Treble loss when backing off vol...

Tony Harris · From: England

This won't apply to PSG players who don't usually have a volume control on the instrument, but for those who play lap steel or guitar. My new Sierra 6 Laptop has arrived and is FABULOUS, except for the treble loss when backing off the volume control. Now I've had this problem on almost every guitar and steel I've ever owned - dozens! Some players live with it or don't notice. A friend of mine looks at it another way - he considers it as gaining an extra bit of 'bite' when he turns up the vol to take a solo. But for me, it's an annoyance. I want the tone to stay the same wherever the volume knob is set. I've solved it on all my other guitars by trial-and-error with the addition of a simple resistor/cap in parallel across the volme pot. (Why don't the guitar manufacturers fit this?). The problem is that the value is different depending on the pickup - and I guess the lead and the amp. Bill Lawrence recomends a 330pF cap with his single coil Strat types, and of course it works perfectly. But what should the value be for a big, hot humbucker? Is there a magic formula - I don't want to open up my new Sierra too may times...
Thanks.

Larry Behm · From: Mt Angel, Or 97362

A Hilton volume pedal is the answer.

Larry Behm

David Doggett · Posted 14 Jul 2003 7:08 am

To prevent this problem you need an active (preamp) pedal like the Hilton, or some other kind of preamp (FX units typically have preamps) between the pickup and the volume control. That's the electronic answer.

There is also a biological component. As music gets louder, the highs begin to hurt or sound harsh first, because our ears are more sensitive to them. So as you increase the volume you need to roll off the highs and increase the bass. That applies to any sound system - your guitar, your PA, the overall mix, your home stereo, your car radio.

Bruce Derr · From: Lee, New Hampshire, USA

There are other ways to fix the problem if you don't want to use a volume pedal. The trick is to reduce the effect of cable capacitance on your signal. The cheapest fix is to use a shorter cable to your amp. A low-capacitance cable would be best. Another approach is to use one of the little signal buffer circuits like the Matchbox or the one Hilton makes. The problem with using an RC shunt on the volume control is the difficulty in selecting the R and C values to precisely overcome the effect of the cable. And then if you happen to use a different cable with lower capacitance, backing off of the volume control will produce the opposite effect (sound will become thin).

Ed Miller Jr · From: Coldwater,Mi USA

Well, this works on a six string, It should work on a steel. take a .001mf cap and solder it across the two lugs of the volume pot. This way it will shunt some highs to the signal when you turn down the volume. Most teles have them, I even put them on my strats.
just my two cents but this is the least expensive way to fix it.

Ed

Jay Ganz · From: Out Behind The Barn

Whether it's a humbucker or single coil
shouldn't make that much difference as
far as the value of that capacitor.
Anything from 250pf to the 330pf will
work fine. The Humbucker is just gonna
have more mids than the single coil.
It's those highs that you're worried about
anyhow.

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My new MP3.com page

Bobby Lee · From: Cloverdale, California, USA

I believe that the capacitor fix described above keeps the highs at full volume, regardless of the volume control setting. Am I correct?

A volume pot connected across an inductor (the pickup) has an "accidental" side effect of being a low-pass filter. This is part of the traditional tone envelope of the pedal steel with a volume pedal. Active pedals (Hilton, Goodrich 10k, etc.) eliminate this side effect, acting more like the fader on a mixing console.

If you really want to control volume at the guitar, without changing tone, you need to install some active electronics between the pickup and the volume control. When the pickup "sees" a constant impedance, no "accidental" low pass filter is created.

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Bobby Lee - email: quasar@b0b.com - gigs - CDs, Open Hearts
Sierra Session 12 (E9), Williams 400X (Emaj9, D6), Sierra Olympic 12 (C6add9),
Sierra Laptop 8 (D13), Fender Stringmaster (E13, A6),
Roland Handsonic, Line 6 Variax

[This message was edited by Bobby Lee on 14 July 2003 at 10:48 AM.]

Jim Bates · From: Alvin, Texas, USA

Sometimes the 'quick fix' is all you will need. Try it with the small capacitor (100 pf) first then try a 220 pf and maybe a 330 pf. Set the volume about 1/2 on and you will hear the difference by the touching the leads of the cap. to the leads of the voulme control. Then, solder in the one you want. I've used this 'trick' very successfully for over 35 yrs. AND, it doesn't need any batteries!

Thanx,
Jim

Stephen Gambrell · From: Over there

And, as a bonus, the higher value cap you use, the more pronounced the "wah" effect will be.

