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FDP Forum / Guitar Mods, Repairs, and Projects / Caps/resistors and impact on volume question

Tinkerer
Contributing Member
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San Diego, CA USA

Mar 24th, 2019 05:57 PM   Edit   Profile  

I have been messing around with the one pickup guitar I finished recently. It has a Kinman P-90 in the bridge, and I wanted to see if I could arrive at a resistor/cap combination that could give me the neck and bridge sounds of a 2 pickup guitar. I wanted to use a switch rather than a pot, so have a spst toggle switch that puts a .012 cap in series with a 33k resistor to ground.

I have another guitar that has a Kinman P-90 in the neck, and in comparing that guitar neck pickup sound to this bridge pickup with the resistor/cap engaged, I think the bridge/cap/resistor guitar not only comes very close to the Kinman in the neck sound, but actually in some ways seems to have more definition.

The one thing is, that when I switch to the "neck" setting, the volume seems to drop a bit- not much, but a tad lower. I assume this is due to the loss of what ever treble frequencies are now going to ground, but is that correct?

If this is correct, is this effect one of the reasons why Fender added a neck pickup to the Esquire?

Thanks!!

Pinetree
Moderator Emeritus
(with many stars)

When I was crazy...

I thought you were great.
Mar 24th, 2019 06:05 PM   Edit   Profile  

I think playing with the height of the pickup would be way easier.




Tinkerer
Contributing Member
*****

San Diego, CA USA

Mar 24th, 2019 06:33 PM   Edit   Profile  

Thanks Pinetree- to clarify, this is a one pickup guitar- the pickup is in the bridge position, and I have added a cap/resistor through a toggle switch connected to ground that I can engage to give me more of a neck position sound.

Peegoo
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Just beyond Mars

there's a world of fools
Mar 24th, 2019 07:00 PM   Edit   Profile  

Ideally, a neck pickup and bridge pickup will both make about the same voltage level.

The reason they sound different has a lot to do with their positions under the vibrating string. A bridge pickup sounds twangy because it senses more high harmonics of a note. The neck pickup has a 'rounder' tone (more hi-fi, with more balanced lows and highs) because the string moves a lot more the closer you get to the center point of a vibrating string.

The fixed resistor is what sets the cutoff point of the cap to act as a high-cut filter. The resistor also shunts some of the signal to ground, and that's what's causing your volume loss.

Reducing the resistance will reduce volume loss, but it will also change the cutoff point of the cap.

Tinkerer
Contributing Member
*****

San Diego, CA USA

Mar 24th, 2019 07:30 PM   Edit   Profile  

Thanks Peegoo- I landed on the 33k by using a tone pot to arrive at the sound I wanted and then measuring the resistance at that setting. Is that an appropriate way to calculate it?

When you say reducing the resistance, do you mean a lower value resistor will reduce the volume loss?

If a change in resistor value, will change the cutoff point of the cap, is it possible that if I go with a resistor value that would result in less volume loss, a different cap value might give me the sound I am getting now, but without the volume drop?

Thanks again!!!

(This message was last edited by Tinkerer at 09:32 PM, Mar 24th, 2019)

Te 52

Laws of Physics

strictly enforced
Mar 25th, 2019 10:06 AM   Edit   Profile  

If you used a multi-pole switch for your "selector," you could probably wire it such that when you switch to the "neck setting," the added resistor and cap are completely bypassed.

It would help if you could publish a schematic or wiring diagram of what you have now.

Tinkerer
Contributing Member
*****

San Diego, CA USA

Mar 25th, 2019 10:45 AM   Edit   Profile  

Here's what I settled on. I moved the pickup towards the nut by 1", because it was a tad too bright where I had originally put it. I then got rid of the 33K resistor and went with a .0022 cap that gets switched to ground with the toggle. This setup gives me what I was looking for.

Thanks everyone!!

Peegoo
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Just beyond Mars

there's a world of fools
Mar 25th, 2019 11:22 AM   Edit   Profile  

Outstanding!

Component ratings are a general reference to give you a good idea where to start, but your approach (using a pot to dial in the sound, measure the resistance of the pot, install a resistor) is always the absolute best way to go. How it sounds is the all-important criteria.

Bubbalou
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USA

THE LOW END OF UPPER TEJAS
Mar 29th, 2019 06:02 AM   Edit   Profile  

Tinkerer, that is the way I do it, using a pot to find the value then using a 1% film resister. I personally use Polyester caps as I perceive some difference (maybe it has a tighter tolerance). I notice a more noticable difference when Playing a guitar in a room with no one else between Polyester and Polypropeline and ceramic but in playing a bass by myself on bass not so much. I don't care if it is placebo affect or what but if what I perceive as better works for me I don't care. Ha! ;)


Tinkerer
Contributing Member
*****

San Diego, CA USA

Apr 9th, 2019 12:52 PM   Edit   Profile  

The saga continues- well I spoke a bit too soon- I found that in a band mix the guitar with the cap switched in, just sounded dull and muddy.

So what I am trying now, is that I added a GFS bridge humbucker that I had in my parts bin. I located it "north" of the Kinman, so closer to the nut. I'm using that pickup as a tone control of sorts by wiring through a 500k pot such that at one end of the sweep it is only the Kinman pickup, and at the other end of the sweep it is the kinman and the GFS in parallel, so producing the middle position were these connected via a 3 way switch. To my ears, the middle position on a guitar always sounds much more like the neck pickup by itself, so wired this way I get Kinman alone, then as the pot is turned variable amounts of the GFS added in, and then the two pickups in parallel- which in my testing sounds like a nice rhythm setting. I have learned that I can never really tell until I hear it with other instruments, but if this works, I like the unconventional aspect of it.

One other thing- I'm doing the controls very bare bones- just this "tone" pot, no volume pot.

(This message was last edited by Tinkerer at 02:54 PM, Apr 9th, 2019)

FDP Forum / Guitar Mods, Repairs, and Projects / Caps/resistors and impact on volume question




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