Richard Long's Waldorf restoration

[Lee in Montreal]

We all have fantasies, don't we? My fetish is RLA's Waldorf. So, after months of research, I finally I found more details on four of RLA's Waldorf. Showing details unseen (by me) before.

http://www.myspace.com/soundmanshorty/photos/33491904#{%22ImageId%22%3A33444481}

Thanks Shorty for the nice documentation of that restoration.

52024

[JeffW]

Pretty sure Shorty was buds with Scotty Fitlin (http://www.audioheritage.org/vbulletin/showthread.php?455-TAD-4002-compression-drivers&p=3132&viewfull=1#post3132), if it's the same guy.

[Lee in Montreal]

I'd be actually very interested to hear from people who have factual experience with such Waldorf because numbers themself don't make sense to me. Let me explain. From redrawing a Waldorf, and with the confirmation from Shorty's restoration pictures, I can say with assurance than the horn path is not longer than a 4520. 8ft for the 4520 vs around 6.5ft, which is in fact even shorter than a 4530. So, theorically, the Waldorf is not designed to go low. The main differences that I see are as follow: bigger mouth than the 4520 and a bigger rear chamber which should translate into a rounder type of bass at, I suspect, a certain loss of efficiency.

The advantage of the Waldorf horn design compared to a 4520-4530 is that the Waldorf doesn't have two consecutive U shaped corners. In fact the Waldorf has only one 90° bend at the upper back (like the Jensen Imperial from which it was inspred), and that bend can even be easily rounded up to avoid resonance and cancellation.

I still think that a back loaded horn with a 2.9m path (9.5ft) tuned to 30Hz and using a pair of 2240 woofers with Fs30 remains a better alternative. But first I must hear from people who have compared the Waldorf with a 4520.

[JeffW]

I wish the search was more functional here, I'm pretty sure I remember Scotty talking about some "modified" scoop horns in some club or set up. I bet that's the same ones Shorty has, but I don't remember the Waldorf part.

[Lee in Montreal]

^^^Whenever I do a search on scoops, I usually end up with this great seminal thread. With Scott mentionning his double 2240h scoops.

http://www.audioheritage.org/vbulletin/showthread.php?3765-Question-on-the-quot-double-scoop-quot-short-throw-horn.&

I still want to squeeze two 2240h in a 5' tall scoop. Be it of 4520 or Jensen Imperial design.

[Don C]

A bit off topic, but google can do a good job of searching here, just put in a search term, then add "site:audioheritage.org" to the end.
http://www.google.com/search?hl=en&source=hp&biw=1044&bih=600&q=double+scoop+site%3Aaudioheritage.org&oq=double+scoop+site%3Aaudioheritage.org&aq=f&aqi=&aql=f&gs_sm=e&gs_upl=1438l17422l0l41l41l2l24l1l0l282l3203l0.4.11 l15

[louped garouv]

there;s a thread over at the wavemusic forum that talks fo the waldorf recently...
and references GSA's build of waldorf clones....

a few pretty interesting points in the discussion IMO, if you haven't seen it...

http://www.wavemusic.com/community/showthread.php?t=11948

[Lee in Montreal]

Been working on a draft for a Waldorf.

Current horn path is 2.10m which makes a tuning for 41Hz. Makes sense if the driver is a 2225h with Fs40Hz. Throat is 3"x34.5" and mouth is 42.5" x 34.5" (154"/3.91m circumference).

52034

Tuning the cabinet to 30Hz for a pair of 2240h is "a bit" more difficult ;)

[Lee in Montreal]

I have forwarded last week the lastest drafts for 18" Waldorf cabinets (using twin JBL 2240 drivers) to a member of this forum, and other forums. Carl is currently building a first cabinet and will measure it. The cabinet is roughly 40" wide by 63" tall.

You will find below the horn path progression. Carl is making the second version (black line). In red, the Jensen Imperial horn path.

http://img.photobucket.com/albums/v668/Lee_Vuong/JBL parts factory/WaldorfvsImperial.jpg

[louped garouv]

aren't most (RLA designed or inspired) waldorf boxes designed for 15" TAD 160* drivers?

what's up with the 18" version Lee?

are you planning on using a FLH above the scoops and below the acoustic lenses?

[Lee in Montreal]

aren't most (RLA designed or inspired) waldorf boxes designed for 15" TAD 160* drivers?

what's up with the 18" version Lee?

are you planning on using a FLH above the scoops and below the acoustic lenses?

RLA did use 15" drivers in his Walrdorf. I am going to twin 18" 2240s on this design. The cabinets are not for me but for that member and not intended to be replicas. I just wanted that extra grunt that 2240s have over 2225s. Those who have modified theit 4520s with 2240s have reported an incredible difference "down there". And I am going with a Jensen Imperial/Waldorf design because the horn parth is much simpler, reducing cancellations. The bass shall be more natural than with a 4520. Experimentation will also be done by increasing the rear chamber volume simply by unscrewing the panel between the rear chamber and the lost cavity below.

I will report. BTW "That person" is an electronic engineer and commercially designs DSPs. The goal is to have fun and experiment.

[louped garouv]

sound like a fun time!

[Ruediger]

Are You guys aware that Richard Long used the dbx boom box in his installations? The current model is the 120A. W/o the boom box something (a lot) will be missing.

Ruediger

[louped garouv]

Are You guys aware that Richard Long used the dbx boom box in his installations? The current model is the 120A. W/o the boom box something (a lot) will be missing.

Ruediger

only if you are playing the older disco, soul, and funk cuts... :cool:

those boomboxes can add too much synthesized
bass to more modern productions/works -- of course -- IMHO and YMMV :)

[Ruediger]

... In fact the Waldorf has only one 90° bend at the upper back ...


That is true. And another much larger one in the lower back, right?

Ruediger :D

[Lee in Montreal]

That is true. And another much larger one in the lower back, right?

