A tone knob cuts treble...but is there a way to cut bass?

[rollo greb]

Hi, I recently wired up my guitar with a 5-way super switch and a flip switch for a variety of different pickup options. The guitar has 3 single coils, and I'm happy with all the sounds except the "two pickups in series" ones. They give a nice thick sound, but are just too muddy to be useable.

So my question is: Is there an easy modification using a capacitor or resistor to cut some of the bass? I'm not really concerned if I lower the overall output a bit, since the series positions are very hot already. If it was just a case of adding a component of a certain value, it would be easy enough to wire it so that it just affected the "in series" positions. Cheers!

PS, I know I could use an EQ pedal, but I would really prefer to control everything with my guitar.

[Sweetfinger]

place a capacitor in series with the pickups in whatever position you want the bass cut. The useful ranges are going to be from .008 mf down to .001. The smaller the cap, the more bass will be cut. Try a few and you'll pretty quickly get a handle on which ones your ears tend to like.

[rollo greb]

cool, thanks. Have you done that before? If so, did you use ceramic capacitors, or higher quality ones like a film capacitor?

[Sweetfinger]

I've done that mod on several guitars, generally on humbuckers in the neck position. I tend to like a little crisper sound there. I've also done it as a fake 'coil split' for my customers who ask for a split, but only have single conductor pickups. I use whatever I find in my cap drawers- usually film types.

[jrfrond]

You can also make it variable (to a degree) if you bridge that small-value cap with a pot. I've found that 50KL usually works best for this application.

[David Schwab]

G&L did this for years on the S-500

Here's the Schematic.

The bass control used a 1 megohm pot and a .0022MF cap.

I used to do this all the time, got it from an old Carvin wiring guide they used to send with their pickups back in the early 70's. It works real well. The size of the cap determines the frequency.. the smaller it is, the more bass (higher cutoff frequency) it cuts.

The 1 meg pot let's you go from no bass cut to full.

[Mark Hammer]

One of the things I like to do is use an "overcompensated" volume pot. Normally, when volume pots are compensated for the treble loss that arises at less-than-max volume settings, a fairly small value bypass cap is used between the input and wiper lugs of the volume pot; generally on the order of 680pf or less. This provides a zero-resistance path for the highs, such that when the volume gets turned down, it only affects signal content in the mids and lows. Upper treble still behaves as if you haven't turned the volume down. If that cap is replaced with a larger value, like 1000pf-1500pf, the effect of the volume pot is shifted downwards such that much of the mids still pass through unaffected by volume-pot settings.

It's not for everyone's tastes, but it has the effect of nicely thinning out a bridge humbucker to complement "chicken-pickin". Turning the volume down to around 7 trims back on low end, and once you start going below 6 you start losing overall volume. You may also find that the differential fading in of bass and treble content makes pinky volume swells sound a little more interesting. Worth a try, particularly since it involves no routing or extra parts other than simply straddling two pot lugs with a cap.

[Chuck H]

You could put the control on a push/pull pot and have the normal treble cut on the "push" position and the bass cut on the "pull". You couldn't use both at the same time this way, but you won't need to drill a hole in your guitar either.

Chuck

[rollo greb]

You could put the control on a push/pull pot and have the normal treble cut on the "push" position and the bass cut on the "pull". You couldn't use both at the same time this way, but you won't need to drill a hole in your guitar either.

Chuck

Actually, I thought of doing that but couldn't seem to design a way for it to work. Have you done it? Do you have a diagram?

[Chuck H]

I haven't done it before. But this will work. The "extra" leads are there because it's difficult to solder more than one lead to the DPDT switches tiny lugs.

HTH

Chuck

P.S. I don't know why, but you can't read the image by clicking it. Right click and use "open link in new window".

[rollo greb]

Thanks very much for that! I'm going to try it.

[Steve A.]

Thanks very much for that! I'm going to try it.

Let us know how this works out for you!

I've had good luck with variations of the Torres Midrange controls:

http://www.blueguitar.org/new/schem/_gtr/dual_mid.gif

While that shows a dual mid control (mid-cut when down- mid-cut-boost when up) it could also be rewired to use a regular tone control in one position and a mid cut control in the other.

(I don't use the mid-cut-boost circuit as much because there is no neutral position- in all positions it cuts the signal level to some extent. With the mid-cut control turning it up to 10 essentially removes it from the circuit.)

For mid-cut you ignore the 1.1M resistor and .001uF cap going to ground and just use the audio tranformer (inductor), 220k resistor and .039uF cap. For the pot you can try anything from 100k to 500k. Linear works better for the cut-boost control; audio taper seems to be fine for the mid-cut control.

Steve Ahola

[Nictrolis]

A cool mod

I know it works pretty well, as I have some similar circuit in my Reverend guitar. They have it standard on most (if not all) of their guitars, and though they don't provide a schematic I'm sure it's pretty similar. It's a very cool knob to have when you're trying to get a lot of different sounds.

[Chuck H]

Let us know how this works out for you!

Hey Steve. If it works out are you gonna post the drawing on blueguitar?

Call it the "Chuck mod" O.K. The Blue Guitar has become an institution here at Ampage. I think it would be very cool to get a space there.

Ha ha

Chuck

[rollo greb]

Well, I FINALLY got my 500k push-pull pot and wired up the above diagram, so I thought I'd post my results. First, you'll have to switch the outer lugs of the pot, or your tone control will work backwards! I used a .001 uf capacitor for the bass cut portion (I thought it might give me extra rolloff), and it works great. A 1meg pot might be better to shunt more signal through the cap, but I don't think anyone makes 1meg push-pull pots.

The treble cut mode (regular tone control) doesn't do much until the pot is almost all the way down, so I'm going to have to try higher value caps for that part.

I rarely use the stock tone controls anyway, so overall I'm very happy with this mod. The bass cut does drop the output, but gives some very nice sparkly tones for clean arpeggiated stuff with the single coils, and makes the "in series" positions actually useable.