Power amp for jbl 4343

[Goldjazz]

Hi im looking at power amps for a pair of 4343s


They are Yamaha Bx-1 Monoblocks. Putting out 100w pure class A each. Will this be sufficient power? Ive read elsewhere that min 300w is desirable for 4343s

http://audio-heritage.jp/YAMAHA/amp/bx-1.html

Alternatively I can wait a while (quite a while) and eventually go for these...

Exclusive M5 monoblocks. 300w each.

http://audio-database.com/PIONEER-EXCLUSIVE/amp/m5-e.html

Thanks.

[BMWCCA]

All I know is what I know. :dont-know:

I've been bi-amping a pair of 4345s for several years now using one Crown PS-400 and one PS-200 and an Ashly XR1001 crossover. I can't imagine needing any more power and I can play them far beyond any reasonable volume level without even flickering the amps' IOC lights with perfectly clear sound. The PS-400 is rated at 190 WPC @ 8-ohms or 660 in bridged mono. I have enough amps to run one bridged on each side but I don't see why I'd want to. Maybe some day I'll give it a try. I also have a Crown Studio Reference-II, rated 355-WPC I've yet to try.

JBL says the maximum power input for the 4343 is 75-watts top and bottom if bi-amped (75 watts for single) and recommended amplifier power is 150-watts per channel. For my 4345s JBL recommends max 200-watts on the bottom using a 400-watt amp and 100 on the top with a 200-watt amp. I guess I'm not giving them as much as I could, but I'm happy with what I'm hearing. I guess what I'm saying is you'll likely be pleased using what you've got, but a bit more wouldn't hurt! :D

[hjames]

I had a pair of 4341s - same drivers, slightly different box size.
I ran mine with an Adcom GFA-555 (200w/ch) later I set them up in Bi-amp mode and used a PAIR of GFA-555s ...




Hi im looking at power amps for a pair of 4343s


They are Yamaha Bx-1 Monoblocks. Putting out 100w pure class A each. Will this be sufficient power? Ive read elsewhere that min 300w is desirable for 4343s

http://audio-heritage.jp/YAMAHA/amp/bx-1.html

Alternatively I can wait a while (quite a while) and eventually go for these...

Exclusive M5 monoblocks. 300w each.

http://audio-database.com/PIONEER-EXCLUSIVE/amp/m5-e.html

Thanks.

[Goldjazz]

[QUOTE=BMWCCA;361725]All I know is what I know. :dont-know:.

JBL says the maximum power input for the 4343 is 75-watts top and bottom if bi-amped (75 watts for single) and recommended amplifier power is 150-watts per channel.

Cheers. So the 100w monos would be under power if connected in non biamped mode using the internal X over?

Ive read a lot on this forum about the benefits of biamping 4343s. So im now wondering if buying big ass monos with the intent of not biamping is a bad idea. If I invest in 300w monos and then decide I want to try biamping then I have way overkill power on the bottom and need to buy another amp for the top.

I do i have a sweet SS integrated Sansui that puts out 130wpc. So that comes close to the 150. But i was under the impression that greater power and damping factor of some big amps would yield better dynamics and tighter bass?

[martin2395]

Don't bother with such big, expensive amps. BiAamping is much more worthwile with 4343's.

I'm powering mine with Krell KSA-50 (highs) and Crown K2 is powering the woofers. Believe me 50W is plenty for the mid/high section, it's only the 2231/2235 that likes power.
The bass is also MUCH better with bi-amping, my woofers are connected directly to the K2 ;)

[BMWCCA]

While I definitely agree on bi-amping, Martin said:
Don't bother with such big, expensive amps. BiAamping is much more worthwile with 4343's.and then wrote:
I'm powering mine with Krell KSA-50 (highs) and Crown K2 is powering the woofers.I guess he's never priced a Crown PS-400 or an Adcom GFA-555. I know what a K1 goes for these days and the Krell will normally bring three-times the price of a PS-400, if not more. And the Krell weighs in at over 60-pounds. The Crown PS-400 weighs about 55 pounds and the Adcom about 34. :dont-know:

[Goldjazz]

Ok so im now going to consider a biamp approach.

Ok so I can get my hands on a jbl 5234a. See attached pic. I assume the "4343 low" text in the windows indicates 4343 cards installed.

I mentioned I have a SS integrated Sansui au10000. That puts out 130 wpc. I will use this as the pre to feed the 5234a and the power section to feed the hf of the speakers. I will then get another power amp.

