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Did you ever get this working? Just curious.

Unfortunately I've been moving the last couple of months. But I plan on it soon. All my stuff is still boxed up.


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It might help everyone to know that his Big Muff is always on. It's his clean tone.

I would think you don't want to use a resistor in series because that would just decrease the volume, which is not what you are going for. As for the other thing I'd suggest just trying and see what works. The dpdt will for sure but I'm not positive about the other way.

Yeah, I just need to make a parts order, so working on my BoM. I havent had much luck searching, but maybe not using the right keywords.

Quick question... I think...

Working on a J Mascis (Dino Jr) spec Big Muff with the help of Kit Rae's wonderful site. I plan on using a mudbunny but including the power filtering too.

Anyways, he bypasses the volume pot for his boost, but I'm wondering the best way to do this. Just a simple SPST between lugs 2&3 seems like it would work, but there would still be signal draw going to ground depending on the position of the pot? So with that logic, a DPDT would work best to remove the pot entirely from the circuit, but that seems overkill. And would I need to add a resistor in series to emulate a dimed volume pot?

The way he works it is he sets his max boost volume with the bypass engaged, for his lead tone. Then he uses the volume knob in non-bypass to set his rhythm volume. Starts high, and works his way back.

EDIT: second question: Might as well not start a new thread...

The mudbunny and a lot of other muff pcbs have the clipping caps after the diodes with a non-polarized cap. But in the original circuits, its a 100v Electrolytic placed on the base side of the cap, not the collector side. What, if any, effect would this have on the clipping?

Any input would be greatly appreciated. Thanks!

i have a csi something multimeter too, a bit different than that, but not much. the test leads are really finnicky at best. I found using the grooves close to the tips opposed to using the actual tips works the best for me. Maybe try that.

And like Jacob said, just make sure you have hte red lead plugged into the mA spot.

where to begin...

My buddy has the Gold Pigtronix Philosopher's Twin Germanium version from Sweetwater. It started having some erratic behavior so he asked me to look at it. I assumed it was just some dirty pot or loose connection. It's only a little over a year old and barely used in his studio. It's beyond warranty though.

Anyhow, what seems to happen is there is some kind of loose connection or something happening that will cause it drop all signal. Then when the signal comes back in, it slowly builds up, but is real noisy. The only visual thing I noticed is one of the ceramic caps looks a little awkward at the leg, like its cracked, but that seems fairly typical. Nothing spilling or anything. There is an optocoupler, VTL5c6 in it and I'm wondering if thats the issue.

I can't for the life of me figure it out. Poked around, havent seen anything out of the ordinary. Voltages seem correct everywhere. Usually Full 18V or 9v depending on the point. As far as I can tell its the Philosphers Tone circuit with an added Grit Stomp that just changes/bypasses R4, I cant remember right now.

Any suggestions on what to check next? I'll try to get a video or sound clip If I can.

I wonder if a copper tubing cutter would work?

Made this video about a year ago on the topic.  pros and cons to both methods I guess:

Link: http://www.youtube.com/watch?v=V-OYXdKMG8s

Edit: ^ Those were thumbs up on my iPad. Apparently that didnt come across that way on the PC.

Why the switch to the 5817 though? Just lower forward voltage than the 4001?

Yes, and because they're different types of diodes with different purposes.

I guess I meant, why wouldnt the 4001 work in series? just too big of a Vdrop?

4001 is used in a "crowbar" formation, where it goes between +9V and ground, with the cathode pointed toward +9V. It shunts the voltage if you plug in the wrong polarity power supply -- which protects the components but will create a situation where your power supply can supply enough current to eventually (and by "eventually" I mean "very quickly in real life") destroy the diode, creating a dead short to ground. However, a battery can't supply enough current to kill a 4001, so it works to protect the components if you momentarily connect the battery the wrong way around. The worst that happens then is you drain the battery a little.

Using a 1n5817 in series with the power supply means that if you connect the wrong polarity of power supply, you will simply get no voltage passing, because the diode will block it completely. The price you pay is the loss of a trivial amount of voltage (0.2V in this case).

When people were powering their effects mostly with batteries, using the crowbar method with the 4001 was perfectly acceptable because it did exactly what was needed and sacrificed no voltage, which could matter when the battery became particularly drained. Now, though, almost no one uses batteries, especially in DIY pedals, so it's better to just use the way that won't kill a pedal.

Why the switch to the 5817 though? Just lower forward voltage than the 4001?

I run at 773.6F. (I set it at 412C, I don't know why I just do.)


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Sorry. Should have read more closely.

No worries! I just responded because I didn't want you to feel neglected 

I think these are usually called 'preamps'. 

Seriously though, if you want to do this, go ahead, seems doable. If it were me I would go for a dual gang for volume control on both the passive and the OD circuit and I would use a 3PDT toggle switch to switch between passive and active. And wire it as such:
1. passive send   4. passive return  7. nothing
2. input from pickup selector  5. output to output jack  6. ground connection
7. to OD board   6. from OD volume pot   9. ground sent to OD board.

The reason for this is so I would hook up the ground connection from the jack to lug 6 of the switch. I would connect the passive volume pot to lug 6 as well so as to complete the classic ground connection as is in almost any guitar. By connecting the ground of the OD circuit to lug 9 I would make sure the circuit only becomes active when in use. Otherwise with a simple DPDT bypass switch or the push pull pot the circuit would still be active and draw power when bypassed as long as the guitar is plugged in. Thus conserving battery life. I've done this in one of my own guitar which has an internal fuzz circuit.

Also, use easily accessible trimpots any control on the board which is not directly accessible on the outside.

Good Info!
I haven't noodled it all out yet. I was planning on using a stereo jack and running in 9V on the ring. so its only ever active with an injector at the pedalboard. The more I think about it, the less I want to do it. haha.

Check out the Ibanez Tube Screamer amp for an example of an amp with integrated overdrive effect.  I think an OD with a flatter response or more tonal options would be better suited for what you're talking about.  Also check out schematics for certain JCM 900 models. Those definitely integrate op amps and clipping diodes for overdrive, although I can't remember how they implement the tone stack.

I was thinking onboard the guitar itself, not on the amp.

Anyone ever see or use an overdrive circuit as an onboard active tone control? I've got a vero timmy that would go well in on of my upcoming tele builds. Also have a kingslayer and fatpants that could work well. Other than committing to the effect on the guitar, Anyone ever see something like this? I keep my timmy on all the time anyways.

I could just use a push pull or even dual gang volume control for active/ passive.

can you get OA126 diodes??