Requesting advice on a JBL 4675C system

Hi, This is my first post, I think. I've perused many threads and deeply appreciate the valuable, collaborative trove of information you have created. My situation: I recently lucked into what I think is a stock JBL 4675C pair at a modest price. 4638TH cabs with two 2035HPL woofers each, 2446H on 2360 horns (no labels), stands, N4638 networks, fine condition, except one woofer had been swapped for an aftermarket driver in 2000 (as chalked on the outside of the cone), and a local speaker technician/sound guy who is helping me has identified a defunct 2035HPL in the other cabinet. We have not checked yet for original diaphragms but will - it seems likely. Even given the flaws, the large-scale sound is the first to command the 8000 cubic foot space of my artist's studio, with which I've struggled for years - the space makes my Klipsch CF-3s sound small. The "wall of sound" effect can keep me going on my elliptical. My studio is basically the size of two double garages stacked: 20' x 22' with several open doorways and a cathedral ceiling that is 16' to the peak, of acoustic metal panels (millions of holes). My "listening position" is generally about 16' away, along the opposite wall from the 4675s, where I work on large murals. I know this is close for these long-throw horns. Sometimes I can wheel whole sections around to face the sound better and will be around 14 feet away. Music only, mostly. My goal is the best SQ I can achieve, before the cost makes it more logical to look for a better, newer system for the space. I'm guessing that upward limit is around 4-5K max. My questions for any esteemed cognosenti who may be reading: which of the following replacements/upgrades seem promising for improved SQ? I'm looking for frequency extension, accuracy, coherence, easy-flowing musicality - and whatever the opposite of "glare" or "hard" is. Music: alt rock, folk, jazz, classical, blues, R&B. I have an Ashly ftx-2001 series iii mosfet power amplifier for the lows and decent tube amps for the rest.

1. I think the 2035HPLs were value-engineered down from the original 4675's 2226 drivers, which have larger (4")voice coils. Would four good 2226s bring a leap in SQ? Or something more modern?
2. Are active crossovers virtually a no-brainer here for best SQ? I don't have one but can acquire and learn.
3. I understand Radian aluminum diaphragms can improve the slightly "hard" sound I hear from the CDs, yes?
4. I can't get berylium or the TAD 4002, but I can obtain the newer Celestion Axi2050 drivers. Anyone tried them on the 2360 horns? I've read about the downsides of diffraction slots and the upside of K-402 horns. Financially the K-402s are perhaps a bridge too far.

Any advice or suggestions you can offer will be deeply appreciated! Thank you for reading.

2226's would be upgrade to 2035's.

Ron sends...

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Originally Posted by spkrman57

2226's would be upgrade to 2035's.

Ron sends...

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Thanks, yes. that's my understanding too. I did not know if using the full bore 2226 x4 in a smaller-than-cinema-sized room might be overkill, but I've read some home users like the sound better.

I don't think your horns are "the problem". Upgrading the compression drivers or at least the diaphragms will help with the "hardness"... not sure how you can do this economically though.

As for frequency extension, you will likely need to add subs and super tweeters. If you have DSP control and don't play back very loudly you can probably lower the output throughout the mid band to effectively extend the top and bottom, but I haven't tried it with these speakers so this is purely a theoretical notion.


Widget

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Originally Posted by Mr. Widget

I don't think your horns are "the problem". Upgrading the compression drivers or at least the diaphragms will help with the "hardness"... not sure how you can do this economically though.

As for frequency extension, you will likely need to add subs and super tweeters. If you have DSP control and don't play back very loudly you can probably lower the output throughout the mid band to effectively extend the top and bottom, but I haven't tried it with these speakers so this is purely a theoretical notion.


Widget

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Great advice, thanks. I rarely exceed about 85 db and use meters to check when the studio is rocking. (Maybe that's why I love the large scale sound - it makes it seem louder and more powerful than it really is). The speakers are crossed at 630. I figured at those levels I was not exciting some of the issues people have sometimes reported. Yes, compression driver options are not economical; I also assumed going in that the right CD/diaphragm and the right DSP technology is maybe the best place to invest the available funds. I've read about the various diaphragm options and beryllium is so expensive and hard to get it makes the Celestion Axi2050 attractive. Can anyone comment from experience if those delivered a substantial improvement over simply switching to aluminum or aguaplas diaphragms? I've read varying experiences. Maybe I must be the guinea pig for the combining them with the 2360 horns.

Hello Skyhorn;

Welcome to Lansing Heritage. :)

For the record I don’t have your LH boxes but have the double 18’s (4719?) and have 2360’s that have had a multitude of drivers on them.