I have seen some debate on what is required for the low freq power amp so im thinking 200wpc to be safe. I have an interest in vintage japanese amps so I will be looking in the accuphase, sansui, yamaha, exclusive or luxman family. Is there any compatiablity with the sansui I should consider?

So does this sound crazy? Switch the sansui to separate mode. Connect my source to the pre in of the sansui. Connect pre out of sansui to the 5234a. Connect hf out of 5234a to the power amp in of the sansui. Connect LF out of 5234a to the second power amp. Connecting the sansui speaker outs to the hf of each speaker. Connect the second power amp speaker outs to the LF of each speaker.

[robertbartsch]

I started bi-amping more than 40 years ago. Back then, big power for consumer amps was 50 watts....

Frankly, bi-amping is tricky to pull off well, so I avoid it now. It is not necessary with todays transistor amps

If I were you, I would consider 200 watts per channel the minimum.

If possible, borrow a big amp and test it out. I think you will find, 100 WPC is not a very good option.

[hjames]

Biamping is not that hard. I've done it with my 4341s, Phil has done it on his 4345s, a number of folks here have done it.
Decide if you want one of the older JBL/UREI crossovers from back in the day, or a newer adjustable active crossover like the Ashley we used,
or an even nicer piece like the Marchand crossover Dhar used in his 4345 (http://www.marchandelec.com/xovers.html)

Decide if you want to biamp horizontal or vertically, like Rolf did with his 4343s.
With vertical you would use matched amps, one for each speaker -
use left channel for Low pass leg, right channel for the high pass leg (for instance).
The claimed gain for this is less load on the power supplies when there is a peak bass moment.

Horizontal means one amp for the Low pass leg, another for the high pass leg, & they don't have to be matched.

[martin2395]

While I definitely agree on bi-amping, Martin said: and then wrote: I guess he's never priced a Crown PS-400 or an Adcom GFA-555. I know what a K1 goes for these days and the Krell will normally bring three-times the price of a PS-400, if not more. And the Krell weighs in at over 60-pounds. The Crown PS-400 weighs about 55 pounds and the Adcom about 34. :dont-know:


I was referring to the Pioneer and Yamaha gear the TS mentioned in his first post as my guess was that a pair of those Exclusive mono's would be around $3000-4000?
I must admit that I forgot about the price differences, I paid e1500 for my both amps which is around $2k.

For me, an example of a big amp was a Yamaha PC5002M and Krell 200B, both at 130 lbs each. The 50 is the smallest one except the KAV series and the KST ;) I still regret selling the Yammie, paid 550 euros for it, including servicing:banghead:

As for active xover goes, I'd look for a more modern design than the 5234/35. I had the xx35 and for me it was a bit 'meh' sounding.
The M552 was already better and the recapped BSS FDS360 sounds the best in my system.
The next step would probably be an Accuphase or Pass crosover but they are very expensive.

[georgebrooke]

Don't bother with such big, expensive amps. BiAamping is much more worthwile with 4343's.

I'm powering mine with Krell KSA-50 (highs) and Crown K2 is powering the woofers. Believe me 50W is plenty for the mid/high section, it's only the 2231/2235 that likes power.
The bass is also MUCH better with bi-amping, my woofers are connected directly to the K2 ;)
Hi,
I'm using Crown F2 and a Pass Aleph 5 ...soon to be replaced with Pass F5. I hope there F5 will support the listening levels that I need but I do expect mid/high improvement
BTW, are you bypassing the switch in your biamping?

George

[Goldjazz]

Biamping is not that hard. I've done it with my 4341s, Phil has done it on his 4345s, a number of folks here have done it.
Decide if you want one of the older JBL/UREI crossovers from back in the day, or a newer adjustable active crossover like the Ashley we used,
or an even nicer piece like the Marchand crossover Dhar used in his 4345 (http://www.marchandelec.com/xovers.html)

Decide if you want to biamp horizontal or vertically, like Rolf did with his 4343s.
With vertical you would use matched amps, one for each speaker -
use left channel for Low pass leg, right channel for the high pass leg (for instance).
The claimed gain for this is less load on the power supplies when there is a peak bass moment.

Horizontal means one amp for the Low pass leg, another for the high pass leg, & they don't have to be matched.

