Tone control issue with Artie's De-Mud Mod

[Emarcey]

Hi All.
Embarrassingly long time between posts (7 years) and also related to my post from 2014... :8:

I have used Artie's mod numerous times in varied configurations since then and am eternally grateful for discovering it.
However, having installed it recently in an LP-style build I encountered an issue which I can't wrap my head around, so asking for advice.

The set up is a simple 2 HB's (mini) 1 volume, 1 tone, 3-way toggle. I used a 500k resistor and .0068uf cap for Artie's mod on the neck pickup (just like I've done before) but in the "neck only" position, the tone control is acting like a volume control. This kind of pot behaviour I usually associate with a short to ground, but In the bridge only position, it works as it should.

Everything is wired exactly as per the standard SD diagram for 2HB/1v/1t.
I have tried the RC both between the coils of the HB (4 conductor) and at the switch (like a 2 conductor).

Can someone offer some insight as to why this is happening?
Thanks in advance

 

[beaubrummels]

I don't think it's related to Arties mod, because it happens regardless of how it's done. Take the de-mud out completely and test if it still happens. I'm thinking something isn't grounded properly (like the tone cap or the pickups) and the tone isn't always functioning correctly.

 

[freefrog]

It's expected as soon as series capacitance is located before parallel capacitance with a LRC filter such as a guitar pickup. For the record, that's how I spot pickups whose wire is broken in a coil: if their wire stays aligned with itself, it forms a capacitor (measuring generally around 4nF) and it does what you describe: the tone pot reacts like a volume control because of the order of hi-pass and low-pass filters.

Solutions:

1-Use a dual TBX pot with demud mod on one side and regular tone control on the other. An elegant solution like Artie's demud mod deserves some creative wiring;
2-Wire the series cap (demud mod) AFTER any regular tone control (pickup> low-pass filter > hi-pass filter). Both pots will then work normally.

I've devoted a whole thread to this question there, with 5spice sims and real life measurements showing what series caps do in various situations: https://www.mylespaul.com/threads/on...e-note.446786/

FWIW.

 

[zionstrat]

Freefrog.. great, great link! There's a lot of good stuff in there and some of it's a bit over my head so I'm going to be digging in deep and appreciate you helping those of us who don't always entirely understand why things work the way they do.

 

[freefrog]

Freefrog.. great, great link! There's a lot of good stuff in there and some of it's a bit over my head so I'm going to be digging in deep and appreciate you helping those of us who don't always entirely understand why things work the way they do.

Thx for the kind words. Always glad to share. Just hope it's helpful. ;-)

 

[beaubrummels]

Solutions:

2-Wire the series cap (demud mod) AFTER any regular tone control (pickup> low-pass filter > hi-pass filter). Both pots will then work normally.

The de-mud mod is supposed to be only for the neck pickup. If you wire it after a master tone, it's going to affect the whole works.

 

[freefrog]

The de-mud mod is supposed to be only for the neck pickup. If you wire it after a master tone, it's going to affect the whole works.

Yes, but neck pickups have their own tone controls in more than a famous guitar... it's not a big deal to connect a neck PU to its own regular tone pot then to some hi-pass series cap in a LP or a Strat, for example...

EDIT - And for guitars with only one master tone: they are the reason why I've evoked the TBX pot trick in the answer 3. ;-)

 

[eclecticsynergy]

Yah, for LP types you wire bass cut after the pots and before the switch.
TBX pot is a great idea for putting it into master tone guitars. Thanks, freefrog.

I've never used spin a split on any guitars because I'm unwilling to give up a control for it.
Seems a TBX type arrangement could be a good option for that too.

 

[Emarcey]

Thanks for all the responses.

To address beaubrummels comment, I have indeed removed the de-mud cap/resistor and tested. The tone pot works "as normal" when removed.

And thanks for that link freefrog!
Re: the TBX pot: TBX pots are hard to find (500k) and stupid expensive here in AUS, but I'll look around and consider it.

