DIY 4344 MKII using Beyma TPL-150

[Drummerboy2]

Hi All, I originally wanted to do a 4345 Clone but I decided to try a 4344MKII version first but in a 3 way. I have the 2245's for a 4345 but I will try with the MCM 55-2963's 15" which are supposed to be very close in sound to a JBL 15". I have two pairs of JBL 2123H's and the Beyma TPL-150 is on their way. I have created a xover for these drivers using Xover Pro software and it looks (Graphs) really nice so far and all drivers seem to match up very well. For now I will be using the 15" Knock Down cabinets from Parts Express that I got last week. This should give me a good feel for what this combo of speakers can do. I will be making an enclosure for the 10" to isolate the 10" from the 15" woofers like in the 4344 and will set the Beyma 150 on top of the cab. I ordered the TPL-150 without the horn so I can get a wider dispersion (120 degrees horizontal) than with the horn (80 degrees). Hope this will work out.

I still need to get the 2245H's reformed. Once I get those done I may take a stab at the 4345. But for now I will just stay with the 3 way 15" version.

Any feedback or info is appreciated.

[1audiohack]

Interesting. I am trying to figure out how to not sound cynical, honest.

So, the only thing JBL in this project is a driver (2123) that JBL never used in a home or monitor application. Granted it’s not a big leap from a 2121/2122.

Add to that a knock down box likely not optimized for the woofer and some type of tweeter (I obviously didn’t look it up) without the normally used waveguide? Sorry but to me this resembles a 4344 like a Mustang resembles a Camaro.

The journey can be very rewarding and or very frustrating. There is truly a multi dimensional skillset required along with a real tool list to help navigate through the fog if you want to build anything that approaches something like the 4344.

I don’t know what your skillset is but if you don’t clone an existing design you might be in for a rough ride.

I am all about DIY and I hope you have fun and it sounds great too, really but what you have proposed is far enough diverged from any JBL design as to render useless any helpful comparisons to your design.

Anymore I just can’t imagine doing this without a measurement rig and DSP. Do you have a way to measure the response when they come together?

Barry.

[grumpy]

Looks like fun. Calling it a custom 3-way based around a 2123 mid might help in concept and execution.
Hope your custom crossover included some 4434-like eq/contouring for the mid, which should make
integrating the other drivers a bit simpler (woofer being mostly box driven, tweeter appearing to need
a reasonable protective slope and perhaps some fore/aft optimization). Would be interesting to see how
this comes out with a good measurement system and listening eval. Expect mid/tweet integration to be
the trickiest. Enjoy the journey :)

[Ian Mackenzie]

Ditto Barry and Grumpy

Disclaimer on support:

Without good driver measurement data (spl amplitude and impedance) from you we can only offer limited general non specific advice where a new member is not closely following a Jbl design.

Unless you have already please invest in a reasonable measurement tool and mic. It will payback with huge time saving and a finished design that you are proud of. You will also learn and appreciate how the whole thing works.

Unfortunately we do see new people come here seeking a customised design consultation over a few posts asking the same naive questions over and over and expecting someone to pull a rabbit out of a hat.

Don’t get hooked on too much internet research. There is no point reading up on a topic and regurgitating it without doing anything.

Yes it happens again and again

The reality is s customised design is one of a kind and the ball is in your court to make it work.

Having said the above good luck with your project.

Quite a few have used the Beyma device and there are numerous projects on diyaudio.com

There are some good Ebooks on loudspeaker measurement.

I recommend you do your own measurements first and establish your own project goals.

The 2123 is nice driver.

An Active crossover with adjustment is a good way to start for the diy person

I would definitely Biamp the woofer and the 2123 or if you can only passive use the Jbl 4344mk11 schematic as a starting point.

[Drummerboy2]

Ditto Barry and Grumpy

Disclaimer on support:

Without good driver measurement data (spl amplitude and impedance) from you we can only offer limited general non specific advice where a new member is not closely following a Jbl design.

Unless you have already please invest in a reasonable measurement tool and mic. It will payback with huge time saving and a finished design that you are proud of. You will also learn and appreciate how the whole thing works.

Unfortunately we do see new people come here seeking a customised design consultation over a few posts asking the same naive questions over and over and expecting someone to pull a rabbit out of a hat.

Don’t get hooked on too much internet research. There is no point reading up on a topic and regurgitating it without doing anything.

Yes it happens again and again

The reality is s customised design is one of a kind and the ball is in your court to make it work.

Having said the above good luck with your project.

Quite a few have used the Beyma device and there are numerous projects on diyaudio.com

There are some good Ebooks on loudspeaker measurement.

I recommend you do your own measurements first and establish your own project goals.

The 2123 is nice driver.

An Active crossover with adjustment is a good way to start for the diy person

I would definitely Biamp the woofer and the 2123 or if you can only passive use the Jbl 4344mk11 schematic as a starting point.



Well, I just wanted some feedback on IF anyone has used these drivers together in any DIY project and NOT free consultation on a custom design. I do have some measuring software and tools. I will just wait for my Beymas to come in and get started on my project. Thanks Everyone for the info and feedback.

[Ian Mackenzie]

Well that’s not what you specifically asked or stated.

Your post was a sprawling story of your options.

Why would you start off with a mix of drivers if you were planning on a 4345? Makes no sense.

This is a JBL forum. That’s it.

[Drummerboy2]

Well that’s not what you specifically asked or stated.

Your post was a sprawling story of your options.

