TH Black Eye (Soldano GTO) prototype build

music6000 said:
Well, Get the soldering iron & 1M resistor & get it done, It's 12.48 am in Western Australia & I need some Shut Eye.
I'm making a cup of Tea & buy the time I drink it, I hope to read a Report!!!
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Hey tcpoint , are you using 110v where you are?
With 240v, we get soldering done twice as quick!!!!
 
So should I swap out the 100k’s for 1m’s given that having a buffer in front eliminated the issue? @Betty Wont let me know if this solves on yours.
 
Dan0h said:
So should I swap out the 100k’s for 1m’s given that having a buffer in front eliminated the issue? @Betty Wont let me know if this solves on yours.
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Yup, if a buffer fixes it that means you're having an impedance mismatch. Buffers typically have a nice high input impedance and a nice low output impedance. Ideally you want a low output impedance from the first circuit going into a much higher input impedance of the second circuit. If the input impedance of the second circuit is too low and/or the output impedance of the first stage is too high, you have a bad mismatch and an unstable circuit.

So give the 1M a shot, could do the trick.
 
I just swapped out the resistor. No worky. I'm going to reroute the wiring from the input and output jacks to the stomp. I will probably have to wait until this evening. I'm going to stick with the 1M resistor.

One more note, The squealing goes away when I turn the volume down on my guitar.
 
tcpoint said:
I just swapped out the resistor. No worky. I'm going to reroute the wiring from the input and output jacks to the stomp. I will probably have to wait until this evening. I'm going to stick with the 1M resistor.

One more note, The squealing goes away when I turn the volume down on my guitar.
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On my builds, the location and shielded nature of any of the wires didn't have an impact on the oscillation at all.
 
I'm no (tube) expert, but I can't wrap my head around how increasing the input impedance would help prevent oscillation.

This seems like a step in the wrong direction to me.... but I'll refer you back to the first phrase of this post. 😂
 
I don't have a clear picture on what the other wires in those ribbons carry or the function of that secondary pcb outside of switching. I can review any documentation regarding that and see if there's some room for improvement re: lead dress
 
Robert said:
I'm no (tube) expert, but I can't wrap my head around how increasing the input impedance would help prevent oscillation.

This seems like a step in the wrong direction to me.... but I'll refer you back to the first phrase of this post. 😂
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because that resistor doesn't just set impedance, it also plays a role in biasing. I also haven't received feedback re: removing the first tube from the circuit so I can isolate where in the circuit oscillation is originating from.
 
well overall, the amp has four friggen gain stages and does attenuate a fuck-ton of signal between each stage. I imagine grounding, trace density, and lead dress are all problematic
 
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and not to kick a project when it is down but I wouldn't build an amp out of tayda parts.
also, I don't have Volt/Amp measurements to work with so I have to wonder aloud if 1/4watt resistors are up to the task.
 
ICTRock said:
I don't have a clear picture on what the other wires in those ribbons carry or the function of that secondary pcb outside of switching. I can review any documentation regarding that and see if there's some room for improvement re: lead dress
Click to expand...
They are standard pedal connections. input, pcb input, ground, 9v, pcb out, and output. Removing the whole apparatus did nothing to change my builds' issues. And the Tayda bashing isn't warranted. They are a quality company and I've never had a problem with a single part of theirs over thousands of builds.
 
ok ... did you shorten that up to going from the input/out jacks to the switch only with shielded then shielded to/from the board to the switch?

even some stuff like the fender blues junior pick up noise from long input traces on the PCB and shortening that to a shielded wire from the input jack to the 68K grid stopper helped tremendously.

I'm also fairly curious about the grounding scheme because I've had some amps where I needed to section off ground points from each other rather than star ground ... same thing for having to use sleeved input jacks that don't physically ground to the chassis. without one on-hand I'm having to plumb the depths of all the various crap I've had to sort over the years.
 
Any connection between the type of pickups being used between the builds that do vs do not oscillate?

This would be the one variable between two builds with identical component selection. (excluding tolerance)
 
I rerouted the input and output leads and it didn't help at all. I guess I could go with shielded cable. I'm busy with other things the rest of the night. I guess I could measure some voltages, tomorrow. I have to turn the gain up higher to get the squeals when using single coils compared to humbuckers.
 
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