Biamping CPA130 for biamping

darg

When in doubt, C4
Roughly a year ago I build some 115 liter cabinets to put a set of Heathkit AS223 in them, powered by an Aiwa P30 driven with an Aurex SY335 with full mods of line stage and phono stage here from AK, the system seems OK and sounds good. I changed the crossover from the single cap for the tweeter to a generic Realistic two way crossover which seem to do a better job with a crossover frequency at 4.5KHz for woofer and tweeter with some L-pad resistors of ca. 6dB to pad down the tweeter.
Still the crossover is not really the best solution and before I tinker with a passive crossover I think about biamping the set either with an active crossover and a set of identical amps or maybe a MiniDSP like I'm doing this already in my main system.
To make a long story short for this I'm looking into a set of two identical amps which don't break the bank. I was looking into Xkitz kits on the bay which would include also the crossover but I would still be left without a good power supply for them. Building a stable and save housing for amps and PS puts me a little bit off since I don't have the means for mechanical work. Building electronics isn't the issue but no workshop for metal work at home.
During my search I found from time to time sets of Biamp CPA 130 commercial power amps. Are they any good for that kind of job or are they too much PA like with not good frequency responses?
I'm looking for something that doesn't overpower the Heathkits and these seem to have a packaged deal with PS and stable build. Any input would be helpful.
 
Looking at the data sheets online, those amps seem up to the job. Specs look fine. Prices are attractive for used units.
 
Thanks, I found this morning the schematics to the EQ9 unit from Biamp that also contains the CPA130 as amp and it looks ok. Discrete power transistors and some OP as pre stages. Might contain some SMT parts but I hope not too many so recap and maybe a little vamping on some caps will make it workable.
Now just the question of active crossover or MiniDSP. I have two running in my main system and I'm not sure if I like, love or hate them. The whole equalizing and phase shifting is a nice feature but the 0.9V max output and some slight hiss noise makes me wonder if I want to go rather just with a set of active crossovers.
 
Just an update,
got two units yesterday. One worked right out the box, the other one was very faint and both channels were muted. Since this one made a slight pop noise when switched on which the other didn't I checked the schematics.
Schematic.JPG

The muti9ng circuit seemed the suspect, odd thing is that bath channels were permanent in mute mode. I figure that the FET somehow got screwed up and was conductive even without power and put the mute point on ground.

Detail.JPG

These things will be a beast to work on due to complexity of having all power transistors mounted in different ways to the heat sinks, partial SMT parts mixed with through hole parts. The affected FET is the SMD version :-( Since I'm not equipped for SMD soldering only way was to get it somehow out of the circuit and now the second amp also works. Need to find a way to get this replaced but not in SMD.

Can't say anything yet about how they sound, had them only on a test box but the built is nice. Dual-Mono PCB's with power supply on each board, the channels only share the transformer. Lets see how they sound today....
 
Just an update,
got two units yesterday. One worked right out the box, the other one was very faint and both channels were muted. Since this one made a slight pop noise when switched on which the other didn't I checked the schematics.
View attachment 836818

The muti9ng circuit seemed the suspect, odd thing is that bath channels were permanent in mute mode. I figure that the FET somehow got screwed up and was conductive even without power and put the mute point on ground.

View attachment 836819

These things will be a beast to work on due to complexity of having all power transistors mounted in different ways to the heat sinks, partial SMT parts mixed with through hole parts. The affected FET is the SMD version :-( Since I'm not equipped for SMD soldering only way was to get it somehow out of the circuit and now the second amp also works. Need to find a way to get this replaced but not in SMD.

Can't say anything yet about how they sound, had them only on a test box but the built is nice. Dual-Mono PCB's with power supply on each board, the channels only share the transformer. Lets see how they sound today....
I bave a cpa 130,i know its an old thread.Can you tell me if the cpa has a normal thump when it turns on connected to apeakers?Is that just a muting circuit for protection on shorts or a no thump muting circuit.Thanks if youre still on here.
 
The circuit is a soft start that keeps the input stages muted (shorted to ground via the FET switch) for a short period after switch on. I could never fix it since I couldn't get the right FET. There is no thump during switch on. I had to get a third one to replace the defect unit that developed another issue after maybe 6 month running ok but with switch thump.
 
ok that makes sense,i guess its of no harm or is it?The thump isnt very bad.I could put a time delay through a relay on the outputs.Maybe not worthit but i i cant afford what i want and these seem plain and simple amps
Thanks for any reply back,no generic fet or npn would work?I guess not.
 

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Had an idea,can we possibly solder some thin solid core wire to the new smd then through hole it? Jus an idea .I havent seen the smd part yet,maybe its too small for that.I also found the j112 j113 versions ,i wonder if they would work.
 
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That's kind like what I did, got a comparable FET and put some extension leads on it but it never fixed the issue. Maybe my had another problem with one of the caps that do the time delay. Just try it out.
I wanted to fix the thump since I was not having anything at the output that could have buffered possible current peaks during switching. Was afraid I fry my tweeter
 
Yea ,or ill jus leave em on for now .I may put a seperate switch on it to turn the speakers on.I want to get another so ill have 130 wpc,each bridged.Theyre decent amps ,my speakers are effecient anyway.
 
A better amp for using two bridged would be the Ramsa wp 9055 but i cant get em cheap anymore..Anyway let me know if you ever find the problem on the cpa130 .Thanks,im thinkin its i cap too .
 
IMG_20180712_123346.jpg Doubt i can work on something so small lol.But like you i think its a cap ,the 50v one.Thatd take a lil time to charge at 15v .It can only be a few things right here
 
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