Why would you start off with a mix of drivers if you were planning on a 4345? Makes no sense.

This is a JBL forum. That’s it.



It's a Lansing Product DIY Forum!

[pos]

Hello Drummerboy2, and welcome on board ;)

2245H+2123+TPL-150 looks like a nice combo with lots of potential (and of course lots of pitfalls as already pointed out).

Not sure about the MCM woofer tho...
The 2245H is a very good and versatile (sub)woofer, and you can replicate the 4345 tuning (280L @29Hz IIRC).

If you go the 2245H+2123H route, you should be able to find plenty of info on active solutions for the ~300Hz crossover.
This is a tricky frequency range to measure, so you better rely on proven solutions there.
One advice regarding that range: keep the woofer and mid woofer on the same baffle to avoid having two different baffle steps in effect around the crossover frequency.
Also try to get the 2245H off the floor to avoid triggering vertical modes in the >100hz range (dust cap at around 1/4 of the ceiling hight is often a good solution).

The 2123H/TPL transition will be unknown territory (around here at least, maybe some have done that on the diyaudio forum), but at ~1200Hz this crossover will be much easier to measure and dial, and with a bit of patience and knowledge you should be a able to get a theoretically perfect acoustical crossover using only in house measurements.
You might need to use the horn on the TPL to get it down to 1200Hz and -more importantly- match directivity with the 2123H.

[Drummerboy2]

Hello Drummerboy2, and welcome on board ;)

2245H+2123+TPL-150 looks like a nice combo with lots of potential (and of course lots of pitfalls as already pointed out).

Not sure about the MCM woofer tho...
The 2245H is a very good and versatile (sub)woofer, and you can replicate the 4345 tuning (280L @29Hz IIRC).

If you go the 2245H+2123H route, you should be able to find plenty of info on active solutions for the ~300Hz crossover.
This is a tricky frequency range to measure, so you better rely on proven solutions there.
One advice regarding that range: keep the woofer and mid woofer on the same baffle to avoid having two different baffle steps in effect around the crossover frequency.
Also try to get the 2245H off the floor to avoid triggering vertical modes in the >100hz range (dust cap at around 1/4 of the ceiling hight is often a good solution).

The 2123H/TPL transition will be unknown territory (around here at least, maybe some have done that on the diyaudio forum), but at ~1200Hz this crossover will be much easier to measure and dial, and with a bit of patience and knowledge you should be a able to get a theoretically perfect acoustical crossover using only in house measurements.
You might need to use the horn on the TPL to get it down to 1200Hz and -more importantly- match directivity with the 2123H.

Hi pos, Thank You for the Welcome to the forum. Actually I have been around the forum for a while but with other projects that didn't work out so well. :(

After some thought, I will have the 2245H's repaired either by myself or someone else.

It's funny you mention the 300hz range for the 2245H and the 2123H, that exactly the xover point I got with the 55-2963's and the 2123H's in Xover Pro. The TPL-150 seems to look better with a xover point at 1500hz, there is a dip around the 1200hz. The specs say it can xover at 1000hz. I know I will have to play with them to get it right.

The TPL-150 can go down to 1000hz without the horn and down 700hz with the horn but I will loose horizontal dispersion. 120 degrees without horn vs 80 degrees with horn.

Thank You for the tips.

[pos]

80° is probably not too far from what you will get from the 2123 around 1.5kHz, so the horn will actually help in getting a good directivity match and a coherent power response.
That 80° nominal figure is most probably only reached above 2kHz anyway, given the size of the horn.
Chances are that the directivity will be quite well matched between 1kHz and 2kHz between the 2123 and TPL+horn, both rapidly gaining direcitivity in that range.

[Ian Mackenzie]

Below is a very good “working” design that will guide you on using your Beyma device.

As l mentioned earlier the real exposure on the Beyma is not here it’s else where.

http://www.audiodesignguide.com/HiEff/HiEff2.html

[Drummerboy2]

80° is probably not too far from what you will get from the 2123 around 1.5kHz, so the horn will actually help in getting a good directivity match and a coherent power response.
That 80° nominal figure is most probably only reached above 2kHz anyway, given the size of the horn.
Chances are that the directivity will be quite well matched between 1kHz and 2kHz between the 2123 and TPL+horn, both rapidly gaining direcitivity in that range.

pos, Thank You. I will give it a try.

[1audiohack]

It's a Lansing Product DIY Forum!

Zactly. :)

We do like to help and we obviously support DIY. The non Lansing drivers chosen for you project just limit our ability to easily do so.

All the best,
Barry.

[Drummerboy2]

Below is a very good “working” design that will guide you on using your Beyma device.

As l mentioned earlier the real exposure on the Beyma is not here it’s else where.

http://www.audiodesignguide.com/HiEff/HiEff2.html


Ian, Thank You. I saw this a while back and actually was going to do it. I saved it just in case I change directions. The Onken cab may be too big for my room that the speaker will be going in to. It's a nice Project if I had the room.

[Drummerboy2]

Zactly. :)

We do like to help and we onviously support DIY. The non Lansing drivers chosen for you project just limit our ability to easily do so.

All the best,
Barry.

1audiohack, I totally understand. I do have a JBL woofer 2245H's that needs to be repaired but for the cab the size of the 4345 will be too big for the room I wanted to put it in. The 73" tv takes up too much room. I will try to figure out how to make it fit. I will just have to shuffle things around if it comes down to it. Even the 4344 MKII may be too big so that's why I wanted to try the knock down cab. I did find some 2235H's if the 55-2963 don't work out.