Ruediger :D
The Jensen Imperial sounds great without a Boombox and Richie didn't have digital crossover. Therefore I can ^robably do much better in 2012 than Rich did in 1979. Also I don't have a boombox on my but used eq from the DCX2496 and the 4520s sound real good. :D

[louped garouv]

The Jensen Imperial sounds great without a Boombox and Richie didn't have digital crossover. Therefore I can ^robably do much better in 2012 than Rich did in 1979. Also I don't have a boombox on my but used eq from the DCX2496 and the 4520s sound real good. :D


I had thought his nickname back then was 'dick short' or something..... ;)
but i wasn't there, don't really know nuthin... only have heard a few old timers talking...

anyhow.....

Please Don't discount the old gear Lee...

I have a few of the RLA and Acoustilog pieces mentioned in that AES paper that Long/Fierstein submitted back when... although not nearly as flexible as a DCX2496, they do still sound very nice when carefully deployed...

you don't need the flexibility of digital when you are having custom electronics manufactured for your installations -- is how I see it...

[Lee in Montreal]

Please Don't discount the old gear Lee...

1972 Technics SL1100a
1977 Technics RS-M85 Twin motors Direct Drive tape deck
2 late 1970s Yamaha P2200
2 early 1980s Yamaha PC2002 and PC1002

Plus the usual early 1980s JBL drivers.

Don't worry, I don't discount the old gear. Quite the contrary ;-)

http://img.photobucket.com/albums/v668/Lee_Vuong/JBL%20parts%20factory/DSCN0975.jpg

[Eaulive]

only if you are playing the older disco, soul, and funk cuts... :cool:

those boomboxes can add too much synthesized
bass to more modern productions/works -- of course -- IMHO and YMMV :)

True. I have the DSP version of the 120A in my driverack and it sounds horrible on newer recordings with already lots of VLF material.

[Lee in Montreal]

That is true. And another much larger one in the lower back, right?

The tall gap at the back is a cost cutting measure. Instead of using a 60" tall rear panel, it is only 48" tall. Therefore a 48" x 96" sheet can do two rear panels.

Carl contacted me to know if he could start posting his progresses. Expect some pictures soon. Notice that I made the first bend differently from a Waldorf. It is rounder and therefore avoids any return/reflection. More difficult to build but bass shall be cleaner.


only if you are playing the older disco, soul, and funk cuts... http://www.audioheritage.org/vbulletin/images/smilies/coolgleamA.gif

those boomboxes can add too much synthesized
bass to more modern productions/works -- of course -- IMHO and YMMV http://www.audioheritage.org/vbulletin/images/smilies/smile.gif

May I add that such a boombox may be needed with bad vinyl pressings only. I have hundreds of 12" singles that sound much better than any CD. They are extremely dynamic and they go loooooooooooowww. No need for enhancement there.

[Ruediger]

The tall gap at the back is a cost cutting measure. Instead of using a 60" tall rear panel, it is only 48" tall.



I did not mean the tall gap at the back. I meant the SCOOP itself, it is the 2nd 90-degree bend.

I also did not mean to suggest that You integrate a boom box. I meant that what You remember as the sound of the Waldorf may be the sound of the dbx and the Bertha combined.

Ruediger

[Lee in Montreal]

I did not mean the tall gap at the back. I meant the SCOOP itself, it is the 2nd 90-degree bend.

There are many ways to end up with the exact same progression on that end, while the scoop has different configuration. Usually you gain or loose 5 or 6 inches of horn path. I designed mine so that it is not really a 90° bend anymore, and it is meant to avoid any possible cancellation. No wonder the scoop is often called a "slide"

54778

[louped garouv]

Lee,
Is there a math equation for determining/optimizing the back chamber's volume for a particular driver?

[Lee in Montreal]

Lee,
Is there a math equation for determining/optimizing the back chamber's volume for a particular driver?

Back chamber determines upper cut-off. Very important if one wants to use the speakers in the midrange. In my case, I didn't even bother as I'd use them for bass. But the panel separating the back chamber and the "lost" volume will be removeable. Therefore some testing will let us know about that. Throat height is a copycat of the original Waldorf.

[Ruediger]

Lee,
Is there a math equation for determining/optimizing the back chamber's volume for a particular driver?

The phase at the rear of the speaker is shifted by pi which corresponds to 1/2 wavelength.

At the frequency where the horns length is 1/2 wavelength the total shift is 2 pi or 1/1 wavelength, which is zero under steady state conditions.

Down to the frequency where the horns length is 1/4 wavelength and up to the frequency where the horns length is 3/4 wavelength the sound from the speakers front and from the horns mouth will add to each other, below and above they will subtract from each other.

For a scoop the frequencies might be 40 Hz, 80 Hz and 120 Hz. The rear chamber should function as a low pass below 120 Hz and should block frequencies above 120 Hz.

There is a paper from D.B.Keele about how to design a horn from the drivers TS parameters. The calculations are for a front loaded horn. The front chamber of the front loaded horn is the rear chamber of the rear loaded horn, and the rear chamber of the front loaded horn has no counterpart in the rear loaded horn (is infinite).

The Keele paper is in the technical references thread of the general audio discussions forum.

Ruediger

[Carl_Huff]

The paper that Ruediger describes can be founds here on DB Keele Jr's personal website.

It's the 11th paper and 2/3rds down the page. "Low Frequency Horn Design using Thiele/Small Parameters" http://www.xlrtechs.com/dbkeele.com/papers.htm
____________
Best Regards,
Carl Huff

[Charles0322]

I have heard these style Waldorfs from RLA and believe this cabinet was meant to be used in a double configuration, utilizing 4 15" drivers.. with the real low end provided by the enormous "Bertha" cabinet

Great to see another fellow Montrealer dedicated to JBL and its mutations.. I fell in love with JBL for it's use in disco systems in local Quebec nightclubs.

