Ross Compressor (attack & blend mods)

[Sindran]

I´m really happy with my DIY Ross compressor, except that popping sound that slow attacks makes.
I did the variable recovery mod, and I really like the medium setting but it makes the popping worse.
    Is that pop-sound supposed to be normal, are everybody really OK with that???
It really annoys me...
Anyway to get rid of that??? 
can I make attack faster by chancing C16? If so, what would be good value?

And another interesting mod:
http://www.diystompboxes.com/smfforum/index.php?topic=40292.0
It looks really interesting, I know the idea works really well in Barber compressor, (i think it´s Ross with blend pot)
Has anybody tried that???

[Processaurus]

And another interesting mod:
http://www.diystompboxes.com/smfforum/index.php?topic=40292.0
It looks really interesting, I know the idea works really well in Barber compressor, (i think it´s Ross with blend pot)
Has anybody tried that???

Just me, I think, but I can say it worked great for me, as far as minimizing the pop, which I objected to, like you.  I've never seen a Barber unit, but from what I've read I have a hunch its a very similar thing, a Ross with a blend mixer followed by an inverting summing/gain recovery stage.  Seems to be a variety of compression feels you can get twiddling different combos of blend and compression.

I did the attack mod (Hammer's 3 way toggle) in the pedal I devised the blend for, and the combination of the blend and the extra pop you get with the new attack times made a range of fun, kinda plunky, enveloped sounds (think that ridiculous Michael Jackson clean strat sound), as well as the more normal sounding compression you can get with the stock attack time (technically its the release time you can change, but whatever) and blend.  I did the Hammer treble recovery mod too and liked it (a small cap in parallel with the series 10K resistor near the volume pot).  I didn't do JC Maillet's suggested mod of increasing the output cap to a big electrolytic (1uF -4.7uF I think) for deeper bass, but I would if I where to use the comp for bass or if I wanted a more full range sound...

I'd sure be interested to hear about if there is a mod for a faster attack within the stock Ross/Dynacomp circuit, though.

[Sindran]

Hey Processaurus;
Is the cap on the bottom of your schematic 22yF?
TL072 is "tubescreamer chip", right?
I have selection of OPamps that fit to TS9 circuit, (from banzai effects, the comments below are from their page).
Would one these be better than TL072 for Ross-mixer?

JRC4558D - Classic Tube Screamer Chip
JRC4558DD - High gain version of the classic chip
RC4558 - made by TI, used in 80s Tube Screamers, sounds warm and soft
RC4558 (generic) - No name clone of the TI RC4558, sounds edgier than the original
RC4559 - High Performance dual opamp, used in many quality audio preamps
LM833N - Low noise dual opamp, known to sound good in Tube Screamer circuits
TL072 - used in a variety of commercial Tube Screamer clones
TL072IP - Low noise version of the TL072, more hifi sound
TLC2272 - increased dynamic range, high drive
NE5532 - audio opamp, low distortion, high slew rate

The point is, I use wah before compressor, and I dont want the compressor to clip.
(my gtr/wah combination can have very high output at some frequensies, that´s why compressor is after.)

What about the clean signal... if you dial the blend knob to "dry", is the sound as good as bypassed signal???
Would you recommend trying to get the clean signal straight from input, as you suggested in your original thread???

[Processaurus]

Its 22uF for that cap.  Any big 10-100uF electrolytic will be fine.
Any modern dual opamp will probably be about the same, and not contribute much noise.  TL072 is what I had around.
Headroom is good, because I tested it/designed it with a guitar with big output humbuckers.  I scheduled the gain so that it seemed close to a 50-50 blend volume wise when the blend knob was in the middle, and since the blend knob would never be all the way dry in normal use, I gave the stage after the blend some more gain so all of it wasn't in the first stage for the clean, and since the transients are quieter after getting blended some, there can be more clean gain after the blend, without clipping.  If it does clip (which would take a huge 6v P-P input signal) I'd make the 130K resistor in the feedback loop of U2a 100K to lessen that gain to 1, or better yet put some LEDs back to back in the feedback loop for soft clipping TS style. 

What about the clean signal... if you dial the blend knob to "dry", is the sound as good as bypassed signal???
Would you recommend trying to get the clean signal straight from input, as you suggested in your original thread???

Sounded fine to me, it may have a bit less treble because it goes through the first transistor buffer stage of the Ross that has the slight treble shunt cap on its base, but it didn't bug me.  Having the blend all the way to clean sorta misses the point of having a effect, but I understand what your getting at.  Opamps are good for getting out exactly what you put in, only louder.

As for getting the clean blend input from the input of the effect, I dunno, if I were to do that I would make the cap to ground near the input smaller or skip it (like the dynacomp) so it didn't bleed any treble.  Maybe higher value resistors for the clean's opamp input stage (500K for R1 and 500K for Rf) to raise the impedance.  It sounded good the way it was hooked up originally to my ear so I didn't bother trying that option.

Hope that explains it a little better.

[Sindran]

Thanks Processaurus, I quess I just have to build that mixer and then come back to you...
I think I have to to order some parts for that, the pot at least...

     About the attack, in some thread somebody said the C16 affects to the attack time. Can anyone confirm that???
That popping sound annoys me more and more. I´m beginning to think there´s something wrong with my Ross...
Does the Keeley-comp for example have that same popping effect???
If not what is the solution???
Is the recovery time so long in stock version to prevent that popping???
...Or is there something wrong with my compressor??? Help me out, I´m gettin P A R A N O I D ! ! !
 

[Processaurus]

I think I have to to order some parts for that, the pot at least...

If you are interested in building it but have a different linear taper pot (25K, 50K, 100K) around, you can easily scale the surrounding resistors to the pot and it will act the same.  This article at Geofex explains the math in panning controls.  No degree needed...

I don't think theres anything "wrong" with your compressor, I'm sure the keeley is the same way, since its a part for part clone of the Ross.