

What do you guys think of this idea :confused:
I think the only way to reduce the internal volume of this enclosure would be to put some bags filled with pebbles inside...

Do it.

put (dry)Sand bags inside, will be also good for Damping and standing waves.

Pay attention on the Power, the E145 below 50hz will start to move a lot, you can evaluate an high pass (line passive) on the amplifier Input.

[grumpy]

Not styrofoam like a coffee cup or cheap cooler.
the blue DOW extruded sheets are very rigid and
incompressible... I understand you're disbelief though :)

just an idea.

[Ruediger]

Try to get acquainted with the Thiele papers. Start with table i.

The natural alignment for your speaker would be alignment #3. That would give you a horrible f3.

Alignment #5 is tempting. That would give you a pretty f3 and would be compatible with your box size. But your Qt is too small. Look at equation 70 how to make Qt larger. Use reasonable cables and reasonable inductors and Qt will get larger. You need to play around a bit with your pocket calculator.

Your box is still too large? Make the port cross section larger, this is good anyways. It requires you to increase the port length. You can have a port with a small cross section and a small length, or one with a large cross section and a large length (for the same result, box resonant frequency). Eat up the excess volume with a bigger port.

The resulting alignment can be plotted and optimized by some friendly forum members.

First calculate, then build a prototype from chipboard, then modify your beauties.

Ruediger

[more10]

Have you simulated the box internal geometry yet?

[more10]

Would you consider adding a sub?

[Ruediger]

Have you simulated the box internal geometry yet?

The plots show the influence of diffraction at baffle edges. The are irrelevant in the low bass range.

Ruediger

[rusty jefferson]

Would you consider adding a sub?
See post 83.

[more10]

See post 83.


My idea would be, to reduce the internal volume from 8ft³ to 5-6ft³ and change the ports from 38hz tuning to aprox. 50hz. This smaller enclosure should gain 2-3db between 50-100hz and give me the punch I´m looking for.
Below 50hz I would use a dedicated sub.

You could use for example 2220 in your current boxes, and use E-145 in a huge MLTL or Tapped Horn.

[more10]

The plots show the influence of diffraction at baffle edges. The are irrelevant in the low bass range.

Ruediger

The plot shows box modes. You are using it for midrange as well.

In case you are curious about your box mode frequencies: http://www.mh-audio.nl/standingwaveinbox/calculator.asp

[Dr.db]

Wow, thanks for the great response!! :)

@berga:
I will definitely use a highpass at 40-50hz after tuning the enclosure higher.

@mortan:
I will use subs below the E-145, there is no alternative! (btw. most of you guys have told me that before, shame on me... )
A 2220 should provide similar or even worse response than the E-145 in this enclosure. I think the 2220 should rather be used in a horn...
The box will definitely have some nasty boxmodes, that is why I´ve put a lot of acoustic damping in the rear of the box. Still kept a reasonable path between cone and ports free.

@grumpy:
I should get styrofoam from "DOW" here, that would be the easiest way to test a smaller enclosure. Sandbags would be nice for the sound, but if one of them gets damaged it would become a big mess...

@Rüdiger:
Could you please post the documents again, I can´t find them anymore.

[more10]

A 2220 should provide similar or even worse response than the E-145 in this enclosure. I think the 2220 should rather be used in a horn...

2220 has an amazing midrange!

[Ruediger]

"General Audio Discussion" -> "Technical References" Thread -> "Thiele Paper"

[Ruediger]

Below is a worked example. It does not fix the problem completely but it can shift parameters in the right direction. It also helps in making educated guesses.

E145 data:
fs = 35 Hz
Qt = 0.25
Qm = 6
Qe = 0.26
Qa is the same as Qm
Vas = 275 ltr
Re = 5.7 Ohm
Re is the DC resistance of the voice coil

Rg is the "Generator resistance". It consists of the amplifier's output impedance, the cables' resistance and the DC resistance of all bass coils in the xover which are in series with the loudspeaker.

The "damping factor" for a certain load is the ratio between load and the amp's output impedance. A damping factor of 200 at 8 Ohm means that the amp's output impedance is 8 / 200 Ohm = 0.04 Ohm.

The specific resistance of copper is 0.015 Ohm * mm**2 / m. Lets assume a cross section of 2.5 mm**2 and a length of 5 m (times 2, back and forth).

Rcable = 0.015 Ohm * mm**2 / m * 10 m / 2.5 mm**2 = 0.015 * 10 / 2.5 Ohm = 0.06 Ohm.

A typical bass coil (inductor) for an 8 Ohm / 1 kHz crossover 2nd order has an inductance of 1.8 mH and a DC resistance of 0.5 Ohm.

Our "Generator resistance" is 0.04 Ohm (amplifier) + 0.06 Ohm (cables) + 0.5 Ohm (crossover) = 0.6 Ohm. You can try 3rd order crossovers as they need more and larger coils.

We put this into equation 70 of the Thiele paper and get a new Qt of 0.274. With this value we can interpolate between alignments 3 and 4.

For a spot landing at a Qt of 0.383 we would need a generator resistance of 3.27 Ohms. A tube amplifier with output transformers may also help you.

You can experiment with large ceramics resistors at your speakers input terminals to get a clue what the impact would be.

Ruediger

[berga12]

You can have room standing Waves issue. Have you some room correction absorber/diffuser?

[grumpy]

I believe the published E145 Vas value is grossly inaccurate... closer to 427, IIRC.
Worth validating.

[Woody Banks]

Beautiful work. Holz was the name given to me in my German language class back in high school. It was the closest the instructor could get to Woody.:D






Shure!
Allthough this photos were taken on a different speaker-project of mine, because right now I´m not in the joinery and cannot take new pictures of the horns...

Best regards,
Olaf

73611

73612

[Dr.db]

@Rüdiger:
I had a look through the mentioned thread but couln´t find the Data.
The series coil in the crossover for the E-145 has 1,5mh and 0,08ohms, so even less then your calculations.
I was told, the smaller the impedance of this coil (and cables etc.) the better the damping factor of the ampflifier and this resulting in a more controlled sound.
Putting big resistors in series would ruin this advantage, but Im no expert on crossovers and open to your ideas.

