owlexifry
Well-known member
ohhhh you’re good then.
they jacks will ground themselves to the enclosure, just make sure there isn’t too much paint around the hole/mount area
Lead Solder Overdrive
- Thread starter synthesiserror
- Start date
they jacks will ground themselves to the enclosure, just make sure there isn’t too much paint around the hole/mount area
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.
Feral Feline
Well-known member
You had me at "...known in the state of Cancer to cause California."
Great build!
Great build!
Big Cheese
New member
Putting one together once I get some last minuet components by the end of the week, Did you ever get the oscillation sorted out?
Gpilcher2001
New member
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!
Thanks!
owlexifry
Well-known member
Taiwan Alpha RV16AF-41-15R1-C25K-3 25K Audio 16mm Metallo Case PC Montaggio Pot | eBay
Un potenziometro da 25K in una custodia metallica Ø16mm con un albero lungo Ø6 x 15mm. Ideale per l'uso in applicazioni audio, strumenti musicali, TV/video e controllo industriale, oltre ad essere adatto per uso generico. Quando effettui un acquisto da una qualsiasi delle nostre inserzioni eBay...
www.ebay.com
Robert
Reverse Engineer
Yes, C25K is correct. StompBoxParts has them as well:
16mm Potentiometer - Short PCB Leg
Top Quality Parts for Guitar Effects Pedals and DIY Music Devices. Knobs, Pots, Switches, Kits, LEDs, Enclosures, Jacks, Wire, Resistors, Capacitors, Semiconductors
stompboxparts.com
synthesiserror
Well-known member
Welcome! I ordered mine from Stompboxparts. If you're in the US, they have reasonable shipping.
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
audioacrylix
New member
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?
owlexifry
Well-known member
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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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!!!
audioacrylix
New member
andrewsrea
New member
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).
