Compression Sustainer

[stringsthings]

as the summer of fuzz was coming to a close, our roving reporter scanned the skies for different circuits ... one day, while digging thru some back issues of "Fuzz Monthly", he came across a strange and wonderful article ...

   .... is it a bird? a plane? a rabbit?  ... nope ... it's another compressor schematic ... 

found this on another forum:


credit goes to "mictester" for the original post

i've got a working build and will post a veroboard layout and soundclip shortly ...

[Mark Hammer]

Interesting.

Only thing I really don't like about it is that there is no way (at least as shown) of having separately controllable distortion amount and compression amount.  If you want more distortion, you necessarily have to have more compression.

"But, but, but....", you say.  And yes, you're right: distortion IS compression of dynamic range, so you don't really "need" compression amount if you have the clipping diodes connected.

On the other hand, if you just want a smidgen of clipping when you dig in, you won't be able to get that PLUS compression.

Ah well, I guess there is no free lunch.  Still, nice to have a few more choices for the cost of a few extra parts, so I can't fault it for that.

[brett]

Hi
I like the look of this.  I imagine it could work well with the right JFET.

Mark - what would happen if you replaced that 100k resistor (parallel with the 2 x 1uF caps) with a variable resistor?  I wonder if you could find a suitable range of resistance that would bleed enough rectified signal away from the "squeezer" JFET so that compression is controlled without having too much interaction with feedback and the drive control?
Or am I missing something?
cheers

[Earthscum]

This thing seems kinda quirky. I don't get the pair of 2.2M's. Wouldn't it be better to have a 1M with a series 100k? Unless it's to increase the 'tolerance' factor?

What exactly does that second OP amp do? Voltage reference. Blah. Personally, I would use it to buffer out the envelope signal and then you can just use part of that signal and mix distortion with clean, all compressed. Just my opinion, though, and I suppose it's nil since I've only ever been able to get 1 comp working, and it was one that I designed using CD4049's and opto. 

[stringsthings]

Only thing I really don't like about it is that there is no way (at least as shown) of having separately controllable distortion amount and compression amount.  If you want more distortion, you necessarily have to have more compression.

i completely agree .... on the forthcoming soundclip, i had to tweak the controls to get a good sound .... so for live use, i would probably recommend having 2 builds ... one for compression and one for distortion ...

... and without further ado ...
here's the soundclip:

http://soundclick.com/share?songid=9599477

1 straight

2 compress Drive: 9:00
Decay: 2:00

3 assymmetrical Drive 12:00
Decay: 3:00

4 symmetrical Drive: 12:00
Decay 12:00

all tracks recorded into Line6 Gearbox .... Roland Jazz Chorus with a bit of spring reverb ....

[stringsthings]

here's the verified layout:



i did substitute a 500k log pot for DRIVE ... and i recommend using shielded wire for the DRIVE control and the input jack connections

and separating the input and output wires as much as possible ... as always with signal-to-noise, YMMV ...

[Earthscum]

Found this just a minute ago and thought of this thread:

http://electroschematics.com/232/audio-compressor/

[amptramp]

In some cases, picking the string in one direction gives a positive output whereas the other direction gives a negative output.  If the output goes positive, there will be no effect on the first cycle whereas if it is negative, it will begin to compress immediately.  If you look at some commercial designs like the DOD 280 or the Ibanez or Dynacomp or Ross compressors (but not the Orange Squeezer), rectification of the control signal is fullwave and all signals are subject to compression regardless of polarity.

Combining a fuzz with a compressor is interesting because of how few extra parts it requires, but the clipping of the fuzz may provide as much compression as you need.

[roseblood11]

What would be the best way to add a tuner output to this circuit? Just take the signal at the non-inverting input and add a simple opamp output buffer, like the AMZ buffer?