Orange Squeezer - mods too subtle

[PBE6]

I built an Orange Squeezer based the GGG layout, with some minor modifications. I used trimpots instead of resistors for R2, R9, R11 and R12 so I could control the ratio, gain, attack and release (respectively).

Only problem is, adjustment to the trimpots are subtle at best. R2 goes from some compression to a lot quickly, and R11 and R12 don't seem to do much at all, even at the extremes. R9 is the only one that's working like it should. Is this normal? Are these mods usually quite subtle so I'm just missing the effect? Or is this subtlety a sign that something's wrong?

[GGBB]

What value and taper pots did you use?  When I built the Orange Smoothie (http://www.diystompboxes.com/smfforum/index.php?topic=105342.0), I made the following notes (included in the build guide):

ATTACK
The 10KΩ attack pot value might seem excessive, but because it is log taper, most of the resistance of the pot is crowded into the last clockwise section of the pot. This results in more even adjustment over a larger range because the added resistance has less and less effect as it is increased. You can adjust the minimum amount of note attack via R11. Less resistance = less note attack.

SUSTAIN
The 500KΩ Sustain pot is also log taper for the same reasons. A 1MΩ pot is an option here if you are really looking for a lot of sustain, but it doesn't give you a whole lot more than 500KΩ, and even 250KΩ will give a good range of control. The minimum sustain is set by R12. Be careful not to go too low (under ~10KΩ) with R12 as it can cause distortion in the compression signal which will impact the compression.

COMPRESSION
The 200KΩ anti-log compression pot which replaces the 82KΩ input resistor has most of its range at the start of the control (low compression) and quickly increases the compression to a typical Orange Squeezer setting leaving about two-thirds of the control for more compression than a typical Orange Squeezer. The range goes from almost no compression to quite a lot. 100KΩ or 250KΩ would also work fine here, but with a different range and feel. Compression is decreased by increasing the resistance before the FET, but as the resistance is increased there is progressively less effect on the amount of compression. Therefore anti-log taper works best. If you choose a 100KΩ here, you will lose a bit of the lower compression range but still have a good range from a little less than a stock Orange Squeezer to as much as possible. Linear taper is a better choice than anti-log when using a 100KΩ pot.

[Mark Hammer]

The trouble with changes to the time constants of compressors is that what you hear depends fundamental on how you play.  Fast release times, for instance, will only be audible if one picks fast.  Pick slower, and you can move the control around all you want, and you won't hear any obvious impact.

Compressors would probably win the "Is this thing even ON?" trophy, if there was such an award.

[PBE6]

If I recall correctly, I used a 200k trimpot for the ratio, a 200k trimpot for the gain (less than specified, but I found there was way too much gain and hiss with the stock 220k feedback resistor - could this be an issue if I'm keeping the gain on the low side?), a 20k trimpot for the attack and a 1M trimpot for the release. This is for a friend who wants to leave it on all the time, so I think the best solution is to just set it and forget it, hence the trimpots.

[PBE6]

Good point Mark. My goal for this design was to add a little bit of punch, kill the highs slightly (it's for a bass player) and add some very subtle distortion (nothing overt, just enough to sound "different"). Subtlety is the operative word.

Would I be correct in thinking that I want a medium attack time (not too short so everything is limited, and not too long so not enough is compressed), and a short release time so that the comp is ready for the next note? To do that I need a little bit of resistance on the attack pot and very little on the release pot, correct?

Does adjusting the other pots have a big influence on the effect of the time constant tweaks? Is it possible for me to adjust myself into a spot on the other pots where the attack and release tweaks are essentially useless?

[Mark Hammer]

The optimal time constants generally depend on: a) the source signal, and b) what it is one is trying to achieve.

So, bass guitar needs different time constants than a grand piano or cymbals, and peak limiting to prevent sudden peaks from overwhelming the PA amp, needs different time constants than reining in the rhythm guitar so it doesn't accidentally drown out the singer.

[PBE6]

Does lowering the gain affect adjustments to attack and release times? Or are they all independent?

[midwayfair]

Does lowering the gain affect adjustments to attack and release times? Or are they all independent?

The gain affects the threshold or the ratio (depending on how you look at it). It does not change any time constants. However, the time constants set how the voltage is stored. If you have less voltage to store, it's going to drain pretty quickly, which is not so different from having a lot of voltage that drains more quickly. Make sense?

[PBE6]

I just tried readjusting the gain, and it helped a lot. The changes to attack and release are now very apparent, from punchy attack to audible bloom. Thanks midwayfair!

[PBE6]

I should mention that I added a 27nF cap from the output to ground to kill the hiss. At half volume (about 2k on the 10kA pot) it should be damping frequencies above 3kHz. Guitarists might cringe at that figure, but my friend was looking for a more old-school vibe for bass so that should be just fine.