Author Topic: stereo pan EA tremolo  (Read 1598 times)


stereo pan EA tremolo
« on: September 21, 2013, 07:43:11 PM »
Howdy folks,

I know there's another thread on this (which I would have linked to but I'm on my phone and it confuses me greatly) and they suggested taking an inverted output into a second EA circuit which seems like a lot of extra components for something that sounds so simple.

Now, I know my way around a fuzzbox but I'm not entirely certain what does what on this particular circuit. I can only assume the input gets sent to ground to decrease the volume as it modulates (like turning a volume knob) so my idea is to hook that grounding point up to a secondary output for panning fun.

Am I declaring my vast ignorance or is this vaguely doable?



Re: stereo pan EA tremolo
« Reply #1 on: September 21, 2013, 08:07:56 PM »
You can reinvent the wheel or....
take a look at the Ibanez ST-810 Stereo Pan. They are both FET based.

I built one with information available online and it does what it's supposed to!
I added dual LEDs to indicate left or right. The panner has one LFO so I had to add a few more components to get the two LEDs going.
The left LED ramps up as the right LED ramps down.
« Last Edit: September 21, 2013, 08:12:14 PM by armdnrdy »
I just designed a new fuzz circuit! It almost sounds a little different than the last fifty fuzz circuits I designed! ;)

Mark Hammer

Re: stereo pan EA tremolo
« Reply #2 on: September 21, 2013, 08:46:48 PM »
The EA Trem "works" by adjusting the effective resistance of a JFET, such that it increases and decreases the gain of another transistor.  The effect is the same as having some sort of "wiggled" attenuator, but it works differently.

If you are fine with using optoisolators of LED+LDR, the Anderton Tremolo can be easily adapted to provide triangle and square-ish modulation, and inverted/opposite modulation.


Re: stereo pan EA tremolo
« Reply #3 on: September 22, 2013, 12:02:10 PM »
I'm going to, at some stage, build a trem, the cardinal, I think, but with mods, namely a phase-shift osc and fets instead of vactrols. the intended case hase an extra hole to fill, so I think "osc speed range switch". this means lower output from the osc, because how they work, so I put an op-amp in. with some gain, I can have some filtering of the osc output, makes a nicer sine as you'll ever see, and more gain means I can get a square-wave out as well. a dual opamp means I can invert that signal, so I can drive fets antiphase in the card.

 so there is no real reason not to do the ea trem in stereo .....
"You've got a suss sus sus sus sus sus sus suspect device."

“Unless you are living in a cave, you know what it means," he said.


Re: stereo pan EA tremolo
« Reply #4 on: September 22, 2013, 01:27:11 PM »
random thought, probably totally convoluted and impractical, but whatever:

in order to retrofit a trem without having to sync LFO's etc., couldn't you use a counter CMOS like a 4017 so one pulse goes left output, the next goes right, then reset? or would there be too much latency or something? hell, even a flip-flop to save on the IC. i haven't given this much thought, myself.
Recovered guitar player.
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