The Link Ian put up is a nice project too but again too big for the room at this time.

I will start the project and see how it goes. If it doesn't work out then I will just have to do the proper size cabs with the 2245H's or 2235H's.

[Ian Mackenzie]

Okay

Makes sense

It’s hard when you have lived with a 73 “ tv

You said you have a 2 pair of 2123H?
So are you planning a vertical arrangement., woofer +2123+Beyma+2123?

That could be interesting

If you are really stuck for room width you could keep the final enclosures narrow (using your 15 inch woofer) like 19 inch wide externally to form a tower. Even stack the 2123’s and the Beyma on top on the woofer box in a narrow array

That way it would be modular

The ports placement is not critical

The other option that “might” work is vent your dual 2123 with a small rear port and run them down much lower at 140 Hz. That would really give you a low distortion mid.

Some Klipsch owners looking to improve have reported excellent results with dual 2123’s.

Two 2123’s in .8 cu ft vented @86 hz will not reach Xmax till 135db (thermal limited at 132 dB 500 Watts 4 ohms)

I imagine it would be very dynamic!

It would be 105 dB sensitivity ref 2.83 v 1 m

The woofer could side mounted like the Allison concept with the enclosure 13 inches wide

The green curve is the ported enclosure dual 2123 (2x 2 in ports 0.4 long)
The yellow curve is the sealed enclosure

The ported enclosure really drives hard down to 86 hz
Passively crossing that over would be a challenge but it’s an option

In fact the 300 hertz crossover passive is not that simple either

Biamp if you can

Food for thought.

[Drummerboy2]

Ian,
Thank You for the info. I really appreciate it.

Yes, my 73" DLP is one of the nicer ones with a picture that rivals plasma. This was feedback from friends that saw it and had plasmas. It's Easy to fix, when the chip went bad and lamp went out I just replaced both myself and now I have a NEW TV again, so it's hard to just give up on it. Great for Live sports and concerts! :) I will have it for a while until something a lot better that doesn't cost a 30 year payment plan to get! LOL! My buddy told me to sell the TV, I didn't laugh when he said that!

Yes, I do have two pairs of JBL 2123's but....when I was opening the package from the seller (he did a great job of packing) and faced the two drivers together with plastic wrap around them so good, it was hard to get all the wrap off. While doing it, one driver slipped and mashed my finger (anyone who has these drivers know they are not exactly light weight drivers) while in the process the edge of the one driver hit the cone of the other and tore the cone! OUCH! So I bought another pair. So I actually have 3 good 2123's and one ripped cone 2123. So I have to have the one repaired or have two reconed to match.

I never thought to use the two pairs like an MTM style arrangement. I would have thought that would be too much but understand the concept of lower distortion via two 2123's per side.

I will make the xovers biamp capable. I will leave myself that option just incase.

I also have Bass Box Pro along with the Xover Pro. I'm still learning with the Bass Box. I also have WinISD for box software. I am leaning towards getting that RTA Software soon help out for measurements. I was going to use a Audio Stepped frequency CD and a SPL meter to start off until I get all the proper measurement tools.

The Beymas come in tomorrow and the ports, Lpads, and Jig (4) come in next week. Then I can get started.

I wanted to do mirror image baffles but I will just do the straight up inline style. Until I do a true JBL clone cab, I will just do it this way for now.

I will post some pics when I have all the drivers together.

Thanks again!

[pos]

Not too sure about MTM idea in your situation...

[Ian Mackenzie]

Pics please

If you don’t end up needing the 3rd 2123 l will have it.

[Drummerboy2]

Pics please

If you don’t end up needing the 3rd 2123 l will have it.

Ian, I will try to get some pics of the pair of 2123' with the one that has a ripped cone by the end of the week. I need to pull them out from where I have them stored and open the box to take pics. If I can't have the one repaired, then I will keep the 3rd good one as a backup if all works out. If I end up going in a different direction if the project doesn't fit my needs, then I will put both pairs up for sale. I will keep you updated. Cool?

[Drummerboy2]

Not too sure about MTM idea in your situation...

pos, Yes, That would be interesting to try. But, two 10" mids would be I think a little too much for my room/s. If I had a bigger room, then this may be something I would like to try. I think the 4345 cab with all drivers would be the biggest size I would go for the room size I have.

[Ian Mackenzie]

No worries

[pos]

pos, Yes, That would be interesting to try. But, two 10" mids would be I think a little too much for my room/s. If I had a bigger room, then this may be something I would like to try. I think the 4345 cab with all drivers would be the biggest size I would go for the room size I have.
Sorry if I was not clear enough: I don't think MTM is a good idea with these drivers, as the C-C distance between the two 2123H would be far too high for the considered crossover frequency.

[Ian Mackenzie]

http://www.diyaudio.com/forums/multi-way/178945-dappolito-design-questions.html

It’s a case by case thing if you actually build one

That said the presentation is not traditional

[Ian Mackenzie]

Those Beyma drivers are quite expensive do take your time

[Drummerboy2]

Those Beyma drivers are quite expensive do take your time

I had a pair of ESS AMT-1D's back in the early 90's. These were really nice sound except that the 12" woofers and passive radiators were the weak links. I always missed the Heil Transformer upper end.

I'm still waiting for these to show from ups, there was a mechanical break down some where according to their website and so I have to wait a little longer for delivery. Yes, I will definitely take my time with them and my project. I saw a post on another thread you had mentioned about using the proper driver instead of subs. So I did take notice and put that in my file. :)

Thanks for the link in the other post.

