"De-Mud Mod"

[Ivan75]

With a series cap before it, a tone control tends to behave like a second volume pot. That's how I spot humbuckers (or single coils) that a broken coil wire made capacitive, for the record (and that's something that anybody can check personally in a few minutes with a capacitor + a pair of alligator clips, BTW).

Hence the clever trick popularized by ArtieToo and consisting to put the series cap between coils: it diminishes a bit the downside that I describe. Now and IME / IMHO, a tone pot before the series cap remains the simplest way to make hi-pass and low-pass filter working nicely with each other, without any change in how the tone pot works. YMMV.

EDIT - That said, there's an alternative solution: using a Fender TBX pot with the (no load) 250k side wired as a regular tone control and the 1M side as a master "bass cut" with a series cap. The two tone controls can't be in conflict with such a pot, since it allows to use low-pass/hi-cut OR low-cut/hi-pass and not the two circuits altogether...

Sorry all for resurrecting an old thread, but this is the only discussion I found that actually tackles some issues. I need some clarification for de-mudding the neck humbucker, but in an HSH configuration where exactly should I put the cap when having a master volume and a master tone which is also a push/pull switch for coil splitting? I could actually ditch the bridge coil splitting, but that's another matter. Here is the schematic but with Duncan's color code, it's actually all DiMarzio in the guitar. So where exactly to put the cap to maintain the tone pot taper function and will I get some hum in the neck or the in-between position (split neck+middle)? There is no hum now, the middle is RWRP. Thank you!

 

[freefrog]

Ivan75: as you quoted me, I'll reply but the context is "special" for me, right now (I've some personal issues to deal with). Please, check your messages center periodically, thx.

 

[Ivan75]

No problem, it's nothing urgent, thank you!

 

[marcello252]

I need some clarification for de-mudding the neck humbucker, but in an HSH configuration where exactly should I put the cap when having a master volume and a master tone which is also a push/pull switch for coil splitting?

In my opinion, as you probabily want to demud the humbucker only when not split, you have to put the Cap +Res between the black wire form the neck pickup and the switch

 

[El Dunco]

I’d love a schematic for a switchable version so I can for example, tighten a passive bridge pickup for chugging without any pedals between the guitar and amp, then take it out of the circuit to fatten it up again for leads, heavy chords etc.

 

[Mincer]

Couldn't you just use no-load pots with the detent in them?

 

[El Dunco]

If your pickups split on a push/pull tone pot, can you still just run from hot to switch without issue?

Couldn't you just use no-load pots with the detent in them?

So it’s variable? That might work. Where would it go in the signal path?

 

[Mincer]

If your pickups split on a push/pull tone pot, can you still just run from hot to switch without issue?



So it’s variable? That might work. Where would it go in the signal path?

Well the pot goes where a normal pot would go, it just has a detent at the end (on 10) that takes it out of the circuit.

 

[Artie]

Bypassing the De-mud mod is as simple as a switch to short out the cap/resistor combo. It could be a SPST switch, or half of a push-pull.

P.S. I just noticed that one of these has the cap value (that I used) wrong. I believe the .001 uf is correct. At least, for my 59 in my guitar. Experimentation is your friend.

 

[Ivan75]

In my opinion, as you probabily want to demud the humbucker only when not split, you have to put the Cap +Res between the black wire form the neck pickup and the switch

Haven't seen your reply on time, thanks, man! First, I'll change the volume pot from the currently installed 470K to a 506K I have, maybe I can hear the difference, if not, I'll put a .022uF Orange Drop in there and see. I don't mind the tone pot acting up, I don't use it on the neck humbucker.
Cheers!

 

[zizyphus]

Hey '59, not sure what you're playing through / what the context is for your question, but If you have an extra pot available, you could wire up the neck pickup in series with a cap and a pot, so the pot acts as a variable bass cut (in the same way that tone pots usually perform variable treble cut). I have a few guitars wired like this. It's helpful for cleaning up a dirty sound, especially an unruly fuzz.

If you like what you get, you can also wire a Fender TBX tone control such that turn it one direction causes a treble cut, and turning it the other direction causes a bass cut. Thats also fun and handy__PRESENT

 

[Ivan75]

Well, I just did it, played it for a while and I'm pretty disappointed. The guitar in question is an MIJ RG Ibanez, HSH, DiMarzio Evolutions with True Velvet single-coil (RWRP) and the cap de-mudding is just not working remotely as expected. I went with the .022uF Orange Drop, it instantly felt like I had a blanket over the amp. It came out just with way too much mid frequencies, almost unusable without serious EQ, cutting the bass and boosting the highs, cutting the mids...I've had way better results before using only the EQ. I guess it's just me, wanting it to sound more like an HSS super strat or a Music Man Luke HSS, without changing the pickups in the first place. So the cap is gone.
Sometimes we just need to accept the core character of a given guitar, I've swapped the stock pickups for Evo's, made the neck and bridge split by a push/pull tone, put a treble bleed and that's it. I'd like the split neck or full humbucker to be brighter/cleaner but I guess that won't happen. The second I played a riff after pulling the cap out, the ''blanket'' was gone. I'm surprised it didn't work though, it was soldered fine.