Cheers hjames. Sounds like Horizontal may suit me as it means i only need to buy one other amp, if the proposal i've said above is ok. I wont be able to match my sansui i would say, and I dont want to sell it. Would there be an advantage with horizontal as you could choose an amp which suits the woofers better and another that suits the HF better? e.g. higher damping factor for the woofers. Or is there no advantage vertical vs horizontal? the other advantage with horizontal is that i could get a higher power amp for the second amp and experiment with normal non-biamped with that amp as well to Rob's experience of keeping it simple.

As for the external X over. I would like to get the benefits of biamping without while maintianing the orignal sound if you know what I mean. So I wonder if the JBL/urei's would be the best with that in mind. I know nothing about the ashley's and the modern ones, but are these digital? and if so does the sampling rate etc of those then potentially become the weak link. I will generally be playing hi sample rate flacs etc through a muscial fidelity m1 dac then sending to the pre.

[martin2395]

Hi,
I'm using Crown F2 and a Pass Aleph 5 ...soon to be replaced with Pass F5. I hope there F5 will support the listening levels that I need but I do expect mid/high improvement
BTW, are you bypassing the switch in your biamping?

George

I plan to bypass it but don't want to touch it with my soldering skills. :)

[pyonc]

Ok so im now going to consider a biamp approach.

Ok so I can get my hands on a jbl 5234a. See attached pic. I assume the "4343 low" text in the windows indicates 4343 cards installed.

I mentioned I have a SS integrated Sansui au10000. That puts out 130 wpc. I will use this as the pre to feed the 5234a and the power section to feed the hf of the speakers. I will then get another power amp.

I have seen some debate on what is required for the low freq power amp so im thinking 200wpc to be safe. I have an interest in vintage japanese amps so I will be looking in the accuphase, sansui, yamaha, exclusive or luxman family. Is there any compatiablity with the sansui I should consider?

So does this sound crazy? Switch the sansui to separate mode. Connect my source to the pre in of the sansui. Connect pre out of sansui to the 5234a. Connect hf out of 5234a to the power amp in of the sansui. Connect LF out of 5234a to the second power amp. Connecting the sansui speaker outs to the hf of each speaker. Connect the second power amp speaker outs to the LF of each speaker.


I've tried both 5234A and Ashly for 4343 in biamp mode. Yea, 5234A with the factory 4343 cards, reading "4343Lo".
My impression is I hear quite good sound from the former despite its old design of the 1970s.
You could get additional sound reinforcement from Ashly by controlling its high/low buttons on the front panel.
Then you have to think about the original sonic tonality of your 4343, I think.
Our forum members rule in favor of the modern-design Ashly for good reason.
(Think about the slope difference: 5234A has 12db/octave while Ashly 24db/octave.)
So, it's up to your personal preferences whether you want to use 5234A or Ashly.
In my case, I love this vintage JBL gear for my own preferences as well as their time-tested quality.

[Goldjazz]

[QUOTE=pyonc;362676]I've tried both 5234A and Ashly for 4343 in biamp mode. Yea, 5234A with the factory 4343 cards, reading "4343Lo".

Cheers pyonc. Yeah authenticity is important to me too which is why I was considering it.

[pyonc]

[QUOTE=pyonc;362676]I've tried both 5234A and Ashly for 4343 in biamp mode. Yea, 5234A with the factory 4343 cards, reading "4343Lo".

Cheers pyonc. Yeah authenticity is important to me too which is why I was considering it.

One more fact for your reference:
Jazz cafe Basie, the most famous jazz club in Japan, uses exclusively JBL vintage gear:
SG520 preamp, SE400S power amp, JBL 2220B (woofer), JBL 375+537+512 (midrange) JBL 075 (tweeter)
And you know what? The channel dividing network is JBL 5232!
Cafe owner Shoiji Sugawara is a well known jazz critic with erudite knowledge of all kinds of expensive modern gear.
Yet he sticks to these vintage JBL gear and the active crossover 5232, though there are much better modern-design crossovers like Bryston 10B, etc.
Those who visited the club testify they feel as if jazz greats from the 1940s and 1950s just walk alive from the records
he plays on Linn, with this great JBL set-up.
Even JBL executives and chief engineer Greg Timbers reportedly were amazed at Basie's sonorous and real jazzy, even modern sound from such vintage set-up, as comparable to JBL signature Everest. Here is the link in this forum:

http://audioheritage.org/vbulletin/s...ad.php?t=12206 (http://audioheritage.org/vbulletin/showthread.php?t=12206)

[BMWCCA]

Really?? You fuss about a nearly 8 year old post from 09-11-2006, 09:47 PM ... :D

Oh I enjoyed the thread—then and now—but I obviously neglected to use enough smilie emoticons for you!! :D ;) :)

I would hardly categorize it as a "fuss". It wasn't as if he'd written harmon/killebrew. (Ahh, memories of the old Adirondack I swung as a kid.)