Bill Terry · From: Bastrop, TX

I had the vol/bypass cap trick on a Tele for a while. I didn't like it. You could always hear a weird, non-linear tonal 'glitch' at some point as you opened the volume.

It might work for some folks, but it didn't for me.

[This message was edited by Bill Terry on 14 July 2003 at 12:29 PM.]

Donny Hinson · From: Glen Burnie, Md. U.S.A.

I'll concur with Bruce, here. The biggest culprit is excess capacitance introduced by cheap cables, or cables that are too long. The problem is also exaggerated when an improper (less that 500k ohms) volume control is used.

Paul Graupp · From: Macon Ga USA

Just as an aside to this conversation; I recall way back when some of us had put a resistor (I've forgotten the value...) across the high end of the foot volume pot and the center arm.

I recall a response from Phil ( ?? ) Goodrich at the time who said all that this did, " was make the highs come in later." The effect we were seeking was a Chalker like tone and this "was the way to get it. " It has something to do with the what this conversation is all about but time has obscured the logic of it from me.

Regards, Paul

Bob Metzger · From: Waltham (Boston), MA, USA

I fall on both sides of this argument.

When I set up a new Tele, I use a push/pull volume pot with both options. When the switch is in, there is no 'circuit' available and when the volume is lowered the guitar loses some highs and you can fall back into the track and inversely, step out front, with more highs when the volume is wide open for soloing. This is very useful in live situations and I like having this available.

With the p/p switch out the tone is exactly the same no matter where the volume pot is turned to. I find this advantageous when recording or doing brighter but quieter fingerpicking passages in the context of a song. And in many other situations, I also gotta have it!

I've been using this 'system' on my Teles for nearly 30 years and I've generalized this to my steels as well. On some of my steels, I've used it on an on-board volume control and I've even used it on volume pedals that don't do what I want them to do, with good success. It works very well and is basically a variation of what Jim Bates is talking about.

This is all about successive approximation. If you have the will and perseverance and minimal soldering skills, it will happen. You have to trial-and-error the cap value, depending on the pickup and pot values you are working with. I find that some value usually between about 120pf and 630pf is right for most gear (.001uf just isn't right for my ears). I put this cap across a resistor that is about 2/3 to 1/2 the value of the pot. (An audio taper pot will always work best in this application.) This circuit now goes 'across' the volume control. There are three lugs on a volume control; one goes to ground, this circuit goes across the other two. You may have to experiment a bit (rev 2 or rev 3) but you will eventually get it right and it will work well.

How well? You guys can/will debate that I'm sure!

Bob M.

Of course, you don't have to use a p/p pot but that's my story of how I developed it. (And I'm stickin' to it!)

[This message was edited by Bob Metzger on 17 July 2003 at 01:17 PM.]

[This message was edited by Bob Metzger on 17 July 2003 at 03:21 PM.]

[This message was edited by Bob Metzger on 23 July 2003 at 12:14 PM.]

Tony Harris · From: England

Thanks everyone for your thoughts on this problem of mine. It's just one of those things whch has bugged me for years. When I want the tone to change I'll use the tone control! I've now found on www.kinman.com/html/FAQ.htm#highloss a formula for this involving the inductance of the pickup, the value of the volume pot, and most importantly the capacitance of the cable. The writer of the article suggests the cap added needs to equal the capacitance of the cable, which could be 1000pf (.001)- less if you're using better or shorter cables. I'll get out the soldering iron and see what works best for me, and report back if it's of any use to others...

Buck Dilly · From: Branchville, NJ, USA * R.I.P.

There is a way to add a small resistor ( I don't recall the value) to the .001 cap circuit on the Volume pot. Ask your guitar tech. what the value should be. THis reduces the degree to which the cap operates, while bleeding back in the highs at the same frequency. Very effective with old DanO's, Lap Steels, and Fenders. It is not a substitute for a $260 vol ped. but it only costs $1. I used banana clips and experimented with different values until I was happy.

Tony Harris · From: England

Tried out a 470pF(in parallel with a 100k resistor) - sounds nearly there, and I'm trying to find some even lower capacitance cable (Bill Lawrence or George L). Did I read somewhere that once the signal's been through a pedal, it's less prone to loss in long leads? Is the impedance lowered or something? Thinking I might add a DD3 delay pedal right after my Goodrich, and wondered whether this might help...?

Jerry Hedge · From: Norwood Ohio U.S.A.

Tony, if you're using a 250K pot,try a 150K resistor in parallel with a .001MFD cap. I've used that combo on Teles and found the tone is about the same throughout the sweep of the pot.

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