It will be difficult to really know what you think about the horns/drivers until you get the system in balance. With one mystery woofer and another dead? that may likely have the frequency response tilted up in the HF if the LF is not doing it’s share.

Also these are voiced to play through a perforated projection screen so they are likely HF upward tilted anyway as screens affect the high frequency more.

Woofers first. If you are you going to buy woofers, the 2216Nd’s just can’t be beat, for the money.

The boxes are tuned to 40Hz so they won’t have much output below that. If you only play up to 85 dB SPL measured on a slow average the demands on the woofers isn’t much unless you EQ them a ton on the bottom. Also at that level you likely won’t drive the ports into nonlinearity if you plug one each. This should push the tuned frequency of the box into the low 30’s and they might (I bet) sound better to you.

2360’s in my opinion are one of the best sounding diffraction horns. I like them quite a lot. Being a 90 degree horn they behave well in domestic settings and are very listenable up fairly close. Since they are a constant directivity horn they require a lot of very high frequency energy from the compression driver. In my opinion the diamond surround Ti diaphragms sound the best in these horns. Aluminum has a slightly subdued high end and on many horns are nicer to listen to but when used on one of these big CD horns you have to EQ them up even more than Ti and I think they then sound strained and overall worse.

The SL diaphragms are the best compromise on these horns I believe. No matter what you drive them with the 2360’s have some resonance about 12.5 kHz and a UHF tweeter is really the only way to get away from that issue if it bothers you.

I think it would be worth exploring the health of the 2446’s to be sure they are all they are supposed to be. Chinese diaphragms have abysmal frequency extension and even the Ti diaphragms get fatigued and with all the fussing around with them you can do the beat ones will not perform. It really takes frequency and distortion measurement equipment to be sure.

You wouldn’t need a ton of DSP for these. Do you have an idea there or did I miss that?

If you get these right they should sound pretty damn good and rock the shop.

Barry.

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Originally Posted by 1audiohack

Hello Skyhorn;

Welcome to Lansing Heritage. :)

Barry.

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Hi Barry,

Thank you very much for taking the time to write out your detailed recommendations and thoughts - they are all extremely on target and helpful to me and I believe they will save me enormous time and confusion. Among other things, it helps nail down which changes is I should move on now and which can can wait a bit. And a few things that are free, like plugging one port, together with a very clear explanation why it could work in this situation! You sent so much excellent and timely advice in this post.

I am delighted to hear your enthusiasm for the 2360 horns and Ti drivers - and for the whole package. Crippled or not, they are beautiful, fire breathing dragons. I did have three working 2035s in the cabs when I fired them up, BTW, having borrowed one from a 3677 I have on hand. But you are so right about getting them up to snuff before making any judgments. My technician will service the 2446 shortly. I should be able to get the SL diaphragms to have here in time.

I've read about the 2216NdÂ’s but thought they were basically unobtanium. Just yesterday I stopped short of acquiring a matched quad of 2226's I found online (since I can use the three 2035's that work in three other smaller speakers (including the 3677) that mysteriously followed the dragons into my studio that same week, - all on their own, I swear). I stopped because I could not decide what to do in this wilderness of driver options. That is when your post arrived. It sent me back to the computer, and I see that the 2216Nd-1's are maybe available as non-replacement items from JBL. I sent an inquiry to Speaker Exchange on pricing. Do you see any reason the newer version might not work? Of course. the cost may be like buying the lower half of a pair of 4367Â’s.

When I said DSP I probably should have said "active crossovers." I'm non-technical and I am hazy in this area. I've read that going active sounds better than the stock N4638 crossovers, though in an artist’s studio simpler is definitely better. But I thought active crossovers might be more flexible when changing out four 15” drivers for more modern ones. I am in no way qualified to measure and design new crossovers myself.


These cross at 630 dB, I believe.


Anyway, thanks again, truly - you made my day.



- William

The JBL 2216ND-1 woofers are available new as non-replacements. They are about twice the cost of new 2226's. This does not seem unreasonable for the latest and most advanced technology, especially given everything Barry and others say about them. Assuming I will use active crossovers, and that I can modify the cab/port sizes if necessary, they seem ideal. Does anyone see any issues with upgrading a 4675C system with JBL 2216ND-1 woofers? Thanks!

FYI, the JBL 2216ND-1 woofers have become hard to get from JBL - they only had two available. However, the 2216ND are currently in stock and on sale at The Speaker Exchange.