Saffron squeeze build report

[vacuumdust]

Just wanted to take a minute and report that I built the saffron squeeze from MarkM's layout on perf and it is seriously one great compressor!  I added an attack control which is just replacing R20 with a 200k pot and it works exactly like it should. I also have a toggle for choosing between the stock .022uf cap and a .01uf (ross/dyna value)...I can't hear a difference between the two (not what I expected). My perfboard was a little small.  By the end I was kind of improvising my own condensed layout but it still came out nice and quiet.  Best comp for guitar I've played through. Thanks to MarkM. Love it when the finished product has zero quirks.

[petemoore]

  Layout is nice for that kind of build.
   I did OS comps and had to re-do the Jfet sections, twisty circuit there by the input. Not exactly the same thing but very nice/small/semi-simple compressor circuit. Use it cause it sounds great ! !

[rsalinger]

Could someone explain this MOD (attack pot) in more detail?

Thanks in advance.

[Mark Hammer]

Could someone explain this MOD (attack pot) in more detail?

The envelope follower section "collects" the absolute voltage of the signal, and averages it out to provide a DC voltage (and corresponding current) that tells the OTA/3080 chips how much gain to provide, or more accurately, how much gain to take away.  It's default is to crank the gain, which is what it does when you stop playing, or play very softly.  Pick harder and it subtracts from that max gain, based on the averaged level of the signal.

The normally 150k resistance, tied to V+, charges up the 10uf cap to ground.  Stop playing and that cap fills up with current, at a rate dictated by the value of that resistance.  When the value of that resistance is reduced, it allows the cap to charge up faster.  When the resistance is higher, the cap charges up more slowly.  It is the voltage that the cap provides for sensing, that dictates the gain level.

So, that resistor/resistance dictates how quickly maximum gain is restored or "recovered", once you stop playing.  It does not really affect the "attack", even though everybody and their cousin calls it that.  But because a very quick gain recovery permits the gain to be up and available in time for the next note, it makes fast picking seem to have a more audible attack.  When the gain recovery is slower, the next notes, and next, and next after that, may well be picked before the cap has had time to charge up fully and restore max gain.  With the gain down a bit, they are heard at lower volume.

Slower recovery time is typically used for those circumstances where you want to hold single notes for a longer time and want the illusion of long sustain.  Faster gain recovery times are better for those instances where you want each and every note to be heard, and expect to be cranking out a lot of them in a short period.  Virtually identical component values are used for "Attack" controls across a wide variety of commercial compressor pedals.   

As you can well imagine, Nashville players are fond of their "Attack" (gain recovery) controls. The usefulness of such a control will depend on the scope of one's playing style.  Someplayers will hjave playing styles where faster recovery time is simply inaudible for them, and other players will pick so fast so often that slower recovery times are a hindrance.  The impact of recovery-time settings will ALWAYS depend on how you pick, and will not be audible  on its own.

[Kipper4]

Is there a schematic link someone can post so i can see what it is your talking about please?

[Mark Hammer]

The parts under discussion can be found in any schematic of a Dynacomp or Ross.

[Kipper4]

thanks Mark

[rsalinger]

Thank you so much Mark. That actually made sense to me... which was sort of surprising to me . LOL.

How would I wire this up? Leg 2 and 3 on the pot would connected and "feed" the 10uf cap to ground, correct?

Thanks,
Rob

[Mark Hammer]

Any 2 adjacent pot legs (1-2, 2-3) are fine, since I doubt anyone has expectations about what ought to happen when you turn clockwise, the way they might for gain, or volume, or treble, or sensitivity, etc.  The main thing is that you have a total resistance (pot+fixed resistor) that ranges from about 10k to 160k or so.  So, for example if all you have is a 12k fixed resistor and a 250k pot, put the 12k in series between V+ and whatever pot leg you want, stick a 330k-390k resistor between the two pot legs you plan to use and run the "other" of the the two pot legs to the junction of the transistors and the 10uf cap to ground.  That will give you the min/max resistance range you want.

And don't be surprised that it makes sense.  EVERYTHING is explainable; you just have to imagine the person you're saying it to.  And believe me, I have plenty of insight into how to be confused about matters electronic, so imagining it is easy! 

[rsalinger]

Thanks Mark you've been very helpful. I'm very new to Compression in general and 3080 circuits specifically.

So, (looking at the SaffROSS Squeeze layout) let me see if I've got it right, then...

I would wire it like this: Leg one would be connected to the 10uf cap to ground. Leg 2 would connect to 3 and then to D1, C15 and R16?

Am I getting this right?

Thanks again,
Rob

[rsalinger]

Wait a minute... it's the other way around, isn't it?
So, which leg is wired to the 10uf cap to ground?

Oh, fiddle-sticks... I'll just never get the whole "pedal thang" sorted out.

I was hoping to etch a board. A friend of mine (who knows NOTHING about guitar pedals), but is a specialist in building DIY Police Radar Detectors, said he would help me with the etching... LOL. I was hoping to "save" money, building a pedal... now, it seems that EVIL-BAY might have been a better solution?

[rsalinger]

Bump...

[rsalinger]

Aha!
http://www.hobby-hour.com/electronics/s/cs2-compression-sustainer.php