Orange Squeezer uneven "release"

[dbarks]

I just built an OS.  Seems to work and sound good but if you adjust the trim pot so you can hear the compression fairly well and hit a chord fairly hard and sustain the chord, the "release" isn't very even.  You can clearly hear two "waves" that sounds like you are juicing the volume pot as the sound decays.

If you set the trim so that you can't hear much compression, it doesn't seem to do this - but admittedly, you can't really tell since there isn't much compression anyway.  Do they all act like this or should I start looking for the cause?

I realize this isn't a Ross style compressor so maybe I have the trim pot adjusted too aggressively.


Dan

[cd]

This is normal.  From a post by R.G.:

There is some very light amplitude modulation as the input signal's level decreases, unless I am hearing things. Any ideas?

Your hearing is excellent. There is some amplitude modulation from the ripple on the envelope follower. This is a common failing of simple, cheap envelope followers that use JFETs as gain modulators. The JFETs follow the ripple on the envelope waveform. To fix this, you'd have to redesign the follower.

OK OK I know what you're thinking, how do I redesign the follower???  Check out the Squeezer+++.

[Mark Hammer]

The other thing you can do - which *will* reduce the "transparency" of the OS a bit - is to increase the release time of the follower by increasing the value of the 4.7uf cap to 10uf or more, and possibly increasing the 100k resistor to 220k or more.  The gurgle you hear comes during the decay phase of the envelope, when small variations in level cause the control element (an FET in this instance) to fluctuate also.  Doing the suggested changes causes the cap to discharge more slowly.  In a sense it is like a deep lowpass filter for the envelope.  Think of the follower like the tachometer on a car - if it is TOO responsive, it becomes irritating, but it becomes more useful if it is more sluggish to respond.

The loss in transparency may occur because the OS is normally set for a very fast attack and decay so that consecutive notes do not impact on each other.  The suggested changes will make it start to behave a little more like a Dynacomp, where changes produced by note N linger a bit and impact on notes N+1 and N+1 if you are picking with any speed.

[bwanasonic]

There  was a recent thread started by *vanessa* that noted differences in the smoothness of this *ripple* between supposedly identical builds:

http://diystompboxes.com/sboxforum/viewtopic.php?t=35349&highlight=

I don't have a firm enough grasp on the architecture to say where to look, but apparently even with the *stock* parts, there is room for improvement, and some units will sound *better* than others without tweaking.

Kerry M