HH Treble Bleed…

[vrstate]

Hi there!

Noob here posting for the first time so…greetings!

As I can’t get my head around this, after reading some posts regarding TB mods I thought to join and ask if it helps in anyway.

I’ve installed TB’s on 4 guitars until now with no issues, strat style with one volume and depending which one two tones.

Now I’m trying to do the same with an HH custom guitar that has two push/push vol pots(coil split) and 1 volume pot. So I installed 2 TB’s, one for each pickup as I usually do, leaving alone the lug that goes to ground, and there’s no change in how the volume pot reacts when rolling back. As soon as I start to roll back, volume stays quite the same until near 0 and the cuts out. Also I can hear the tone darkening from the very begining of the roll off.

I’m in contact with luthier whom in the first place suggested that the values I was using weren’t correct and the supplied new ones, same result. Bit its taking me ages to communicate with them.

I’ve read in other posts that this could be a wiring issue, leading the vol to act as a tone pot. This is way off my expertise so before I decide to take it to a local shop I would like to sort it out.

Thanks in advance!!!

Regards

[reTrEaD]

Hello vrstate , and welcome to GN2.

EDIT: Skip the rest of this and go directly to Yogi B' reply

Feb 19, 2024 10:34:00 GMT -5 vrstate said:

an HH custom guitar that has two push/push vol pots(coil split) and 1 volume pot.

I'm guessing you meant to say 1 tone pot?

Feb 19, 2024 10:34:00 GMT -5 vrstate said:

So I installed 2 TB’s, one for each pickup as I usually do, leaving alone the lug that goes to ground, and there’s no change in how the volume pot reacts when rolling back. As soon as I start to roll back, volume stays quite the same until near 0 and the cuts out. Also I can hear the tone darkening from the very begining of the roll off.

These symptoms are exactly what I would expect if there was a direct connection between the Wiper and the CW lug of a volume pot.

Let's consider the possible causes ...
The capacitor(s) is (are) shorted.
You created a solder bridge between the Wiper and CW lug of your volume pot(s).
The resistor(s) you're using has (have) a very low resistance value.

The first place to start would be to remove the TB parallel network (capacitor and resistor).
Does (do) the volume control(s) function normally without them?
If so, it's likely the problem is either the cap(s) or resistor(s).

Use a multimeter (If you don't own one, buy one. They're dirt cheap.) set to measure resistance. Measure between the two ends of the paralleled capacitor and resistor. The capacitor will not provide a conductive path to direct current unless it is defective. So we should only read the value of the resistor. Typical value for a TB resistor is something like 120k ohms or 180k ohms. It doesn't need to be exact. But if the value you measure is only a tiny fraction of that, we've begun to track down the problem.

Next step would be to separate the cap and resistor. Is the low resistance reading present across the capacitor? Or is that reading present when measuring just the resistor?

[Yogi B]

The issue appears to be that the volumes are wired using the 'backwards' (or independent) wiring style: where the output from the pickups is wired to the pots' wiper terminal (the centre lug) and the wire to the output jack (via the switch) comes from the clockwise terminal (AKA lug 3). Whereas, with a normal single volume setup those connections are reversed.

The sole advantage of independent wiring is that in the middle (both pickups selected) position you can turn one volume to zero, but that's ideally just the same as the outer positions of the switch.

You've already discovered the disadvantages: it completely messes up the taper of the volume control; as the volume is reduced, the load upon the pickups constantly increases — this results in the treble being rolled off at a faster rate than any significant volume reduction; and finally treble bleed's can do very little to mitigate that effect.

The fix would be to swap to normal 'forwards'/dependent wiring for the volumes, by swapping the 'input' (from the pickup) & 'output' (to the switch) connections for each volume pot. This means, in each of the outer switch positions, the volumes will have the response you're used to from your single volume guitars. The difference is when both pickups are selected: while each volume will affect its associated pickup much more than the other pickup, isn't completely isolated. This means turning either volume control to zero will mute both signals, which is the deal breaker for some people and why (even with its disadvantages) backwards wiring still has some proponents.