All the best, Charles


I'd be actually very interested to hear from people who have factual experience with such Waldorf because numbers themself don't make sense to me. Let me explain. From redrawing a Waldorf, and with the confirmation from Shorty's restoration pictures, I can say with assurance than the horn path is not longer than a 4520. 8ft for the 4520 vs around 6.5ft, which is in fact even shorter than a 4530. So, theorically, the Waldorf is not designed to go low. The main differences that I see are as follow: bigger mouth than the 4520 and a bigger rear chamber which should translate into a rounder type of bass at, I suspect, a certain loss of efficiency.

The advantage of the Waldorf horn design compared to a 4520-4530 is that the Waldorf doesn't have two consecutive U shaped corners. In fact the Waldorf has only one 90° bend at the upper back (like the Jensen Imperial from which it was inspred), and that bend can even be easily rounded up to avoid resonance and cancellation.

I still think that a back loaded horn with a 2.9m path (9.5ft) tuned to 30Hz and using a pair of 2240 woofers with Fs30 remains a better alternative. But first I must hear from people who have compared the Waldorf with a 4520.

[Lee in Montreal]

In some ways, I prefered the sound from my 4530 over the 4520.

4530 have a tight articulate bass and impressive kick. It's missing some roundness in the bass though. The Waldorf has the same 7ft horn length as the 4530 but with larger mouth and much bigger rear chamber. which should allow to get tight yet deper bass. I think it will be an improvement over the 4520 and 4530. ;)

[Charles0322]

In some ways, I prefered the sound from my 4530 over the 4520.

4530 have a tight articulate bass and impressive kick. It's missing some roundness in the bass though. The Waldorf has the same 7ft horn length as the 4530 but with larger mouth and much bigger rear chamber. which should allow to get tight yet deper bass. I think it will be an improvement over the 4520 and 4530. ;)

I was an employee of Stereo since day 1, after the first fire.. I no longer worked there.. I have been recently and am not impressed with the changes.

I am looking into options for a smaller style system.. some flying stacks mixed with RLA emeralds..

was looking into driver options, JBL, TAD, BMS perhaps the homegrown Transparence..

2395 and walnut 2397 combo maybe.. within a 4350 style flying cabinet.

Some of the DIY work on here is on par with exceptionally fine cabinetry. I myself am a cabinet maker and although speakers often get dismissed as "boxes" the pride and craftmanship on this board is inspiring to say the least.

On the Waveboard I have been pouring over the thread where they are talking about mixing various types of cabinets

LansingHeritage is one of the most interesting and informative sites for my interests.

[Lee in Montreal]

On the Waveboard I have been pouring over the thread where they are talking about mixing various types of cabinets

LansingHeritage is one of the most interesting and informative sites for my interests.

Yeah. I tried to pitch in on that thread. But it seemed that some had the universal truth... Not fun.

Glad to discuss with somebody from Stereo. One of the "hot spot" around the world for scoop fans and RLA derived speaker systems. Been there about 10 years ago. Still need to go back to take measurements ;-) I don't remember what model of Levan horn was used. The 30" deep of 48" deep. I wonder how many stacks they now run. 3 stacks, 6 stacks. Also, those Waldrof, are they with 18" drivers now? They look odd in some way.

I am organizing a big indoor party this summer in Quebec City for 100 people, celebrating "Shoeclack déchainé" which was a punk/new wave bar that lasted from January 1980 to end of 1984. I'll bring my system and will probably rent some more on location. if there wasn't a racecar in my garage, I would store some PA equipment. ;-)

[Charles0322]

Stereo is four stacks and some flying horns and 2405,s for support.. they got rid of two of the Berthas.. still running TAD TL-1603 in the scoops..

powered by LabGrupen amplifiers..

the booth monitors are nice sounding, some TAD 4001 with the TAD wood horn copy, not as nice as ones Ive seen built here, but the booth sounds amazing.. they have two TM-1201h underneath that wood horn

as for the other place... hey, there are some great ppl there, but I find this place more akin to a library and the other site like a pick up game of hockey ;)

[Lee in Montreal]

I have to go there soon. Curious as how they avoid bass cancellation if they run 4 stacks in corner. Or maybe they solved that problem by having 4 stacks on the same side firing in the same direction. BTW Somebody posted a picture of those nice monitors in the DJ booth.

Lee

[Eaulive]

I am organizing a big indoor party this summer in Quebec City for 100 people, celebrating "Shoeclack déchainé" which was a punk/new wave bar that lasted from January 1980 to end of 1984. I'll bring my system and will probably rent some more on location. if there wasn't a racecar in my garage, I would store some PA equipment. ;-)

You need another set of 4520s? :applaud:
mmmh let me think... punk/new wave... is this gonna break my speakers? :D

[Lee in Montreal]

You need another set of 4520s? :applaud:
mmmh let me think... punk/new wave... is this gonna break my speakers? :D

And lots of reggae, funk and 1980s industrial dance stuff...

http://www.youtube.com/watch?v=kLUIntu9Axo

[Charles0322]

There are the same problems as before, but way worse now that the space has been opened up, and two bass bins removed.. Incredible fatigue. Whatever dsp and filtering is going on, is badly programmed to say the least. I think they removed the bass cabs so that it was a more pleasant monitoring situation in the booth. Hell of a trade off and i dont go there anymore. My Urei 813b,s are from the original booth before 2002

[Eaulive]

And lots of reggae, funk and 1980s industrial dance stuff...

http://www.youtube.com/watch?v=kLUIntu9Axo

Not really my stuff for casual listening, but when you're in a dance club and the ambiance is good (and the sound is good and loud) it probably is a lot of fun.

[Carl_Huff]

Hello all,

I'm the guy building the prototype of Lee's interpretation of the classic Waldorf scoop loudspeaker. I've never heard a Waldorf cabinet but I've been a long time fan of the old JBL 4520 and 4530 scoop loudspeakers. Lee was kind enough to share with me his drawings for a dual driver cabinet that was inspired by the classic Waldorf cabinets as designed by Richard Long so many years ago. I jumped at the chance to build a prototype and will most likely build a pair.

