TH Black Eye (Soldano GTO) prototype build

[Betty Wont]

Well, I'm throwing in the towel. I've built 3 of these from different parts with 3 different buffers and they all act the same in most testing conditions. The only condition they don't oscillate is when plugged into a battery powered amp. I stupidly sent one out to a customer thinking the buffer addition fixed it, but it was just the isolated amp. So that one got to travel the US before I binned it. This has been the most frustrating and expensive failure I've had in pedals by a factor.

 

[benny_profane]

If it’d be an option, I’d gladly deal with angled pin headers if that would help mitigate the issue by increasing board routing space. I’ve been holding off building mine until a good solution was found.

 

[Dan0h]

I’ve been playing around with having the power section and the audio section separated as far as possible from each other in the enclosure. Turrets and Perf board, but it’s such a spaghetti dinner worth of wires to get everything where it needs I haven’t had the time to assemble it all. I’m thinking the reason most old school tube pedals came in larger enclosures is the space issue. You get the screeches when things are too close.

With all that said I’ve had no issues with my black eye build since dropping down to a AT7 in V1 (as long as it’s after a buffer).

 

[Paradox916]

@MichaelW You seem to collect buffers, buster!

I've got one or two of each of the examples you mention. If you want to turn your PPCB Dual Looper into a buffered one, check out the Effects Layouts Storyboardist Micro Buffer, Klon-buffer on a jack.

@vigilante398 you ever get that buffer sorted out? Would something like that work well you think?

 

[vigilante398]

So my friend swore up and down that the AMZ amp-like buffer would be perfect so I ordered PCBs for it which arrived yesterday, and it doesn't get rid of the oscillations in this build. I've tried the tubescreamer buffer and simple JFET buffer on vero and now the amplike buffer on PCB, I guess Klon buffer is next?

For those that have placed a buffer in front and successfully resolved it, what buffer are you using?

 

[music6000]

So my friend swore up and down that the AMZ amp-like buffer would be perfect so I ordered PCBs for it which arrived yesterday, and it doesn't get rid of the oscillations in this build. I've tried the tubescreamer buffer and simple JFET buffer on vero and now the amplike buffer on PCB, I guess Klon buffer is next?

For those that have placed a buffer in front and successfully resolved it, what buffer are you using?

Your tapping into the Footswitch, what happens if you put it between Power jack & Input Jack???

 

[vigilante398]

Your tapping into the Footswitch, what happens if you put it between Power jack & Input Jack???

Not sure what you mean. The buffer needs to go between the input jack and the circuit input, and the footswitch is the most convenient spot to stick it in there.

 

[Dan0h]

So my friend swore up and down that the AMZ amp-like buffer would be perfect so I ordered PCBs for it which arrived yesterday, and it doesn't get rid of the oscillations in this build. I've tried the tubescreamer buffer and simple JFET buffer on vero and now the amplike buffer on PCB, I guess Klon buffer is next?

For those that have placed a buffer in front and successfully resolved it, what buffer are you using?

Both the General Tso buffer in front and the Klon buffer in front work for mine.

 

[music6000]

Not sure what you mean. The buffer needs to go between the input jack and the circuit input, and the footswitch is the most convenient spot to stick it in there.

I mean before the ribbon cable, not after.
From Input Jack into Buffer, from Buffer to Input Jack pad on the PCB, Power from Jack into Buffer, Ground from Jack into buffer.

 

[Mcknib]

I built the pcb version using 12AX7s and breadboarded the circuit using 6948s

Both oscillated! The first thing I normally suspect is myself until proven otherwise

Long story short I went over the circuit with a fine tooth comb nothing affected the oscillation in the power supply, the only thing I could get to alter the oscillation was tapping V1 pins 2 and 3

I had noticed that the tube filaments weren't exactly glowing in fact you could barely see them light up in a darkened room

So I thought not enough current to heat these beasties so electron flow ain't happening

I changed V1 from a Sovtek (admittedly taken from an old amp) to a JJ and the oscillation instantly dissapeared

I also changed V2 just because

I checked it in every possible configuration max gain, different amps, different guitars and pickups etc

I now have a very silent gloriously glowing gain machine that works as intended thanks @vigilante398 and cheers for your time, teachings and quick responses it's very much appreciated

Here's a very short strum on my phone, no mics and no actual playing I had the fear getting too close to an unboxed HV circuit, gains maxed you'll hear very little circuit background noise all I do is 2 chords let it ring change pickups and tone on the pedal

Black aye.mp4

drive.google.com

Obviously as you can see in the short vid title this is the Scottish version

 

[vigilante398]

I mean before the ribbon cable, not after.
From Input Jack into Buffer, from Buffer to Input Jack pad on the PCB, Power from Jack into Buffer, Ground from Jack into buffer.

Okay gotcha, I see what you mean. I can certainly give it a try.

 

[Betty Wont]

Okay gotcha, I see what you mean. I can certainly give it a try.

I tried this. No go. I tried the pedalpcb simple buffer, a cornish buffer, and putting buffered pedals before, after, and both. No change.

 

[vigilante398]

I tried this. No go. I tried the pedalpcb simple buffer, a cornish buffer, and putting buffered pedals before, after, and both. No change.

