Wiring help needed ...

[mikettf]

Hello,

I don't see the schematic for this on the 'net anywhere ...

('87 Charvel Model 6 sans mid--boost)

Neck/Middle Volume

Bridge Volume

Master Tone (Push-Pull split Humbucker)

3 on/off switches

This is what it looks like ---



Any help in finding a schematic or filling in part or all of the one above will be appreciated.

TIA

MikeTTF

[mikettf]

Here's how far I am with help from a couple nice guys ... ;D

Comments?

[UnklMickey]

Welcome Mikettf,


glad to have you on board.

sometimes things happen really fast here, sometimes it takes days. it all depends on who's around at any given time.

i am happy to see you've taken the initiative to post images, and be specific about what kind of help you need.

i'm not familiar with the stock wiring of the Charvel model 6.

from your second post, and the functional descriptions you've described, i'm sure i'll be able to fill in the blanks. unfortunately my week has been unusually busy. i'm almost never on-line on weekends. the soonest i'll be able to help you with this will be early next week.

i hope one of our other members will be able to handle this and post before then.

c'mon guys jump in here!

and +1 for doing so much on your own

unk

[mikettf]

Thanks Unk! ;D

A couple of guys have me this far ...

[JohnH]

Good diagram.

One feature of it which I think is a very good idea is the numbering of the connections. It makes it very easy for us to contribute to a discussion, referring clearly to each point.

I think basically, the design is fine and will work. Here are two thoughts:

The volume controls are wired in a traditional way (as on many Les Pauls for example). However with both active, if you turn one down toward 0, it will cut out both pickups. This can be improved by reversing the connections so the wiper goes to the pups, and the outer lug goes to output. ie, per your diagram, reverse 3/4 and 6/7.

My view is that the arrangement that you have is better for making overall changes in volume, setting individual pickups to different volume settings, particularly if you want to use a low volume setting, say to 'clean up' a distortion pedal. The reversed way however, is better for mixing pickups, with one at full volume mixed with a small amount of the others.

Since it is just swapping wires to the pots, it is easy to try both in relation to your playing style.

Whether you do this or not, there can also be an issue that the treble gets muted as you turn down the volume. This is due to the capacitance of the lead to the amp. You can partly compensate for this by adding a 0.001 capacitor (= 1nF) to each volume control between the lugs 3/4, and another between 6/7.

cheers

John

[mikettf]

Thanks John!

I am more interested in mixing in a low amount of Bridge or Neck - so I may try your suggested reversed way first.

MikeTTF

[mikettf]

Hi John,

Couple of questions?

I'm told that if I swap 3/4 - 6/7 I'd better have Linear pots or else the volumes will have a very narrow range - with the final bit of ccw rotation affecting the majority of the volume.

I've already bought pots with an "A" on them - I believe these are Audio Taper?

Your comments appreciated!

MikeTTF

johnh said:

Good diagram.

One feature of it which I think is a very good idea is the numbering of the connections. It makes it very easy for us to contribute to a discussion, referring clearly to each point.

I think basically, the design is fine and will work. Here are two thoughts:

The volume controls are wired in a traditional way (as on many Les Pauls for example). However with both active, if you turn one down toward 0, it will cut out both pickups. This can be improved by reversing the connections so the wiper goes to the pups, and the outer lug goes to output. ie, per your diagram, reverse 3/4 and 6/7.

My view is that the arrangement that you have is better for making overall changes in volume, setting individual pickups to different volume settings, particularly if you want to use a low volume setting, say to 'clean up' a distortion pedal. The reversed way however, is better for mixing pickups, with one at full volume mixed with a small amount of the others.

Since it is just swapping wires to the pots, it is easy to try both in relation to your playing style.

Whether you do this or not, there can also be an issue that the treble gets muted as you turn down the volume. This is due to the capacitance of the lead to the amp. You can partly compensate for this by adding a 0.001 capacitor (= 1nF) to each volume control between the lugs 3/4, and another between 6/7.

cheers

John

[JohnH]

Mike

'A' is for audio taper as you noted, rather than linear (which is usually denoted 'B')

I think it is another aspect where personal preference applies. With either volume control arrangement. both pot types will work and cover the same range of control, but the part of the range where the action takes place will vary. With the reversed arrangement, the linear pot will give a more gradual reduction as you reduce from high volume, and a more sudden fall at low volume. I don't know which is best. But here is a link to a basic LP setup which uses these two reversed volume pots, using the audio pots that you have:
www.guitarelectronics.com/product/WDUHH3T2202

Another variation involves adding a resistor in parallel with those extra 0.001 caps, which will also shift the control range a bit. (these resistors are in the range 150k up to say, 470k)

So no fixed answer, all these options work but are a bit different, and lots of room for experimentation! (sorry if you wanted a single clear answer)

John

[UnklMickey]

mikettf said:

...I'm told that if I swap 3/4 - 6/7 I'd better have Linear pots or else the volumes will have a very narrow range - with the final bit of ccw rotation affecting the majority of the volume....

you were told right. wrong.

this problem is somewhat true of linear pots even if they are used normally.

about the ONLY thing i don't like about ampeg tube amps is their use of linear pots. everything happens from 0 to 3. from 3 to 10, only a slight increase.

when you wire the pots "backward" it makes things worse. you no longer have a voltage divider (other than the series resistance in the pup and the portion of the pot between the wiper and ground) * so now majority of control is between 0 to 1.

you can "get by with" a linear pot for a volume control.

you can "get by with" a volume control wired backward.

you won't "get by with" a linear pot wired backward.

unk


*JohnH just pointed out to me that there will be a voltage divider formed by the wiper-to-hot of the pot and the resistance of the other pickup. (if both are switched on) so it's not so bad if the other pickups is on "10".