I started the project by scaling Lee's drawing to extract dimensions and angles for the cut pieces. I used AutoCAD's TrueView 2012 (available from the AutoCAD site for free) to do that. After making the cut list, I transferred the shape of critical parts to poster board for use as templates to make the cutting process easier and repeatable. Below is a PIC of the template for the 'driver bucket end caps'. Each cabinet requires three of them.

54807

I made them by ...

#1) Cut 3 pieces roughly to size and stacked them up and tacked them together for machining and easy handling using a brad gun.
#2) I transferred the shape to the wood using the poster board template
#3) I I rough cut the wood with a bandsaw to a shape that was a half inch larger than the finish part and then ...
#4) Trimmed off that half inch using a table saw to get a clean edge and flat surface that was the finish size.

[Carl_Huff]

I cut the rectangle panels from full size sheets using my Festool plunge saw. What a great tool! It cuts as clean and accurate as a traditional cabinet saw but is portable and stores away on a shelf when not in use.

54808

[Carl_Huff]

The first assembly to go together was the driver bucket. This portion of the cabinet is the most difficult portion to build because it is made up of multiple angle cut pieces. Below is a PIC of the assembled driver bucket upside down and without the bottom board applied.

54809

[Carl_Huff]

Having proven myself stupid too many times, I've learned the hard way that it is always wise to dry fit the pieces before committing to 'glue & screws'. Here is the driver bucket being test fit for squareness and the expected clearance between panels. You can see in this PIC the two added braces to center make rigid the top of the driver bucket.

54810

[Carl_Huff]

This PIC show two more templates that will be used to make the lower section of the horn flare that attaches to the driver bucket as well as the supports for the scoop that is at the horns mouth.

54811

[Carl_Huff]

Everything fits so it's time to glue and screw the top and back panel to the first side panel. You should notice that a reflector has been installed in the upper back corner of the cab.

54812

[Carl_Huff]

That's it for this week's installment. This a weekend project for me. Unfortunately my day job and other responsibilities obligate me to other things during the week. I plan to continue this build and will post my results as I move along. My long term intent is to load the cabinet with a pair of JBL 2240's and measure the results. The panel between the driver bucket and the lower cavity will be made in such a way as to allow me to test changing the size of the resonant cavity immediately behind the drivers. I've got some other drivers that I want to try in this cab as well. One of them is an aging Altec 604. I am curious just how much usable upper band I can squeeze out of it.

I want to thank Lee for sharing his design with me. It's been fun to build!
_______________
Best Regards,
Carl Huff

[Eaulive]

Lee's gonna have to fly down to California to listen to those :D
I'm gonna be in San Jose in march, but that's still too far :(

[Carl_Huff]

Lee's gonna have to fly down to California to listen to those :D
I'm gonna be in San Jose in march, but that's still too far :(

Anybody that wants to come is invited! It's always a good time to tip a glass and to listen to some good music with like minded people.
_____________
Best Regards,
Carl Huff

[Lee in Montreal]

I can't wait to see the follow-up. Quite a few guys in the UK also watching. :eek:

[Carl_Huff]

The body of the cabinet is now complete. This bugger is big and heavy. It is getting increasingly difficult to move about as I add mass to it. I am guessing that it will weigh in at 250 plus pounds when completed. Industrial casters will be going on the bottom for sure!

54904

I have yet to build the exit section of the waveguide that assembles immediately below the driver bucket. There are also two stiffening ribs that fit between that and the back of the cabinet that I have yet to install.

In the above PIC I am about to secure the flexible MDF that will form the lower scoop.

[Carl_Huff]

54905

Here is a closeup shot showing detail of the driver bucket. The driver baffle board will mount flush with the forward edge of the cabinet. A piece of 3/4 x 1 1/2 inch trim will wrap the front edge of the cabinet just as JBL did with their scoop cabinets.

I probably spent too much time 'futzing' with the body of the cabinet, but I wanted a nice square box with tight corners. I've still got a couple of days work (weekends??) before I am ready to load the drivers. I've ordered a gallon of primer. It's a big cab. Maybe that's not enough!
____________
Best Regards,
Carl Huff

[Lee in Montreal]

Hi Carl.

Small progresses are better than standing still. Good job. Please have a look at Shorty's Waldorf and check how the front panel is recessed, allowing reinforcement strips all around. Do you think you'll be able to do the same on yours?

http://www.myspace.com/soundmanshorty/photos/33496214

54909

[Carl_Huff]

Hi Carl.

Small progresses are better than standing still. Good job. Please have a look at Shorty's Waldorf and check how the front panel is recessed, allowing reinforcement strips all around. Do you think you'll be able to do the same on yours?

Hello Lee,

It may look like small progress but getting that cabinet square was an all day test of my physical fitness, patience and skill! Ha, ha ...

Yes! That is my intent. The recess that you describe will be created by the 3/4 by 1 1/2 trim board that I described in my previous post. The drawing that you sent to me did not include a trim piece applied to the forward edge. I thought that not having one might lend itself to splintering when the cabinets are being muscled about. I studied the online PICs of the Waldorf and JBL scoop cabs and saw that they all had a forward trim board (as shown in the PIC that you posted) that stands proud of the cabinet face. As result of seeing that I adjusted your drawing to include a trim board. I was sure to keep your overall dimensions and left all internal elements unchanged. The addition of the trim board to the face of the cabinet is the only change that I have made to the drawings that you sent me. I hope that you approve!
_____________
Best Regards,
Carl Huff

[Lee in Montreal]

The baffle is recessed by 1" and uses 1" x 3/4" extra framing. The total width of the frame becomes 1.5"

54911

[Carl_Huff]

Lee,

What you proposed exposes the end grain and laminates of the plywood to potential tearing and splintering.
54917


And here is what I proposed. The plywood edge would be protected from potential abuse. No big difference
54918
____________
Best Regards,
Carl Huff

[Lee in Montreal]

Both will work ;-)

Lee

[Carl_Huff]

Both will work ;-)

Lee

Yea, I wouldn't have made the change if it were not for the crappy 'import' plywood that I am using for this project. This plywood seems prone to damage easily. It is much softer than what I usually buy for projects and as such is much harder to work with. I've learned my lesson. It's back to Baltic Birch for me!
_____________
Best Regards,
Carl Huff

[JoMoCo]

:lurk:Carl, enjoying your progress & look forward to seeing the results

[Lee in Montreal]

With the intention of simplifying the understanding of building a rear loaded bass horn, here are 4 simple formulas to help get a little understanding of the basic elements. There are more formulas, but it's a start to help understand how they work.