@berga:
I definitely have standing waves issues, who hasn`t ;)
So far there are no absorbers or electronic corrections, but I have moved the speakers to different spots and have listened to them in two different rooms so far.
There are the usual peaks and dips in my rooms, but these aren´t responsible for my major issues. In these huge enclosure they reach very low (for this speaker), but loose efficiency below 100hz.
The complete lowend below 100hz is weak, not just several frequencies...


@grumpy:
I was told the same and always simulated with VAS=427....


@Woody a.k.a. Holzy:
Thanks, I really cherish your competent feedback!

[Dave M]

Dr.db (http://www.audioheritage.org/vbulletin/member.php?10608-Dr-db), I really admire your skill to make such a beautiful enclosure!

Supporting E145, JBL did E145 with 2215H "staggered" for UREI 813C. They didn't cut the low end of E145.
801C is a coax unit made with E145+2425H.

http://www.jblproservice.com/pdf/UREI%20Time%20Align%20Series/813C-L,R.pdf

[Ruediger]

@Rüdiger:
1) I had a look through the mentioned thread but couln´t find the Data.

2) The series coil in the crossover for the E-145 has 1,5mh and 0,08ohms, so even less then your calculations.

3) I was told, the smaller the impedance of this coil (and cables etc.) the better the damping factor of the ampflifier and this resulting in a more controlled sound.
Putting big resistors in series would ruin this advantage, but Im no expert on crossovers and open to your ideas.

@grumpy:
4) I was told the same and always simulated with VAS=427....


1.) General Audio Discussion, 3rd entry: Technical References, 11th entry therein.
2.) I did some example calculations with "typical" values, to show the principle.
3.) Yes and no.
A speaker with a Qt of 0.7 or more is crap, cause you can't find reasonable alignments for such speakers.
A proper amp should have a damping factor of 200 or better (my personal opinion),
but cables and series coils allow you to adjust a speaker's Qt and thus meet the requirements of a certain alignment.
Less is not always better.
You can experiment with big resistors in series, so you see what you have to expect. When your done with your experiment hide the resistors :)

4.) Is there nobody in Northern GY who can measure TSPs?

Ruediger

[Ruediger]

I looked around for a hopefully understandable article about how to measure TSPs. This is what I found and recommend: http://sound.whsites.net/tsp.htm.

If you just want to know Vas you don't need to measure all the other parameters, just Fs and Fb, and Vb of course.

Ruediger

[gibber]

The plot shows box modes. You are using it for midrange as well.

In case you are curious about your box mode frequencies: http://www.mh-audio.nl/standingwaveinbox/calculator.asp


The plots do show "box modes", but not in the sense of "room modes" as you would have them if your point of observation is inside the "room" (i.e. cabinet).
Rather the effect of the baffle shape on 0° (= on axis) amplitude frequency response at wavelengths similar in size to the "baffle" dimension is plotted.
And that again is not the same as power response into all angles of the room, but it is also not a consequence of internal modes of the cabinet.

[gibber]

I´ve had these enclosure in my living room for a couple of weeks now.
As some may have noticed in my other thread (musically sub), I´m not satisfied with the low end.
I hoped the E-145 would reach down low in these huge enclosures, but unfortunatelly they have rather lost efficiency in the low end.

My idea would be, to reduce the internal volume from 8ft³ to 5-6ft³ and change the ports from 38hz tuning to aprox. 50hz. This smaller enclosure should gain 2-3db between 50-100hz and give me the punch I´m looking for.
Below 50hz I would use a dedicated sub.

What do you guys think of this idea :confused:
I think the only way to reduce the internal volume of this enclosure would be to put some bags filled with pebbles inside...


Before you do all that, why not try Rüdiger's idea and use the speaker you are happy with, but tuned to a higher Qts? If you don't mind the loss a series resistor brings, of course.

You like the midrange this very deep (for JBL) cone offers, and i agree with the advice given by others already that 2220 has a similar midrange quality but would not offer more bass.

The E145 was preceded by the K145. Same deep extended basket -- 100% compatible. That unit is superficially similar, but most E145 had a different (slightly thicker and larger) cone than K145 ex-factory. Your E145 most likely also has that thicker cone kit with the double roll suspension, right?

Now, quite a few K145s were not reconed with their original cone kit as it became obsolete. The E145 kit was used instead.
Most 2nd hand K145 have the common problem of lost energy in their AlNiCo circuit due to mechanical shock, temperature, and just age. That weakness might be your gain. All you need to do is avoid to re-mag such an AlNiCo speaker.

Your E145 will have a Qts close to 0.21, a fully magnetized K145 comes in at 0.23. If you get a second hand K145 with E145 cone kit, it's likely you will see a Qts of 0.4. I have seen K145 with a Qts in excess of 0.5

If a K145 has been re-magged already, use a rubber hammer and softly but not too softly tap the magnet to voice your bass response. The K145 has a design flaw in that the magnet is too shallow for the AlNiCo material used. That makes the magnet very sensitive to loss of energy, and hence allows the hammer procedure described. You would have to hammer a lot harder on the comparatively long magnet of a 2205, 2220 or 2231 ;-) so i don't recommend it

Now here's a free offer: i have two K145's with E145 cone kit for you to try out. They are not interesting as possible purchase, as one is 8, the other 16 ohms. But they would at least allow you to try the idea. If interested let me know, they are only 800km from you so cheap domestic shipping
Ralph

[Dr.db]

I´ve made the experience, using much thinner cables than usual delivers a "thicker" bass, due to less control through the amp.
Is this the same as your idea?


You can experiment with large ceramics resistors at your speakers input terminals to get a clue what the impact would be.


Which value would you suggest ?
I would try some of the Mundorf 25w cement resistors, or which would you use?



3.) Yes and no.


Why doesn´t the series resistor ruin the benefits of a low resistance inductor?




You can experiment with big resistors in series, so you see what you have to expect. When your done with your experiment hide the resistors :)


How would I "hide" them? Through them out of the network after testing and using a inductor with bigger resistence instead?



If you don't mind the loss a series resistor brings, of course.

What would that be?
Less power from the amp because higher resistance?
Or any loss in sound quality?

I understand your idea with the K-145.
But my worry would be, that it is very hard to find two drivers with an identical loss of magnet strength. Different sounding drivers would certainly hurt the soundstage though...
But thanks a lot for your kind offer!