[Goldjazz]

Thanks for that Basie link, what a crazy cool guy that swifty seems. Amazing setup. I'm not sure if Basie club is still there, If so, I wish I knew about this place a month ago when I was in Japan. I visited a number of amazing hifi shops all over the country (including Kendrick Sound, a few Hifido and others). I listened to many different JBL's 4333's. 4343's, 4344, and a Paragon. The Paragon was the most impressive experience - sitting across from it I could feel the kick drum on hotel california inside my chest, one day I'll get one:) But I decided on a pair of 4343's, I heard a few pairs of these driven from various setups and I liked these. The one's I've bought will be a a bit of a "project" refoaming required, and probably recapping but I'm super excited, they wont arrive for several weeks. I'll certainly be calling upon this forum to help me once again as with the 4311 restoration I did.

[pyonc]

Thanks for that Basie link, what a crazy cool guy that swifty seems. Amazing setup. I'm not sure if Basie club is still there, If so, I wish I knew about this place a month ago when I was in Japan. I visited a number of amazing hifi shops all over the country (including Kendrick Sound, a few Hifido and others). I listened to many different JBL's 4333's. 4343's, 4344, and a Paragon. The Paragon was the most impressive experience - sitting across from it I could feel the kick drum on hotel california inside my chest, one day I'll get one:) But I decided on a pair of 4343's, I heard a few pairs of these driven from various setups and I liked these. The one's I've bought will be a a bit of a "project" refoaming required, and probably recapping but I'm super excited, they wont arrive for several weeks. I'll certainly be calling upon this forum to help me once again as with the 4311 restoration I did.

Yea, it's still there, of course. I guess your choice of 4343 was right, if you love jazz.:bouncy:
Here is a couple of Youtube links on this Basie club and its owner Sugawara san's drum solo:

https://www.youtube.com/watch?v=NeBwWO9BoBo
https://www.youtube.com/watch?v=rXLm3cK0YpA

[Goldjazz]

Yea, it's still there, of course. I guess your choice of 4343 was right, if you love jazz.:bouncy:
Here is a couple of Youtube links on this Basie club and its owner Sugawara san's drum solo:

https://www.youtube.com/watch?v=NeBwWO9BoBo
https://www.youtube.com/watch?v=rXLm3cK0YpA


cool, thanks for the clips. Yes love jazz there will definetley do the job, although my name doesn't come from loving jazz it's a long story: )

[Goldjazz]

Ok,

So what do we think about two Accuphase P-300 amplifiers driving the 4343's in Biamp mode? 150 Wpc into 8 ohms.

http://audio-database.com/Accuphase-kensonic/amp/P-300-e.html

Regards.

[pyonc]

Ok,

So what do we think about two Accuphase P-300 amplifiers driving the 4343's in Biamp mode? 150 Wpc into 8 ohms.

http://audio-database.com/Accuphase-kensonic/amp/P-300-e.html

Regards.

Currently I'm using Crown DC300A Series II for lows, and D-150A for highs in biamp mode.
Main reason is its great damping factor, which means tight bass.
Crown's damping factor is greater than 750 from DC to 400 Hz, according to its manual.

I see Accuphase P-300's damping factor a bit below average, given the range 0 to 50.


Dumping factor

20 (for 8-ohm load and 20Hz - 20kHz) or more

[martin2395]

I tried my 4343's in full pasive mode again, after a few months running be amped.
Hell, they sound much better in passive mode :blink::blink: The bass matches perfectly and they highs are so much smoother and fuller sounding!!

[pyonc]

I tried my 4343's in full pasive mode again, after a few months running be amped.
Hell, they sound much better in passive mode :blink::blink: The bass matches perfectly and they highs are so much smoother and fuller sounding!!

Really? What a pleasant surprise to know that! Many who bimaped 4343 hardly looked back at their passive mode days...
I guess the passive mode has restored the original sonical characteristics of 4343, which you can hardly achieve with biamp set-up.
Actually, The reason I stuck to 5234A crossover is with the stock 4343 cards, I could expect it to produce the original sonority of 4343 in full passive mode. I also swiched back to full passive mode recently to A/B with biamp mode, and I see biamped sound with 5234A is almost identical to the passive mode, but with more bass and highs.