[Drummerboy2]

Those Beyma drivers are quite expensive do take your time

The Beyma TPL-150's came in today. These are some very nice top quality built drivers. I will try to post some pics tomorrow. Now I just have to order the caps from Erse for the 4344 MKII xovers.

[berga12]

don't do 4344 crossover, do custom crossover....this beyma have to work down to 1000-1500hz, not above....you just waste a beautiful sounding tweeter in this case...

[berga12]

some example:
http://www.audiodesignguide.com/HiEff/HiEff2.html

another example on a 3 way http://www.audioheritage.org/vbulletin/showthread.php?34338-2245-active-3-way/page2

[gdmoore28]

Hi Drummerboy-

I'm following your project with interest. I'm not a JBL guy, so I have to drag slowly thru the dizzying array of 22__ this and 22__ that model numbers! Somebody needs to print a scorecard.

Anyway, having almost zero experience in JBL components (other than installing a hundred of their cabinets when I worked in ProSound), I won't be chipping in with advice.

I have had experience with the MCM woofer that you originally intended to use. It is a well built and good sounding speaker, but don't believe the specifications that MCM publishes. Several purchasers have done their own TS specs on those drivers, and they tend to be way off as published. Especially in sensitivity ratings. So, if you decide to use them as you get your JBL woofs lined up, be sure to measure them in your woofer program.

So, that will be my total contribution here, but I am looking forward to watching your build progress. Hang in there, buddy, and don't let the naysayers get under your skin. Proceed with confidence and joy. :) :)

GeeDeeEmm

[Drummerboy2]

don't do 4344 crossover, do custom crossover....this beyma have to work down to 1000-1500hz, not above....you just waste a beautiful sounding tweeter in this case...

Hi berga12, I do have a custom xover for these three drivers as a back up. When I was doing the xovers the software showed there was a big dip around the 1khz. I'm sure I can do a notch filter to smooth out that dip. Thank You for the info and advice.

[Drummerboy2]

Hi berga12, I do have a custom xover for these three drivers as a back up. When I was doing the xovers the software showed there was a big dip around the 1khz. I'm sure I can do a notch filter to smooth out that dip. Thank You for the info and advice.

here some pics of my new Beyma's. I apologize for the pics being upside down. My ipad does this every so often.

[Drummerboy2]

Hi Drummerboy-

I'm following your project with interest. I'm not a JBL guy, so I have to drag slowly thru the dizzying array of 22__ this and 22__ that model numbers! Somebody needs to print a scorecard.

Anyway, having almost zero experience in JBL components (other than installing a hundred of their cabinets when I worked in ProSound), I won't be chipping in with advice.

I have had experience with the MCM woofer that you originally intended to use. It is a well built and good sounding speaker, but don't believe the specifications that MCM publishes. Several purchasers have done their own TS specs on those drivers, and they tend to be way off as published. Especially in sensitivity ratings. So, if you decide to use them as you get your JBL woofs lined up, be sure to measure them in your woofer program.

So, that will be my total contribution here, but I am looking forward to watching your build progress. Hang in there, buddy, and don't let the naysayers get under your skin. Proceed with confidence and joy. :) :)

GeeDeeEmm

gdmoore28, Thank You for the heads up and info. This is the info I was looking for. I will look into this. Hopefully they are not too far off in the dbs as their specs say. I have read that these MCM 55-2963's do sound pretty good after a long break in period. I wanted to share the link where a fellow did a basic Clone of a 4350 or 4355 cab with these drivers and said they were really nice but I can't find the link now.

[gdmoore28]

I wanted to share the link where a fellow did a basic Clone of a 4350 or 4355 cab with these drivers and said they were really nice but I can't find the link now.

I've seen the project you are referring to and was impressed with the job he did in making the JBL clones. Doing a project like that is not only fun, but can only increase your knowledge of speaker building. I know that JBL purists may be a little offended at the copy-catting, but I think it's a cool alternative, and especially when $$$$ is tight. Looking forward to your progress.

By the way, those Beyma drivers are fantastic according to their tech sheets and to those who have used them. Looking forward to your impressions.

GeeDeeEmm

[dino]

Welcome to the Lansing form.
As you can read we have some hard core jbl enthusiasts on this site. But pretty much know their shit!!! You were better off using the jbl 2245h woofers paired with the jbl midrages than added the Beyma TPL-150. Which is a fantastic hf driver. I have a 3way set up using all Beyma drivers. But this is not the site to ask question on a custom build on other drivers than jbl,altec.if you surf the web you can find a bunch of project using the Beyma tpl-150. There is a posting here somewhere about a 3way build using jbl 2245h- 2118-and a Beyma tpl-150h. Maybe you can use some of the info to help yourself on your build

[dino]

I am using the Beyma tpl-150H
Beyma 10 mid
Beyma 18 woofer
Beyma tpl is cross over at 1.5kh

[Drummerboy2]

I am using the Beyma tpl-150H
Beyma 10 mid
Beyma 18 woofer
Beyma tpl is cross over at 1.5kh


Nice job! I can just imagine how they sound!