 

[Chistopher]

I don't think you did it right. Firstly the cap value is 0.0047 uF, not 0.022 uF, which is a substantial difference. Second, your results don't sound like the intended effect of the mod. Generally a "blanket over the amp" effect is what happens when you cut a substantial amount of highs and midrange, not when you apply a bass cut; but then you say it makes the highs more prominent?

Send a picture of the wiring so we can get to the bottom of this.

 

[Ivan75]

Thanks for chiming in Chistofer, I was aiming for 22nF intentionally, I thought the 47nF would not be enough. The cap was placed between the black hot wire of the neck pickup and the switch lug. There it is again, the spot is marked in red. Note the treble bleed is not on the schematic, but it's wired properly and is fully functioning on the volume pot. I may be mistaken but the result made no sense, to my surprise. The tone pot wasn't working at all (I expected it to work like another volume pot when neck was selected), and I think I've noticed a bit of phase shift when the split neck inner coil is used with the middle. Thanks again!

 

[freefrog]

Thanks for chiming in Chistofer, I was aiming for 22nF intentionally, I thought the 47nF would not be enough. The cap was placed between the black hot wire of the neck pickup and the switch lug. There it is again, the spot is marked in red. Note the treble bleed is not on the schematic, but it's wired properly and is fully functioning on the volume pot. I may be mistaken but the result made no sense, to my surprise. The tone pot wasn't working at all (I expected it to work like another volume pot when neck was selected), and I think I've noticed a bit of phase shift when the split neck inner coil is used with the middle. Thanks again!

The "bit of phase shift" between coils in parallel would be expected when one of the PU's/coils only is in series with a cap but... 22nF in series before a volume pot won't really de-mud the tone of a standard 6 strings guitar: it mostly filters frequencies under the 82hz of a low E string.

The de-mud mod generously shared by ArtieToo relies on a 10nF cap. Rickenbacker used 4,7nF series caps (which is the value of input caps in regular treble boosters). The famous BT control involves 2,2nF caps (wired in series after the "normal" tone control in order to avoid any conflictual interaction between low pass and high pass filters, as you know)...

And if the tone control doesn't work no more because it has been accidentally disconnected during the mod, it can't behave like a second volume pot because of a series cap.

That being said, I agree with Christopher: your initial comment about the "blanket" effect suggest that something gone wrong in the mod, albeit the schematic that you share in the last post is right.

it's almost as if the cap had been wired from hot to ground instead of being in series with the neck PU... In which case it would be normal for the tone control to not work no more: lowering it would just rise the low pass filter from 22nF to 44nF, giving the sound of a tone pot @ 0/10 in both cases anyway.

All that being said in order to help, just like my PM's to you.

 

[freefrog]

Footnote - The BT control is already illustrated by Joe Gore in the video that I mentioned in my post 5. Here is another interesting vid, showing clearly the effects of a series cap with a "proper" value (it's not about the de-mud mod but still demonstrates the tonal difference due to a low value series capacitor) :

https://youtu.be/k_NnyvLusj0?si=2skxDOk_odKwvdbR&t=326

 

[Ivan75]

''it's almost as if the cap had been wired from hot to ground instead of being in series with the neck PU... In which case it would be normal for the tone control to not work no more: lowering it would just rise the low pass filter from 22nF to 44nF, giving the sound of a tone pot @ 0/10 in both cases anyway.''

Well, as I can see, I used the cap of the ''proper'' value and wired it correctly (wire-cap-switch lug), yet, this happened. Now, the guitar cavity here is very small, it's very cramped inside, and it's shielded with copper foil. If the cap to switch solder joint was, in fact, touching the shielding by accident, that would ground the signal - it should be no signal at all, right? If not, could that be the culprit of the ''blanket'' effect? I would just like to get to the bottom of this...Note the wire color codes, it's Seymour Duncan color codes in the schematic while in fact it's DiMarzio colors. So, the black hot wire on the schematic corresponds with the red one on my pickup, (north start). And that's fine, which makes me confused...