Ross compressor weird fuzz sound

[DanielB]

Hello all, how are ya?
Im getting a weird fuzz sound outa my ross compressor i have just built. I have read somewhere that the drop across R13(i think) 150k resistor should be next to nothing (which makes sense going to the base of a BJT right?), i have a 1Vish drop which seems large to me.
My ic voltages are as follows
         1            2            3             4            5                6            7             8 
      NC          4.33         4.36        0             0.7            1.58        9.12        NC

and transistors are as follows

              Q1                     Q2                   Q3                    Q4                     Q5       

C          8.19                     8.06                7.2                   7.2                      9.11

B          1.44                    1.59                 .0029               .0049                   7.19

E          .93                      1.06                   0                     0                        6.7



If anyone could help that'd be awesome cause im going mentally insane!!

Thank you
Daniel

[scuzzphut]

Hi Daniel,

Not much help here - but I get the same thing - although only when I set the sustain past 3 o'clock.
Built from a Tonepad PCB - commenting here really to say that you're not alone and to remind me to check back for any advice 

[DanielB]

Yeah I've built one before which worked fine.. If i find the problem i will let you know! Mine only seems to do it when the "Attack switch" is in the 2 lower resistance states.

[Mark Hammer]

Sounds like envelope ripple.  People regularly describe bad envelope ripple as "distortion".  In this case it is essentially a kind of tremolo, but at audio frequencies.

A few things to check on.  First, make sure the 10uf cap to ground from the Attack switch is the stated value and properly connected to ground.  Second, make sure that the transistor is properly oriented for each half of the rectifier circuit.  losing half the rectification can lead to more audible ripple.

[DanielB]

Hey Mark thanks for the info! Which transistors are the rectifier transistors?

Thanks

[Mark Hammer]

Those would likely be called Q3 and Q4 in most schematics; the ones with a 1M+diode combination to ground from the base.

[DanielB]

Awesome thanks! I'll give it a shot!

[DanielB]

Well the 10uF cap was coming up as 20uF so i tested a 10uF and replaced it and that one also said 20uF when i put it in. confusing!

[DanielB]

So I've changed Q3 and Q4 and the cap to ground and checked my connection to ground and its all ok but i still get the fuzz.. With the variable recovery switch set to 160k its alright but the other two positions sound like an overdrive. Any ideas??