Love Squeeze compressor. Nasty and subtle distortion on the sustain

[nonost]

Hi everyone. I've already built a Rothwell Love Squeeze using the tagboardeffects layout (https://tagboardeffects.blogspot.com/2012/02/rothwell-love-squeeze.html). The pedal is working great although I can hear a subtle nasty distortion on the sustain at higher settings. It's very subtle, but you can hear it. It's totally ok for live but I'm afraid that it's not so good for recording. The pedal sound as the demos I've heard: transparent but with a good amount of squish at high settings(although it dulls the treble a bit). I've used BAT43 (0.270Vf) instead of 1N5817 (0.190Vf). Tried different opamps and 2N5457 with no luck. Has anyone experimented something like this?

Cheers! 

[Perfboard Patcher]

Hi nonost,

I found a schematic at http://revolutiondeux.blogspot.com/2012/06/rothwell-love-squeeze-compressor.html .

What does this effect exactly do? (I'm talking to myself  ) Considering the values for R5, R13 and R9 I'm guessing that it limits the signal and when it does not it's (on the verge of) sagging or clipping. I think I need to build this circuit for myself.

Do you use some kind of high output pickups? Could it be that a high input level causes Q1 to distort? If you back off the guitar signal a few dBs with the guitar volume pot but leave the comp pot full on does that make the sound to become less distorted?

[Jeema]

I've been working on a similar (but simpler) JFET based compression circuit of my own, and what I've found is that 2n5457s (from different manufacturers especially) have wide variability in their sensitivity when used as voltage-controlled resistors like it's being used in this circuit.

It's possible that the ones you are using are more sensitive than the ones used in the original, in which case the circuit may be compressing harder and quicker than the original circuit was designed for.  That could be what's giving you the flutter/distortion you hear on release.  Raising the value of R13 would compensate for this if my thinking is correct...

[Tubebass]

You could be hearing envelope ripple. Try increasing the value of the cap after the envelope rectifier and see if it gets any better.

[Zounds!]

I built this using the same layout and had some distortion using high output pickups. Not sure if it's the same type of distortion you're getting, but running the pedal at 18v cured it for me.

[nonost]

God I'd totally forgotten that topic! I'm so sorry guys.

Jeema was right about 2n5457 transistors, they can vary a lot from different manufactures. I got new ones and suddenly I got a lot more output than before. With the old ones I had to crank the vol pot to get unity at higher comp settings while with this new one  the vol pot sits around 12:00. I can't remember if the subtle distortion went away, I will check it out. I will also try it running at 18v as Zounds! said.

I did change the cap that Tubebass suggested but it changed the tone of the pedal in a way a disliked, but I'm aware it works to other people.

Thank you all! I will let you know soon.

[Mark Hammer]

If you look at the design of the Love Squeeze, the EA Tremolo, and the Roland Funny Cat, you see a common element.  A JFET is used as a variable resistance to set the gain of a stage.  In the case of the Funny Cat it is used in conjunction with a LOT of envelope ripple, that creates a certain kind of distortion.  In the case of the EA Tremolo, it is used to set the gain of another transistor in a manner that fluctuates so as to create rises and falls in volume.  In the case of the Love Squeeze, it is used to adjust the gain as the input signal decays so as to provide a relatively constant level.

With any effect that uses a sidechain (envelope follower), undesirable artifacts can occur when there is more than a certain level of envelope ripple.  These can often be described by people as sounding like distortion.