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Carvin BX amplifier compressor sensitivity

LHbassist

LHbassist

Supporting Member
Apr 4, 2003
1,421
2,310
Reno, Nevada
#1
Just a feeler- does anyone know if it's possible to alter the sensitivity of the compressor on these amplifier heads? I have a BX 500, and a BX 1500. I really love them both. No issues, and they are quite versatile workhorses. The only thing I don't like about them, is the compressor. They are way too sensitive, to the point where, if you try to use hm, there is just too much compression, too soon in the sweep of the control. I also own a very rare Pearce B2P, now semi-retired.. that has absolutely the best single knob compressor I've ever heard in any bass amp. Yeah, I know- comparing the two is not really fair. I would like to decrease the sensitivity of the Carvin compressor. Is there anyone familiar enough with these amps/ circuits, to instruct me on how to do so? I'm a lifelong Luthier, and have pro level soldering skills. I've replaced caps and other parts in amps over the years... but most of the modern amps- are all plug in modular boards, or just made so poorly, that you replace the amp entirely if they fail. There is no warraty issue on these, as some of you know, they are not making them anymore. Sad, because these are the best line of bass amps and cabs they ever made.
 
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#2
Have you opened those amps up? This is just a guess. But I bet the components on those boards are miniscule, and were installed by Chinese robots. Trying to remove/replace them would likely damage the board.

(I say this as someone who has tried, with mixed results, to rescue a few turn-of-the-last-century pieces of medical equipment produced by now-defunked companies. It CAN be done in some cases. But it is delicate work. Ny skills were maxed. And sometimes I wound up burning the board, traces, and a couple of neighboring components to the point of no return. I had warned those facilities that repair was a longshot. I even impressed myself that I was able to troubleshoot the circuit under such conditions. Even with a magnifying lamp and good reading glasses I struggled to see what was going on. :cool:)

Finding a schematic for one of those amps (especially since the company folded and then came back as something else) will likely be a challenge as well.

Honestly? If it were me, and I had a couple of amps like that, and loved almost everything about them except the compressor, I would probably hunt down a compressor pedal I liked and work with that instead.

But I hope I'm wrong, and that you find a solution you prefer to all of my bad news. :D
 
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#4
two fingers said:
Have you opened those amps up? This is just a guess. But I bet the components on those boards are miniscule, and were installed by Chinese robots. Trying to remove/replace them would likely damage the board.

(I say this as someone who has tried, with mixed results, to rescue a few turn-of-the-last-century pieces of medical equipment produced by now-defunked companies. It CAN be done in some cases. But it is delicate work. Ny skills were maxed. And sometimes I wound up burning the board, traces, and a couple of neighboring components to the point of no return. I had warned those facilities that repair was a longshot. I even impressed myself that I was able to troubleshoot the circuit under such conditions. Even with a magnifying lamp and good reading glasses I struggled to see what was going on. :cool:)

Finding a schematic for one of those amps (especially since tue company folded and then came back as something else) will likely be a challenge as well.

Honestly? If it were me, and I had a couple of amps like that, and loved almost everything about them except the compressor, I would probably hunt down a compressor pedal I liked and work with that instead.

But I hope I'm wrong, and that you find a solution you prefer to all of my bad news. :D
Click to expand...

Both schematics have historically been easily available online, but only for one specific board revision in each case. The BX500 uses quite a few surface mount parts, but working on mine years ago wasn't impossible, even with what were at that time beginner skills with SMT rework. So yeah, "do you feel lucky?", or something like that. ;)
 
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#6
Funny, I had both of those amps, and really liked the compressor. But I didn't have it on all the time, only when I had to do a bit of slapping, so, it worked great for that. Barely had to turn it up, so I guess it is a bit sensitive. If you want compression on all the time, then, yeah, I'd research some pedals.
 
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#7
Passinwind said:
Both schematics have historically been easily available online, but only for one specific board revision in each case. The BX500 uses quite a few surface mount parts, but working on mine years ago wasn't impossible, even with what were at that time beginner skills with SMT rework. So yeah, "do you feel lucky?", or something like that. ;)
Click to expand...
And even if someone had the schematics, wouldn't they also need to have a fairly intimate knowledge of how the compressor circuit functions, in order to know what changes to make?
 
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#8
Old Garage-Bander said:
And even if someone had the schematics, wouldn't they also need to have a fairly intimate knowledge of how the compressor circuit functions, in order to know what changes to make?
Click to expand...

Yep, and since it's a VCA based design it's likely to be a fairly deep dive IMO and IME.

And then there's also the issue of the schematic not including a board layout of any kind... ;)
 
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#11
two fingers said:
Have you opened those amps up? This is just a guess. But I bet the components on those boards are miniscule, and were installed by Chinese robots. Trying to remove/replace them would likely damage the board.
Click to expand...

I'm being slightly nitpicky here but I wanted to make sure it is known that Carvin amps were all USA made. For the price, they were unbeatable.
 
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#16
Jim C said:
Just based on SWR's, does the sensitivity of the compressor become more reasonable when the first volume stage is lowered?
Understood that you might like the tone better with the volume higher but thought I'd mention it.
Click to expand...

I have tried running the input gain very low, and then trying the compressor. Same thing, overly sensitive- too much compression, coming on too soon.
 
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#17
My current use of these amps is becoming more limited, and I've been using them as Bill Whitehurst does- compressor off, or barely on at all. I have a Zoom B3 multi effects pedal that has several compressors in it. I find myself not using them in any patches at all. All in all, my Pearce is the best head I own. But even that amp- sits unused now.. Most of my gigs- the few remaining, are small amp, or in-ears. The BX 500 and BRX 10.2 will be onstage in a local casino next weekend. My Pearce is simply nowhere near as easy to adjust on the fly as these Carvins with the graphic EQ's. Thanks to all of you for the replies!
 
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#19
TheSeagoats said:
I'm being slightly nitpicky here but I wanted to make sure it is known that Carvin amps were all USA made. For the price, they were unbeatable.
Click to expand...

I have owned lots of Carvin gear. I was a fan.

That said, they likely bought fully-assembled circuit boards from overseas. Then the fine folks in California put those circuit boards into the casing.

So, while the amps were "Made in USA", the components on those circuit boards were very likely soldered by the aforementioned Chinese robots.... if we're picking nits. :D
 

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