Fc is cut-off frequency

55098

[Carl_Huff]

It has been a while since I posted anything. Altho obligations have slowed me I haven't quit work all together. Here is a recent PIC showing that I have the majority of the cabinet completed. As you can see the scoop flare and bracing are complete. The next step is to cut and apply the baffle board. I have two freshly reconed JBL 2240s on their way as I write this. They should arrive mid next week. This weekend will be about tidying up and applying primer to the box. Hopefully next weekend will the first round of tests and measurements using a pair of JBL 2240 drivers.

55099
_______________
Best Regards,
Carl Huff

[Lee in Montreal]

Ah.... Look at that mouth. It's huge.

BTW Great job Carl. I like very much the double skinning around the rear chamber. Perhaps you could make some holes in the center section/brace.

[Carl_Huff]

Ah.... Look at that mouth. It's huge.

.... Perhaps you could make some holes in the center section/brace.

I've thought about that. The reason that I haven't cut holes in that center section brace is that part of what I want to do is evaluate the possibility of having two different loudspeakers in the cab, in particular an ALTEC 604 duplex or PAS 15 inch coaxial next to a JBL 2240. I want to experiment with different sized rear chambers when different drivers are loaded. Perhaps I should drill the holes that you suggested but make myself a plate that could be attached to seal off the two compartments from one another when I get to that part of the experiment.

A while ago when I worked up the numbers for the optimum recommended rear chamber behind a single JBL 2240 the volume worked out to be roughly the volume now afforded by leaving that center section brace solid. What do you think?
____________
Best Regards,
Carl Huff

[Lee in Montreal]

I've thought about that. The reason that I haven't cut holes in that center section brace is that part of what I want to do is evaluate the possibility of having two different loudspeakers in the cab,

As far as I know, wether in a horn or bass reflex cabinet, you can't have two different drivers. Unless perhaps the only difference is the tweeter section. You'll be sharing the same "space" anyway as the horn path is common to both drivers.

[Carl_Huff]

Putting two different drivers in the cab is a trick popular among Decware Jensen/ Imperial owners.

Both the Altec 604 and PAS CXL-2580C coaxials have surprisingly similar T/S params to the JBL 2440 in this box. And of course the Altec and PAS drivers are full range.

I invite others to comment.

55121
____________
Best Regards,
Carl Huff

[louped garouv]

I wonder how the Acoustilog TD-1 was deployed at the Garage originally...
my understanding is that the stacks at the time were:

Bertha/Levan, Waldorf, JBL 2397 & 2395, Ring radiators

thinking that the two woofers in the waldorf had slightly different operating bands...
a'la the JBL 'helper woofer' style configuration
:)

kinda the same idea, although with the same drivers used.... right?

[Carl_Huff]

"kinda the same idea, although with the same drivers used.... right?"

Yes!

You would think with this style of cabinet being so old and recycled in so many products that there would be more empirical information and published experiments to be found on the web. With modern DSP processor/ crossovers being so cheap I would think this cabinet style would have been well documented and exploited. Instead about all that you find is speculation as to the audibility of comb filtering resulting from the output of the scoop merging with that which is direct radiated.

Maybe there is a good reason for the void of information that has completely escaped me. We shall see!
_____________
Best Regards,
Carl Huff

[Lee in Montreal]

Let's see where the resonance will be in the Waldorfs with two 2240s. Then use one driver in the cabinet' usefull range (30-300Hz ?) and the other from 30Hz up to where the resonance starts. Which will diminish the amount of resonance (80Hz ? )

[maxwedge]

It has been a while since I posted anything. Altho obligations have slowed me I haven't quit work all together. Here is a recent PIC showing that I have the majority of the cabinet completed. As you can see the scoop flare and bracing are complete. The next step is to cut and apply the baffle board. I have two freshly reconed JBL 2240s on their way as I write this. They should arrive mid next week. This weekend will be about tidying up and applying primer to the box. Hopefully next weekend will the first round of tests and measurements using a pair of JBL 2240 drivers.

55099
_______________
Best Regards,
Carl Huff
Bad Ass!
Hope you're a young guy....you know, to move them around!:D

[Carl_Huff]

"Hope you're a young guy....you know, to move them around!"

Tugging on this thing always reminds me that I am definitely not as young (and fit!) as I used to be.
____________
Best Regards,
Carl Huff

[maxwedge]

"Hope you're a young guy....you know, to move them around!"

Tugging on this thing always reminds me that I am definitely not as young (and fit!) as I used to be.
____________
Best Regards,
Carl Huff
Well, tugging those around is better than going to the gym, lol.

Good job. :rockon1:

[Lee in Montreal]

I can't wait to se pictures with the 18" 2240s installed and the cabinet painted (a generous coat of Shellac before sanding and painting will make the wood surface stronger)

Carl, don't forget to generously stuff the rear chamber. ;)

http://www.homedepot.com/catalog/productImages/400/13/13cdc247-11b9-477b-920d-9bb589099e3a_400.jpg

[Carl_Huff]

The Zinsser products are really good. I've used them often in the past. However for my last few projects I have been using MagnaClaw black primer from Campbell Finishes. It covers really well, dries quickly and works well under a Duratex textured finish. It runs about $40 per gallon plus cost to ship.

55171

___________
Best Regards,
Carl Huff

[hjames]

I do like the look of those cabinets ...

An interesting idea - covering the wood with thick black finish.
I tend to prefer the look of the wood itself ... let the grain sing.

i just got a pair of (non-JBL) speakers with black painted oak top caps.
Didn't like that look, so I wiped them down with MEK and removed most of the paint,
then sanded them down, and rubbed in 4 coats of Watco Danish oil (Cherry finish).