[Goldjazz]

Currently I'm using Crown DC300A Series II for lows, and D-150A for highs in biamp mode.
Main reason is its great damping factor, which means tight bass.
Crown's damping factor is greater than 750 from DC to 400 Hz, according to its manual.

I see Accuphase P-300's damping factor, which I thinks seems to be below its mid-point. (0 to 50 range).


Dumping factor
20 (for 8-ohm load and 20Hz - 20kHz) or more



Ah yes damping factor. So I guess horizontal biamping with two different amps might be the ticket. One suited for LF with a high damping factor (> 100?). The crowns are pretty polarising from what ive read, ive not heard them. However the LF prowess of the dc300a seems unanimous. I wonder if the high damping factor, workhorse crown on the bottom and some refined class A accuphase action on top could be the answer...yikes that sentence sounds a little wrong :)

[Goldjazz]

I tried my 4343's in full pasive mode again, after a few months running be amped.
Hell, they sound much better in passive mode :blink::blink: The bass matches perfectly and they highs are so much smoother and fuller sounding!!

By full passive you mean not biamped? Yep I hear ya. Most accounts ive read have preferred biamping but a few who have not. One of the repliers said something like just get 200 wpc and dont worry about biamping cause its hard to pull off. Thats probably the sensible thing to do. But im not sensible :) I enjoy tinkering, having a go. Ive gotta get another amp anyway so if its at least 200wpc I can compare biamped with and not.

I am a bit uncertain by power requirements for using a single amp and biamp. Jbl suggest 150wpc min in the 4343 spec (I assume for 1 amp) so im not sure what the power requirements for the LF and HF amps in a horozontally biamped system would need to be to cope with sudden spikes etc. Kendrick has plenty of videos of 4343s operting with a single amp powered at 110wpc (sansui mos aux1111,luxmans etc) and he obviously knows what he's doing.

[pyonc]

By full passive you mean not biamped? Yep I hear ya. Most accounts ive read have preferred biamping but a few who have not. One of the repliers said something like just get 200 wpc and dont worry about biamping cause its hard to pull off. Thats probably the sensible thing to do. But im not sensible :) I enjoy tinkering, having a go. Ive gotta get another amp anyway so if its at least 200wpc I can compare biamped with and not.

I am a bit uncertain by power requirements for using a single amp and biamp. Jbl suggest 150wpc min in the 4343 spec (I assume for 1 amp) so im not sure what the power requirements for the LF and HF amps in a horozontally biamped system would need to be to cope with sudden spikes etc. Kendrick has plenty of videos of 4343s operting with a single amp powered at 110wpc (sansui mos aux1111,luxmans etc) and he obviously knows what he's doing.

In my opinion, the greater the damping factor, the better for the woofers of 4343, as it means tighter bass.
Crown K1's damping factor is unbelievable 3000!

By the way, according to our forum guru 4313B, Crown amps were exclusively used with all 43xx monitors.
So, Crown, I think, is the right match at least with 4343, one of the best in this 43xx series.

[BMWCCA]

The crowns are pretty polarising from what ive read, ive not heard them. However the LF prowess of the dc300a seems unanimous. I wonder if the high damping factor, workhorse crown on the bottom and some refined class A accuphase action on top could be the answer...

I believe the questions concerning "musicality" of the Crown amps refers to the later (cheaper) pro models. I've not seen any complaints about the DC300A-II or PS400 running full range. Again, I've used the DC300A-II and D150A-II to bi-amp my 4345s and recently switched to PS400 and PS200 mostly for the turn-on delay feature. But then I found I preferred the sound as they seemed to have a bit more punch and a more open sound. Their sonic superiority over the D-series was also praised in Scott Fitlin's thread a long while back:
http://www.audioheritage.org/vbulletin/showthread.php?25918-Crown-Amps&p=329458&viewfull=1#post329458

[martin2395]

By full passive you mean not biamped? Yep I hear ya. Most accounts ive read have preferred biamping but a few who have not. One of the repliers said something like just get 200 wpc and dont worry about biamping cause its hard to pull off. Thats probably the sensible thing to do. But im not sensible :) I enjoy tinkering, having a go. Ive gotta get another amp anyway so if its at least 200wpc I can compare biamped with and not.

