Treble Bleed cap on volume pot in a pedal: does that make sense?

[zjokka]

This mod was very effective on my guitars, so was wondering: I'm using my booster mostly at maximum gain and hence have to keep the volume quite low. Would it matter if I would put a cap and resistor in parallel across the volume tabs to fight potential treble loss?

zj

[Seljer]

Yep, you'd get more treble in your sound as you lowered the volume knob (though there wouldn't be any difference when maxed out)

[sfr]

Many commerical volume pedals already have this implemented - I believe my Ernie ball one does.  Depending on what you're using for a volume pedaal, another option might just be to put the booster in the volume pedal, and use the volume pedal to control the gain of the boost.

Another option would be the Anderton volume pedal retrofit, which I believe is in his DIY projects for Guitarists book.  In addition to helping with treble loss, it has the advantage of avoiding treble loss, it also removes the volume pedal pot from the signal chain, which will help avoid the problems of pots going scratchy over time.   I believe there's a layout for it over at Diyguitarist.com, and there may be one over a GGG as well, I know they have layouts for some other anderton projects.

-Joshua

[zjokka]

thanks for the comments.

this is a booster pedal with tone control: the fat boostered. Now I benchtested it and debugged some other stuff on it I'm beginning to believe is has paralysed the treble control in the FB. This seems likely to my knitwit electronics mind because they are in parallel, not in series...

will test that later,
J

[rockgardenlove]

Yep, I did this on my FuzzFace as I really don't think it sounds any good with the volume rolled down.

I think adding an output buffer with variable gain might be an even better solution though.

[zjokka]

The treble bleed didn't affect the treble control on my fb  the groundpath of the treble control was broken. Cut the treble bleed out and put it back when I found the mistake.

Rockgardenlove, I have a similar problem with my fuzz. Having opted for the 500k pot the pedal is really loud, even at minimal settings, should swap that pot back. Fuzz Face with minimal gain and volume maxxed sound very very good to me.

Don't quite understand why there isn't more written about this.

What value do you use? I used 0.001 uF and 150k in parallel.

zj

[rockgardenlove]

I'm on a 100k and .0001uF cap, pretty close.  It's a little bit better, but still far from perfect.

It still rolls off the treble though somewhat, but it's not as bad.

[Mark Hammer]

I gather the nature of the question is whether the same thing that works well on a guitar will work as well on an active circuit.  The short answer is "Yes" but be careful what you wish for.

Anything that introduces clipping will normally do so by introducing lots of gain, simply because of what some things need to clip, and what sort of signal the guitar delivers.  When you add gain, you increase risk of hiss and noise accumulation.  When you add a bypass cap, you make the high end more "immune" to attenuation such that when you turn the volume down the treble is essentially free to "ignore" that volume pot setting.  At the guitar end, the biggest threat is not from hiss but from 60hz hum, and from treble loss along the cable.  Consequently, a bypass cap works in our favour.  In a high-gain pedal of any type, that sort of bypass cap can be tantamount to saying "Yes Mr. Hiss, no need to wait in line.  Come right this way.  We have a table waiting for you."

But not always.  I'm very fond of my modified Anderton Tube Sound Fuzz.  The way I have it set up is with an op-amp gain stage ahead of the invertors.  The "drive" is set by the level of the volume pot after that op-amp gain stage.  So, if I slap a bypass cap across that volume pot, I get a little more treble drive at lower volumes.  Or rather, I cut back on bass drive, but not on treble drive as I turn down from max.  That, it turns out, can have a really nice effect in terms of achieving gritty medium overdrive sounds with bite - an instant Rickenbacker effect in the right circumstances.  Since the stages that come after that all have some sort of treble-cutting caps in place, the risk of accumulated hiss escaping the pedal is very low.  Were I to stick that bypass cap on the output volume pot, though, the hiss might be far more noticeable.

It is NOT unreasonable to attempt to do what you're thinking, but it is best to make it defeatable, or else have some way to permit the bite but keep the hiss under control.

[rockgardenlove]

That's a good point right there...my Fuzzface is dead quiet, so I never really had to consider that, but if you had a noisier pedal it would probably be pretty bad.

[sfr]

If the hiss and noise of that type is high frequency enough, perhaps adding a lowpass filter in addition to the treble bypass, with the passband high enough to let most of the "sparkle" through, but low enough to cut out the majority of unwanted hiss is another option?  I know it's a fine line to tread, but I was able to side step a similar problem by notching out the highest band in a graphic EQ after my signal chain, while still retaining some of the treble boost sound I was shooting for.  Probably need an active filter for a sharp enough roll off.