[Dr.db]

Your E145 most likely also has that thicker cone kit with the double roll suspension, right?


75623

[wsilva]

Dang!
Your cabinets are just plain stunning.
Awesome work :thmbsup:

[gibber]

What would that be?
Less power from the amp because higher resistance?
Or any loss in sound quality?

Sound quality is more immediate if the coil is wired directly to the amp. Not necessarily always better, but often so. It's what i believe is the reason why active setups sound better than passive ones in many cases.
What i meant though, was the power that goes unused in the resistor. Kind of defeats the high efficiency idea you surely had in mind when starting this endeavour. While going for a lower flux density you have the coil directly coupled to the amp. Still would cost you a full dB in efficiency, i would estimate. But a nicer route than going for a resistor which Rüdiger if believe mainly brought up for a quick sanity check on the general idea.

Another hint as to Rüdiger's comment on a baffle. Recommended for the Smith horn actually was not a baffle as used by Westlake or TAD with the Smith horn. The original note by JBL suggested something only very few people can do (you can!). Namely a bent 5...15 cm high section of wood above and below the 2397. Sometimes such a circular baffle arrangement is sold together with that horn on eBay. Perhaps search Google-Pictures ...



I understand your idea with the K-145. But my worry would be, that it is very hard to find two drivers with an identical loss of magnet strength. Different sounding drivers would certainly hurt the soundstage though...


No big problem getting similar magnet strength as i explained. I may sound a bit unconventional but works very well.
Or get some nice frames and start hunting for a pair of E-series cone kits :
http://www.ebay.de/itm/JBL-K145-Vintage-Alnico-Bass-Speaker-/222388480245?hash=item33c762e8f5:g:jhIAAOSw-0xYiIpn
Could measure B accurately before putting the coils in instead of going the indirect route (via two times same Qts)

Here's my K145-16 with the E145-16 cone kit (number reads 64194). It has the same cone as yours i believe, just 16-Ohm so cone kit number may differ :
756267562775628


But thanks a lot for your kind offer!

No need to decide now. Shoot me a PM if interested at any time now or later.
Ralph

[Ruediger]

I compared the data for the E145 with that of other speakers, 275 liters seems more plausible to me than 427 liters. But that is reading COFFEE GROUNDS.

Well defined filters do have a predictable amplitude response, phase response and step response. Known filter families are Butterworth, Bessel, Cauer, Chebyshev, Linkwitz-Riley.

For a certain filter characteristic you need a certain Q. Amplifier and speaker are fixed, cables and inductors are your adjustment screws. This plot shows the amplitude response for an underdamped, overdamped and correctly damped speaker.

75629

Now imagine a speaker with open terminals (not connected to anything), excited by an air blast. The cone will oscillate some small time before it stops. Now short-circuit the terminals (connect them to each other) and excite the speaker again. The cone will stop almost immediately. Now connect the terminals with an 8 Ohm resistor and repeat the experiment. The speaker will stop quickly, but not as fast as when short-circuited.

When the generator resistance is small the speaker will be "tightly controlled". But the amplitude response is overdamped and your bass is gone.

Calculate the value of the required resistor, it should be something like 3.3 Ohms. Buy cheap cement resistors, take care that they don't burn anything. 3.3 Ohms is 3 pieces 10 Ohms each connected in parallel.

This is not meant to be the final solution.

Ruediger

[Dr.db]

@ Ralph:

If I´d be using K145 with magnet loss I think the sound would be less dynamic, right?
But this is the reason I picked the E145...
Besides that, I think the C8Re145 recone kit is obsolete.

Baffling the 2397 horn would look pretty odd, or I might have a wrong idea about it. Do you actually have a photo of that?


@ Rüdiger:

The graphs illustrate your intention quit well, I kind of understand it.
Its what I´ve had experienced with using much too thin wires "producing" more bass because of less control.

But I don´t understand the overdamped situation yet.
A low genereator resistance and tightly controlled speakers should be a "normal" situation in most cases I thought. So this would represent the natural behaviour of the speaker, not an overdamped.
In my simple understanding, a speaker cannot have to much control e.g. be overdamped, as this would simply be the most natural response I reckon. But every lack of control e.g. underdamping would add more artificial bass.
Don´t get me wrong, I´m not an expert and it´s just a guess.

What would be the final solution without the series resistors?
Thinner wire and a thinner wired series inductor?

[gibber]

If I´d be using K145 with magnet loss I think the sound would be less dynamic, right?
< snip >
Baffling the 2397 horn would look pretty odd, or I might have a wrong idea about it. Do you actually have a photo of that?
< snip >
In my simple understanding, a speaker cannot have to much control e.g. be overdamped, as this would simply be the most natural response I reckon. But every lack of control e.g. underdamping would add more artificial bass.
< snip >

I think most here try to make suggestions in response to the midrange transition and bass shyness issues you reported.
Both things you'd like to improve on. If you don't try the suggestions in your setup, you won't know. I mean, even if someone did give you concrete evidence that a suggestion did work in his/her environment, you still wouldn't know if it works in yours.

Fitting a resistor or making up four semicircular "baffles" for your horn from a piece of cardboard would do the trick. And probably take less time than it would for any of us here to produce a reasonably solid report on what such a change did in a system that is, after all, different from yours.

Ralph

[Dr.db]

I´ve ordered two 3,3ohms 40w cement resistors for testing, but they´ve not arrived yet and I won´t be at home the next week.

I believe baffling the midhorn would look pretty odd, I have no idea how to implement this idea to be good looking...

[Dr.db]

I will try the "resistor-test" for shure, but I allready have another idea in my mind if this won´t work for me.

Besides my love for the E-145, I think I could be open to a driver change.
Changing to a 10" & 15" combo might do the deal.
I would challenge to "problems"; gaining very low freq. and having a midrange-cone that is better suited for my 1,2khz crossover to the horn. The downside would be a loss in the midbass punch...
I could rebuild my enclosure to house a small subchamber for the 10" midrange. This would be some nasty work, but I have an idea how to do that and maintain the aesthetics.