[Drummerboy2]

Welcome to the Lansing form.
As you can read we have some hard core jbl enthusiasts on this site. But pretty much know their shit!!! You were better off using the jbl 2245h woofers paired with the jbl midrages than added the Beyma TPL-150. Which is a fantastic hf driver. I have a 3way set up using all Beyma drivers. But this is not the site to ask question on a custom build on other drivers than jbl,altec.if you surf the web you can find a bunch of project using the Beyma tpl-150. There is a posting here somewhere about a 3way build using jbl 2245h- 2118-and a Beyma tpl-150h. Maybe you can use some of the info to help yourself on your build

dino, Thank You for the advice/info. I will look it up.

[dino]

Thanks. Good luck with the new speaker project

[Drummerboy2]

Thanks. Good luck with the new speaker project

Here are the 2245H's I was talking about that need repair. The one that is showing the back seem ok. The other has a crushed dust cap and is rubbing when you gently push down on it, so this is the one that may need a reconing kit.

I will try to post some pics of the 2123's I have.

[speakerdave]

They don’t look like 2245 cones. Maybe 2240.

[Drummerboy2]

They don’t look like 2245 cones. Maybe 2240.

Why is that? due to the color?

[speakerdave]

Why is that? due to the color?


They have that stiff double half roll surround which is typical of SR woofers like the 2240: high FAR, no low bass. 2245's have a foam surround and a cone weighted with aquaplas.

[Drummerboy2]

Hello all, here's and update to what I have done. I know it's been a while but I was laid off again and had to wait for awhile to get the funds for these drivers, horns and lenses. Today I was able to buy some JBL 2420's and 2307's in excellent condition, I also bought some Kenrick 2308 lenses to go with my 2245H's and 2123H's. So I'm just missing the JBL 2405's for the supper tweeter. If I can't find any the Beyma version will work but I want the original JBL's.

I will be gathering the parts next for the Xovers for the 3435 II's while I wait for the woofer to be reconed along with any other parts for the cabs.

[Ian Mackenzie]

Just be aware the Beyma slot has lower sensitivity than the 2405H.

Try Jammin Jersey in Northridge CA

[Drummerboy2]

Just be aware the Beyma slot has lower sensitivity than the 2405H.

Try Jammin Jersey in Northridge CA

I went to the website but it looks like its no longer a working website. I will call the number tomorrow that came up in a search.

[Ian Mackenzie]

https://jamminjersey.com/detail/007490/jbl-2405h-ceramic-magnet-slot-tweeters

Click on the link and you can email Mark Leonard. I bought a large shipment recently and it was well organised.

[Drummerboy2]

https://jamminjersey.com/detail/007490/jbl-2405h-ceramic-magnet-slot-tweeters

Click on the link and you can email Mark Leonard. I bought a large shipment recently and it was well organised.

Ian, Thank You. I placed the order today for the 2405H's. once I receive these, I will have all the JBL drivers to start the build. I also picked up some foilcals for the my project. I just need the pot covers for the pots to look like the originals. I now need to pick up some more wood for the cabs, I already have half of it.

I dropped off the the 2245H's woofers yesterday to Upland Speaker repair to be reconed. So once I get these back I will send the 2123H's in to him to be works on as well (the one I accidently messed up while unpacking it).

[Ian Mackenzie]

No worries,

I might ask you to return a favour at some point.

[macaroonie]

Is it just me or have 2405 prices skyrocketed lately. 077s even more so.

[Ian Mackenzie]

Yes. Particularly if searching for them in EBay. And you don’t know what condition they are in.

From Jammin Jersey they check everything and tell you if it’s original diaphragms etc. l am saying this on experience with a large shipment of drivers. Everything was double boxed and carefully packed. We also have Edgewound who can pretty much repair or re build most things. His work is exceptional.

[Drummerboy2]

Today I bought some speaker mounting kits for the 2245H's. So now I just need to find a source for the knobs for the L-pads. The one's I'm finding are expensive, the cheapest are $69 for 4.

[Ian Mackenzie]

Try Parts Express

[Drummerboy2]

Try Parts Express

I went there but nothing. I did find an old thread that had some that looked like the originals over on the EHC website.

http://www.ehcknobs.com/index.php?id=PO

I need to call them tomorrow and see if I can buy them and what the min purchase quantity is.

[Drummerboy2]

No worries,

I might ask you to return a favour at some point.

No Problema! :)

[Drummerboy2]

Here are some pics of mine JBL 2420 with 2307 horns. They are in really good condition except for the circle type scratches on one of them. If it wasn't for those scratches these would have been in mint condition.

They also measured 6.0 ohms for one and 6.2 ohms for the other. These were said to come out of a working cab. The only other issue is the push button speaker post were loose, so I just tighten them up. I already ordered the 16 ohm replacement diaphragms, so these should be here by Friday.

So now I'm just waiting on the 2405s to come in next, maybe late this week or early next week.

All seems to to be coming along pretty smoothly for now, hopefully it continues that way.

[Ian Mackenzie]

They are nice

[Drummerboy2]

Hello, I had this info on my laptop but it died on me a year ago. I can't locate any info for the original JBL 4345 raw driver impedances. I just want to make sure that the 2420 and 2405 are what they are supposed to be. What I have is the 2420 is 16 ohms on the label but they measure 6.0 and 6.2 ohms, so this would be the 8 ohms. I have already order the 16 ohms diaphrams to match the label on the 2420 driver's. I haven't received the 2405's yet so I don't know if they are 16 or 8 ohms.

All the 4345 network schematics I have seen here show the drivers I have and a few that show 8 ohm pots which lets me know those are 8 ohm drivers being used for those networks, but can't find any original 4345 network schematics with the driver's impedance.