55172

55173
Haven't tapped them down flush yet - waiting for the finish to dry.

[louped garouv]

i bet the black is for 'that' professional clubsound, industrial look and/or durability concerns......

[Carl_Huff]

My background is Pro audio and more recently Cinema sound. It seems that my cabinet color pallet has been traditionally limited to black! Perhaps it is time for a change.
_____________
Best Regards,
Carl Huff

[louped garouv]

there is always Battleship Grey!

;)

[Carl_Huff]

HJames,

I like the looks of that Smith horn that you have at the edge of your PIC.
______________
Best Regards,
Carl Huff

[hjames]

Thank you - its my main system in that room ...
L200 cabinet with 2234, 2405 slot and the external horn

55181
Nice sound - but nothing like these club systems ... wow!


HJames,

I like the looks of that Smith horn that you have at the edge of your PIC.
______________
Best Regards,
Carl Huff

[Carl_Huff]

My freshly reconed JBL 2240s showed up today. They look good. If all goes as planned I will be measuring them in the cab this weekend.
________________
Best Regards,
Carl huff

[Lee in Montreal]

Drum rolls................. :eek:

[Carl_Huff]

My Saturday progress to report:

Once the last bit of glue dries, the cab will be ready to receive it's baffle board and JBL 2240 drivers. Tomorrow (assuming the weather holds) is test sweeps day.

The measurements will all be IGM (In Garage Measurements) I wonder what my neighbors will think? Ha, ha ...

55207

55208

55209
_____________
Best Regards,
Carl Huff

[1audiohack]

.
The measurements will all be IGM (In Garage Measurements) I wonder what my neighbors will think? Ha, ha ...

That your watching Star Wars! My wife calls our garage "Chirp Labs"

[Lee in Montreal]

It's almost there. One more day. Before gluing the front baffle, make sure that you have the same distance between the rear of the baffle and the throat, as the throat is high. It should be 3.25". Horizontally and vertically. ;)

[Carl_Huff]

Sorry fellas ...

Measurements are put off for a week. It was a rainy and windy day in (usually sunny) Bakersfield.
_____________
Best Regards,
Carl Huff

[Lee in Montreal]

Pictures. Pictures. Pictures :D

[Mike F]

Thank you - its my main system in that room ...
L200 cabinet with 2234, 2405 slot and the external horn

55181
Nice sound - but nothing like these club systems ... wow!

That beautiful horn most definitely needs a better support:p

[I want TAD]

Good work!!

[hjames]

That beautiful horn most definitely needs a better support:p

Yeah - that's an old picture from when I first set I up ...
- I have a wooden support underneath it these days -
its much better, but it still deserves more ...

55231

[Carl_Huff]

It's almost there. One more day. Before gluing the front baffle, make sure that you have the same distance between the rear of the baffle and the throat, as the throat is high. It should be 3.25". Horizontally and vertically. ;)

There is only one place where these drivers can go! If they are exactly centered over the buckets there is roughly 1/4 inch clearance on all sides.

If the weather holds tomorrow (Sunday) is test day!
______________
Best Regards,
Carl Huff

[Carl_Huff]

I finally found some free time when the wind wasn't blowing! My first round of measurements.

Notice the JBL active monitor setting on the cabinet for prospective. This cabinet is huge, even by my standards!

55320

Two JBL 2240s each enclosed in their own bucket. There are no holes in the dividing partition between the drivers or in the board that separates each driver from the chamber below it. I used Dirac Live software to do the testing. Altho Dirac Live is a product that optimizes your loudspeakers for use within a listening room, it can be used to plot nearfield loudspeaker response. Here is my test setup.

55321

Dirac Live runs as an application on the laptop, a USB Pre is the measurement microphone preamplifier. I use an Earthworks M30 with a calibration file for the measurements. The amplifier in use is of my creation. It is in fact a Hypex class D amplifier module and linear power supply. Dirac Live works by taking a series of measurements (9 in this case) and averaging the results for view. I wanted an accurate (worst case??) set of measurements. To accomplish that I placed the microphone at a one meter distance from the loudspeaker and took 3 measurements moving the microphone from left to right, first at a high position (inline with the center of the cones), low (one foot off of the ground in front of the scoop) and then midway between where cross coupling between the out of phase signals should be the worst.

3 measurements at the 'high' position ...

55322

3 measurements at the 'Low' position ...

55323

And finally 3 measurements midway between

55324

[Carl_Huff]

And here are the results!

They are shown normalized to 1/12th octave. You can clearly see the 'phase funnies' at 120 and 300 Hz. All scoop cabinets have them. It is just the nature of the beast. The notches amount to about 6dB each.

55325

I then used the Dirac Live editor to create an EQ target curve that could result in a filter set being generated. The red line that is superimposed is my idea of a target curve. It is a typical home theater kind of curve that includes the usual subwoofer bump. The 'pull tabs' left and right are cutoff high pass and low pass filters.

55326

And here is how close Dirac Live thought that it could come to my ideal curve. Not bad!

In my experience Dirac Live is quite good at predicting the end results when confirmed by taking another round of measurements.

55327

As you can see the phase funnies are gone! Only the ripples at 35Hz remain. With reasonable EQ applied the cabinet is down 3dB at 28Hz. Only another round of measurements in a real setting will tell if the results are in fact as projected. These measurements were taken out of doors. If I had taken these measurements indoors room gain and room modes would have played into the equation and the results would have undoubtedly been different. However I am quite pleased with the results. Altho it has taken me much longer than I had expected, I am glad that I built this cabinet and have a clear incentive to continue the experiment.

Thanks again to Lee for sharing this design. More to come.
_______________
Best Regards,
Carl Huff

[Carl_Huff]

And here is my experiment #2 in preparation.

55371

I've removed one of the JBL 2240 drivers and attached a baffle board to hold a UREI variant of the classic Altec 604 duplex driver.

