Multiple volume pot wiring

[dannyhill]

Hi all,

I was pondering something about multiple volume pot wiring schemes where a 3 way toggle is used i.e. 335, LP, Black beauty (3 HB), firebird (3HB).

I suspect this is all subjective and depends on the style of playing but what are the advantages/disadvantages of the following alternatives:
(1) Two volume and two tone, dependent wiring with treble bleeds.
(2) Two volume and two tone, independent wiring with treble bleeds, with larger volume pots if any treble loss for variable loading of pups is necessary.
(3) Master volume (treble bleed), master tone and two dependent volumes - a larger pot can be used for the master volume to compensate for loss of high end due to increased load on pups. Rheostat option for individual volume pots?
(4) Master volume (treble bleed), master tone and two independent volumes - a larger pot can be used for the master volume to compensate for loss of high end due to increased load on pups. With larger volume pots if any treble loss for variable loading of pups is necessary. Rheostat option for individual volume pots?

I usually use the first but I'm starting to see that many prefer 3 or 4 as its easier to control blending in the middle position with any loss in high end from two volume pots in parallel with the master volume pot being compensated by a larger master vol pot value.

What do you think?
Cheers,

D

[JohnH]

That's a good question.

I'm 100% in favour of 1.

I think backwards wiring of volume controls (for independent wiring) adds noise by increasing the output impedance of the guitar so the signal is more vulnerable, plus the pot taper gets messed up because it only really cuts into the volume level as you get to low settings, plus the tone gets messed up at lower volume because it is shunting the pickup. Higher values and treble bleed can't avoid these issues.

Tone pots should be before volume controls rather than after IMO, for reasons discussed on other threads about 50's wiring

With those two issues, version 1 is the only one that I think works properly. Having standard forwards, modern wiring is a best compromise IMO. As you roll down a 500k normal volume pot, the max output impedance is 1/4 of the pot+pup, ie around 125 to 130k for a 500k pot (at mid volume). Wired independently, it is the total pot +pup or maybe more than 500k, at min volume.

Treble bleed with cap plus resistor, further decreases the output resistance, which is good, and also reduces the initial fall of volume as you turn down, making it easier to set in between mixes.

With modern wiring, if you are seeking a mix that is not all of both pups, it is easier to set if both are turned down slightly first

Heres a variation that i think would be fine, for those who wanted really good control of mixes in parallel, avoiding some of the issues above:

Each pup has a pot wired just as a series resistance, so at zero setting it is at zero resistance and not affecting the pup. These pots would be maybe 50 or 100k. Then from that, a normal master tone and volume, with treble bleed. The two extra pots would give very good control when used together to balance the pups in combination, and have a small effect when used on their own. This arrangement might suit those who want to add just a bit of one pup to the other - too subtle for me, so Id stick with version 1.

Also, for mixes, once you add a series option, its much easier to configure the controls for smooth mixes

cheers
John

[dannyhill]

Ah, the great sage speaks!

Many thanks for that John.
Should I read forward wiring as dependent wiring and backwards as independent?
Not sure I understand "Tone pots should be before volume controls" - is this a 50s thing? 50s wiring seems to be an easy way to paint yourself into one tonal corner if you liked it there and didnt want to bother about treble bleeds. Right?

I was reading all sorts about independent wiring sucking tone and taking off some treble end. Then I head that in order to have Gretsch like wiring in an LP or 335 they would increase the value of the pot they use for master volume in order to compensate for the extra load. I think with Gretsch wiring the pots are dependent, right?

But I also heard that several artists swap out a tone pot for a master volume as it helps them to set the middle position balance then adjust master volume for levels. Just one pot to kill the sounds too and just one for doing swells without the need for a volume pedal. But I hear you enter the muddy ground very quickly when you roll of the individual volumes, anyway to compensate that without screwing with the tapers and/or pup voice?

I mean if you play jangly/trebly music, invariably in middle position and with tone up high or maxed out, the Gretsch wiring might be useful then? For example Jeff Foskett of the Beach Boys does that to all his Gibsons and Epis. With the firebirds he has 3 volumes, one master volume and no tone control, but then it is a dark guitar.

Obviously if you are switching between lead and rhythm in a more rock style then a classic LP wiring is much more appealing. My understanding that it will take you to more places but you need to know how to get there.

Independent wiring = easier to blend whatever 'resultant sound' the pups give you with load changes?
Dependent wiring = truer sound although slightly less intuitive to blend?

BTW Great quote on the Gretsch pages:
"On inferior guitars, like Gibsons for instance, the volume controls don't work correctly in the middle position. The Gretsch master knob is also in a good spot for doing swells. I don't see how anyone could play a guitar without a master volume and master tone." I can hear Mr Paul turning in his grave.

