3630 mod

karyoker said:
Does anybody have a source for the chips needed in the 3630 mod?
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The Burr-Brown opamps mentioned in the article are discontinued, but http://www.rswww.com lists the Texas Instruments TLE2074 as a replacement. They're about £5 each. I think I'm going to get four and replace both the TL081 and the LF347 devices in my 3630; does anyone know whether the TL081 are in the signal path?

In the UK, you can get the THAT components from http://www.profusionplc.com/; two 2180 and two 2252 cost about £25.

HTH,

Jon.
 
does anyone know whether the TL081 are in the signal path?
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Two sections are in series with the vca (2150), the 8,9,10 section at the signal input, then the the vca (2150) and the signal output is the 12, 13 14 section. The other 2 sections are in the control ckts.

If you are interested in more complete schematics I can provide you with a down load link on xdrive or email them to you..
 

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Interesting... So what are the LF347s doing? I notice the original article doesn't say anything about replacing the TL081s, which is unusual given how much abuse that type usually gets from the golden-eared crowd ;-)

I'd be interested to know what the (full) Black Lion mod kit contains; seems like a complete new set of components. Anyone here done one?

Thanks for the offer of schematics; I might take you up on that if I get into modding this unit beyond straight component swapping.

Jon.
 
They are used as general purpose proc and isolation amps in the control or processing ckts and incidently are very similar in specs to the lf 353.
I just looked at a DBX 160x schematic and it uses the lf 353 in the signal loop versus the tl 081 as in the 3630..
Im in the process of swapping for a DBX 166 When I get it I'll see what it's got in it... But I sure would like to see whats in a DBX 480 or 482
 
OK, taking another look at my 3630, there's clearly been a design change or two since the original mod article was written. It talks about 3 LF347s - mine only has one, and a pair of TL084s (which I'd already swapped for TL074s). Mine also already has THAT 2252s instead of DBX 2252s (guess the stock finally ran out) , and THAT 2150As instead of DBX 2150s.

If your 3630 schematic talks about TL084s (not 81s, my mistake) then I'm guessing it was updated too - maybe there's half a dozen different variants out there...

If I put a pair of THAT 2180s in there, I'm guessing I don't need/want the trimming circuit (R7, R66 & friends) going to pin 4 - the 2180 datasheet says to leave pin 4 open circuit.

BTW if you still want a pair of THAT 2552s I can send you a pair for $15 plus postage.

Jon.
 
BTW if you still want a pair of THAT 2552s I can send you a pair for $15 plus postage

Let me get back to you Jon I'm out of town just updated a couple of systems Now it's fun time want to help do a few gigs with them...
 
I'd be interested to know what the (full) Black Lion mod kit contains; seems like a complete new set of components.
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The full Black Lion kit contains exactly that--a set of new components--56 in total. It's quite a bit more comprehensive than the recording.org article because it deals with the 3630's noisy gating problems and control voltage distortion in the level detection circuit. Plus it alters the knee, and it changes the compressor from a feedforward design to a feedback design. It eliminates Peak/RMS selection as well.

Also, it doesn't swap out the 2252, just the VCA. There's really no need to, because they're essentially the same IC. It uses the THAT2181 instead of the 2151. Also, many of the 3630's left out an important 33 ohm source-impedance resistor that needs to be installed if you're upgrading the VCA. Because THAT VCA's are sensitive to source-impedance problems and inductive errors, you can see oscillations in the control-voltage circuit that impede the VCA's performance if that resistor is omitted.

So what are the LF347s doing?
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Some versions used a TL084 for the input/output, some used an LF347. The other 347 (U4) is an input/output buffer for the gating circuits.
 
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