The driver which come to my mind first are 2235h and 2123h.
The 2123 would work very well with my crossover network with a small change to one inductor.
But I´m looking for a thougher bassdriver than the 2235. The 2235 has 8,5mm xmax but only 11mm xmech, so it has some mechanically risks I don´t like.
Maybe the TAD TL-1603 would be a better choice :confused:

When housing a small subchamber for the midrange, my enclosures will still have 7 ft³ internal volume for the bassdriver.
I believe the JBL 2235h works best in 5-6 ft³, but 7 ft³ would be to much!?
Any idea if the TAD TL-1603 will like the 7 ft³ or is it to much as well?

[grumpy]

Some previous conversations:

http://www.audioheritage.org/vbulletin/showthread.php?5042-2397-baffle

My mind drifts to "early great helm" images if the baffles get exaggerated (a bit).

[gibber]

Apart from the effect on Qes, the lossy effect of resistance is max where the impedance curve is lowest. And of course nearly no loss at resonance. That is perhaps where the resistor is most different compared to making the magnet a bit weaker

The baffle is odd, yes. Certainly is not something you'd see every day.
http://www.myaudioshop.com/speakers/full_range/pioneer/2401-original-prototype
And of course the larger frontal aspect with baffle might straight away be used for a larger horn that follows the same principles as 2397 (vanes inside, etc) such as the TH-4001.

Anyways, will be interested to see if (and what) the resistors do for you or not.
Ralph



EDIT: post crossed with Grumpy's, there's a similar old Pioneer/TAD picture there. Btw, TL1603 are not a lot cheaper than 1601B's ...

[Dr.db]

In case I would use a 2235h, what do you guys think about an enclosure bigger than 5 ft³ ?
Does this make any sense?

According to this article:
http://www.lansingheritage.org/html/jbl/reference/technical/1983-subs.htm

Greg Timbers writes about an 12 ft³ enclosure for the 2245h... Could I assume, that a 6ft³ for the 2235h would be they way to go?

[AudioFan]

I have built full range systems and dedicated subs using various JBL LF drivers, including the 2235X and 224X series. I saw that old GT article from the 80's back when it was new, and built a several subs based upon the information in it. I built the larger 12cf enclosures for a couple of 2245H drivers with the 30" long ports and used a JBL B63A crossover. I also built several subs using the 2235H drivers. The last one I built was for two 2235H drivers that had 6cf for each driver. It also used a JBL B63A crossover. I used that one as a center channel sub under the front center channel in my upstairs media system. I had several JBL/UREI 6290, Ashly FTX2000III and MFA8000 amps to power the bass and 6260's used on the mid/high frequencies. I was using JBL/UREI and Ashly active crossovers on those systems.

I also tried using a DBX 120X-DS as a crossover for added bass emphasis back when VHS had very compressed and limited VLF. I also tried using a DBX 1BX-DS to "unlimit" and "expand" those same bass limited VHS sources. That type of electronic "enhancement" is certainly not needed now days with the BluRay recordings available. My friends all thought that it sounded great with the old movies of that era. That was a few years ago, but I still have a few of those subs in use today. They have tremendous output capability even in the 30 ~ 20Hz range. Their LF response drops off quickly lower than 20Hz due to physical limitations and a steep 24dB LF filter I inserted into their line level input. I built the dual 2235H sub enclosure to look like a coffee table. It is hard to hide a 12cf sub otherwise. I had built a small dual width rack to sit on top of this sub and placed the center channel speaker on top of that under my flat screen. The center channel speaker was pretty large as it had all the drivers from a pair of JBL L7 speakers incorporated into it. That was the only way I could have a balanced output to match the other L7's and L5's I was using as L&R mains and surrounds at the time. They managed to blend with the combined output of the other speakers and provided the ULF for action movies. I had three JBL PSW-D115 subs placed in other positions around the room to provide a smoother and extended bass. 759447594375945

[Dr.db]

Thanks a lot for those nice pictures :)

Have you compared a 5 cubic-ft. enclosure with a 6 cubic-ft. ?

Does the 2235h hast enough mechanical damping in the bigger enclosure?
What tuning-freq. did you use with the 6 cubic-ft ones?

[AudioFan]

The 6cf enclosure for single JBL 2235H for a 25Hz tune had a 5.5" round x 12.75" long vent. I built that as 2 drivers in their own enclosed volume in one enclosure.
The 5cf enclosure for single JBL 2235H for a 25Hz tune had a 5.5" round x 16.13" long vent. I built those similar to a S7+ system in a vertical configuration.
It was hard to discern any difference between them, as they were built a couple of years apart and used in different rooms. They both provided very good bass in the rooms they were in. But, the 5cf systems had the 2235H in a 3-way configuration crossing at 650Hz on top. The 6cf system was a dedicated sub that crossed at 80Hz. I did build a few larger enclosures around 8cf that only required a 5.5 round vent x 8.6" long. They had a better efficiency on the very bottom. However, all of these systems started dropping off around 30Hz. They still had good output, but they did loose 6dB or more by 25Hz.

The JBL 2245H in a 8cf cabinet tuned to 25Hz is similar to a 2235H in a 5cf with slightly less extension at the lowest frequency. In a 12cf box the 2245H has a much better advantage reaching lower with less effort. (2-5.5" vents x 12.75" long) With any of these I feel you need to add a LF cut off to prevent possible damage to the driver. There are many ways to acquire real bass and many drivers to do it with. I have used PS1400, PSW-D115, 4645, 3635, HTPS400, B380, B460, and many others. Several are better than those we have discussed, but I like the sound and performance of an all JBL system built with drivers and components that I can afford, (or have on hand). I have quite a few older systems stored in my shop, as well as a few older systems I built in the past.

7595975960759617596275963

[Dr.db]

That´s a great collection I have to admit! :blink:


Thanks a lot for sharing your experience.

[AudioFan]

Dr. db,

I had the good fortune to pick up another JBL HTPS400 yesterday on eBay. It was a great deal at only $200 BIN + shipping. I hit the button and sent a "Pack and pad it well" message to the seller. Hopefully it will arrive with no damage. It is smaller and lighter than many of the items I have purchased and had shipped to me recently. I will add it to the small system in my den as the old Sony 10" Sub that was purchased 14 years ago as a temp fill in quit on me.