So far this is where I'm at with the experiment:

• PedalPCB simple JFET buffer - soldered up on vero and put separately in front, solved the problem; wired inside the enclosure and the oscillation was gone, but there was a ridiculous amount of noise, regardless of how much filtering I added to the power rail
• Tubescreamer-style 2N3904 buffer - same results as simple JFET buffer. Seemed to work outside of the enclosure, but as soon as I pulled it inside it got really noisy.
• AMZ "amplike" op-amp buffer - pretty sure I messed up on the vero layout so I optimistically ordered a bunch of PCBs (seriously if anyone wants a 3PDT PCB with a preassembled SMD buffer on it, hit me up I have 100); has absolutely no effect on the oscillation

External things that worked:

• when I test pedals that I'm building I typically don't waste time with a guitar, I just keep a riff stored on a looper and run that through the pedal. Obviously this has an output buffer on the looper, and when I run the looper with no guitar on the input through the Black Eye there is absolutely no oscillation
• I've been playing a lot of bass lately, and when I run my active bass through it there is no oscillation

Another suggestion @music6000 had that I'll try tonight is silicone damper rings. A million years ago I built a high gain preamp that had oscillation problems that went away when I physically held the tube, which indicated the problem was the tube itself oscillating. I have a handful of these on hand already, so we'll see if that helps.

 

[Betty Wont]

Another suggestion @music6000 had that I'll try tonight is silicone damper rings. A million years ago I built a high gain preamp that had oscillation problems that went away when I physically held the tube, which indicated the problem was the tube itself oscillating. I have a handful of these on hand already, so we'll see if that helps.

I use those on my amp tubes and they didn't help this situation either. They look cool though!

 

[Deperduci]

I'm still trying to find why mine is quiet-ish when I use ECC81/mild gains(not to unity maxed out on all knobs) and no response from 83/ax7's 81's are psvanes, and tried both JJ's and tung sols for ax7's. I wish I could get them to working outside the box then I'd attach to a SS power board and call it good...

 

[music6000]

So far this is where I'm at with the experiment:

• PedalPCB simple JFET buffer - soldered up on vero and put separately in front, solved the problem; wired inside the enclosure and the oscillation was gone, but there was a ridiculous amount of noise, regardless of how much filtering I added to the power rail
• Tubescreamer-style 2N3904 buffer - same results as simple JFET buffer. Seemed to work outside of the enclosure, but as soon as I pulled it inside it got really noisy.
• AMZ "amplike" op-amp buffer - pretty sure I messed up on the vero layout so I optimistically ordered a bunch of PCBs (seriously if anyone wants a 3PDT PCB with a preassembled SMD buffer on it, hit me up I have 100); has absolutely no effect on the oscillation

External things that worked:

• when I test pedals that I'm building I typically don't waste time with a guitar, I just keep a riff stored on a looper and run that through the pedal. Obviously this has an output buffer on the looper, and when I run the looper with no guitar on the input through the Black Eye there is absolutely no oscillation
• I've been playing a lot of bass lately, and when I run my active bass through it there is no oscillation

Another suggestion @music6000 had that I'll try tonight is silicone damper rings. A million years ago I built a high gain preamp that had oscillation problems that went away when I physically held the tube, which indicated the problem was the tube itself oscillating. I have a handful of these on hand already, so we'll see if that helps.

Another thing I found is the tube's are prone to be more sensitive to pinging if enclosure is knocked with them fully pushed in.
I pulled mine up a whisker from being fully seated in the Socket & it cushioned the tube's sensitivity considerably.

 

[MichaelW]

So my friend swore up and down that the AMZ amp-like buffer would be perfect so I ordered PCBs for it which arrived yesterday, and it doesn't get rid of the oscillations in this build. I've tried the tubescreamer buffer and simple JFET buffer on vero and now the amplike buffer on PCB, I guess Klon buffer is next?

For those that have placed a buffer in front and successfully resolved it, what buffer are you using?

Buffers that DO work:
General Tso's (Thorpy)
Cornish Buffer (any buffered Cornish pedal)
Klon style
TC Electronic Bona Fide (Built into my tuner)

Buffers that do NOT work:
PPCB Simple JFet Buffer. (Used on the output of my Amentum Boost build)

 

[MichaelW]

@vigilante398 I may have a few more buffered pedals lying about I can try if it will help. Just lemme know.

 

[vigilante398]

@vigilante398 I may have a few more buffered pedals lying about I can try if it will help. Just lemme know.

Thanks, I appreciate it. I'll see what parts I have on hand so I can throw together a few more tryout circuits. I'll take a look at the ones you posted and see what I can try out the easiest.

 

[music6000]

Buffers that DO work:
General Tso's (Thorpy)
Cornish Buffer (any buffered Cornish pedal)
Klon style
TC Electronic Bona Fide (Built into my tuner)

Buffers that do NOT work:
PPCB Simple JFet Buffer. (Used on the output of my Amentum Boost build)

Another Member used the PPCB Simple JFet Buffer on the Input of their Black Eye and it fixed the Squeal?
My Simple Jfet Eyelet also worked but outside the pedal, Will not fit internally!