MXR M87 Bass Compressor Demo

[Duckman]

http://www.jimdunlop.com/blog/?p=3800&u ... dium=email

I just saw this. Intresting features for an analog compressor in such a small package. SMD rules here, obviously.

[matt239]

MXR Bass Compressor. - Does anybody know what's actually inside one of these?
THAT or DBX chips, or similar? Could be opto, but seems like too many controls..
Sounds pretty good. Sounds good on guitar, but there's not that many demos..

[triplesevener]

I was under the impression that it was FET-based, almost like an 1176 in pedal form. As far as bass compressors go, this one is by far and away my favorite (although I don't own one).

[pedalgrinder]

This one would be a great candidate to get guts shots of it. But i bet it's all smd. Absolute ballbreaker to trace if thats the case. But a schematic of it would definately be nice.

[matt239]

Bump! Anybody seen inside one yet?

[friedtransistor]

Bump again! I really would like to know if it's feasible to make this one or if it's all digital crap...

[pedalgrinder]

I think they are so expensive that no one is willing to even put a screwdriver to it. they are worth $300 there abouts but if you can score the schematic and have the time and patients like $50 bucks but hard to say if anything digital in there.

[kusi]

i have one in the studio, i try to open it and make some gutshots tonight.

cheers!

[kusi]

here some gutshots:
https://drive.google.com/file/d/14bKNbj ... sp=sharing

it's a analog 1176-ish fet compressor:
n-ch jfet for gain-reduction (q16 mmbfj113 n-channel) and a discrete gainstage of 3 npn transistors (q14 q15 q17 mmbt5089), similar to a 1176.
didn't check the circuit around the gr-amplifier or the around meter.
looks like there is a switching-powersupply for higher voltage.
input-op is a tl061, output a 2262c.
(sorry no time for more details or even trace it completly xD)

i like the sound of the compressor, i use it all the time while bass-tracking on the di. it's a bit noisier than a 1176-software-compressor, but the general characteristics/functions are similar.