[JohnH]

*JohnH just pointed out to me that there will be a voltage divider formed by the wiper-to-hot of the pot and the resistance of the other pickup. (if both are switched on) so it's not so bad if the other pickups is on "10".

Thats right - thats why the reversed arrangement is the best for mixing pups, with one at 10, you can fade the other fully up or down without losing the sound from the first. The issue Unk points out, is why the non-reversed arrangement is better for overall changes in volume.

[mikettf]

Okey doke. So if I reverse 3 and 4 / 6 and 7 and use Audio Taper pots ... I should be OK?

Mike TTF

unklmickey said:

mikettf said:

...I'm told that if I swap 3/4 - 6/7 I'd better have Linear pots or else the volumes will have a very narrow range - with the final bit of ccw rotation affecting the majority of the volume....

you were told right. wrong.

this problem is somewhat true of linear pots even if they are used normally.

about the ONLY thing i don't like about ampeg tube amps is their use of linear pots. everything happens from 0 to 3. from 3 to 10, only a slight increase.

when you wire the pots "backward" it makes things worse. you no longer have a voltage divider (other than the series resistance in the pup and the portion of the pot between the wiper and ground) * so now majority of control is between 0 to 1.

you can "get by with" a linear pot for a volume control.

you can "get by with" a volume control wired backward.

you won't "get by with" a linear pot wired backward.

unk


*JohnH just pointed out to me that there will be a voltage divider formed by the wiper-to-hot of the pot and the resistance of the other pickup. (if both are switched on) so it's not so bad if the other pickups is on "10".

[UnklMickey]

i think that's the best plan for de-coupled volumes.

you should expect good control of blending 1 pup when the other one is at max. getting reduced volume when only one is selected, or both are reduced, will occur from 0~3. those numbers will be even lower for linear pots.


unk

[mikettf]

Thanks for the help! ;D

I'll let you guys know how the finished project turns out (waiting on switches to arrive from AllParts)

MikeTTF

unklmickey said:

i think that's the best plan for de-coupled volumes.

you should expect good control of blending 1 pup when the other one is at max. getting reduced volume when only one is selected, or both are reduced, will occur from 0~3. those numbers will be even lower for linear pots.


unk

[UnklMickey]

good, we'll be glad to hear back about this.

[mikettf]

Unk, John and all ...

Finished the wiring job you guys have helped me with. ;D

A couple circuit comments -

No hum or noise, whatsoever. (2 Lace Sensor Gold's and a SD Screamin' Demon)

Reversing 3/4 and 6/7 results -

The PU blending is perfect for me ... soften the bridge with a little neck ... brighten the attack on the neck/middle with a little bridge - works great - one doesn't turn the other down.

The treble bleed off is really excessive ... turn down any PU to "8" and 90% of the treble disappears. I didn't wire in the "bleed caps"

Do you still recommend .001's between 3/4 and 6/7? Any certain type - brand etc.?

I used an Orange Drop .022 Tone pot cap - producing a very nice range with the tone control.

I used Audio taper pots and am totally pleased with their function.

Save for the treble bleed off, I couldn't be happier with it.

Thanks for the help!

MikeTTF

=====================================

Couple of pics ---

Not super neat ... but it works!

[JohnH]

Mikettf - nice job, and I'm glad it is working out. I can understand that that treble bleed would be like that. I expect it sounds OK if one is a full volume, but if both are turned down, or if only one is active and turned down, then the bleed can happen. It is caused by the resistance of the pot and the capacitance of the guitar lead forming a low pass filter - which reduces more the higher the frequency.

Those 0.001 caps will help. The value is a best guess and the best value will depend on the judgment of your ears. So if you want to get a selection to try, I'd suggest, 470pF, 680pf, 1nF, 1.5nF and 2.2nF. Caps in this range are only a few cents each, but you'd need two of which ever you select.

I notice you have a perfect set-up for testing this, with rear access to your controls. You can try all these with a couple of alligator clips to attach them to the pots. I'd focus on getting the best results with just one pup selected.

The effect depends on the guitar lead. A shorter lead causes less treble loss, so you should test with your most commonly used lead length.

I don't think cap type makes any significant difference, although some say that the ceramic disk types don't sound as good as other types. You might find that is all that is available in the small values however, and I would not worry if so.

That is the simplest thing to try and Id recommend that first.

But just to be complete, theres more steps you could take to fine tune your volume control system.

In addition to the bleed caps, some people put a resistor in parallel with the cap, in the range 100k up to say,470k. This makes the bleeding a little more consistent across the volume control range, and also gives a slightly smoother start to the volume drop as you reduce from 10. With the resistor the best cap value would tend to be a bit larger than without.

Extreme solution: Put in an active buffer circuit. That is what I am doing on my guitars but most people would not want to do this. I use this to give me much clearer highs, and a low impedance output that will drive any length of cable or effects inputs. Theres a tonal change because the cable is now isolated from the pups. I use this with two volume controls, and some extra resistors to give independence at all settings - see the LPmaximiser on the schematics page.

Something like that would be easy to add later if wanted - looks like you have plenty of room. Id try the simple bleed caps first.

John