I am a bit uncertain by power requirements for using a single amp and biamp. Jbl suggest 150wpc min in the 4343 spec (I assume for 1 amp) so im not sure what the power requirements for the LF and HF amps in a horozontally biamped system would need to be to cope with sudden spikes etc. Kendrick has plenty of videos of 4343s operting with a single amp powered at 110wpc (sansui mos aux1111,luxmans etc) and he obviously knows what he's doing.

Yes, not bi-amped. The biggest problem I had was that I couldn't get the bass to blend with the rest of the units. It sounded like a set of big monitors with 2 external subwoofers no matter what I did - flipping the polarity or changing matching the gain of both amps. Also, while my BSS crossover could be considered "high-end PA" it still has it's own sound signature.

I think that passive bi-amping with new networks with very good coils for the bass, maybe Jantzen or Mundorf and two healthy poweramps would give the best result on the 4343.

[wpod]

that really makes the difference. That being said, when I run my 4343a straight (not biamped) , I use a Krell KSA 200S Class A power amplier (200 wpc) and I can play it full volume and it sounds very clean. When I'm running my tube amplifiers straight, I sometimes use a pair of Harmon Kardon Citation II stereo power amps bridged to mono (120 watts per channel) Just for an experiment, I tried to run the Cit IIs full volume but the tube amps (120wpc) seem too be more powerful than the 200 wpc Solid state amps. Go figure. I get my best results biamping using the JBL M 552 electronic crossover with the Krell KSA 200s on the bottom and a single Citation in Stereo mode on the top. If you're a DIY kind of guy, I would look into building one of Nelson Pass's Class A amplifiers that are on the DIY Audio website. The Pass F5 Turbo V3 is good for over 100 watts of Class A amplification. Good Luck, Paul

[pyonc]

[QUOTE=martin2395;362859]Yes, not bi-amped. The biggest problem I had was that I couldn't get the bass to blend with the rest of the units. /QUOTE]

Hummmmm..... Bass overwhelming enough to dump mids/highs? How coudd it be, with your active crossover? That's new to me. Maybe your xover with 24db/octave gets into play here, compared with the 12db/octave of 4343's passive network. Just my guess.
According to the theory, 12dB per octave crossover slope will not cut off as much information above certain Hz, 300Hz in 4343's case, as fast as a 24dB per octave crossover slope. And steeper slopes do add complexity to the crossover, however, and depending on the system configuration, may have no real sonic advantage over 6dB or 12dB slopes, according to the theory.

[martin2395]

It's not overwhelming at all, It's simply not blending well with the mid/high section. It's like I mentioned before - a 3 way monitor with subwoofer added.
24dB should be even better because it cuts the woofers quicker giving less overlapping between the woofer and the midwoofer.

An interesting fact: the bass blends better when you use the 'LOW' terminals on the back of the cabinent but it loses a lot of power :blink:, connecting the speaker cable directly to the 2231/2235 gives the tightest and most powerful bass.
I really think that the 3143 with that rubbish rotary switch (even cleaned) is the problem.

[pyonc]

An interesting fact: the bass blends better when you use the 'LOW' terminals on the back of the cabinent but it loses a lot of power :blink:, connecting the speaker cable directly to the 2231/2235 gives the tightest and most powerful bass.

Really? That's surprising. Direct connection to woofers, not going through back binding posts, produces such tight bass?
If that's the case, I just wonder what's the whole purpose of these speaker terminals on the back.
Not just 4343, but the entire line of big JBL speakers with binding posts on the back.

[BMWCCA]

Really? That's surprising. Direct connection to woofers, not going through back binding posts, produces such tight bass?
If that's the case, I just wonder what's the whole purpose of these speaker terminals on the back.
Not just 4343, but the entire line of big JBL speakers with binding posts on the back.

Duhh!


I imagine you guys have talked about and tried lots of things to get the most out of the system. I will mention a few things that I would do if I had a pair at home for my primary system.

