Treble bleed woes

grappagreen

Hi all,

Picked up a nice S type guitar recently and been spending some time getting to know it. One thing I noticed off the bat was the treble bleed. Rolling off the volume resulted in a very thin/wiry tone with no bottom end and I really didn't like it after a while. 

Having taken a look inside I could see a cap in the volume pot so I've removed this to have a listen. The thin/wiry tone has now been replaced with wooliness as I roll off which is sort of inevitable I suppose

Is there any way to get in between the two extremes above.

Si

Danny1969

Yeah it's the value of cap and sometimes a resistor added as well.  A capacitor acts as though higher frequencies pass through it easier than low frequencies so in a tone control the cap is used to shunt more higher frequencies to ground which reduces them and in a treble bleed the cap is used to allow higher  frequencies to be attenuated less than low as the pot is turned down. With the wrong value this will lead to a too thin sound but it will never really be totally linear without being active. 

I normally experiment with different values as it depends on the impedance of the pickups and the value of the pot. 

Funkfingers

Photographs of your current controls wiring should help to diagnose the issue.

The usefulness of a treble bypass network on the volume pot depends on the nominal resistance value of the pots and the pickups fitted in the guitar.

If, for example, the control components are inexpensive or damaged by repeated heating, they may no longer be passing the signal efficiently.

The thin/wiry effect could be because of the capacitor and/or resistor value.

ICBM

Danny1969 said:

I normally experiment with different values as it depends on the impedance of the pickups and the value of the pot. 

And the capacitance of the guitar cable, to a large extent.

Try it using the shortest possible cable directly from the guitar to the amp and then you'll know which is the main cause.

If you have a lot of true-bypass pedals which are all turned off, the effective capacitance of the cable is huge, since all the cable length to the amp is added together, plus that of the plugs (which can be surprisingly large).

steamabacus

As mentioned above, you could experiment with different cap/resistor values in the treble 'bleed' circuit or, alternatively, you could experiment with '50s wiring' (or output loading).

Although a bit lacking in modern YouTube production quality, David Collins (Ann Arbor Guitars) has an excellent series of videos on all aspects of guitar wiring where he has the guitar pickups connected straight out to a box of tricks where he demonstrates the effect of the various options with the help of an oscilloscope to show what's going on visually.

Episodes 4 and 5 cover Treble Bleed and Output Loading / 5os Wiring ...

ICBM

Just because I forgot to say it earlier, the correct term for the components fitted to the guitar volume control is treble *pass*. (They allow treble to bypass the control.)

Treble *bleed* is what the capacitance of the guitar cable does. (Which does indeed cause the problem grappagreen has found, when the treble pass network is removed.)

I know this is something of an uphill battle... but it does actually make it easier to understand what's going on if you use the right terms.

Winny_Pooh

I like the kinman mod, resistor and a cap, but yes it will make things a bit thinner, but thats often what you want with a fuzz.

Corvus

When I do Strats I have short lengths of wire that can poke out from under the scratchplate, leaving off a few screws. It's far easier to try cap & resistor combos out then. Next string change you can ditch the fly leads, till then tuck 'em in the cavity.

I prefer the Kinman style. Takes a bit of experimenting to keep the right amount of top & bass - try clean and with dirt, and fuzz if you use it. Fuzzes can really show up differences in cap/resistor combos when you roll off the vol pot.

Bitsbox is good for getting small numbers of caps & resistors and post is quick & cheap.

edited: I prefer series/Kinman style. Brain fail after doing parallel combos for bass cut yesterday.

grappagreen

Really appreciate the posts all.

I'm going to have a play with the Kinman treble pass (see what I did there ) circuit and see if I can find something that works. Can anyone advise what caps/resistors I should buy to experiment with (the guitar has relatively low output single coils)

It's interesting that Fuzz has been mentioned; the current issue really jumped out at me when rolling off the volume into a Blackstone MOSFET OD pedal which can be very fuzz like and cleans up in the same way.. 

I'll update as things progress.

Si

ICBM

My favourite values for a treble pass are a 680pF cap in parallel with a 220K resistor - surprisingly, it actually works equally well on both a 500K and a 250K pot. I think the reason for that is that it’s most dependent on the guitar cable - essentially that’s what it’s compensating for - and I always use the same cables. Whether that applies so much for other people I can’t be sure... it’s one of those things where there is no ‘right’ answer, it all depends on your gear, your ears and what you want to hear.

Corvus

I think that^^ is on my current Strat, or might be 820pf.

The bits I keep for this are 680pf, 820pf and 1nf (1000pf) caps. Also 1.5nf but don't think those ever get used on single coils.

130k, 150k, 200k, 220k resistors. 

Get some heatshrink as well esp if you're going to do the fly lead / tucking in thing. It's all pennies anyway.

grappagreen

Thanks all.

Parts ordered!

Corvus said:

When I do Strats I have short lengths of wire that can poke out from under the scratchplate, leaving off a few screws. It's far easier to try cap & resistor combos out then. Next string change you can ditch the fly leads, till then tuck 'em in the cavity.

I prefer the Kinman style. Takes a bit of experimenting to keep the right amount of top & bass - try clean and with dirt, and fuzz if you use it. Fuzzes can really show up differences in cap/resistor combos when you roll off the vol pot.

Bitsbox is good for getting small numbers of caps & resistors and post is quick & cheap.

edited: I prefer series/Kinman style. Brain fail after doing parallel combos for bass cut yesterday.

Thanks so much for the Bitsbox link - I've started on my journey of understanding electronics and was finding it a nightmare to find a parts site that I could bloody understand. Looks like I can now easily grab what I need to get into some of the projects!

Si

Corvus

No worries Si, good luck with it
Cheers
Bill