R-Comp/D-Comp Clone - no treble?

[taeagan]

I built one and then also breadboarded another.  I noticed that it really seems to eat treble.  Anybody else notice this?  I'm not much of a compressor kind of guy, I just built one because I had the parts laying around.

[Ringwraith]

Holy crap, I was just going to ask the same thing! LOL
I just built my D-Comp last night & noticed the same thing.
It was 3 in the morning so I only played it a few minutes but noticed the treble thing right away.
I was going to fiddle with it some more before my final conclusion but seeing how you noticed it too I thought I'd jump into this thread.

I'm interested in hearing what others with more experience on these comps have to say.
I've used an old Boss CS2 for years & although it's pretty noisy, I seems to bring out the treble if anything.

Cheers
Sean

[BDuguay]

Depending on the layout you chose, there might be an input cap value mistake. Use the search and check the archives. I can't remeber off hand but it was something like the input cap was listed as .02 and should really be .002
B.

[Mark Hammer]

This has come up before.  One of the things I suggested that seems to have made some folks happier with their pedal was to place a cap of roughly .01uf in parallel with the 10k resistor imediately prior to the output pot.  This works in a manner analogous to a "bright" switch on an amp.  Not the be all and end all, but as I say some folks were very pleased with the outcome.

And yes, Brian is right.  There was an error in an earlier version of the Compreross PDF at Tonepad, and it listed a cap that should have been 220pf as being 2200pf.  I'm sure it did wonders for reducing hiss, but wasn't all that great for single coil pickups!

[Ringwraith]

I used this layout which I think is on a few sites...
http://www.generalguitargadgets.com/diagrams/geo_d&r_comp.pdf

It says the input cap is 0.01 I just changed it to 0.001 & it brought back a lot of high end.
Is this the one we're talking about??? C1 is the input cap right?
What 220 cap are you talking about? Am I missing something?

Thanks
Sean

[Fret Wire]

C1 is the input cap. The 220pf (C2) cap Mark is refering to is on the Ross version, and is not used on the Dyna version.

[petemoore]

You're probably socketting and possibly using a higher quality opamp than the original had [I don't Know[ [741 in originals?...]
 COmpressors tend to lift the high end hiss factor, it could be the original schematic as shown was designed to tone down or eliminate high end noise, wider frequency response may not suffer as badly from added noise...some high end component placement may help offset noise even more...I just let 'some' high end through, to the point where that HF rolloff cap is smaller but still noticably attenuates highs a touch.
 By itself I wouldn't call it noisy, it's a compressor after all.

[BDuguay]

I built mine from the tonepad layout, with the correct value input cap, and it's fine. Mind you, I play a Tele through an AC30 so, I don't know if that makes a huge difference.
B.

[Processaurus]

I hated my ross clone until one day I tried putting a pedal with a buffered bypass in front of it (in this case a sansamp gt2).  Whoa, all of a sudden the treble was back!  Thats the sound I wanted!

My suspicion is the cap fom the input to ground loads down the guitars pickups (especially single coils) causing classic "tone sucking", like old wah pedals that don't have true bypass, except here the tone sucking was on the front end of the effect.

rather than modify the ross circuit, I just buffered the input to the effect with the jfet buffer at GGG  (http://generalguitargadgets.com/index.php?option=content&task=view&id=69&Itemid=100), and it worked wonderfully.  Its better to have more treble going into the circuit then to boost treble afterwards, because then you boost noise from the compressor, which can get bad with high gain effects.  The buffer can fit on a piece of perfboard the size of a thumbnail, so its easy to find room for it.

I really recommend this to anyone who isn't impressed with how their dyna/ross clone sounds, for me it was the difference between using it to make music with or not.

[BDuguay]

Now that you mention it, my compressor comes right after a buffered splitter in the chain. The buffer splits to 2 outputs, the second out goes to a tuner only.
B.

[taeagan]

I tried plugging that buffer in at the input and it didn't really make a difference.  It still sounds quite "woofy" if that makes any sense to anyone.  I also removed that cap that ties to ground right at the input (220pF or 2200pF, I forget which).  Is there anything else that you can do with this to improve treble response?  I'm using mostly Gibsons with humbuckers, bridge position.  I'm not necessarily looking for crazy sustain with the compressor, really just more limiting and evening out of the volume.  Thanks.

