Orange Squeezer Noise

[Blues Lyne]

I still haven't had enough down time to get out the soldering iron and try some the cap changes, but I did have a couple of minutes to play though it today.  Before when I was adjusting the trim pot, I had the guitar volume down so I was only hearing noise from the OS.  I left the volume knob in the same spot and there was a spot on the trim pot, around noon, where the noise got less.

Today, I was curious about how the trim pot setting changed the tone I turned it up to around 3:00 and the hiss was much louder, but when I played trough it, the guitar was also much louder.  Unity was down around 8:30 (it had been around 1:00 before).  When I set the volume pot for unity, there was barely any hiss.  Anything from 9:00 up is a pretty serious boost and get's really noisy, so there it's a little more touchy this way.  The tone seems a little thicker and compressed, so I'll have to try it at rehearsal Friday night and see if it still works for what I was using it for.

The pot is wired backwards, so as you turn it clockwise it get's quieter.  Is this the way it's supposed to be?  I'm assuming that if I wire it normally, the taper might be better, but would that effect the hiss?  It doesn't seem like it from my limited knowledge, but I really don't have any experience with the workings of compressors.

[Mark Hammer]

The 82k resistor, FET, and trimpot form a virtual voltage divider (volume pot).  The envelope or "rectified signal", when applied to the FET gate, reduces the resistance of the FET.  As the resistance provided by the FET and trimpot get smaller, relative to the 82k resistor, the signal gets attenuated.  Unlike the Dynacomp, where the gain is adjusted based on signal level. here the gain remains constant and what is adjusted is the signal level fed to the gain stage.  Naturally, if you make the resistance of the FET+trimpot high enough, you WILL notice an increase in volume at the same time as noticing a difference in the compression behaviour of the circuit and the hiss.

[Blues Lyne]

Just to update things, I rewired the volume pot so that turning it clockwise turned the volume up.  Of course it's got a much better taper now.   I adjusted the trim pot to between 1:00 and 3:00 where it initially seemed to have more noise when the volume pot was left in one position.  However, because I now get unity at a lower volume pot setting, it resulted in dramatically less noise.  Now at unity volume, there is some barely detectable noise when it's on, but nothing you would notice unless you were really listening for it. 

Thanks for all your help.