Treble bleed circuit

A

andyg_prs

New member
Hi,

I have a lovely Vigier Ultrablues, currently HSS although planning on making that HSH. I'm told by the UK Vigier distributor that the volume pot is 1 Meg. It has no treble bleed circuit at all!

I want to be able to control gain using the volume knob but really want to lose as little treble as possible. I was told by a tech once that there was a danger of things sounding too trebly as the volume gets turned down....but as I'mm yet to ever experience that, so far I'm discounting that concern.

So the question is...based upon a 1 meg volume pot, what do you consider to be the most effective treble bleed circuit for my guitar?

Picture of the controls in case it's of any use.

IMG-0232.jpg

Thanks,
Andy
 
Mikelamury said:
I started using variable treble bleed circuits and it's MUCH easier and cheaper than trying different components. I've used the V treb by PMT and DARKMOON makes a variable treble bleed circuit as well.
Click to expand...

Sounds like a cool idea.....now to try and find something similar in the UK. Also, would prefer to keep the volume pot at 1 Meg to match what's there now.
 
Which values would work for you can only be found out by trying out a few. The effect varies based on cables, pickups, guitars, etc.

You can buy a pack of assorted values of caps on ebay or pick up some common values locally from a electronics repair place, they won't cost much. A basic cap only type treble bleed will allow the highest amount of treble to appear as you roll down the volume. If the holes of the lugs on the volume pot aren't blocked then you can just bend the legs of the cap and stick them in there without soldering for testing purposes. 1nF cap is where I'd start and then go up or down in value depending on the amount of treble bleed effect required.
 
Mikelamury said:
Guitarelectronics.com ships to UK and they carry the v-treb by PMT. And the circuit doesn't affect the sound when the pot is on 10.
Click to expand...

Why buy a $10 circuit if you can make a more versatile one for considerably less? Just put any cap less than 1 nF in series with a 100k trim pot.
 
Chistopher said:
Why buy a $10 circuit if you can make a more versatile one for considerably less? Just put any cap less than 1 nF in series with a 100k trim pot.
Click to expand...

i hadn’t looked into trim pots but I will - I also wasn’t sure whether just the resistance was variable on the pre made device and if the resistor and cap were in series or parallel or if there was any other circuitry going on.

I thought the capacitance was key to what frequencies bled through - but I confess to not understanding the science…
 
Chistopher said:
Why buy a $10 circuit if you can make a more versatile one for considerably less? Just put any cap less than 1 nF in series with a 100k trim pot.
Click to expand...

Why? Convenience. It's much easier to spend a couple extra dollars on the v treb. Than looking up different components, figuring out which one you want to try, purchasing and trying and what if you don't like it? Or worse, you end up settling, thinking you like it? There not that much more expensive and make your life ALOT easier.
 
Mikelamury said:
Why? Convenience. It's much easier to spend a couple extra dollars on the v treb. Than looking up different components, figuring out which one you want to try, purchasing and trying and what if you don't like it? Or worse, you end up settling, thinking you like it? There not that much more expensive and make your life ALOT easier.
Click to expand...

If you can solder in the PMT, there is no additional difficulty in doing it yourself. If you try it out and don't like it, you want like the PMT one either. Only difference is you've saved a few bucks.
 
andyg_prs said:
i hadn’t looked into trim pots but I will - I also wasn’t sure whether just the resistance was variable on the pre made device and if the resistor and cap were in series or parallel or if there was any other circuitry going on.

I thought the capacitance was key to what frequencies bled through - but I confess to not understanding the science…
Click to expand...

The capacitor adjusts what frequencies make it through, the resistor adjusts how much of that frequency gets through. The trim pot allows you this amount, as it acts as a variable resistor.
 
On many models PRS uses a 180pF cap with no resistor. This arrangement raises the resonant peak a bit as the volume pot is dialed down, making the pickups sound more singlecoily as you roll back. I like this, and it works on a wide variety of guitars.

For tone that doesn't get brighter through the range of the pot, a larger cap like 1000pF with a resistor (or trimpot) in series will be more natural.

Many of the prewired treble bleeds use a cap and resistor in parallel, but many say that can mess with the taper of your volume pot.
Not sure how it would behave with a 1 Meg pot though.
 
For strat style guitars, one popular maker uses 150k and 680pf in parallel combination, on a 500k Audio taper control. If you want to adapt this for a 1M pot, I suggest to half the capacitor value, and double the resistor value. So you end up with 330pF capacitor and 300k resistor in parllallel. If the effect is too strong you can add a resistor of 120k in series with the parrallel RC combination.
 
I got a handful from MojoTone years back for $2 each
you can search for them on Amazon and get a better price but its $2
get several as the shipping is the same for one as it is for twelve

on my guitars with the treble bleed, I use the pickup height to distort the input of the amp and roll back the volume to clean it up

heres how mine are set up

on the bridge
roll your bridge volume back a quarter turn
adjust the pickup up until it just start to get nasty
then move to your neck and set it the same way with the volume still rolled back a quarter turn

now when you roll up it will be thick and distorted
roll back for clean
 
Hey guys,

I wanted to check something with you. I started with a 470 pf cap in parallel with a 220k resistor.....the sound still got much too dull as I started to turn down, so nowhere near enough trouble was bleeding through...but I was far more distracted with how the taper of the pot was impacted....almost no change in volume for the first 2/3 of travel.

So I went straight to just a 220pf capacitor alone. It works pretty well. But I would still allow more treble to bleed through ideally.

I went to 100pf, but even with the volume on full, it totally changed the sound of the guitar - it lost all the bass. So, for example, my lovely rich neck single coil no longer sounder like that, it was bright and thin sounding.

On a different forum I was told that my volume pot must be faulty. That when it is completely open, the capacitor should have no effect. Is that true?

Currently I've gone back to the 220pf capacitor alone.

Thanks,
Andy
 
Last edited:
No regular pot goes completely open or zero, there will always be some resistance in 0-5ohm range that will let the bleed effect to be present barely on full volume, good news is that you need to be monitoring through a studio setup to actually hear that.

Anyways, 220pF is close to 180pF, which is what PRS uses. It should not give you a very prominent bleed effect as you roll down the volume. Check whether it's not 2nF, that would give you a very thin sound as you roll down, also check if you're using 50s or modern wiring scheme. If the parallel cap+resis setup was too much on the taper then try out the series cap+resis, it doesn't widen the taper as much.
 
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