Was there any 4345 crossover networks that used 16 ohm drivers for the 2420 and 2405? I want to make sure before I place orders for NEW replacement diaphrams on the 2405's. Thanks!

[Ian Mackenzie]

It’s a first world problem with building these vintage systems.

To explain the actual measured ac impedance of the nominal 16 ohm drivers is around 12 ohms.

The dcr as l recall is around 6-7 ohms.

The newer compression drivers with titanium diaphragms are/were available in a 8 ohm labelled impedance. The dcr on those is around 3-4 ohms.

The 2405 has a measured impedance of about 10 ohms
Jbl approach to labelling impedance has always created impedance.

Looking at the 3145 networks there is a 20 ohm resister across the compression driver. This has the effect of making the drive look like an 8 ohm load for the 8 ohm L pads.

You most likely have the right diaphragms. If the compression driver was in fact a Jbl marked 8 ohm version just leave out 20 ohm resister.

[Drummerboy2]

It’s a first world problem with building these vintage systems.

To explain the actual measured ac impedance of the nominal 16 ohm drivers is around 12 ohms.

The dcr as l recall is around 6-7 ohms.

The newer compression drivers with titanium diaphragms are/were available in a 8 ohm labelled impedance. The dcr on those is around 3-4 ohms.

The 2405 has a measured impedance of about 10 ohms
Jbl approach to labelling impedance has always created impedance.

Looking at the 3145 networks there is a 20 ohm resister across the compression driver. This has the effect of making the drive look like an 8 ohm load for the 8 ohm L pads.

You most likely have the right diaphragms. If the compression driver was in fact a Jbl marked 8 ohm version just leave out 20 ohm resister.

Ok, so lets see if I got it.

2420 with 8 Ohm diaphrams (measure 6.0-7 Ohms) remove the 20 Ohm resistor from the network?
2420 with 16 Ohm Diaphrams (measure 12 Ohms) leave the 20 Ohm resistor in?

Does this rule still apply if I want to use the "Super 3145" network?

Thank You for all the help!

[Ian Mackenzie]

Ok, so lets see if I got it.

2420 with 8 Ohm diaphrams (measure 6.0-7 Ohms) remove the 20 Ohm resistor from the network?
2420 with 16 Ohm Diaphrams (measure 12 Ohms) leave the 20 Ohm resistor in?

Does this rule still apply if I want to use the "Super 3145" network?

Thank You for all the help!

If you are referring to measured impedance YES and YES (referring to charge coupled I assume)

The thing to understand is that a multi meter will only give you a dead or alive resistance which is always much lower than the actual AC impedance of the driver. Its only possible to measure the impedance with Clio or the Dayton Dtas or LMS.
JBLs labelling conventions and polarity conventions have always caused confusion so don't stress.

[Drummerboy2]

If you are referring to measured impedance YES and YES (referring to charge coupled I assume)

The thing to understand is that a multi meter will only give you a dead or alive resistance which is always much lower than the actual AC impedance of the driver. Its only possible to measure the impedance with Clio or the Dayton Dtas or LMS.
JBLs labelling conventions and polarity conventions have always caused confusion so don't stress.

Thanks, for the help and info. I wasn't really stressing, just wanted to make sure I didn't have to do anything else if the driver impedance wasn't correct. So now I think I have a better understanding of this network and drivers. so I can concentrate on ordering the network parts and can start build them while waiting for other items to come.

I still need to receive my 2405's from Jammin Jersey. Once this is in I can start on the Front baffles and making everything is measured correctly before I start on the cabs. I still need the knobs like the originals and get some L-Pads. I'm seriously thinking of doing the external Xovers for these speakers.

Things will start to slow down on this build due me starting a new job on Monday. So hopefully I can do a little at a time.

[Drummerboy2]

Today I opened up the 2420 CD's to check them out. I found that they had different driaphrams as you will see in the pics, but that wasn't all I found. The one diaphram that looks after market was damaged. Good thing I bought the replacements. The foam was a little bad on one more than the other.

here's the pics:

[grumpy]

Foam looks pretty typical. The broken dia just looks original and busted. The other could be from a 2421 (Al) or 2425/6 (Ti).
Good time to refresh the insides :)

[Drummerboy2]

Foam looks pretty typical. The broken dia just looks original and busted. The other could be from a 2421 (Al) or 2425/6 (Ti).
Good time to refresh the insides :)

really? I thought the diamond shaped suuround of the diaphrams was the original one and the broken was after market. If you look closely the foam that was covering the damaged diaphram says it all. Look at how the wire that connects the diaphram to the cover is going over the diapram so when it was screwed down it was resting on the edge of the diaphram, it's imprinted on the foam perfectly.

The seller want to refund the amount of the diaphram which is cool. Everything else is in good shape.

I guess when I replace the diaphrams in both it will be a good idea to use some masking tape and fold it with the sticky side outside and run it through the gap where the voice coil is inserted to pick up any loose particles that may rub on the new diaphram.

Ok, the foam looks like that normally for it's age. I will be careful not to dislodge any more of it. It would be great to replace it with newer type of foam.

[rogerjulien]

Take the chance and get some
https://www.parts-express.com/radian-1225-16-diaphragm-fits-most-jbl-1-16-ohm--294-722
those are quite good.
The dia with the diamonds is the newer type, often titanium.
The turbine pattern is the old and aluminum.
Replace in aftermarket is also "Altec 604 802 804 806 808 904" on ebay but they look like titanium and the turbine pattern goes the other way round.

Foam is sticky and will fall apart by touching it, any open foam or felt will do,
just to upsorb backward reflection.