FWIW, this is the first time I've tried this with a 2 HB/1V/1T configuration. In my PRS-style build (2 HB/2V/2T) I used a bass cut for the neck pickup and standard treble cut for the bridge.
Since 2014, Artie's was my go-to for neck HB's until I discovered the bass cut a few years ago. I also use Leo Fender's PTB circuit in nearly all my strats now too!

Thanks again. There's some good info here.

Cheers

 

[freefrog]

Thanks for all the responses.

To address beaubrummels comment, I have indeed removed the de-mud cap/resistor and tested. The tone pot works "as normal" when removed.

And thanks for that link freefrog!
Re: the TBX pot: TBX pots are hard to find (500k) and stupid expensive here in AUS, but I'll look around and consider it.

FWIW, this is the first time I've tried this with a 2 HB/1V/1T configuration. In my PRS-style build (2 HB/2V/2T) I used a bass cut for the neck pickup and standard treble cut for the bridge.
Since 2014, Artie's was my go-to for neck HB's until I discovered the bass cut a few years ago. I also use Leo Fender's PTB circuit in nearly all my strats now too!

Thanks again. There's some good info here.

Cheers

You're welcome.

Yes, TBX pots are expensive... and can be moody once mounted. But I've used them for many wiring solutions and they are very handy when it comes to optimize a single tone control!
AFAIK, they are only available with a 250k side and a 1M side... But the 250k pot is really useable as a regular tone pot for any PU, since it's no-load when full up.
Another idea would be a dual gang 500k pot. Not optimal since it would end with twice 500k in parallel but as long as the two pots in it are not linear, it should work without too much conflict between lo-pass and hi-pass filters.

eclecticsynergy : my last use of a TBX was to wire it as a splitter for a Wide Range RI humbucker, that I've modified to be a 3 wires pickup... The pot is not really a "spin-a-split", since the 1M part of a TBX is not progressive at all. it's rather an on/off SC splitter as it is. But it should be possible to make it less abrupt by adding some resistor to it in the RG Keen fashion:
http://www.geofex.com/article_folders/potsecrets/potscret.htm

FWIW. I wish you all a nice week-end.

 

[Emarcey]

Thanks for the additional information freefrog.

AFAIK, they are only available with a 250k side and a 1M side... But the 250k pot is really useable as a regular tone pot for any PU, since it's no-load when full up.
Another idea would be a dual gang 500k pot. Not optimal since it would end with twice 500k in parallel but as long as the two pots in it are not linear, it should work without too much conflict between lo-pass and hi-pass filters.

Yes, 250k/1M. My ignorance shown through there! However you just answered the question I was going to ask about the 250k pot with a HB.
The TBX kits are more readily available now than I thought, and are around $35AU with postage. Not a huge investment in the realm of guitar stuff really. I just seem to have a problem with parting with my money sometimes!

I managed to find a TBX mod for treble cut/bass cut on guitarnutz2 (HERE). So that same scheme work with a dual gang A500k?
I'm leaning towards just getting the TBX and having a go.

Cheers,
Mick

 

[freefrog]

Thanks for the additional information freefrog.



Yes, 250k/1M. My ignorance shown through there! However you just answered the question I was going to ask about the 250k pot with a HB.
The TBX kits are more readily available now than I thought, and are around $35AU with postage. Not a huge investment in the realm of guitar stuff really. I just seem to have a problem with parting with my money sometimes!

I managed to find a TBX mod for treble cut/bass cut on guitarnutz2 (HERE). So that same scheme work with a dual gang A500k?
I'm leaning towards just getting the TBX and having a go.

Cheers,
Mick

Hello,

If you talk about the second schematic posted on guitarnutz2: they're putting the hi-pass filter before the lo-pass one, which would precisely be the signal path to avoid with dual gang 500k, IMHO...

There's a reason why the G&L or Reverend lo-pass / hi-pass filters are wired as they are and that's the signal path that I'd follow with a dual gang 500k pot : https://tonefiend.com/wp-content/uploads/GL-Tone-Circuit.jpeg

If time permits, I'll post some 5spice sims to illustrate why I prefer this solution.