55372

Hopefully I will have results that I can post late tomorrow.
________________
Best Regards,
Carl Huff

[1audiohack]

Hi Carl;

Will Dirac show you the phase response of your SPL measurements?

Barry.

[Carl_Huff]

Hi Carl;

Will Dirac show you the phase response of your SPL measurements?

Barry.

The Dirac Live application displays impulse and amplitude vs frequency plots. No other plots. However they tell me that phase is part of what gets analyzed by the magic code that creates the corrective filters.
_______________
Best Regards,
Carl huff

[Carl_Huff]

Hello all,

It has been too long since I posted to this thread. I have abandoned my tests using the Altec/ UREI duplex loudspeaker. A single driver version of this cabinet would be an interesting project for such a driver but I never found a satisfactory driver to pair the duplex with in this dual cabinet. So out comes the the duplex and back in goes a JBL 2240 driver. The test cabinet is still missing a trim board on it's face, but has received its first coat of primer and is now in touchup mode. My next step is try a JBL 2360 horn and 2446h driver combination crossed at 650Hz.

More to come ...

55853

55854
____________
Best Regards,
Carl huff

[Mr. Widget]

That is a very formidable looking pairing. I bet it will be quite impressive!


Widget

[maxwedge]

That is a very formidable looking pairing. I bet it will be quite impressive!


Widget
I agree!:bouncy:

[Carl_Huff]

Yea,

I don't think it practical to build anything bigger. I have to 'muscle down' the 2360 horn, driver and bracket assembly (ie: 90 lbs) to put this beast in the garage.

If I leave the horn in place, the overall height is nearly a foot taller than the garage door opening! Geez ...
_____________
Best Regards,
Carl Huff

[4343]

Yea,

I don't think it practical to build anything bigger. I have to 'muscle down' the 2360 horn, driver and bracket assembly (ie: 90 lbs) to put this beast in the garage.

If I leave the horn in place, the overall height is nearly a foot taller than the garage door opening! Geez ...
_____________
Best Regards,
Carl Huff

You could lay it on it's side, with the horn lined up above the woofers. I'd want to run a huge inductor on the bottom woofer to filter the mids out of it positioned like that though, (or do it actively). Beats lifting the horn!

[Carl_Huff]

You could lay it on it's side, with the horn lined up above the woofers. I'd want to run a huge inductor on the bottom woofer to filter the mids out of it positioned like that though, (or do it actively). Beats lifting the horn!

I tried running the cabinet on it's side and didn't like how it sounded. There was an unpleasant 'phasey coloration' that you could clearly hear as you walked back and forth in front of it. I am guessing that the wave emerging from the mouth being out of phase with that from the loudspeakers mixing in the same horizontal plane has something to do with it. In any case the cabinet sounds much better in the upright position.
______________
Best Regards,
Carl Huff

[4343]

I tried running the cabinet on it's side and didn't like how it sounded. There was an unpleasant 'phasey coloration' that you could clearly hear as you walked back and forth in front of it. I am guessing that the wave emerging from the mouth being out of phase with that from the loudspeakers mixing in the same horizontal plane has something to do with it. In any case the cabinet sounds much better in the upright position.
______________
Best Regards,
Carl Huff

I was getting at the same effect, just closer to the crossover frequency. The two woofers side by side will produce nulls unless they are mutually coupled, and they don't do that much above 200 Hz. Limiting one to the maximum coupling freq eliminates that.

That "phasey" effect when laid on the side can be lessened by using a pair, top to top, so the lows from the horn mouths can form a "phantom center" right where the upper freqs are radiating. (Just what you need, another pair!:D)

I used to use 8 of the single 15" scoops stacked like that. The bottom 4 were only driven up to 200 or so, while the top 4 went up to the XO point. Back then I would have traded my truck for a pair of those big CC horns you have. Would have had to trade it for a bigger truck in any case, as it was stuffed...

[Carl_Huff]

I played music thru this combination for the first time yesterday (ie: Memorial Day). I was struck immediately by the 'easy dynamics' and efficiency. This is the first time I've spent serious time around a JBL 2360 horn. It is very listenable and not at all what I had expected. And I hadn't expected it to sound as good as it did in close proximity. I plan to get much more serious and take measurements that I promise to post.
_____________
Best Regards,
Carl Huff

[1audiohack]

This is the first time I've spent serious time around a JBL 2360 horn. It is very listenable and not at all what I had expected. And I hadn't expected it to sound as good as it did in close proximity.
Best Regards,Carl Huff

They aren't perfect but they definitely don't suck. :)

[Carl_Huff]

They aren't perfect but they definitely don't suck. :)

Yes! That's a great way to describe what I heard.
______________
Best Regards,
Carl Huff

[bigh1229]

The pix of those waldorfs are cool but to stand next to them is something else!!!!!!!!!!!!!!!!!!!!! My 10 year old son is the proud owner of them now along with the single ones restoring 8 lenses now

[Carl_Huff]

Pioneer is offering what looks to be clones of the old Richard Long dance club cabinets ...

http://pioneerproaudio.com/en/products/index.html#gs_wave_series

_____________
Best Regards,
Carl Huff

[Lee in Montreal]

Damn. You are 100% correct. And this is definitely a nice exemple of plagiarism. ;-)

[Carl_Huff]

They have even copied the classic JBL 2395 lens.

And no credit given anywhere to the originators. Geez ...
_____________
Best regards,
Carl Huff

[Mike F]

Damn. You are 100% correct. And this is definitely a nice exemple of plagiarism. ;-)

Look at it as "Imitation is the best form of flattery" I wonder if TAD quality components are used.

[Lee in Montreal]

I wonder if TAD quality components are used.

The Bertha is designed for twin 18" woofers. TAD makes four different 18" drivers.

[louped garouv]

there is no mention of TAD components being utilized in the pioneer offering that I could locate....

[Lee in Montreal]

there is no mention of TAD components being utilized in the pioneer offering that I could locate....

