Ross Compressor attack switch..

[F2HF2H]

hey, ive built this ross compressor:
http://fuzzcentral.ssguitar.com/ross.php

i dont know which switch position is the high/med/low attack control..
any help
thanks

[F2HF2H]

anyone?

[MartyMart]

The Fuzz Central link explains it well enough, so your "middle" part of the switch is the slow setting ( 160k )
the side that you've wired the switch to the bottom of the 10k and bottom of the 39k ( in relation to Q3/Q4/Q5 collector, is fast ( 10k ) and the
side that's wired bottom of 10k and top of the 39k ( putting them in series ) is the medium setting ( 40k )
you should be able to hear this, in particular when your "sustain" pot is past 2 o'clock.
If you can't remember the way each "side" of the switch is wired AND can't hear it, then take the back
off and have a look inside to make a note of that, as you can have the switches outer lugs wired either way ..... of course !!

MM

[Zero]

On this site it is also explained for the MXR Dynacomp, which is virtually the same thing as a Ross Compressor (just a couple of capacitors difference).
It's in Spanish, but you should get the point from the pictures...

http://www.pisotones.com/Articulos/DynaMod/DynaMod.htm

Zero

[Mark Hammer]

Short-ish version.  (Using Tonepad diagram as reference: http://www.tonepad.com/getFile.asp?id=9 )

The 3080 is kept at maximum gain unless the envelope follower subtracts from that.  Normally, gain is kept high via the the voltage presented at the base of Q5, which is essentially a voltage "stored" in the 10uf cap just before it.  The 150k resistor going to V+ determines how fast that 10uf cap to ground "recharges" each time the envelope signal discharges it.  Since more resistance allows less current to come through, and less resistance allows more current to come through, when that 150k resistance is decreased it lets the 10uf cap recharge faster.  So, 150k = longer chargeup time (slower rebound from maximum squish, and seemingly longer sustain), and 10k = fastest chargeup time (quick clamp on peaks but fast rebound and better response to subsequent notes when picking faster). 

Some people like to have a continuously variable "Attack" pot, but differences between pot positions are often imperceptible.  Personally, I advocate for a slow, medium, fast switch (10k, 39k, 150k, or a roughly 4:1 change) and it appears I'm not alone in that.  Both EHX and Keeley have adopted a similar approach.

[lowstar]

tc electronics and t-rex (well, same syringe different needle) opted for the variable attack (poti).

cheers,
lowstar

[Mark Hammer]

tc electronics and t-rex (well, same syringe different needle) opted for the variable attack (poti).

cheers,
lowstar

At one level I understand the desire for continuous control. Hell, I suffer from that clinical condition too. A buddy who produces the Retro-Sonic line of pedals, started out with a 3-position switch at my suggestion, then finally had to knuckle under to consumer demand for a continuous control.  So the "condition" is fairly widespread.

On the other hand, the thing about the recovery-time mod is that it alters how much time is needed between notes; its appearance depends so much on one's picking style that it can be all but inaudible unless one is playing just...so.  Sure, you can move the pot another 10 degrees clockwise, but unless your playing deliberately milks what that control adjustment permits, you simply won't hear it.  This is not one of those it-will-sound-like-wherever-you-set-it-to controls.

Note that the recovery-time mod, while called "Attack", is NOT an attack control.  It only appears to affect the attack indirectly, by suppressing gain for subsequent notes played very soon after an initial peak.  It is quite possible that companies like T-Rex - which put out a higher-end product - may be including an attack control which actually IS one; i.e., it determines how quickly the gain reduction is imposed in response to any peak at any time.  If that is the case, then a continuous control may well be appropriate, since this would have an impact on essentially all notes, not just the ones that come too soon afterwards.

Never mistake the silk-screened legending on the box for what goes on underneath.

[lowstar]

well, in that case i might have to trace it. i just looked inside and saw the ca3080 and the rest of the components, so the bells went off in my head saying "ross comp", and playing it, the attack control definitely changed the sound like an attack control on a normal comp would.

cheers,
lowstar

[Mark Hammer]

Oh, it may well BE what you think it is.  I'm just saying you shouldn't let the legending be the final judge.  Let the circuit do the talking.

Incidentally, last night I wired up a Dynacomp (U-Stomp layout) for a modular system I'm working on and hope to show here in a few weeks.  I wired up the recovery control as a pot instead of switch.  Why?  Because I ran out of toggles and the pot+knob was cheaper than buying a toggle at Rat Shack!