[GUYGELLA]

8 ohm version:

https://www.parts-express.com/radian-1225-8-diaphragm-fits-most-jbl-1-8-ohm--294-720




Take the chance and get some
https://www.parts-express.com/radian-1225-16-diaphragm-fits-most-jbl-1-16-ohm--294-722
those are quite good.
The dia with the diamonds is the newer type, often titanium.
The turbine pattern is the old and aluminum.
Replace in aftermarket is also "Altec 604 802 804 806 808 904" on ebay but they look like titanium and the turbine pattern goes the other way round.

Foam is sticky and will fall apart by touching it, any open foam or felt will do,
just to upsorb backward reflection.

[toddalin]

The seller want to refund the amount of the diaphram which is cool. Everything else is in good shape.




Have you any idea what an original tangential diaphragm would cost..., if you could even find one?

Tell the seller that the damaged diaphragm would cost as much/more than you paid for the driver(s) so actually, if he wants to make good, he should give you a complete refund, at least for the one. ;)

BTW, I have an original aluminum 2421 (aluminum diamond surround) sitting in the closet that I was able to find an original tangential diaphragm (that had been mislabled) replacement. This is in my center channel and my mains have the tangential diaphragms so I was extremely jazzed to find this one..., and for only $65.

The seller had it in a 2425 box and listed it as a 2425. I figured someone blew out a 2420, replaced the pair, and stuck the good one in the box..., which was the case. :D

Right after the sale, I got a message from the seller saying that there had been a mix-up, and this was not a 2425 diaphragm, and I could cancel the sale if I wanted. Yeah..., Right!

I think he figured it out and recognized the true value. (Perhaps hundreds of $$$, or more, to the right buyer.)

[Drummerboy2]

Take the chance and get some
https://www.parts-express.com/radian-1225-16-diaphragm-fits-most-jbl-1-16-ohm--294-722
those are quite good.
The dia with the diamonds is the newer type, often titanium.
The turbine pattern is the old and aluminum.
Replace in aftermarket is also "Altec 604 802 804 806 808 904" on ebay but they look like titanium and the turbine pattern goes the other way round.

Foam is sticky and will fall apart by touching it, any open foam or felt will do,
just to upsorb backward reflection.


Yes, I had already purchased the Radian 1225-16's a while back when I had purchased the 2420's just incase. Glad I did.

[Drummerboy2]

Take the chance and get some
https://www.parts-express.com/radian-1225-16-diaphragm-fits-most-jbl-1-16-ohm--294-722
those are quite good.
The dia with the diamonds is the newer type, often titanium.
The turbine pattern is the old and aluminum.
Replace in aftermarket is also "Altec 604 802 804 806 808 904" on ebay but they look like titanium and the turbine pattern goes the other way round.

Foam is sticky and will fall apart by touching it, any open foam or felt will do,
just to upsorb backward reflection.


Thank You for the info on the foam. I just need to find some new foam and then remove the old foam. Just one more thing to do but I was already ready for this. LOL!

[Drummerboy2]

Today my JBL 2405H super tweeters came in. They do show some signs of wear and are missing the JBL model decals but are in good condition.

[Drummerboy2]

Here are my Kenrick Lenses.

[Drummerboy2]

I'm planning on replacing the diaphragms in my JBL 2420s this weekend and wanted to know what is the proper procedure for doing this. I have never done this before on a CD and don't want to make a mistake and cause them to accidentally rub.

Anyone here have any suggestions on how to do this?

I have brand new Radian 16 ohm diaphragms.

Im still looking for some foam for the back cap. Kendrick had some but we're really expensive for the two.

Thanks.

[toddalin]

I would suggest that you be very careful handling the "horseshoe" clips. While they are silver grey in color, they are ferrous and will be drawn toward the magnet, right though the diaphragm, and leave a pair of "vampire bite" marks in your diaphragm.

This is a very common mistake and you see these "bites" all the time.

[Drummerboy2]

I would suggest that you be very careful handling the "horseshoe" clips. While they are silver grey in color, they are ferrous and will be drawn toward the magnet, right though the diaphragm, and leave a pair of "vampire bite" marks in your diaphragm.

This is a very common mistake and you see these "bites" all the time.

Wow, I didn't know that! Thank You for the info! Glad I asked here!

I did find an older thread about felt for the back cap, there was a link to McMaster-Carr for that item. I ordered it just a few mins ago.

I'm slowly getting there with my parts and repairs!

[grumpy]

Another alternative in an adjacent/current thread:

http://www.audioheritage.org/vbulletin/showthread.php?41755-Replacement-diaphragm-options-for-2425J&p=430265&viewfull=1#post430265

[Ian Mackenzie]

I'm planning on replacing the diaphragms in my JBL 2420s this weekend and wanted to know what is the proper procedure for doing this. I have never done this before on a CD and don't want to make a mistake and cause them to accidentally rub.

Anyone here have any suggestions on how to do this?

I have brand new Radian 16 ohm diaphragms.

Im still looking for some foam for the back cap. Kendrick had some but we're really expensive for the two.

Thanks.

If you have no experience then get a professional technician to do it like our Edgewound at Upland loudspeaker repairs. It’s not as simple as it might seem and to do the job properly requires cleaning out the magnetic gap and careful centering of the diaphragm with test equipment.

The Radian diaphragms are designed to be a drop in replacement for the Jbl diaphragms. The motional impedance curve a similar so it should work in with the crossover okay. There may be some response variations however so expect to hear some subtle differences.