The first picture in the previous message showed some of the speakers "stored" in my shop. That as only the right side, I actually have all of those in stereo pairs. What you can see are: (2-JBL 3635 18" subs on an Ashley FTW2001 Mosfet amp bridged for 1200w, S38, L222, L80T, L100T3, 4722, 4628B). There are also 4648, 4612, L7, L5, L3, L1, S36, CL505, 4645, PSW-D115, PSW-112, PS1400, HTPS400, HTPS300, 8400, L112, L150, L65, L200, L300, L166, L212, L20T, L18, L20T3, L88, S1, S36, S412P, S2, S105, 4425, 4602, others. Those in the picture are hooked up to switcher and amps, so they can be switched in and out to listen to in my shop.

The next picture shows some of the L7's and L5's I had in a media room 9.4 system using L7's as mains and custom made center along with the l5's as side, surrounds, and rears. I used three PSW-D115's around the room with the dual 2235H sub in front under the center channel using the drivers from a pair of L7's. The next picture is of 12cf sub boxes made for the 2245H woofers I mentioned earlier. The side is off so you can see some of the internal bracing. It is arranged to divide the interior into non-divisible areas to decrease resonance or baffle vibrations. The enclosures were overlaid with another layer of MDF before being covered with a veneer. The last picture is of another enclosure I built for a dual 2240H three chamber 6th order bandpass. I built several others for 15" drivers. I tried many things - some actually worked. I did best when I followed the advice of many of the members of this site, but it was fun to try a few wild ideas too.

My last build was a mod of the 4345 - kind of. I used the 2245H, 2202H, 2441, 5309, 076/077 and a poorly design passive crossover. (About 7' tall and over 600 pounds each. 1.5" to 2.25" walls) I later changed that to active crossovers and amps. I am still working on that one. I probably need to change the old style Hartsfield upper mid horn and lens for something a few decades newer. I am looking a several MF drivers and tweeters now.

[AudioFan]

For some reason only some of the pictures get posted....75993759947599575996

[Dr.db]

@Ruediger:

I have tried these 3,3ohms resistors just in front of my speaker inputs.

76320

The sound was different, but didn´t really cut it ;)
I´m still missing lows so I will be changing the E-145 to something else....

[AudioFan]

Dr. dB.

Did you find another woofer to try in your system yet? I have LE14A, LE14H, LE15A, 2235H, and several other 15" JBL LF drivers if you are interested in trying them out. I know that you have built a beautiful set of enclosures and are just trying to find that LF driver to compliment the other components and enclosure that you have. Perhaps you could build a quick and dirty 5~6 cf box out of MDF with a removable front baffle to accommodate different LF drivers. A LF driver adaptor plate and another for the port could be incorporated into that baffle. Then you could R&R various LF drivers and modify the port length and volume to find the LF driver that suits the performance and sound characteristics you are seeking. You could place it next to your completed enclosures, or even build a small temporary enclosure to hold your HF drivers to place on top of it to preserve the setback and height of your current system. That way you would be able to contrast and compare the sound of you current enclosure and drivers to that of the test setup and drivers. I have done this in the past to assemble comparative speaker systems while trying out different drivers and components before building the final finished enclosure. Sometimes I was just trying to find a way to get the sound (components) I wanted in a an enclosure that would fit in the real estate (area) that was available.

AudioFan

[Dr.db]

Dear Audiofan,

thanks a lot for your very kind offer, but unfortunatelly I´m not located in the U.S. ;)
The german forum-member gibber has allready offered me to try some of his woofers though.

Right now I´m thinking about the following 15`s:
JBL 2235 (well known but limited xmech)
TAD 1603 (expensive but probably the best)
Beyma 15LX60 (cheap but good reputation)
JBL LE14H-3 (similar to 2235 but a little smaller)

But LE14H-3 is very hard to find, most distributors won´t sell these.

[AudioFan]

Dr. db,

I have owned and used all but the Beyma woofers in various projects. I think that the JBL 2235H and TAD 1603 will be the best options for the enclosures you have built. In a properly designed and engineered enclosure, the JBL 2235H X(max) is more than sufficient to reproduce very high levels of LF energy. I know that I have seen graphs someplace on this site showing specific output levels of this driver at low frequencies. Also, your room showing your pictures of with your enclosures does not appear to be a very large volume. I would think that the "room gain" with a couple of 2235H drivers in a good box and a couple hundred watts per driver would allow realistic LF output even with very loud musical or movie sound tracks. The 2235H can handle well over their rated power for brief periods, and with a 90dB/M/W sensitivity they can put out a prodigious amount of bass and still retain the ability to blend with a midrange. I saw a thread on a pair of B380 clones being built that might interest you: (http://www.audioheritage.org/vbulletin/showthread.php?35324-JBL-B380-Clones).

Good Luck,

AudioFan

[berga12]

if you want a full JBL system go with 2235h biamp....could be also passive biamp... don't worry about x-mech.

if you want one of the best go with TAD 1603, for me is one of the best driver in the 15" range.

[Dr.db]

if you want one of the best go with TAD 1603, for me is one of the best driver in the 15" range.

Have you compared both?
How do they differ in sound and output?


@ Audiofan:

I´m shure the 2235 is capable of very high output.
Just wondering if the 1603 is any better...

[berga12]

No direct comparison as I've 4x2235 and the 1603 was single in 170lt tuned 27hz

seems more efficient,quicker a bit, nice low end,modulation wonderfull.

gives a bit more punch

[Dr.db]

Sounds pretty nice, if I get the chance I give them a try.

[AudioFan]

See: (http://www.usaudiomart.com/details/649202848-tad-tl1603-drivers-two-pairs-available/), (http://www.canuckaudiomart.com/details/86875-tad_tl1603_15inch_woofers_pair/)

[AudioFan]

See: (http://www.usaudiomart.com/details/649202848-tad-tl1603-drivers-two-pairs-available/), (http://www.canuckaudiomart.com/details/86875-tad_tl1603_15inch_woofers_pair/)


Check out Scott Fitlin's (RIP) #8 >> comments from (http://www.audioheritage.org/vbulletin/showthread.php?20088-Explain-Tad-woofers-Help/page6)

[berga12]

I want to add that TAD is the Japanese response to JBL....yes of course, they copy JBL and do it better on some parameters several years after.

also the 12" of TAD (the grey one) is a revisited 2202h with some improvements, but basically a copy.