[dannyhill]

Hi again John,

I guess, what I mean is: what are the drawbacks of a Gretsch type scheme and are there ways around it?
Cheers,

Danny

[JohnH]

You have planted a seed, and maybe it will grown some 'sage', which sometimes tastes good in a cheese sandwich.

Its a good question, how best to configure an arrangement where individual as well as master volume controls are wanted. And there is nothing wrong with wanting that.

At risk, in a passive setup up, is a loss of treble both at full settings, due to extra loading on the pickups, due to extra pots between hot and ground and at lower settings, depending on how its done. loss of treble due to independent wiring, or lack of effective treble bleed.

I'm not sure how exactly a classic Gretsch is wired, Ive seen various versions. My friend has a 6120, and when he was getting a lack of treble in some cases, he let me investigate with a meter. It turns out the Gretsch Filter-trons are quite low impedance (about 4k from memory), suggesting that they can tolerate quite a lot of loading, like a single coil, and that the master volume is 500k. So it has every reason to sound bright and clear, except at lower volume since there is no treble bleed. The answer for him was to ditch his 20' cord and use a 10' and keep the volume up high when possible. And it sounds great, especially the way he plays it.

What I'm saying there, is that the Gretsch pickups are particularly suitable for use with multiple volume pots.

But I think it is good to think a bit more generally, so I was playing around with the latest 5spice, looking at a pickup followed by two volume controls.

If we say that the ideal tonal balance for a typical humbucker comes with 500k volume and tone pots (just an assumption), we could replicate the load caused by that with two 500k volume pots and a no-load tone pot. I had a play around, and the most consistent tones seemed to be from each volume pot being forwards wired, with treble bleed cap and resistor, but somewhat lower cap values than normal.

The first volume pot would be associated with the pickup, the second, after the toggle switch, is for master volume. Given a master volume, maybe the first pickup volume pot need not go to zero (maybe put a fixed resistor on it to ground), which also allows it to be configured with a flatter taper for easier mixing with the other pup, and more optimized treble bleed.

John

[dannyhill]

Hi John,

Seeds are good.

"At risk, in a passive setup up, is a loss of treble both at full settings, due to extra loading on the pickups, due to extra pots between hot and ground and at lower settings, depending on how its done."
Can this be overcome by using a 1MEG pot master volume?

"loss of treble due to independent wiring, "
Do you mean connect each pickup to the wiper on the volume pot? Why can we not connect to the in lug as in dependent wiring? BTW I've heard people lift the other outside lug so the individual pots act as rheostats, but then in the middle you could never completely switch one off right?

"or lack of effective treble bleed."
Sounds like some experimentation or SpiceWorld calcs needed.


"I'm not sure how exactly a classic Gretsch is wired, Ive seen various versions. My friend has a 6120, and when he was getting a lack of treble in some cases, he let me investigate with a meter. It turns out the Gretsch Filter-trons are quite low impedance (about 4k from memory), suggesting that they can tolerate quite a lot of loading, like a single coil, and that the master volume is 500k. So it has every reason to sound bright and clear, except at lower volume since there is no treble bleed. The answer for him was to ditch his 20' cord and use a 10' and keep the volume up high when possible. And it sounds great, especially the way he plays it."

That's interesting, so low impedance pups (usually single coils not HBs) tolerate loading and therefore can be used with low impedance pots. I have one with 4-5kOhm pots and the other 2 from 7-10kOhm

"What I'm saying there, is that the Gretsch pickups are particularly suitable for use with multiple volume pots."

Unless we use larger pots? But then we get the same problem when we roll off past 7 on a 1MEG I guess?

"If we say that the ideal tonal balance for a typical humbucker comes with 500k volume and tone pots (just an assumption), we could replicate the load caused by that with two 500k volume pots and a no-load tone pot. I had a play around, and the most consistent tones seemed to be from each volume pot being forwards wired, with treble bleed cap and resistor, but somewhat lower cap values than normal."

For forward wiring I would say dependent volume pots wiring?


The first volume pot would be associated with the pickup, the second, after the toggle switch, is for master volume. Given a master volume, maybe the first pickup volume pot need not go to zero (maybe put a fixed resistor on it to ground), which also allows it to be configured with a flatter taper for easier mixing with the other pup, and more optimized treble bleed.

Sounds interesting, a treble bleed with parallel cap would give a flat taper too. This is the Rheostat setup you had in mind right?

Danny

[sumgai]

Obligatory reference to parsley, rosemary and thyme.

[JohnH]

yes..im refering to forwards = normal=dependent wiring.

I tried the 'rheostat' version, where the two individual volume controls were just adding series resistance to each pup. I think it would work fine for mixing pickups, but not so good for using them seperatley, ie, you might want to use the two pickups with one at full and the other reduced (thats how I use them).

