Orange Squeezer Tremolo Mod

spargo · July 19, 2011, 11:46:28 PM

So I was breadboarding an orange squeezer, tweaking a few things, etc. Was working pretty good. Then I came back to it the next day and added a 3PDT to the breadboard (instead of straight in/out). Messed around with a couple pot values, and I'm not sure exactly what happened...but now I don't have a compressor anymore. I have a tremolo.

No joke. It isn't half bad either, just a bit distorted! Definitely a square wave.

So my question is, could a FET possibly be fried? I plan on swapping them out to check, but just wondering if anyone else has tried out this mod before.

CynicalMan · July 19, 2011, 11:57:37 PM

A long shot, but are you using a 1Spot? When they're shorted, that sometimes happens for me.

spargo · July 19, 2011, 11:59:45 PM

Yes I am...that's a very weird problem. Usually shorts would totally mute it. I'll check things out.

CynicalMan · July 20, 2011, 12:09:36 AM

I think that when they short, they shut down for a moment to avoid damage, then they turn on again. This can cycle over and over again indefinitely without damage, but you do get a ticking or tremolo effect. You could disconnect the adapter and use a multimeter to see if the power input is shorted at the circuit.

spargo · July 20, 2011, 12:19:39 AM

Unplugging the power supply, the multimeter shows no solid continuity from pos to neg. But plugging it back in and measuring the voltage doesn't work either. There appears to be some kind of partial short, maybe through a resistor? First glance everything seems fine, but maybe I bumped a part on the breadboard - I'll look more in depth.

In the meantime, I shall name the effect the "1Spot Tricky Trem Squeezer."

spargo · July 20, 2011, 01:28:48 AM

Upon further inspection I can't find a short of any kind anywhere.

Upon further testing, I've discovered there are no issues from when power is activated up until about 45 seconds later. At that point, the tremolo effect fades in over a span of 3-5 seconds and continues indefinitely.

spargo · July 20, 2011, 02:13:26 AM

Replaced all of the FETs. Same problem.

spargo · July 20, 2011, 03:51:11 AM

Replaced the opamp and the problem is gone. I think it got fried. Which is sad, because it was a $3 opamp that was sounding good, OPA2134. I replaced it with an NE5532, and my Compressor-Tremolo has now turned into a fuzz. The trimpot is having no luck biasing correctly and it's nothing but grit throughout the full spectrum.

egasimus · July 20, 2011, 04:08:13 AM

Audio probe the thing to find where the distortion begins to occur, and start from there. Perhaps a fried electrolytic cap? First of all though, try yet another opamp.

vendettav · July 20, 2011, 07:23:12 AM

dude be careful with those ICs.. what if the next one you put it in turns it into a ULTIMATE LASER HUMAN KILLING MACHINE!!!

aaaaaaaaaaaaaaaaaaaaaa

Mark Hammer · July 20, 2011, 10:26:29 AM

But you know, 1-Spot issues aside, that's an interesting thing you've stumbled onto. Indeed the basic OS could be adapted serve as either tremolo or compressor. One need only change the "modulation" source driving the JFET from the envelope signal coming off the op-amp to a suitably adapted LFO. Heck, for that matter it might make for an interesting pedal if the amplitude were varied by both an LFO and current pick attack together.

Definitiely worth exploring.

R.G. · July 20, 2011, 10:51:32 AM

Good point, Mark.

Inside every compressor lurks a variable gain amplifier that can be per... uh, DIverted to other uses.

Mark Hammer · July 20, 2011, 11:26:20 AM

Crap! Now you've got me thinking, and that's NEVER a good thing (especially when I should be doing my actual job).

One of the things we like about tube-bias tremolo in amplifiers is the way that modulating the bias of the output stage affects the clipping characteristics of the output tubes. I'm sure that's not everything, but it is certainly part of it. The OS presents us with a humble JFET to be battered about by a gate signal. I wonder if an OS could be co-opted to capture at least a little bit of the tube-bias mojo.

Or am I dreaming?

puretube · July 20, 2011, 06:39:52 PM

Quote from: Mark Hammer on July 20, 2011, 11:26:20 AM
Crap! Now you've got me thinking, and that's NEVER a good thing (especially when I should be doing my actual job).

One of the things we like about tube-bias tremolo in amplifiers is the way that modulating the bias of the output stage affects the clipping characteristics of the output tubes. I'm sure that's not everything, but it is certainly part of it. The OS presents us with a humble JFET to be battered about by a gate signal. I wonder if an OS could be co-opted to capture at least a little bit of the tube-bias mojo.

Or am I dreaming?

No,
you ain`t...

Just bias your Fet to fit into above schemo...

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Orange Squeezer Tremolo Mod