To my mind, building a 4350/55 fully TAD would be one dream, but the cost is 3-4times higher...

I would go with TAD 1603 in your cabinets(with smaller volume, I suppose 150-170Lt) !!!


(and sell to me your E140 for my 4560 horn setup!! ehehe Just kidding).

[Dr.db]

I think the TAD TL-1603 is the way to go.

The 1601b shares the same cone but has a huge Alnico motor... Interesting, but I´m not shure if these are modern designs that would withstand high currents e.g. heat like a JBL 1500AL. Or if they will demagnetize like most Alnico´s from the past...

[Ruediger]

@Ruediger:

I have tried these 3,3ohms resistors just in front of my speaker inputs.

<snip>
The sound was different, but didn´t really cut it ;)

I´m still missing lows so I will be changing the E-145 to something else....

I had no working internet for a couple of days. So this reply is a bit late.


The resistor just changes the driver's Qt (increases it) so that you can find an alignment which matches your boxes. Part of the alignment is a properly tuned port.


You may remember these replies:


<reply #1>
Thiele is good for you. Thiele is very good for you!

Try to get acquainted with the Thiele papers. Start with table i.


The natural alignment for your speaker would be alignment #3. That would give you a horrible f3.


Alignment #5 is tempting. That would give you a pretty f3 and would be compatible with your box size. But your Qt is too small. Look at equation 70 how to make Qt larger. Use reasonable cables and reasonable inductors and Qt will get larger. You need to play around a bit with your pocket calculator.


Your box is still too large? Make the port cross section larger, this is good anyways. It requires you to increase the port length. You can have a port with a small cross section and a small length, or one with a large cross section and a large length (for the same result, box resonant frequency). Eat up the excess volume with a bigger port.


The resulting alignment can be plotted and optimized by some friendly forum members.


First calculate, then build a prototype from chipboard, then modify your beauties.


Ruediger
</end of reply #1>


<reply #2>
A worked example

Below is a worked example. It does not fix the problem completely but it can shift parameters in the right direction. It also helps in making educated guesses.


E145 data:
fs = 35 Hz
Qt = 0.25
Qm = 6
Qe = 0.26
Qa is the same as Qm
Vas = 275 ltr
Re = 5.7 Ohm
Re is the DC resistance of the voice coil


Rg is the "Generator resistance". It consists of the amplifier's output impedance, the cables' resistance and the DC resistance of all bass coils in the xover which are in series with the loudspeaker.


The "damping factor" for a certain load is the ratio between load and the amp's output impedance. A damping factor of 200 at 8 Ohm means that the amp's output impedance is 8 / 200 Ohm = 0.04 Ohm.


The specific resistance of copper is 0.015 Ohm * mm**2 / m. Lets assume a cross section of 2.5 mm**2 and a length of 5 m (times 2, back and forth).


Rcable = 0.015 Ohm * mm**2 / m * 10 m / 2.5 mm**2 = 0.015 * 10 / 2.5 Ohm = 0.06 Ohm.


A typical bass coil (inductor) for an 8 Ohm / 1 kHz crossover 2nd order has an inductance of 1.8 mH and a DC resistance of 0.5 Ohm.


Our "Generator resistance" is 0.04 Ohm (amplifier) + 0.06 Ohm (cables) + 0.5 Ohm (crossover) = 0.6 Ohm. You can try 3rd order crossovers as they need more and larger coils.


We put this into equation 70 of the Thiele paper and get a new Qt of 0.274. With this value we can interpolate between alignments 3 and 4.


For a spot landing at a Qt of 0.383 we would need a generator resistance of 3.27 Ohms. A tube amplifier with output transformers may also help you.


You can experiment with large ceramics resistors at your speakers input terminals to get a clue what the impact would be.


Ruediger
</end of reply #2>


With the 3.3 Ohms resistors you can make a spot landing. f3 == fs, fb == fs, fs == 35 Hz. Vas / Vab = 1.414, thus Vb = 194 liters which is 6,9 cuft.


You don't need to find an exactly matching Thiele alignment. There are approximate methods.


You need to modify your boxes' tuning such that fb == fs == 35 Hz.


What is the net volume of your boxes, and what are the dimensions of your port tubes?


Ruediger

[Dr.db]

The internal net volume is about 8 cubic feet.

The ports are 4" in diameter and 3,5" in length....

[Ruediger]

E145H

Dr. dB, if the data you gave me is correct, and if the E145's parameters are correct, then you should be quite close to a proper alignment with an f3 in the 35-38 Hz region. That would be excellent.

Some data is approximate (8 cuft) or not equal to the required value (6.9 cuft), the port tubes leave room for discussion, the E145 Vas parameter could be incorrect, and finally:

You might be expecting too much bass:)

Below I show the calculations so that you can make them yourself, and apply them to other projects.

Box resonant frequency:

fb = c / (2 * pi) * sqrt(A / [Vb * L])

c = speed of sound, ca. 344 m / sec @ room temperature
A = vent area
Vb = box volume
L = effective vent length (Leff below)

The vent can consist of one or more tubes of equal length.

If the vent shape is not circular an "effective radius" Reff is calculated by considering a circular vent with equal area:

A = r**2 * pi -> r = sqrt(A / pi) (Reff below)

The "effective length" Leff of a vent tube is its actual length L plus inner end correction Li plus outer end correction Lo:

Leff = L + Li + Lo

A free standing port has an end correction of 0.85 * Reff,
a flanged port has an end correction of 0.61 * Reff, so for a vent which is free standing on the inside and flanged on the outside the calculation is:

Leff = L + 0.85 * Reff + 0.61 * Reff = L + 1.46 * Reff.

These values are approximate.

If the vent consists of several tubes (2 in your case) then there are two cases:

When the ports are close to each other the calculation is that for one vent with twice the vent area. Replace "twice" with "number of ports".

When the ports are not close to each other then the end correction must be considered separately for each port.

Your partially rounded port is not easy to calculate, and it is neither really flanged nor really free standing at the inside. The openings are neither really close to each other, nor really apart from each other.

My guesstimate is: two ports with end correction = 1.5. Simple mixed-case formula from above: end correction = 1.46. Not a big difference.

Now the calculations.