You are correct. Not much tech info. But I don't see what other woofer Pioneer would use in its professional offering.

[Horn Fanatic]

I just found this thread today. I'll try to put this as tactfully as I can. I'm a bit disappointed at how little some folks on this forum know about rear loaded horn design.

This comment especially caught my eye;

"I still think that a back loaded horn with a 2.9m path (9.5ft) tuned to 30Hz..."

I don't know what he means by "tuned", but as a matter of fact, the path length of a rear loaded horn has nothing to do with the horn cut-off frequency. Horns are not "tuned", bass reflex enclosures are tuned.

And this one;

"Experimentation will also be done by increasing the rear chamber volume..."

A comment by one who doesn't understand the relationship between the chamber volume, horn throat, and horn length.

I don't mean to offend, but I'm reading some misinformation here that begs to be cleared up.

[speakerdave]

I'm sensing a lot of bated breath. Perhaps you could fill us in or provide links to good information.

[Lee in Montreal]

Well, I am awaiting enlightement. :D

[more10]

Anyone who wants to educate himself about horns and horn theory, http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=82144. It is in Swedish but the links still works :-)

Everything there should be sound engineering and science, except for the stuff written by Jonathan Weiss .

[Horn Fanatic]

Well, I am awaiting enlightement. :D

Allow me to ask you a question.

Do you know what the function of the chamber in a rear loaded horn is, it's relationship to the throat, and why in concert as an acoustical element, they dictate the length of the horn?

Have you ever wondered why, in JBL literature regarding the 4530 and 4520 enclosures, where it's written that the speaker acts as a direct radiator above 150 cycles?

Do you know how the proper horn cut-off frequency is determined for a given driver? Hint, it's not fs.

Last question for now. Are you familiar with filter math?

[Horn Fanatic]

I'm sensing a lot of bated breath. Perhaps you could fill us in or provide links to good information.

I'm sensing sarcasm. As for links? What I reveal here does not come from links, it comes from years of study, research, testing, and practice based on the writings of a who's who of acoustical and electrical engineers dating between 1919 to the mid-seventies. It is those articles and books I used as a basis for writing my horn design program, not buying into canned software. It hasn't failed me yet.

[Horn Fanatic]

Anyone who wants to educate himself about horns and horn theory, http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=82144. It is in Swedish but the links still works :-)

Everything there should be sound engineering and science, except for the stuff written by Jonathan Weiss .

I found a translation to that forum thread some time ago. Nothing there piqued my interest except for mention of a rear loaded horn enclosure designed by a chap named H.H. Klinger. I actually obtained a copy of his book on loan through the library in Malmo. Oddly enough, he recommended loading his enclosure with an EVM 15L.

[Lee in Montreal]

Yowsah!!! Did anybody piss in your cereals this morning? Just out of nowhere, you revive a 4 year old thread and give shit to everyone... :eek:

[NickH]

it seems some replies here need a bit of tact. Get some.

[Horn Fanatic]

Yowsah!!! Did anybody piss in your cereals this morning? Just out of nowhere, you revive a 4 year old thread and give shit to everyone... :eek:

I see now it was pointless of me to impart some knowledge about horn design on this thread. It's a shame I had to encounter someone who feels that I insulted his delicate sensibilities. It's obvious you're unable to answer any of my questions, so your tack is to display indignation and victimhood, rather than curiosity. I was under the impression this forum was a place of learning, but I see that I was in error.

It's not my loss, it's yours.

Good day.

[1audiohack]

I have learned a lot here and I was hoping to learn something more. :(

Barry.

[louped garouv]

Agreed, it could have been a nice discussion methinks...

As the gentleman from WA mentioned, I do also find value in the older papers...
As did the folks behind Richard Long & Associates...
you'll see influences from Olson, May, etc in their design philosophy...

Basically, trying to get the most out of a limited resource...

[Carl_Huff]

With this thread recently resurrected I thought it appropriate to post a PIC of the finished cab.

66130
_____________
Best Regards,
Carl Huff

[grumpy]

Very clean/industrial... in a good way :)

[Lee in Montreal]

That's two 18" 2240s ;-) That cabinet is 5' tall if I remember...

[NickH]

Damn, now I have to build 2 new bass horns now, lol.

Very nice build.

How do they perform?


Nick

[Carl_Huff]

Damn, now I have to build 2 new bass horns now, lol.

Very nice build. How do they perform? Nick

They work surprisingly well. With a little EQ they reach reliably into the mid 30's, are very 'live' sounding. They definitely have that dance club 'wump' to them when pushed. I have been using them with JBL 2360 horns loaded with BMS 4590 coaxial CDs. The combination can be overwhelming.

Frequency response is shown back in post #88 when I had the cabinet loaded with 18 inch JBL 2240 drivers. The drivers in the recent PIC are 15 inch TADs. The TADs are a little smoother and extend a little lower. These cabs are the size and weight of a refrigerator, but a whole lotta fun!
_____________
Best Regards,
Carl Huff

[NickH]

Ya I can relate. I have my in my second story game room. Getting them upstairs was not fun. Those would probably end in a trip to the hospital, :D.

I'm buying 2226's to put in mine. I'm currently running mine with a qsc gx7 running some parts express Dayton pro 15's in them in parallel. The tops are 2446's being driven by a jbl 6260. Its quite the experience. They can get up to 120dba at my chair. And it sounds quite nice at that volume too, but not for long if I do it too much. Don't need to kill the ears. I use a minidsp for the crossover at the moment. I'm working on a analog crossover at the moment to replace it. The minidsp is limited on its output voltage. Plus I'm still trying to get over the analog psychosis too.

That bass wump is really addictive. I've honestly considered not even running a sub with mine high passed at 40hz too.

Nick

[Herman Chigrin]

trying to cover 80 to 500 Hz with the ability of decent outputI was always very curious by the JBL and similar scoops. But I was always concerned by the frequency dip around 200 Hz. Is this an issue? And of course the most important question is what are these good at and what are their deficiencies as far as sound quality?Thanks guys!