Lead Solder Overdrive

At what knob settings does oscillation occur? What influences it? Gain, Mid, Presence, guitar Vol knob?
Did you clean the board after soldering?

Have you tried with other ICs? 5448 instead of 072?
 
At what knob settings does oscillation occur? What influences it? Gain, Mid, Presence, guitar Vol knob?
Did you clean the board after soldering?

Have you tried with other ICs? 5448 instead of 072?
the gain knob, and generally when it's over I'd say 80%. the pitch of the oscillation changes as the knob is turned. oddly when I put my finger on the bass pot it pretty much goes away. the residual noise is likely a mix of the absurd amount of gain and the crappy wiring in my apartment. I use an isp hum eliminator and decimator to combat that.

I have not tried different IC's. that's worth a shot for sure.
 
the gain knob, and generally when it's over I'd say 80%. the pitch of the oscillation changes as the knob is turned. oddly when I put my finger on the bass pot it pretty much goes away. the residual noise is likely a mix of the absurd amount of gain and the crappy wiring in my apartment. I use an isp hum eliminator and decimator to combat that.

I have not tried different IC's. that's worth a shot for sure.
Putting one together once I get some last minuet components by the end of the week, Did you ever get the oscillation sorted out?
 
Hello! New to this forum. Names Greg. I’m curious about this build and am looking into sourcing parts to build one for myself. Just wanted to verify that the presence pot is 25k reverse audio? If that’s the case does anyone have a source for this?

Thanks!
 
Hello! New to this forum. Names Greg. I’m curious about this build and am looking into sourcing parts to build one for myself. Just wanted to verify that the presence pot is 25k reverse audio? If that’s the case does anyone have a source for this?

Thanks!
 
Hello! New to this forum. Names Greg. I’m curious about this build and am looking into sourcing parts to build one for myself. Just wanted to verify that the presence pot is 25k reverse audio? If that’s the case does anyone have a source for this?

Thanks!
Welcome! I ordered mine from Stompboxparts. If you're in the US, they have reasonable shipping.
 
Putting one together once I get some last minuet components by the end of the week, Did you ever get the oscillation sorted out?
got side tracked with other projects. just got it boxed up, and now that it's grounded in the case, the oscillation is basically gone. if i crank the gain AND the mids, it will make a funny honk noise when i turn off my gate. but under normal use cases, the problem i was having before is effectively solved. i test everything extensively before i go drilling expensive enclosures. this would be the second time i reported a problem and it turned out to be grounding because it wasn't boxed yet. shout out to Robert for sorting that out for me both times. what a guy
 
Hi, I have boxes mine up and it still suffers from oscillation at high gain levels. I am guessing there is not a fix for this yet?
the fix is building it properly.
there’s enough information available on this thread and others (including mine) on how to do that.

if you want some real help, it might be good for you to post your own troubleshooting thread (this is someone else's build report) and attach close, in-focus pictures of your build, and it might be easier to identify potential issues and/or give you some tips.
 
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Hi, I have boxes mine up and it still suffers from oscillation at high gain levels. I am guessing there is not a fix for this yet?
Double check everything. If you can use a short ribbon cable and breakout to the footswitch just to keep leads long. Do what everyone says and route wires along the side above and away from the PCB and it will work perfectly.

I knocked mine out today in an hour or so and it worked perfectly first time. And fwiw, I didn’t use shielded wire or any other tricks some have done.
You can do it!!!
 
you-can-do-it-tv.gif
 
the fix is building it properly.
there’s enough information available on this thread and others (including mine) on how to do that.

if you want some real help, it might be good for you to post your own troubleshooting thread (this is someone else's build report) and attach close, in-focus pictures of your build, and it might be easier to identify potential issues and/or give you some tips

the fix is building it properly.
there’s enough information available on this thread and others (including mine) on how to do that.

if you want some real help, it might be good for you to post your own troubleshooting thread (this is someone else's build report) and attach close, in-focus pictures of your build, and it might be easier to identify potential issues and/or give you some tips.
Thanks ,
the fix is building it properly.
there’s enough information available on this thread and others (including mine) on how to do that.

if you want some real help, it might be good for you to post your own troubleshooting thread (this is someone else's build report) and attach close, in-focus pictures of your build, and it might be easier to identify potential issues and/or give you some tips.
Will do ,great feedback ....
 
This shouldn't be happening. I just pulled out the prototype to confirm, it doesn't oscillate at any setting of the controls.

Try routing your Input / Output wires further away from the PCB. When I route the input wire between the capacitors like you have in your pic I do get oscillation.

I resolved the noticeable hiss by changing C8 to a 220pF and resolved the oscillation by changing R10 to a 510K resistance. Before that, I was getting serious oscillations with the gain above 2 o'clock, the mid past 12 and the bass at 9, and using shielded lead wires from the jacks to switch, far from the PCB. I also employ star grounding for the shielded cables and only allowing ground to chassis via the output jack (I use cliff jacks for the input).

Having worked on a few SLO100's in my day, this solution made the pedal sound closer to the real amplifier, which never got as fuzzy as the Soldano pedal design. This pedal design also has more high frequency and less mid-push compared to the amp design, as the latter dumps highs using a 1n cap to AC ground in the 3rd gain stage, which my 220pF C8 fix gets it a bit closer.

I believe the condition causing the oscillations is the filter network created by C4. C5, C6, R7, R8, and the gain pot. This is nearly identical to a gain stage in the SLO 100 amp, except it is missing the snubber-load resistor before the IC input #3 (tube grid on the actual amp) and the amp's gain stage produces much less gain than this pedal design (it uses three more stages to get done what this does in one stage). That said, there is a great similarity of this filter circuit and the resistor-capacitor oscillator tremolo circuits found in amplifiers. This filter network has the makings of a motor (oscillator) when C6 loses its path to ground as the gain is turned up.

My only other deviation in components is in using an ICL7660CPAZ charge pump (very quiet and reliable), socketing the ICs and clipping diodes.

With the aforementioned changes, I can put everything on full and it is on the edge of oscillating. I think it sounds most like the actual amp with the gain at 2 o'clock (or less), the mid full-up, the bass at 9 o'clock, treble at 9 o'clock and presence to taste (into a Fender Twin and a Marshall 4x12).
 
Nice build!
I know I saw someone in a Facebook pedal group with a hand built SLO pedal, judging from the control layout, I’m guessing it was a PPCB board as well.

As someone mentioned elsewhere, wonder if using shielded wires from the switch to jacks would help cut the oscillations?
The oscillation has nothing to do with the input/output cable whether you use shielded one. In my experience was the oscillation was cause by the feedback loop resistor on the gain section. Just make sure the resistor (R10= 1meg) is good and properly soldered. This also goes to the 100pf capacitor that goes with it.
 
@synthesiserror

Hey dude, awesome looking pedal.

Could I ask you a question.

My breakout board has a space for LED, CLR as well as the power. Would you use these or the ones on the board ? Either way what would you do with what’s left empty ?
 
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