Vb = 8 cuft = 8 * 28.3 liter = 226 liter

Two ports with
diameter = 4" = 10 cm
length = 3.5 = 8.9 cm

Total port area A = d**2 * pi / 4 * 2 = 78.5 cm**2 * 2 = 157 cm**2

Effective radius (ports combined)
Reff = sqrt(157 cm**2 / pi) = 7.1 cm.

Combined ports: effective Radius = 7.1 cm,
7.1 cm * 1.5 + 8.9 cm = 19.55 cm

Separate ports: Radius = 5 cm,
5 cm * 1.5 + 8.9 cm = 16.4 cm

The difference is 3.15 cm. Build with temporary ports, measure and adjust. Better: avoid such uncertainties in the 1st place.

Box resonant frequency:

fb = c / (2*pi) * sqrt(A / [Vb * L]) =

(344*100cm/sec) / (2*pi) * sqrt(157cm**2/[226*1000 cm**3 * 16.4cm])

"cm" can be cancelled completely, the remaining unit is "1/sec" ->

1/sec * (344*100) / (2*pi) * sqrt(157 / [226*1000 * 16.4]) =
35.6/sec = 35.6Hz

This would be a perfect match for Thiele alignment #5 if Vb was right: Vas / Vb = 1.414 -> Vb = Vas / 1.414 = 194 liter = 6.9 cuft. Let's calculate with proper Vb:

1/sec * (344*100) / (2*pi) * sqrt(157 / [194*1000 * 16.4]) =
38.4/sec = 38.4Hz

This would be a perfect match for Thiele alignment #5 if fb was right.

Summary: If the published E145 data Vas is correct the calculations look promising. I attach a flow chart about finding an approximate solution.

Ruediger

[AudioFan]

Ruediger,

Excellent work from you as usual. Dr. db was also looking at the JBL 2235H as a possible substitute in this enclosure. With the same enclosure volume, what would the 2235H do in this box with optimized ports for same? I have built several 2235H based systems that worked out very well in the past as dedicated subs or as the LF component of a multi-way speaker in a similar sized encloure.

Thanks for your hard work.

AudioFan

[Ruediger]

Ruediger,

Excellent work from you as usual. Dr. db was also looking at the JBL 2235H as a possible substitute in this enclosure. With the same enclosure volume, what would the 2235H do in this box with optimized ports for same? I have built several 2235H based systems that worked out very well in the past as dedicated subs or as the LF component of a multi-way speaker in a similar sized encloure.

Thanks for your hard work.

AudioFan

Hi AudioFan,

the box is much too large for the 2235H. Below I attach a few notes about what can be done with the 2235H.

But why settle with just one bass speaker per box? Why just shake the house when you can rattle the foundation?

With Thiele alignment #3 the E145H will have an f3 of 62 Hz in a box of 62 liters without any Qt-changing resistors. Qt will remain 0.25.

Dr. db's box has a volume of ca. 226 liters. Minus 62 liters and some more for the woodwork to accomodate the E145H.

That should leave ca. 130 liters for a 2235. See the attached notes for an approximate design (36 Hz, 129 liters).

With some fiddling it should be possible to get the two drivers into the boxes. One could gain a few liters by mounting the 2235H reversed, with the magnet at the outside. That would improve the cooling too.

Should somebody go this way he would need to design the crossover 1st, in this scenario the E145H behaves like a 62 Hz highpass of fourth order and should be complemented by a properly designed lowpass for the 2235H.

Alignments for the JBL 2235H 15" Bass Loudspeaker

JBL 2235H

fs = 20 Hz
Re = 6.0 Ohm
Qt = 0.25
Qm = 2.5
Qe = 0.28
Vas = 460 Liter

Thiele Alignment #3, QB3
Qt = 0.259
f3 = fs * 1.77 = 20 Hz * 1.77 = 35.4 Hz
fb = f3 / 1.25 = 35.4 Hz / 1.25 = 28.3 Hz
Vb = Vas / 4.46 = 460 L / 4.46 = 103 L

Thiele Alignment #15, B6 (requires an active filter)
Qt = 0.299 must be made fit (see below)
f3 = fs = 20 Hz
fb = f3 = 20 Hz
Vb = Vas / 2.73 = 460 L / 2.73 = 168 L

Keele's Method (see flow chart, f3 and Vb can be adjusted)
Qt = 0.25 must be effective value
f3 = 36 Hz
fb = 29 Hz
Vb = 129 L

Notes
Qm and Qa are the same
Vab and Vb are the same

Qt (total Q) can be made larger if required
Qt can be calculated from:
Qa acoustical Q (also mechanical Q)
Qe electrical Q
Re DC resistance of loudspeaker voice coil
Rg Generator resistance = Output impedance of amplifier plus
loudspeaker cable resistance plus DC resistance of
inductors which are in series with the loudspeaker

1/Qt = 1/Qa + (1/Qe) * [ Re/(Rg + Re) ]

[AudioFan]

I read this article many years ago and built several subs based upon the information it included, (http://www.lansingheritage.org/images/jbl/reference/technical/1983-subs/page7.jpg). I built 12cf 2245H, 8cf 2245H, 5cf, 6cf 2235H. I also read about this sub: Certified Bass for the Certifiable by James S, Sherwin in Audio Magazine around 1990. Link on site: (http://www.audioheritage.org/vbulletin/showthread.php?11718-2235-reconing-for-subs). I built that dual 2235H sub unit as well. I also built one with 2-2235H drivers as pictures in one of my earlier posts to this thread. It can be seen below a center channel system composed of all the drivers from a pair of JBL L7 systems. They all seemed to work fairly well with the JBL B63A crossover inserted in front of the sub amp. I tried everything from Phase Linear 400 and 700B to UREI 6290 and Ashly MFA6000 and MFA8000. However, they are so efficient that you really don't need a ton of power to reproduce very high levels of LF output. I think that a bridged UREI 6260 is adequate to power either one of these subs.

AudioFan

[Dr.db]

Thanks a lot for your extensive explanations!

I have to admit, these calculations are a little confusing to say the least... But I believe they are absolutly right.
What I have actually done was copying the JBL Everest DD55000 enclosure.
That box is a proven design so I thought I´d just stick with that... If you have a look at the puplished freq.resp. it indicates a weak bass. A 4344 is much more linear in the bass than the DD55000...