---

Also, another semi-related point is that with a two-volume global-tone setup you are stuck using what is effectively '50s wiring for the tone control: where the tone control is wired between the volumes & the output jack, rather than modern wiring where the tone control is wired in between a pickup and its respective volume. If you're not familiar, the issue with fifties wiring being that as you reduce the volume control(s) the frequency range that the tone control cuts becomes lower and lower. Until, at low volumes, the tone control cuts most of the signal, acting less as a treble cut and much more like an additional volume control (see this thread for further info). Again there is a workaround for this, but unlike the above it is not just a wiring change, it requires doubling the tone pot — either keeping it as a single control using a dual-gang pot, or splitting it into separate tones for each pickup via the use of a stacked concentric pot.

[reTrEaD]

Feb 19, 2024 14:37:20 GMT -5 Yogi B said:

The issue appears to be that the volumes are wired using the 'backwards' (or independent) wiring style: where the output from the pickups is wired to the pots' wiper terminal (the centre lug) and the wire to the output jack (via the switch) comes from the clockwise terminal (AKA lug 3). Whereas, with a normal single volume setup those connections are reversed.

Brill.
I didn't think to check for that possibility. Well done, sir.

[stevewf]

Feb 19, 2024 14:37:20 GMT -5 Yogi B said:

... it requires doubling the tone pot — either keeping it as a single control using a dual-gang pot, or splitting it into separate tones for each pickup via the use of a stacked concentric pot.

I thought I'd point out that you might be able to keep your current tone knob if you use a dual-gang pot, whereas the concentric pots require a different type of knob(s).

[vrstate]

Feb 19, 2024 14:37:20 GMT -5 Yogi B said:

The issue appears to be that the volumes are wired using the 'backwards' (or independent) wiring style: where the output from the pickups is wired to the pots' wiper terminal (the centre lug) and the wire to the output jack (via the switch) comes from the clockwise terminal (AKA lug 3). Whereas, with a normal single volume setup those connections are reversed.

The sole advantage of independent wiring is that in the middle (both pickups selected) position you can turn one volume to zero, but that's ideally just the same as the outer positions of the switch.

You've already discovered the disadvantages: it completely messes up the taper of the volume control; as the volume is reduced, the load upon the pickups constantly increases — this results in the treble being rolled off at a faster rate than any significant volume reduction; and finally treble bleed's can do very little to mitigate that effect.

The fix would be to swap to normal 'forwards'/dependent wiring for the volumes, by swapping the 'input' (from the pickup) & 'output' (to the switch) connections for each volume pot. This means, in each of the outer switch positions, the volumes will have the response you're used to from your single volume guitars. The difference is when both pickups are selected: while each volume will affect its associated pickup much more than the other pickup, isn't completely isolated. This means turning either volume control to zero will mute both signals, which is the deal breaker for some people and why (even with its disadvantages) backwards wiring still has some proponents.

---

Also, another semi-related point is that with a two-volume global-tone setup you are stuck using what is effectively '50s wiring for the tone control: where the tone control is wired between the volumes & the output jack, rather than modern wiring where the tone control is wired in between a pickup and its respective volume. If you're not familiar, the issue with fifties wiring being that as you reduce the volume control(s) the frequency range that the tone control cuts becomes lower and lower. Until, at low volumes, the tone control cuts most of the signal, acting less as a treble cut and much more like an additional volume control (see this thread for further info). Again there is a workaround for this, but unlike the above it is not just a wiring change, it requires doubling the tone pot — either keeping it as a single control using a dual-gang pot, or splitting it into separate tones for each pickup via the use of a stacked concentric pot.

Thank you all for such thoughtful replies.

Yogi, I did read about the backwards wiring on another post, but as it was for a Jaguar guitar I didn’t know if this would relate to mine with HH.

I will give the tweak suggested a shot and come back as soon as I try it. Regarding the middle position thing, I don’t really mind lossing some control there, as I usually stay on the neck either split or Humbukcer.

See you in a bit, cheers!!

[vrstate]

Hey!!!

I’ve just swapped center and outer lugs and now is working as intended!

Thank you everyone for you help, if I’d have to figure it myself or wait for the builder to come back, another month would have passed by.

Very much appreciated, really!!!

All the best ya’ll,
Miguel

PS. I’ve noticed that the Tone pot is behaving a bit different after the mod. Until half way down it’s hardly noticeable being the last 3rd more aggressive cut. Could this be caused after the mod?