Get rid of the bi-amp switch. Hardwire it in which ever mode you want it. The switch is not that great.
If you can work out bi-amping do so. The difference in the 2245H and 2122H will be amazing. The crossover will have to be non standard. Neither driver is flat around crossover so the voltage drives will need to be adjusted to get proper acoustic bandpasses.
The network components should be updated and this isn't easy. All the capacitors should be polypropylene and you would want to use air core inductors where ever possible. I believe the 4345 used some tapped iron cores. Those are hard to replace with aircores because the surrounding network topology would have to change and all of the values have to be re-engineered. I would suggest leaving them alone unless you are really good at this stuff.
If you can swing it, go to a biased network. The difference is unbelievable.
The ring radiator hates passive networks. A major improvement in the upper range would be to drive the 2405 from its own little amp. You only need 3 or 4 v rms. The 2405 does 110 dB for 2.83v. It is padded way down in the system. There is little real power at those frequencies anyway. You only need to know the voltage output of the amp, power is irrelevant. The 2405 is about 12 ohms and won't draw much current. I would use some little chip amp with a 2ond or 3rd order low level highpass in front of it. Take off the passive network to the ring and just feed it straight. Make sure the amp doesn't make a DC thump on turn on or turn off. That will fatigue the diaphragm. The amp will also have to have really low noise characteristics as any hiss will be really loud directly into the ring. I used to use an old Marantz 1030 integrated amp to run my rings. I could separate out the power amp section and the tweeters always sounded really good.
The L-pads aren't so hot either, particularly after all of these years. Once you have your preferred balance, it is fairly easy to measure each leg of the L-pad and replace it with fixed resistors.
I notice from many of the pictures that the system is elevated on blocks. It is very good to get the 2245 up off of the floor to minimize midbass fatness.
BFT is my emphasis.

[pyonc]

Hi BMWCCA,
Thanks for posting Greg's insight on this matter.:applaud:
I wish I were tech savvy enough to do as Greg advises...
Anybody has done this before, like Greg advised?

[BMWCCA]

Hi BMWCCA,
Thanks for posting Greg's insight on this matter.:applaud:
I wish I were tech savvy enough to do as Greg advises...
Anybody has done this before, like Greg advised?
My 4345s "clones" came to me with all of those mods except the separate amp for the UHF. I also don't run them on stands but I do have them on casters.

[Goldjazz]

.... I would look into building one of Nelson Pass's Class A amplifiers that are on the DIY Audio website. The Pass F5 Turbo V3 is good for over 100 watts of Class A amplification. Good Luck, Paul[/QUOTE]

Yeah another 4343 owner recommended that to me. This is something I want to do eventually. I think I'll first focus my efforts on restoring the 43's. So I'd like something to drive them with as soon as theyre done. I'd love to go Class A, but as you know getting anything above 100WPC in Class A is not easy, your Krell looks awesome. That's why I wanna understand the power requirments for biamping the 43's, cause there's so many Class A options around the 100WPC but from what I understand that's not enough juice.

There is available a Perreaux PMF3150 http://www.perreaux.com/assets/file/archive/048-PMF3150.pdf which puts out 300W, CLass A driver stage, Class AB output. I've read elsewhere that damping factor is around 400. Could be an option for the bottom?

[Goldjazz]

So this is the project, I haven't got them yet. They're B's, the serial numbers are around the 18000 and are closely matched.

[pyonc]

So this is the project, I haven't got them yet. They're B's, the serial numbers are around the 18000 and are closely matched.

Nice pair! Don't forget to have your 2121 drivers and 2231A woofers reconed with genuine JBL kits.

[martin2395]

The recone's are NLA for a long time now. They only way to restore them is to put new surrounds ;)

[richluvsound]

You beat me to it Martin. They look good enough to re-foam .
Just re-build the networks to a CC version .

Rich

PS ….. you might find the F5 Turbo lacking … Good for Bi-amping ,but no very competent gripping a 15"

[Goldjazz]

You beat me to it Martin. They look good enough to re-foam .
Just re-build the networks to a CC version .

Rich

PS ….. you might find the F5 Turbo lacking … Good for Bi-amping ,but no very competent gripping a 15"

Yep I'm hoping just a refoam is required for the drivers. As for the charged coupled network I need to read up a lot more. Here's a link that I found useful about its benefits as applied to the k2 that other novices like myself may find helpful
http://www.lansingheritage.org/images/jbl/specs/home-speakers/1993-k2-s5500/page12.jpg

Without knowing anything at all about the subject my immediate concern would be the change in voicing. I'm inclined to start with a recap that members would deem not too much of departure from the original sound and start by experimenting with single and biamp and external x overs. Then trying fancy improvements. I want to get a baseline of the orignal sound first without the influence of old caps and go from there.

[grumpy]

I want to get a baseline of the orignal sound first without the influence of old caps and go from there.


Note that you can do this by building up a CC network, and -not- charging it.
A bit more money (more caps) but not much more work. Then the next level
of comparison is just a 9v battery away :)

That's a really nice speaker find (like a minimum effort fixer upper in a nice neighborhood).

