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Author Topic: Controls_Tone Capacitors  (Read 1005 times)

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Offline frankenxtein

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Controls_Tone Capacitors
« on: December 27, 2012, 11:30:54 AM »
Cheap mod replaced .047uF ceramic with .01uF O/P. in Cheap Dean Vendetta.

      These guitars are bottom of the line, they are very dark, I don't want to discuss the guitar so much as Controls,  Tone Capacitors. The only reason I did this was brighten it up, yep its a bit brighter than its twin (we have the brown and black).  I will replace its capacitor too.
  The O/P (oil paper) thing is sure overblown from what I've read, but if someone wants to believe magic stories. I found the one I used, in a bag of caps I had acquired. lol
    I plan on replacing the controls on both before I settle on the value. .047uF might be fine. They are setup B500k Volume and A500k Tone.
       Seems they reverse A & B in some guitars?
       I was thinking to try 1000k anyone have any experience with that?
« Last Edit: December 27, 2012, 11:35:29 AM by frankenxtein »
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Offline Schprocket

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Re: Controls_Tone Capacitors
« Reply #1 on: January 15, 2013, 08:35:57 AM »
Franx, A and B refers to whether or not a potentiometer's resistance increases at a linear or a logarithmic rate but I'll have to look up which is which.

The logarithmics are commonly used as gain potentiometers - volume controls - because setting them at half-way sounds to the human ear half as loud as when at full gain/volume. Half-way represents either substantially lower, or higher, than half of full resistance, depending on how it's connected.

Linears are used when you want the resistance to change linearly with it's rotation, so a half-way setting is half of maximum-resistance.

So for your tone control, you'd likely use a linear pot which if you have a multimeter (resistance checker) should read around 250k for your 500k pot when set to the mid-way point.

The tone circuit is a filter of some description (which escapes me because it's been 30 years since I actively used this theory but my guess is low-pass :) ). A capacitor effectively 'shorts' AC of a particular frequency (generated by the pick-up) and the pot determines by how much by controlling the AC current flow.

Upping the resistance of the tone pot to 1 Megohm (i.e. 1000k) whilst keeping the same cap may sound like it's not having much effect until you come down from 11 to 5.5 on the dial :) after which the tone effect should 'sound' like it used to all the way down to 0.

The only way to know for sure though is to try it out and listen - you won't hurt anything unless you get ham-fisted with the soldering iron :)
...they discovered only a small asteroid inhabited by a solitary old man who claimed repeatedly that nothing was true, though he was later discovered to be lying.

Offline frankenxtein

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Re: Controls_Tone Capacitors
« Reply #2 on: January 15, 2013, 10:04:26 AM »
Thanks Schprocket  :)
I will be ordering a few more pots soon. 
    The logic seems if you want to get a more mellow tone like a LesPaul with humbuckers you would use 300k volume pots, 500k value for tone. My hearing is so bad I tend to turn up the tone all the way anyhow lol. The overall tone of the guitar is effected by the volume control(s).
     Pretty cheap mods, even if one uses 5x the price US made pots, and caps. Quick connect wiring to the pickups, and/or isolated switches, is something for anyone wanting to experiment to seriously consider. Pots wear out!

BE AWARE THAT: touching any original solder connection in a vintage instrument will reduce the resale value.
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Offline Schprocket

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Re: Controls_Tone Capacitors
« Reply #3 on: January 15, 2013, 05:34:15 PM »
In the bad old days, pots used to be wire-wound until it was discovered that the same could be applied to a carbon film resistor.

Either type is susceptible to a little bit of localised 'plating' of dirt, particularly where there's any DC-biasing component in the signal - this is sometimes why a 'healthy' volume pot can sometimes generate 'scratchy' noises in amps because of the high resistance spots on the track.

Aerosol-based ellectrical contact cleaner acts like the sports coach's 'magic-sponge' in cases like this - a quick spray into the gap just near the terminals and rotate the shaft back & forth over the spot where the noise is being generated from and it usually comes good if it's just plating.
Just be careful none of the solvent gets anywhere near certain plastics and paint finishes and keep well away from poorly-sealed LCD displays.

Wire-wounds are generally a sturdier construction - they might even add a little inductive-reactance (AC resistance) to the circuit which might colour the tone a little. In this case, for a given value using carbon-film pots, you might get away with a wire-wound pot of a marginally lower value but again experimentation and ears would be required here :)
...they discovered only a small asteroid inhabited by a solitary old man who claimed repeatedly that nothing was true, though he was later discovered to be lying.