[Ringwraith]

I'm having a hard time with it as well.
I've tried a few "mods" but I agree, it's still woofy as hell!!
And that's with a stock US Tele & Strat!! (sigle coils)

I'm pretty disappointed now that I've played with it for awhile.
I'm going to muck around with it some more but man it really kills the treble!
I did the #1 mod from this page http://www.lynx.bc.ca/~jc/pedalsDynacomp.html
& taking out the cap really boosts the treble so I'm hoping I can just
fiddle with the value to flatten it out.
I only had a few caps to try & so far it's not happening for me.
It's compression is nice but I don't like how much top end it removes!!
I don't understand how folks dig the stock MXR's so much.
Maybe our build isn't quite the same as the real deal??

I pulled some parts out of my Boss CS-2 to cover what was missing in
my order but I'd like to compare the two side by side now! hehe
I'm pretty sure the boss didn't take out all this high end. Mind you it can be pretty
dirty & the MXR seems cleaner but maybe the MXR is just masking the dirt! LOL

Cheers
Sean

[taeagan]

Removing that cap (C11 in the geofex article) made a big difference!  The treble is back!  It still sounds a bit woofy though.  I'm not all that thrilled with it.  I'm going to keep looking around for something else.

[powerplayj]

If lowering/removing C11 brings back the treble, which cap should be increased for more bass?

I know the trimmer regulates the voltage at a certain point in the circuit but, what affect does it have on tone?

The FXDoctor has a few comp mods, one being a trimmer to make the voltage sag as low as 3V to change the pedal's attack.

[Fret Wire]

The FXDoctor has a few comp mods, one being a trimmer to make the voltage sag as low as 3V to change the pedal's attack.

JC has this mod on his site:
http://www.lynx.net/~jc/pedalsDynacomp.html

[powerplayj]

Mine is rev D with all the pcb mounted pots, switch and LED.  My C11 is a 100uf electrolytic so, I don't think it applies to the mods in the link below.  I can usually find my way around a schematic but, this layout has me puzzled, plus the mounted pots cover up the cap ID numbers.  Anyone have a D version and know what my equivalent caps (C?) would be for C1 and C11?

[cooljage]

I'm building a ross comp, and I accidently had a .22uF cap in place of the 220pf cap, and it sounded like crap.  I went out and bought a ceramic 200pF cap, and popped it in, and now I have more treble than I know what to do with.  This leads me to a few questions.

1. I went from having no treble to too much treble, by switching those caps, and other people in this thread have completely taken out the 200pF cap to get more treble.  I feel like if I took it out, it would make my ears bleed.  Could this mean something else is the problem?

2.  Can you only get ceramic caps in pF?  I was told this at a local electronics store, yet the parts list asks for a film.

3.  I feel like I have to crank the level and sustain pots to get any reasonable volume level.  is this normal?

I can provide pictures of my wiring and board, and sound clips if necessary.

[Mark Hammer]

1.  There are all manner of values between .22uf and 200pf.  Perhaps something like 470pf or even 680pf might be more to your tastes (although quite frankly, the usual request is for more treble from compressors, not less).  Keep in mind that capacitors in parallel have their values added.  So, if you happened to buy a package of a small handful (say, 4 or 5) 200pf caps, you can consider soldering in a second one in parallel with the one already in there.

2.  Ceramic caps come in different types, but the big flat disc ones used to be pretty much ALL you could get in values up to maybe .47uf.  Conversely, plastic film caps can be found at pretty much all used values, right from non-polarized ones in the 4.7 - 10uf range, right down to a couple of picofarads.  Not all dealers will carry all types of caps.  If it's a walk-in industrial dealer, chances are there may be only a couple of values they carry in more than one composition type, or at more than one voltage rating.

3.  The Dynacomp circuit should have plenty of volume, though it is not intended to be some high gain monster where you have to keep the volume control at 8:00 to get effect/bypass volume balance.  Note, as well, that the Dynacomp design (as do many others) produces compression by *reducing* gain in response to harder picking.  That means that LESS compression provides the potential for MORE volume.  Back off on the compression a bit and see if that gets you what you wanted/expected.