JHS Pedals Overdrive Preamp

[jeffwhitfield]

I highly doubt this is a complex circuit so shouldn’t take long to trace. It’s a precursor to the DOD 250. Very interested in seeing what this circuit looks like. Sounds interesting.

JHS Pedals, Kansas City USA— Overdrive Preamp

www.jhspedals.info

 

[giovanni]

I think JHS is all smd, usually.

 

[Robert]

You can trace an SMD pedal (and measure all of the component values) without destroying it, no problem.

 

[Coda]

Obviously they're referring to the original pedal they based theirs on...not the new one. I'm hoping that they didn't use a bunch of SMD components. If so, getting a good trace might prove more difficult. Hard to get a good read on SMD components when they're on the board...and I'm not gonna destroy the pedal in the process. Figure if I can get a decent trace and ID all the components then it can be replicated pretty easily. Shouldn't be complex at all. Heck, I'm betting they used mostly through-hole for this one. Guess we'll see.

Given what it’s based on, there shouldn’t be that many components to begin with.

 

[jeffwhitfield]

You can trace an SMD pedal (and measure all of the component values) without destroying it, no problem.

I'll try with my multimeter, which is a pretty good one. I've done a bit of tracing with it. Shouldn't be a problem I don't think.

 

[cdwillis]

Does anyone have any tips for tracing to measure smd components? I tried measuring smd resistors on my EHX Ram's Head reissue out of curiosity and for practice, but I could not get my multimeter to pick up any of the values at all.

 

[jeffwhitfield]

Does anyone have any tips for tracing to measure smd components? I tried measuring smd resistors on my EHX Ram's Head reissue out of curiosity and for practice, but I could not get my multimeter to pick up any of the values at all.

What make and model of multimeter do you have? Were you measuring with the power off on the pedal?

 

[cdwillis]

Just a cheap DMM I picked up from Walmart I think. The pedal was on my bench with nothing plugged into it at the time. I didn't think I'd need power flowing to measure a resistor. It doesn't have automatic range, so I'd flip through several ranges trying the same resistor and couldn't pick anything up anywhere. Never had this issue measuring through hole resistors.

 

[jeffwhitfield]

Nope. Don’t need power. In fact, you can’t have power running through it when measuring the value of components.

Cheap multimeters are kind of hit and miss. Many of the cheap ones can’t measure capacitors well, much less resistors.

 

[phi1]

If it’s smd, something to consider. Not sure if this has been mentioned yet, but capacitors usually can’t be measured accurately in circuit. It’s not a great idea to desolder smd film caps and re-solder because they can be damaged by the heat (resistors are more durable, as I understand it). So, so isolate a capacitor for measurement, you need to desolder other connected components instead of de-soldering the cap.

This info from pedalpcb himself, in this thread.

Help with tracing a pedal.

I am trying to trace the KMA - Tyler The Freq Splitter. I am having trouble figuring out how to determine the SMD capacitor values. There are no markings on the caps and if I am correct they can not be measured in place. I am unsure of the values of C1, C4, C5, C14, C15. I am guessing on the...

forum.pedalpcb.com

 

[jeffwhitfield]

If it’s smd, something to consider. Not sure if this has been mentioned yet, but capacitors usually can’t be measured accurately in circuit. It’s not a great idea to desolder smd film caps and re-solder because they can be damaged by the heat (resistors are more durable, as I understand it). So, so isolate a capacitor for measurement, you need to desolder other connected components instead of de-soldering the cap.

This info from pedalpcb himself, in this thread.

Help with tracing a pedal.

I am trying to trace the KMA - Tyler The Freq Splitter. I am having trouble figuring out how to determine the SMD capacitor values. There are no markings on the caps and if I am correct they can not be measured in place. I am unsure of the values of C1, C4, C5, C14, C15. I am guessing on the...

forum.pedalpcb.com

Yup. That's what makes tracing with SMD boards such a pain in the ass.

 

[Willybomb]

I could use a modded 250 for bass.

Put a pair of red LEDs across gain pot pins 1+3, pair of Bat46 (might have been 41) to ground, add a clean blend and you're golden.

 

[Matmosphere]

I don’t own any JHS pedals. I bought one but took it back due to a weird quirk. I think the reason I don’t own any is because virtually everything they sell is stuff I can build myself.

I don’t have much of an opinion of Josh. He seems like an ok guy. Everyone makes mistakes. I think if anything the way he gives back is by promoting other peoples stuff. He is constantly talking about pedals made by other people. So theres that.

Also, like a lot of other companies, he kind of turns a blind eye to the traces and PCB‘s made that copy his stuff.

Reading my comment again it comes across more negative than I intended it to.

I’m more annoyed that the topic keeps coming up every month or two. Seems like every time these things get traced there isn’t anything revolutionary new. I suspect this will be the same.

Honestly if you want to have a MXR distortion that sounds better to you then get out a breadboard or throw some extra sockets on a PCB and work it out. There are more than enough resources around to help you and you might find something you like better than what JHS likes.

I don’t mean that as dig on anyone, I hardly ever use a breadboard, though I do occasionally socket stuff.

 

[jesuscrisp]

I'd just check the SMD resistor values, pot values and the diodes etc., get the circuit topology drawn up (should be straight forward DOD250) then breadboard it and try to match the tone to find the correct cap values. Starting with stock 250 ones of course and adjusting from there.

 

[jesuscrisp]

Looks like I was wrong about the big one, it is indeed through hole. (image from Facebook)

 

[Feral Feline]

Looks like it will be an easy-peasy trace for you, Jeff.

“Little do the tracers know — all the through-hole components are dummies, a ruse… the real circuit is all SMD hidden between the battery and the TH components! Mwah haha haahhh. Oh darn, was that my outside voice I just used!?” — Jawersh Heethkit Skawtt

 

[Big Monk]

Maybe it wouldn't need to be $180 if it wasn't in such a GD humongous enclosure with a ginormous custom circuit board.

 

[jesuscrisp]

Maybe it wouldn't need to be $180 if it wasn't in such a GD humongous enclosure with a ginormous custom circuit board.

180$ is the "small" one, this one is like 300$ or something.

 

[Big Monk]

180$ is the "small" one, this one is like 300$ or something.

Yowza.

 

[music6000]

Yowza.

I think the Big Box was limited, Sold Out!

 

[jeffwhitfield]

Got the pedal today. And...well...it's SMD. All is not lost though. Good news is that most of the circuit can be traced. Only components with no lookups are a handful of capacitors. Even then, most of them look like they might be pretty easy to figure out though a bit of trial and error. I'm gonna trace the circuit, record the values that are readable, and then figure out the rest after setting up a breadboard.