At this point I have to say I´m absolutly not a bass-addict that aims a boomy response. This is what I usually dislike with most commercial speakers... But with the E-145 alone the bass is too thin and lacking body in the music.

Using the E-145 in a small subchamber and mate it with a 2235 was an idea I was allready thinking about. But at the end I would say they are still too close and not different enough to run in the same enclosure.
This is why I thought about using a 2235 with a 10" midrange instead...

[Dr.db]

I was very lucky to find a pair of barely used TAD woofers locally!

In around a week I while have time to swap them in and compare them to the E-145. I will reduce the internal volume to about 6 cubic feet e.g. 170liters. This is the enclosure size I could read about in other threads so far. I guess the two ports should be about 8" long to obtain a 35hz tuning....
What do you guys think about enclosure-size and tuning?

763957639676397

[JeffW]

A tribute to Lansing speakers using TAD drivers....

[Dr.db]

A tribute to Lansing speakers using TAD drivers....

A tribute to Lansing-Heritage-Forum, not speakers....

Please read the title and my first post accurately as this thread is a tribute to all forum-members that have helped me over the years on this board.
JBL choosed to stop selling parts to the DIY-community and if you want to purchase a current model you have to go with other brands. Otherwise I would have bought the 1500AL, but no way to buy them anywere...

[grumpy]

Even so, there is a Lansing heritage element in many TAD products 😎

[JeffW]

I was mainly joking, shoulda put a smilie in there.

I don't really care what drivers folks use, and I have a few TAD myself.

[Dr.db]

I was mainly joking, shoulda put a smilie in there.

I don't really care what drivers folks use, and I have a few TAD myself.


No harm meant ;)

[berga12]

go down to 25-28hz in 170Lt.

[Dr.db]

These TAD 1603 woofers have additional venting-slots at the side of the magnet.
There is a little foam-piece inside of each of them.
Is this to stop dust and dirt to enter and should remain inside? Or do I have to remove these?

77912

[Earl K]

Keep the foam filters in place .

They are particulant protection ( to the coil venting ) .

:)

[Dr.db]

Thanks for your quick answer!

[dn92]

Leave the foam !
Tune Fb to get 32Hz, with 180L you will be close to TAD and Rey Audio speakers designs. TL-1603 can be used like TL-1601b used by Rey Audio. RM-7VC has a big enclosure probably more for one TL-1601b than your 225L. You can also try not reducing the volume, with lower Fb.
225L Fb 30Hz might work well, close to Rey Audio RM6-VC but for one driver, (be carefull adjusting a bit the mid/high level to adapt them).

[Dr.db]

Thanks a lot, very interesting info´s!

Do you know about the original TAD bassreflex-ports?
What dimensions do they have? What would be the the length for two 4" ports?

[dn92]

For TL-1601a (T/S parameters are a bit different) TAD used for TSM2/2402 around 135L of volume and Fb 32Hz.
There were two 100mm ports (Japanese do not use units from the Middle Age :D), with a length of 105mm. Suprisingly if you try to simulate them you will find another length, but this is the right one. Depending upon your exact volume and damping you'll have to adjust the length by doing impedance measurements.
For RM-11BC using TL-1601b (T/S identical to TL-1603) I don't know the ports length, only that the port diameter is larger, around 120mm, but Fb is also 32Hz, with a larger volume than for TSM2/2402, something around 170L.

PS: Next time I'll be around Hamburg I can come with some measurement tools to help if needed.

[dn92]

These TAD 1603 woofers have additional venting-slots at the side of the magnet.
There is a little foam-piece inside of each of them.
Is this to stop dust and dirt to enter and should remain inside? Or do I have to remove these?

77912

These are second hand units or not coming from a fresh stock ? The actual ones have a different orientation for the binding posts (as 1601a and 1601b). If there are from second hand you should check their T/S parameters, there are plenty of aged TAD speakers on the market, removed from studio monitors or PA loudspeakers. If you have any issue with one of them, the good address in Europe for getting recone kits is in Germany (hornstudio.de).

[Dr.db]

These are second hand units or not coming from a fresh stock ? The actual ones have a different orientation for the binding posts (as 1601a and 1601b). If there are from second hand you should check their T/S parameters, there are plenty of aged TAD speakers on the market, removed from studio monitors or PA loudspeakers. If you have any issue with one of them, the good address in Europe for getting recone kits is in Germany (hornstudio.de).

Indeed, they are second hand coming from another DIY-guy here in germany. He bought them new at hornstudio.de around 6-7 years ago... To be honest I have no measurement tools to check TSP.



PS: Next time I'll be around Hamburg I can come with some measurement tools to help if needed.

You are very welcome!
Unfortunatelly I don´t live in Hamburg anymore, I have moved to Rostock. Thats about 200km away... But if you are around, feel free to give me a visit.

[dn92]

Not so old then and were not used for PA, they should be OK then.
To tune the br ports length it is useful to have somthing for measuring the impedance response such as a Dayton DATS that is not so expensive.

Thanks for the invitation, same for you if you come to Paris

[mica]

Indeed, they are second hand coming from another DIY-guy here in germany. He bought them new at hornstudio.de around 6-7 years ago... To be honest I have no measurement tools to check TSP.



You are very welcome!
Unfortunatelly I don´t live in Hamburg anymore, I have moved to Rostock. Thats about 200km away... But if you are around, feel free to give me a visit.

Hi Dr.db,

I'm wondering why you're not using the active system with ethernet interface?
You can resolve a lot of frequency and phase response issues, experiment with different drivers, etc., all being very easy and comfortable without the need to mess with X-overs.
As your drivers are very efficient, you just need one 6-channel amp or three 2-channel amps of moderate power and one DSP 3-IN 6-OUT or 4-IN 8-OUT (better) for future use in 3-way+SUB or 4-way system. Later on you can expand to more powerful amps if you like.

Mica

[Dr.db]

The initial plan of this project was to run the speakers by a single amp and minimise the equipment...

[mica]

The initial plan of this project was to run the speakers by a single amp and minimise the equipment...


The passive system does not allow any errors and it is very difficult to optimize it in an original design like yours.
In any case, we hope that the project will continue.

[Dr.db]

That´s true, thank you!

[Doctor_Electron]

Very Sick. Please keep it that way!:)

[Dr.db]

My pleasure. :)