[Goldjazz]

Note that you can do this by building up a CC network, and -not- charging it.
A bit more money (more caps) but not much more work. Then the next level
of comparison is just a 9v battery away :)

That's a really nice speaker find (like a minimum effort fixer upper in a nice neighborhood).

Cheers. Ok so if a cc capable can be built that yields the original sound and easily flick between the constanr bias being on or off that would be cool, I would try that. If anyone can link to a suitable thread own that would be appreciated. I could start ordering the bits and building it if its external.

[Goldjazz]

Still on the hunt for good amplifications options for these 4343's so if anyone's had particularly good results please let me know what you're using. Was just checking out the specs of the Sansui B2301 power amp, looking through the service manual. Seems Sansui believed it was a good match for the 4333 at least judging by this image.

[Mr. Widget]

Still on the hunt for good amplifications options for these 4343's so if anyone's had particularly good results...Why not get the Perreaux amp you mentioned earlier? I've heard the 4343s sound quite good with far less.


Widget

[Goldjazz]

Why not get the Perreaux amp you mentioned earlier? I've heard the 4343s sound quite good with far less.


Widget

Yeah I hesitated because ive not heard much about the perreaux. Digging through past threads there are a couple of positive accounts of them though.

[hjames]

Yeah I hesitated because ive not heard much about the perreaux. Digging through past threads there are a couple of positive accounts of them though.

Ask Opimax here on the forum. He's got Perreaux gear for his 250s.
They are powerful and sound very nice.

[martin2395]

I'd never buy an old Perraux poweramp, if the outputs blow (they have no protection) then it's a doorstop.

My choice would be Bryston 3B/4B and then buy the most recent version you can afford.

[hjames]

I'd never buy an old Perraux poweramp, if the outputs blow (they have no protection) then it's a doorstop.

My choice would be Bryston 3B/4B and then buy the most recent version you can afford.

Like any old amp, have it checked and have caps replaced as needed.
If the semiconductors blow, have it rebuilt by a pro ...

[Goldjazz]

Ask Opimax here on the forum. He's got Perreaux gear for his 250s.
They are powerful and sound very nice.

Thanks, will do

[Goldjazz]

I'd never buy an old Perraux poweramp, if the outputs blow (they have no protection) then it's a doorstop.

My choice would be Bryston 3B/4B and then buy the most recent version you can afford.

Thanks for the advice. I've sent the Perreaux amp specs to a trusted tech I've used before, see what he thinks, but thanks for the word of caution regarding lack of protection.

I hadn't considered Bryston before, but the specs of the 4b seem to tick all the boxes. The only issue is availability of them where I am, there's a few available worldwide so I'll need to weigh up shipping cost and power transformers but this could be an option.

[Allanvh5150]

I have worked on many Perreaux amps and I have never seen an output device fail into a short circuit. The ones I have seen always fail into an open circuit. In general, mosfets do not require and protection circuits because they have a positive temperature coefficient which means when they increase in temperature, the resistance of the junction increases which in turn brings the power dissipation down, self regulation.

The older Perreaux amps are brilliant at what they do.

Allan.

[Goldjazz]

I have worked on many Perreaux amps and I have never seen an output device fail into a short circuit. The ones I have seen always fail into an open circuit. In general, mosfets do not require and protection circuits because they have a positive temperature coefficient which means when they increase in temperature, the resistance of the junction increases which in turn brings the power dissipation down, self regulation.

The older Perreaux amps are brilliant at what they do.

Allan.

Cheers Allan your comments give me a bit more confidence, but a bit over my head I must admit. If my tech is also positive I may give it a go. Thanks

[Bill Shenefelt]

Don't bother with such big, expensive amps. BiAamping is much more worthwile with 4343's.
I'm powering mine with Krell KSA-50 (highs) and Crown K2 is powering the woofers. Believe me 50W is plenty for the mid/high section, it's only the 2231/2235 that likes power.
The bass is also MUCH better with bi-amping, my woofers are connected directly to the K2 ;)

I have home built 4343 monitors with a Marchand crossover using a Heathkit 250w/channel on the 136A bass drivers and an Amber 100 w/channel amp on the top end with JBL designed passives and JBL supplied components for the passive upper crossovers. What slopes and what frequencies are you using in the Marchand? I have never gotten my 4343's to sound as good to me as my initial built L-300's. The 800 cps crossover to the horn on the L-300 seemed to allow better impact from the bass driver. I would sure like to get things sounding better though. Hate to waste money to buy coils and caps to go passive on the bass to mid crossover expecially if the active performs better.