Not keen on 1M pots - too high an impedance at mid volume IMO

But I have something brewing with all forwards wiring , using 500k pots, and T Bleeds, and I think it will work OK.
John

[dannyhill]

Oooooo!

I am starting to think that the standard LP wirings and the various 'standard' variations provide easier access to more of the tonal parameter space and allow for those who switch from lead to rhythm mid-song, whilst Gretsch wirings and it various 'standard' variations provide easier/faster access to a few regions of the tonal parameter space which is why people who like to play with the tone on full and like to switch at the same volume prefer that setup.

Keep in mind that anything that you can come up with will:
(a) Be most gratefully appreciated
(b) eventually, if to replace a Gibby wiring, have to work also for series, HOOP and series/parallel OOP 'modes' as well with switchable tone caps and switchable series caps (for series taming, strangle and HOOP).

Good luck!

Danny

[JohnH]

This might be the sort of thing:



The circuit has a pickup modeled within the dotted blue box at left (a fairly low wind 5k hb or single coil), and the cable and amp load in the box at right.

Two volume pots are shown with treble bleed, lower left has both pots rolled down from 100% to 5%, and the graphs at right show one only rolled down in stages, the other being at 50%

You can see see somewhat consistent shapes in the tone as it rolls down, but also some variation in tone in terms of the peak height and frequency. Its not quite as consistent in all variations as would be a single volume pot, but Its probably workable.

I note that this should take account of all kinds of different wiring and tone controls, and it does not do so. Ill leave that to you to try.

[dannyhill]

Hi John,

Thanks for that.
Lets see if I understand. This is for two volume or two volume and one master?
I can try? :-)
Looks daunting....

D

[JohnH]

This is for a sustem two pickup volumes and one master volume. But what is shown is just one pickup, as if you had selected one pickup and the other is disconnected, that being the first thing to test. If you had selected a middle position with 2 pups, the left side of the diagram with pup and pot with treble bleed would be doubled.

What I thought was, you could get the program (thats the latest version, released last week), build that diagram and make it run, then you can insert your bass cut caps, tone controls etc and see what they do. All you need to get your head around is how to relate the schematic symbols to the actual components, and there arent very many of them.

[dannyhill]

Hi John,

I will try. I'm due some time off next week, first since August and will crack on with it then.
Where can I download it?
Cheers,

Danny

[JohnH]

Mar 6, 2013 15:43:57 GMT -5 dannyhill said:

Hi John,

I will try. I'm due some time off next week, first since August and will crack on with it then.
Where can I download it?
Cheers,

Danny

www.5spice.com/

For anyone else who has used it before, the latest free version seems to have a few nices extra features, while being very similar to use.

[dannyhill]

Ok, not so bad.
I tried to start by replicating yours but I need a tutorial in 5spice. :-)
My graphs dont look like yours, same ball park though.





Any tips for things to try?

D

[JohnH]

well done

on the analysis page, set frequency 20 to 20000, and 100 steps per decade

[dannyhill]

Cool.
More tomorrow.

D

[dannyhill]

Hi John,

Is this right for no tone load, two volumes in middle position with pups in parallel?:




Seems a bit odd, but then I don't remember when I last saw two pickups combined modelled.
Cheers,

D

[JohnH]

Good..i think, unless you have already fixed it, the two sources are out of phase.

Id suggest not putting the bass cut cap in untill the plots are looking more normal. Also, i think 150k is s better vslue for treble bleef
J

[dannyhill]

Hi John,

I fixed that.
How's this looking for 2vol, one master vol one master tone?


Rolling off the master tone, master volume at max, 2 vols at max:


Rolling off the master volume, master tone at max, 2 vols at max:


Whats the solution to avoid the midrange dip when rolling off the tone?
Cheers,

Daniel

[JohnH]

I think the volume pots which are not being varied look like they are running at mid turn 50%. Right click on each pot to chsnge that. At full with all pots, you should get about 0db at low and mid frequencies.

I think the tone pot is working but smaller treble bleed values are needed. Have you tried the values that i used above?

[dannyhill]

Hi John,

Thanks for that. Obviously there is something I am missing here.
What is wiper %? When I set them to 100 for the two pup volumes all my curves sit on top of each other.


D

[JohnH]

What i meant was, when you are varying the controls, you get to set the % in the sweep commands, being the position of the wiper, assuming a linear pot.

When you are doing a run where a certain pot is not changing, it will use the wiper position in its parameters. The default, and as shown on your diagram, is 50%. So if you have not adjusted this, the pot is at mid position not at full. To change it, on the schematic view, right click on the pot, click edit value, or edit parameters, change the % to 100%, or whatever you want.

J