On my do to list is to measure a radian diaphragm and work out any crossover tweaks required for the popular legacy systems.

https://m.facebook.com/UplandLoudspeaker/about

http://www.audioheritage.org/vbulletin/showthread.php?22039-JBL-D8R2425-Diaphragm-Replacement-for-JBL-2426H-Compression-Driver

[Drummerboy2]

If you have no experience then get a professional technician to do it like our Edgewound at Upland loudspeaker repairs. It’s not as simple as it might seem and to do the job properly requires cleaning out the magnetic gap and careful centering of the diaphragm with test equipment.

The Radian diaphragms are designed to be a drop in replacement for the Jbl diaphragms. The motional impedance curve a similar so it should work in with the crossover okay. There may be some response variations however so expect to hear some subtle differences.

On my do to list is to measure a radian diaphragm and work out any crossover tweaks required for the popular legacy systems.

https://m.facebook.com/UplandLoudspeaker/about

http://www.audioheritage.org/vbulletin/showthread.php?22039-JBL-D8R2425-Diaphragm-Replacement-for-JBL-2426H-Compression-Driver

Seems like I will just need some masking tape to clean out the gap where the voice coil goes in and a Oscillator for a curtain frequency to make sure there is no buzzing? correct? If there is buzzing just slightly tap on the diaphragm surround mount til buzzing stops? Correct?

[Ian Mackenzie]

You need a reasonable signal voltage which l don’t recall off hand and sweep oscillator and a power amp. Ideally an oscilloscope to evaluate the sine wave. Also ear muffs.

One slip of the screw driver and it’s game over.

If l were you l would ask Edgewound to do it.

[grumpy]

IF dead set on DIY, here's some old man ranting for you:

You may also need to open up the holes slightly on the diaphragm 'frame' and/or put a -slight- bevel/relief on the outside of the frame where it meets the top plate... to allow for more -minor- adjustments (ONLY if needed).

Tech Manual calls for 2.83v input 550-1.2KHz, but is slim on details like... is that RMS, peak, peak-to-peak and with the driver 'loaded' (horn attached) or hanging in the breeze (on the low end of the frequency range in particular). I'd keep it below 2v p-p regardless, working your way up from much less.

Do you have a way to measure this? A -normal- Digital voltmeter will not likely give you a good reading at higher audio frequencies (often calibrated for 60Hz). An oscilloscope would be good...using it properly, better. Along with hearing protection (as has been noted), and tolerant family/neighbors.

Hearing the distortion of a voice-coil barely touching does take some experience (other times it's quite obvious). Then there's the phase plug to diaphragm spacing... probably other things I'm not thinking of.

All that said, sometimes you get lucky (or are ok with it being non-optimum). Have a way to measure on-horn frequency response later?

Mostly, if the process does not go so well and something is damaged, you have ZERO remedy, but maybe gained some experience.

It may sound like I'm leaning toward a recommendation of leaving it to the pros (as most should)... but if you have the time, interest, and can afford to make a few mistakes, have at it! :)

(is there an emoji for getting off of a soapbox?)

[Drummerboy2]

You need a reasonable signal voltage which l don’t recall off hand and sweep oscillator and a power amp. Ideally an oscilloscope to evaluate the sine wave. Also ear muffs.

One slip of the screw driver and it’s game over.

If l were you l would ask Edgewound to do it.

I will talk with Ken when I pick up my 2245H that he is doing.

thanks

[Drummerboy2]

IF dead set on DIY, here's some old man ranting for you:

You may also need to open up the holes slightly on the diaphragm 'frame' and/or put a -slight- bevel/relief on the outside of the frame where it meets the top plate... to allow for more -minor- adjustments (ONLY if needed).

Tech Manual calls for 2.83v input 550-1.2KHz, but is slim on details like... is that RMS, peak, peak-to-peak and with the driver 'loaded' (horn attached) or hanging in the breeze (on the low end of the frequency range in particular). I'd keep it below 2v p-p regardless, working your way up from much less.

Do you have a way to measure this? A -normal- Digital voltmeter will not likely give you a good reading at higher audio frequencies (often calibrated for 60Hz). An oscilloscope would be good...using it properly, better. Along with hearing protection (as has been noted), and tolerant family/neighbors.

Hearing the distortion of a voice-coil barely touching does take some experience (other times it's quite obvious). Then there's the phase plug to diaphragm spacing... probably other things I'm not thinking of.

All that said, sometimes you get lucky (or are ok with it being non-optimum). Have a way to measure on-horn frequency response later?

Mostly, if the process does not go so well and something is damaged, you have ZERO remedy, but maybe gained some experience.

It may sound like I'm leaning toward a recommendation of leaving it to the pros (as most should)... but if you have the time, interest, and can afford to make a few mistakes, have at it! :)

(is there an emoji for getting off of a soapbox?)

I have all the test equipment to do it but I will talk with Ken about these when I pick up my 2245Hs he is doing.

[Ian Mackenzie]

Good plan

[grumpy]

:thmbsup: Ken's a good guy. Hope it all comes together.

[Ian Mackenzie]

Absolutely

The whole job is only as good as your drivers so it’s worth getting them right.

[Drummerboy2]

Ok fellas, I'm back to report I got both my 2245H reconed and my 2420H horns repaired with new Radian Diaphragms by Ken @ Upland. Ken did a great job on both and now I can get back to my JBL 4345 build.

[Ian Mackenzie]

That’s great news