 

[freefrog]

Below is a 5spice sim showing how a pickup would respond with a dual gang bass/treble cut. That's with linear virtual pots but "you'll get the picture".



The upper pic is the response of the PU with lo pass (regular tone control) before hi pass (series cap).

The bottom pic is the same thing with the PU through hi pass then lo pass filter.

In the second case, center position would obviously cause a volume drop.... and a dull tone. Hence my advice above.

FWIW, once again.

 

[Emarcey]

You're a legend mate! Thanks for your time. Seems the TBX is the way to go!

 

[Emarcey]

Just thought I'd pop back with an update.

I got a couple of TBX pots and have installed one into one of the two guitars. All went smoothly and I'm pretty satisfied with the result.
The taper takes a little getting used to, as things happen very quickly within the rotation, but I'm finding the sweet spot for the neck HB after playing with it for a while.

My only criticism is, overall, the tone is definitely darker than when I had the standard 500k tone pot wired in. I find I'm using the bass cut even with bridge pickup which is counterintuitive.
I'll continue to play as is and see how it goes. I am going to hold off on installing in the second guitar until I've spent some more time with the first one. It will be a while before I play in a band situation to really get a feel for it due the recent explosion of covid.

Anyway, thanks to freefrog for your idea and input!

Cheers,
Mick

 

[freefrog]

My only criticism is, overall, the tone is definitely darker than when I had the standard 500k tone pot wired in. I find I'm using the bass cut even with bridge pickup which is counterintuitive.

As a matter of fact, if you've wired the 250k side as a no-load pot, the guitar should sound brighter.

Now, that's the problem with guitar wiring: each harness introduces a hint of parallel "stray capacitance". Theoretically, a pot doesn't measure more than a few pF but practically, the measured capacitance of a whole harness varies widely.
Sometimes, even a slight difference suffices to shift the resonant peak of pickups from a frequential peak to a frequential dip in the response of the loudspeaker(s) used. In which case the perceived sound changes noticeably if not paradoxically - for instance a really high pitched resonant peak can absurdly give a sound perceived as darker because the energy of the pickup as a LRC filter is focused in frequencies that a guitar cab can't reproduce... in the same way, more stray capacitance is a theoretical source of darker tone but can be felt as making the sound "brighter" simply because it aligns on a high mids frequency promoted by the cab.

Then there's the Fletcher-Munson curve... Oh, well...

Glad to know that TBX works for you anyway. Enjoy!

 

[Artie]

I have indeed removed the de-mud cap/resistor and tested. The tone pot works "as normal" when removed.

I'm glad you're getting this sorted out, but that is bizarre. The de-mud shouldn't have any affect on the tone pot. I guess you stumbled into the are where reality doesn't quite fit with theory.

 

[Emarcey]

ArtieToo - I don't have a strong enough understanding of theory to give you a proper explanation.
I have used your mod in 2HB, 2V, 2T configuration before and don't recall experiencing this phenomenon, but something about 1V, 1T surely upset the system.

I have since started installing a bass cut set up for my neck HB's with 2V 2T, and that seems to work best for me now.

Thanks mate!

 

[Artie]

ArtieToo - I don't have a strong enough understanding of theory to give you a proper explanation.

Something did occur to me. Is there any chance, that in the de-mud, or on your tone control, that you accidently missed a decimal point? Like doing a .1 uf rather than .01 uf, or somesuch?

Just a thought.

 

[Emarcey]

Something did occur to me. Is there any chance, that in the de-mud, or on your tone control, that you accidently missed a decimal point? Like doing a .1 uf rather than .01 uf, or somesuch?

Just a thought.

Yeah, I have definitely used the specified (recommended) value. I have also previously experimented with varying cap values to alter the amount of bass cut, but am confident they were all within the right value range. I at least understand that much.
Thanks for asking though.