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A buddy of mine brought me a vintage phase 90 (6 single opamp version). I passes signal just fine but the phase signal gives me nothing. I've checked all of the ICs and they each are getting powered properly (9V on pin 7 and 0V on pin 4). I pulled out the audio probe and I noticed that the signal gets attenuated after the first capacitor and then comes out of the input buffer incredibly weak. From their I think the simple filtering in the rest of the audio path kills the signal off. Any phaser folks had experience with this?
I'm getting the appropriate 5.1V off of the Vref so I don't think that's an issue. I've been using the Electrosmash phase 90 analysis page to help me sort through the signal path.

Hey everyone, my name finally came up on the KoT waitlist and I got mine in the other week. Naturally I pulled it apart to see what the famed high gain mod actually was. Turns out the drive pot is the same value as the standard but the resistor in the feedback loop changes values.

I'm attaching the schematic I came up with from tracing mine. Certain resistors in each side where carbon comp as well so I've noted that in the schematic with CC.

Hope some folks find this informative. This community has been super helpful to me so I wanted to pass this info along.

Edit: Updated the schematic to include the serial number, IC value, and fixed the clipping diodes sections.

So I'm looking to build a couple of fuzz pedals but I don't want to make a fuzz face, big muff, or bazzfuss. I really don't want to have to play around with germanium or specific hfe values and such. Anyone got any recommendations for a good silicon fuzz that uses common transistors but doesn't have all the hassle?

I was originally thinking of doing the DBA Supersonic Fuzz Gun but it looks like it's finicky with transistors.

I was wondering if anyone could explain the bass control from the Friedman BE-OD to me. From simulating it, it seems to be an active band-pass filter  where the pot shifts the center frequency. Anyone got any more info on it?

Build doc from the Thermionic Distortion for reference: http://www.pedalpcb.com/docs/ThermionicDistortion.pdf

Just finished up the the Pedal PCB Thermionic Distortion (Friedman BE-OD). Super easy to build (first time with 1/8W resistors) and I love the top mounted jacks. It sounds absolutely immense. I have the internal trimmer all the way down because it was too much gain for the guitars I had running through it. I initially got some weird high pitched feedback that was kind of annoying, but that was when I was using TL072s. I switched it over to NE5532 like the build doc calls for and it went away.

Pardon my Kurt Vonnegut reference

Can anyone explain to me the theory of how input/output/coupling capacitors work? I know we all go with the "bigger means more bass" mantra but what actually makes that true? Is it forming a high pass filter with the input impedance of the next stage or something more complicated? Also, how much does reactance play into it if any?

Does anyone know where to get those massive Radioshack communications knobs that people use for expression pedals?

I know Radioshack is having a sale but I don't want to buy 20 of them just to get free shipping.

So I've built the Madbean Turnabout and it sounds really friggen good. The only problem I'm running into is that the output volume is super high. I can barely turn the volume knob before it's crazy loud. Any thoughts on how I would go about taming my output volume?

Does anyone have a template for a 125B with top mounted jacks and power? One that accommodates board mounted pots would be great.

I'm trying to put one of Aion's boards into a 125B to start moving all my pedals to top mounted jacks.

So today I traded a couple of DIY kits for car repair. Didn't think that would ever happen.

Anyone else ever do any strange trades?

Hey guys,

I was looking at Aion Electronic's schematic for the Zendrive and had a questions. I was wondering if there's a reason that we tie lug 1 to the wiper in the tone controls. From what I understand, the signal is looking for the path of least resistance which will always be from the wiper to lug 3 since the path from 1 to 2 is essentially an infinite resistance since it doesn't go anywhere. Is there a reason we tie lug 1 to 2 instead of leaving lug 1 floating in these types of circuits? I noticed that the gain pot has a similar thing going on too.