Treble bleed mod question. Why is it needed on some but not on others?

[PoPo75]

I've been playing guitar for over 20 years at this point. I have changed countless pick ups through out the years. Only until recently (the last 3 years or so) did I require the need for the treble bleed mod. Almost ever guitar I've ever owned in the past I put in Dimarzio pick ups. When I was a kid I threw in whatever volume or tone pot I could find. I never experienced the loss of high end with the volume turned down.

That is until I bought a Washburn Idol a few years back. It came stock with Seymour Duncan '59 and JB combo. The pickups sound great but this was the first instrument that I ever had to deal with the muffled sound with the volume down.

Also, a friend gave me a set of Dragonfire pickups. They sound OK but the same loss of highs occurs.

Out of about 20 guitars this only happens on 3 or 4 of them. My completely stock Gibsons do not do this either. Some of the guitars I own have small (dime size) pots some have the large ones. Some are import some American.

Here is an example: 1980's era korean Les Paul copy, Dimarzio X2N in the bridge, Dimarzio PAF in the neck. Standard (modern LP) wiring using the stock (dime sized) 500k pots, .047 caps on the tone controls. No coil tapping or any other mods.

With this guitar over the entire sweep of the volume control the "tone" stays the same on both neck and bridge. No drop of highs. Back when I used to play out I was using a Marshall Artist 4203 through a 4x12 cab. I never used a footswitch OR the clean channel. To "clean up" the sound for the cleaner parts of the song I would just roll back the volume. Then back up to 10 for the dirty/heavy parts. This is the one of the reasons why I still play this guitar to this day. I want to have this availability on every guitar.

Soooo my questions are:

Why does the treble loss occur with only some of the guitars in my collection?

Why would it happen to my Seymour Duncan and Dragonfire equipped guitars and not the Dimarzio equipped ones?

Is the cause the construction of the pickups or the electronics?

Did I just get lucky in the past to never have to use this mod?

Thanks for any help or ideas!!

[Chuck H]

Way too many variables and not enough comprehensive documentation to give a definitive answer, BUT:

It seems to be a problem with hot pickups. It's also a problem with high value volume pots. Since the combination on your guitars is somewhat random there is no more finite explanation.

Amps have changed too. Preamp gain is much higher than it use to be. This often means cutting highs in the preamp above a certain threshold that you may still be able to hear

It's NOT a brand issue. That perception is just a coincidence. Pickup technology only goes so far. The implication that one brand has a secret formula that doesn't cause this anomaly is erroneous and coincidental.

Since it's apparent on more than one of your guitars it's clearly NOT a rarity. For a long time guitars and amps were designed analogous to each other with a range in performance being more predictable than it is now. We are at a crossroads where things are changing. The breadth of variance in either device allows for more incompatibility.

The best solution would be to take each guitar, one case at a time. A particular guitar with it's particular resonant character combined with a given pickup with it's own particulars can indeed be maximized by choosing the correct pot and cap values along with peripheral circuits like "bright cap"s on the volume control (bleeder is generally used to describe a cap to ground that REDUCES high end).

I think it's very likely that the new genre of high gain amps and their particular voicing may have a role in your problem. If not the evolution of pickups themselves. Manage it on a case by case basis and don't shy away from bright caps on the volume pot. They're standard fare on many top end guitars for good reason.

P.S.

"Here is an example: 1980's era korean Les Paul copy, Dimarzio X2N in the bridge, Dimarzio PAF in the neck. Standard (modern LP) wiring using the stock (dime sized) 500k pots, .047 caps on the tone controls. No coil tapping or any other mods.
With this guitar over the entire sweep of the volume control the "tone" stays the same on both neck and bridge. No drop of highs."

Hogwash!!! That may be (or have been) your perception, but it isn't true unless that guitar is equipped with a low impedance preamp or a bright cap on the volume controls.

[Mick Bailey]

With this guitar over the entire sweep of the volume control the "tone" stays the same on both neck and bridge. No drop of highs."

Hogwash!!! That may be (or have been) your perception, but it isn't true unless that guitar is equipped with a low impedance preamp or a bright cap on the volume controls.

Yes; as soon as you move the control you change the curve of the frequency response. How much this resolves to anything noticeable is another thing, because the amp dynamics and the frequency response of our hearing also changes with input volume too. Even with a bright cap it changes, though the cap maintains the illusion of consistency to some degree.

At a very basic level you can model a guitar's circuit with PSpice and do an AC sweep analysis to see how the rotation of the volume pot affects frequency. I know there's a lot more complexity in a pickup's signal than a simple AC source can achieve, but it gives a rough outline.

Also remember that as we age our HF hearing response tails off. This means that we increasingly notice things getting muddy because for a given signal content it would need to have a higher level of 'bright' tones compared to what it would have when we were young. In a passive guitar that doesn't happen. When our sensitivity beyond a certain level ceases completely no actives or bright caps will work!

[PoPo75]

Thanks for the replies. As you guys stated, the decrease in highs is ALWAYS present. And you are correct. I've read the science behind why it happens. My perception is and has been that that particular guitar has little to no loss of highs. Of course, that's just the way I'm hearing it. I will definitely take each guitar on a case by case basis now.

I noticed a "bright cap" was mentioned. I thought that was always an amp mod and I was unaware that they were being used on guitars.

The bright cap is different than the treble bleed mod? I will also research that further.

Thanks guys. Great info!!

[Mick Bailey]

Bright cap, bypass cap, bleed cap, treble cap - all amounts to pretty much the same thing - a cap between wiper and non-ground side of the pot.

[pdf64]

If the guitar tone control is used to any degree (rather than just being ignored and left on '10') then '50's wiring' can give the illusion of reducing (or even reversing) the normal treble loss over much of the volume control range.
This entails wiring the tone control to the volume control wiper, rather than to the pickup 'hot' or volume control 'hot'.
Maybe the Korean LP copy mentioned in the OP had this arrangement?
Pete

[PoPo75]

If the guitar tone control is used to any degree (rather than just being ignored and left on '10') then '50's wiring' can give the illusion of reducing (or even reversing) the normal treble loss over much of the volume control range.
This entails wiring the tone control to the volume control wiper, rather than to the pickup 'hot' or volume control 'hot'.
Maybe the Korean LP copy mentioned in the OP had this arrangement?
Pete

I think it has the "modern" wiring. But I will double check. In the future though I'm going to try the '50's wiring.

[Steve A.]

If the guitar tone control is used to any degree (rather than just being ignored and left on '10') then '50's wiring' can give the illusion of reducing (or even reversing) the normal treble loss over much of the volume control range.
This entails wiring the tone control to the volume control wiper, rather than to the pickup 'hot' or volume control 'hot'.
Maybe the Korean LP copy mentioned in the OP had this arrangement?
Pete

I was going to post the same thing. Along with the idea that hotter pickups with a higher DC resistance might need the cap more than vintage pickups. When I use them I usually use a 180pF cap which is what I have found in PRS guitars.

Steve

[daz]

When I use them I usually use a 180pF cap which is what I have found in PRS guitars.

Steve

Wow, coincidence ! I have always used 250pf or above and i never liked PRS guitars. But yesterday i picked up a santana SE model at GC and fell in love and got it dirt cheap. And not 1 hour before i read your post i opened it up to find the 180pf cap ! I never thought anyone used a cap that low for a TB. So i was a bit surprised then read this thread. Anyways, i kinda like it tho i will probably try a 250pf because i think i may find it a bit too dark when i roll of the volume still. But it does have advantages over a 250pf or above in some contexts. Not sure till i have more time with it and do a complete setup to my specs.