The Dual Volume Problem

[skh515]

Can someone explain the problem with dual volume pots? I think it’s happening on my custom wired Strat.

Would a master Volume and a blend pot work better?
For example, instead of having 2 Vols and 2 Tones, would 2 Tones, a Blend and a Master Volume be a better choice?

[ArtieToo]

Re: The Dual Volume Problem

Just for the record . . . I did not pay this guy to ask this.

Ahem . . . Twin volume controls can be wired either of two ways:



In fig. 1, if you turn one volume control all the way down, you short the other pup to ground also. In other words, both volumes affect both pups.

Most dual-volume guitars, like LP's, use fig. 2. Here, the interaction problem is better, but instead you get a situation where, as you turn the volume down, you also change the "loading" of the pup. That is, the effective value of the pot. Which, in turn, slightly alters the tone of the pup, usually, in a negative way. (Rolls off the highs.) Still, its better than the method in fig. 1.

Basically, thats all there is to it.

[skh515]

Re: The Dual Volume Problem

So a 500k pot acts like a 300k, 100k, 50k, etc. as you turn the Volume down?
And what about the Vol/Blend idea?


Check's in the mail, right Artie?

[ArtieToo]

Re: The Dual Volume Problem

So a 500k pot acts like a 300k, 100k, 50k, etc. as you turn the Volume down?

Exactly.

And what about the Vol/Blend idea?

I think its a great idea. Let me know if you need help with a diagram.

Check's in the mail, right Artie?

You did remember to sign it this time . . . right?

[skh515]

Re: The Dual Volume Problem

I think its a great idea. Let me know if you need help with a diagram.

I think I know how to do it, but I'll let you know if I run into a problem. Either way, thanks for the offer.

You did remember to sign it this time . . . right?

I thought you were paying me to ask the question!
No wonder I never got the check!

[ArtieToo]

Re: The Dual Volume Problem

I thought you were paying me to ask the question!
No wonder I never got the check!

I never did have a head for business.

[skh515]

Re: The Dual Volume Problem

I never did have a head for business.

I wired one of my strats with a separate Vol for the bridge pup (Hotrail). The neck and middle pups (Lil' 59 and Ducky) share a 3-way switch, Vol and TBX control.

It works O.K. most of the time. If one or the other Vols in all the way down there is no problem. If I turn the bridge up to about 6, there is a noticible tonal shift between, say, 7 and 10 on the primary Vol. As I approach 10 it sounds more single coil-ish (an increase in treble and a drop in mid/bass). Is this the "loading" you mentioned? That would fit in with the dropping K values of the pots. If I'm not mistaken.

It doesn't sound bad, it's just strange. I thought maybe this was a double Volume effect.

I could replace the second Vol with a blend pot if it gets annoying, I guess. Or I could use it to make my doubles sound more like singles. That might make the Ducky really sound like a single.

[BlueGuitar]

Re: The Dual Volume Problem

... Most dual-volume guitars, like LP's, use fig. 2. Here, the interaction problem is better, but instead you get a situation where, as you turn the volume down, you also change the "loading" of the pup. That is, the effective value of the pot. Which, in turn, slightly alters the tone of the pup, usually, in a negative way. (Rolls off the highs.) Still, its better than the method in fig. 1.

I beg to differ, kind sir. If you check the Gibson site you'll see that LP's are traditionally wired up as Figure 1:

http://www.gibson.com/relations/schematics/diagrams/lespaul2.gif

However, I do agree with you about the advantages of the wiring in Figure 2; for starters you have much more control over blending the two pickups (without having to worry about muting your guitar!)

In checking over the wiring diagrams in the Donald Brosnac book, it looks as though Figure 2 wiring was most popular on the jazzier guitars (like the hollow and semi-hollow boxes).

One drawback with Figure 2 wiring is that you might get slightly more noise with both volume controls set to 0.

It is easy enough to see which method of wiring was used on a two-pickup guitar with two volume controls and a selector switch: put the switch in the blend position and turn one of the volume controls down to 0. If that mutes both pickups then Figure 1 wiring was used. If that test does not affect the other pickup then Figure 2 wiring was used.

BTW some of the Gretsch C&W guitars had the best of both worlds, so to speak. In addition to the separate volume controls wired up as per Figure 2 they had a master volume control wired up as per Figure 1.

--Thanks!

Steve Ahola

[ArtieToo]

Re: The Dual Volume Problem

I beg to differ, kind sir. If you check the Gibson site you'll see that LP's are traditionally wired up as Figure 1:

Cool . . . I stand corrected.

I've never actually owned an LP. Thats just what I've been told everytime this subject comes up in here.

btw - I have a solution to both of hese problems. But, so far, its only tested in the "lab". I told Scott about it. As soon as I can acquire a dual-volume control guitar to test it, I'll publish it.

The trick is . . . trying to stay ahead of inflation. Its most definitely, an uphill battle.

[Farkus]

Re: The Dual Volume Problem

Dudes, a question...

If you have your guitar set up like in figure 1, what is the advantage of having two volume controls as each acts as a master? Or is it that when both pups are selected that they work only for their respective pickup (ie they're NOT masters when both pups are selected)? I've never owned a Les, so I'm wondering about this...

Mark

[ArtieToo]

Re: The Dual Volume Problem

The advantage of fig. 1, is that when you have one pickup selected, it can have its own volume control, and acts like a "normal" volume control. So, you can easily balance the output of two different pups.

The disadvantage being, when you select both pups, both volumes are active, and both pots contribute their "load" to both pups. I don't think, that in normal operation, you'ld ever turn one down all the way though. I imagine you use the volumes to just "balance" the output.

[BlueGuitar]

Re: The Dual Volume Problem

Dudes, a question...

If you have your guitar set up like in figure 1, what is the advantage of having two volume controls as each acts as a master? Or is it that when both pups are selected that they work only for their respective pickup (ie they're NOT masters when both pups are selected)? I've never owned a Les, so I'm wondering about this... Mark

With a Les Paul wired per Figure 1 you get the interaction between the two volume controls only when the selector switch is in the middle; with a single pickup selected the other volume control is not in the circuit.

It works basically the same when wired up per Figure 2, but with the latter arrangement you have much more control over the blending of the two pickups. For example, you could add 10% of the bridge pickup to the neck pickup to brighten it up a bit. With the guitar wired per Figure 1 setting the volume control of the bridge pickup to "3" or lower would essentially mute the neck pickup.

So what are the advantages of Figure 1 wiring- and why is it the traditional choice for Les Pauls? With the volume control set to "0" you have grounded out the input of your guitar amp to squelch any noise. Wired as per Figure 2, with one pickup selected and the corresponding volume control set to "0" the load to ground on the input of your guitar amp would be 500k (or whatever value pot you are using) which will not mute your amp. Although the signal from the pickup is grounded out (muted) there can be other noises from your guitar or cable which are picked up by your amp.

[ArtieToo]

Re: The Dual Volume Problem

Although the signal from the pickup is grounded out (muted) there can be other noises from your guitar or cable which are picked up by your amp.

Thats interesting . . . and yet, one more thing I never considered.