Volume & Tone controls

norm mcdaniel · From: waco tx

Hi Guys. I have built several non pedal steels and they work pretty good BUT the volume control works very well(lotsa volume)but the tone is not so good. Im using a 250 pot with an .022 cap. can I use some other size to keep the tone from getting muddy or what ever you would call it? Or should I just do without a tone control? What are your excellant suggestions.

Norm in Waco Tx

G Strout · From: Carabelle, Florida

Norm, what kind of pickup do you have in the guitar? Single coil? Humbucker? Are the pots linear or audio taper?
Have you tried using a volume "treble bleed" capacitor? This is used on a volume control pot to prevent treble frequency loss as the volume pot is turned down. Placing a small capacitor (usually .001 MFD) between the input and output terminals of the volume control pot usually will help. As the volume is reduced, the capacitor allows high frequencies to bleed through to the output and keeps the tone from getting muddy at lower volume settings.
gary

John Burton · From: Manassas, Va

Single coil or Humbucker?
Single coil uses a 250k pot, while a humbucker needs a 500k ohm. Sounds like you may have a humbucker pickup with a 250k pot...just guessing.

norm mcdaniel · From: waco tx

John Iv got a P-90 in one and telecaster bridge p/u in another.

Thanks guys for the answers

Norm in Waco Razz

G Strout · From: Carabelle, Florida

Either 250K or 500K pots can be used with any passive pickups however the pot values will affect tone slightly. Generally using higher value pots (500K) will give the guitar a brighter sound and lower value pots (250K) will give the guitar a slightly warmer sound. The higher value pots put less of a load on the pickups which prevents treble frequencies from "bleeding" to ground through the pot and being lost. For this reason, guitars with humbuckers likely will use 500K pots to retain more highs for a slightly brighter tone and guitars with single coils use 250K pots to add some warmth by slightly reducing the highs.

Most guitars and basses with passive pickups use between .01 and .1MFD (Microfarad) tone capacitors with .02 (or .022) and .05 (or .047) being the most common choices. The capacitor and tone pot are wired together to provide a variable low pass filter. This means when the filter is engaged (tone pot is turned) only the low frequencies pass to the output jack and the high frequencies are grounded out (cut) In this application, the capacitor value determines the "cutoff frequency" of the filter and the position of the tone pot determines how much the highs (everything above the cutoff frequency) will be reduced. So the rule is: Larger capacitors will have lower cutoff frequency and sound darker in the bass setting because a wider range of frequencies is being reduced. Smaller capacitors will have a higher cutoff frequency and sound brighter in the bass setting because only the ultra high frequencies are cut. For this reason, dark sounding guitars with humbuckers typically use .02MFD (or .022MFD) capacitors to cut off less of the highs and guitars using single coils like your P90 and Tele bridge pups typically use .05MFD capacitors to allow more treble to be rolled off. Keep in mind that the capacitor value only affects the sound when the tone control is being used (pot in the bass setting or turned somewhat to the left) The tone capacitor value will have little to no effect on the sound when the tone pot is in the treble setting(turned all the way to the right.)

norm mcdaniel · From: waco tx

Thanks again guys. I will try these suggestions. Im sure these answers will work for me

Norm
In Waco Tx

Steve Ahola · From: Concord, California

norm:

Here are some notes in addition to what G Stout had to say. Bear in my mind that they are just my own opinions and there are different schools of thought on some of this.

As a minimum I like to use decent quality 630v caps- polyester (mylar) tends to be a bit warmer than polypropylene which can be a bit harsher. I avoid the "little greenies" which some electronics parts houses carry, as well as most anything from Radio Shack. I usually get them from Mouser Electronics, although you can also deal with guitar amp specialty shops like Antique Electronic Supply. There are connoisseurs who will get the boutique caps like Bumblebee copies which can sell for $10 or 20 each (ouch!) They sound great but it is hard to justify the cost.

So how does the pickup sound with the tone control all of the way up to 10? Too bright or just right? A lot of lap steel pickups are mounted close to bridge and they are extremely bright if run without a tone control. With pickups like that you might start with the tone control set to 0 and then start turning it up gradually until the sound gets really nice.

Sometimes you can just barely crack open the tone control before it starts to get too bright. One trick is to use a 250k audio taper pot which will respond more gradually than, say, a 500k linear taper pot. Another trick is to increase the size of the tone cap; a bright pickup usually needs at least a 0.05uF tone cap. If that is still too bright you can solder a second cap in parallel. Adding a 0.022uF cap would bring the net value up to ~0.072uF; adding a second 0.05uF cap would bring it up to 0.1uF. If you want to get fancy you can wire the second cap up to a push-pull tone pot, to allow you to switch between the two values. Another variation would be to use two different types of capacitors, like a ceramic disc cap in parallel with a mylar cap.

It goes without saying that the pickup itself is very critical. Some vintage pickups (or vintage design pickups) can be very bright and are not usable without a tone control. A modern design pickup can be a lot smoother.

One last note: there are two different ways to connect the tone control to the volume control. The older way was to connect the tone control in parallel to the output of the volume control and the output jack. For some reason about 50 years ago many of the mfgs started connecting it to the hot lead from the pickup(s) which was like the input to the volume control. Many people consider the older method to be much better, and Gibson is now doing that as part of their "Memphis wiring".

To translate that in simple terms the hot terminal of the tone control will be connected to the volume control by a wire or the lead of the tone cap. If it is connected to the middle terminal (wiper) of the volume control, you have the preferred "Memphis wiring". If it is connected instead to the ungrounded outside terminal you have the modern wiring. Simply move the wire from the outside terminal to the middle terminal and you should now have the Memphis wiring. You can easily change it back if you want.

Steve Ahola
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