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Forum Home > Layout Gallery - GuitarPCB Build Documents, Mods and Tips > TONE TWEQ

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This is an active, true tone control or equalizer. It is useful for both guitar and bass instruments. Each band will boost or cut the signal.

Start with each control in the center or 50% position. Turn the control clockwise, CW to BOOST and counter-clockwise, CCW to CUT the signal.

After achieving the desired tone setting, adjust the final volume level to suit. As with all active equalizers, best results are usually achieved by cutting frequencies rather than over-boosting. However this EQ can also give some enhanced tonal characteristics to help overdrive and amp or pedal as desired (see video). There is some interaction between adjacent bands. This permits smooth transitions in the tonal setup.

Now you have the perfect tone ready for your next song!


This will also be useful as a pre-set tone change to be punched in for solo’s or to change guitars from humbuckers to single coils, etc. It may also be useful in combination with certain effects either on the pedal board or as a built-in board in a combo pedal. So many uses so grab a few!


Board Dimensions (W x H) only - 1.96” x 1.20” inches.

Build Document

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Remember this board can be used not only as a stand alone but will make a great Active Tone Control for another circuit as well. So many uses, so grab a few!

As a side note 9mm pots with (nut and washer) will fit perfectly on the Tone TwEQ boards and will also match the Lug Numbers on the board perfectly.   Give you any ideas?  :)

Mod Note: Standard 6 string Guitarists who play loud and do not wish any possible sub-harmonics leaking through can populate C1 and C2 with a 68n to 100n capacitor instead of 220n, making it Bass Ready.

April 24, 2015 at 10:04 AM Flag Quote & Reply

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Very cool!!


April 24, 2015 at 8:10 PM Flag Quote & Reply

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Courtesy of Wilkie1

I’m building up an Animal (G2) board. I will be inserting the Tone Tweq into the middle of the circuit bypassing the Animal tone circuit completely. We all know that in the Pete Cornish design he used a simple Low Pass Filter for a tone control.


How do you do this? It is so simple!

  1. Remove the Tone pot from the Animal board. (Or don’t install it to begin with!)
  2. Attach the INPUT of the Tone Tweq to pad 3 of the Animal tone pads.
  3. Attach the OUTPUT of the Tone Tweq to pad 2 of the ANIMAL tone pads.

C17 cap does not need to be removed when installing the Tone TwEQ without a tone pot. The reason is that the #1 pad is not being used and therefore, the C17 cap is not attached to the signal path. Hence, there is no filtering caused by the cap.

That’s it!

If you don’t want to include the additional level control of the Tone Tweq, remove the Tone Tweq level pot and attach the pad 3 of the Tone Tweq level pads to the pad 2 of the Animal tone pads.

Now the level control of the Animal will set the final volume output of the pedal. Another option is to use a trimmer pot for the Tone Tweq level control.


Other circuits that employ this similar tone circuit can be bypassed in the same manner.

In regards to the BMP OPamp build:

If you hook into the circuit at pin 7 of IC1B, you can discard the rest of the circuit and feed directly into the input of the Tone TwEQ. This would add the active tone circuit of the Tone Tweq to the BMP OP AMP V2 and also replace the final VOL pot. The combination would give much more tone control to a great circuit and add an additional gain option.


This mod could be done without any cutting of traces or modification of the circuit board. Just connect the input of the Tone TwEQ to the Pad A on the BMP board and ignore all components downstream from that point.

Here is a handy guide for using it in series.

  • Download it for a large clear view:
  • Please read the information contained within carefully!
  • This is an Active EQ and needs to be treated like one!
  • Do not turn things "Full Up" just because you can!
  • This is a tool that needs to be used properly.

Here is an alternate wiring guide courtesy of Wilkie1:

Another simple mod is to take the main circuit Volume Control output Lug 3 and wire it directly to the input of the Tone TwEQ so now you will use the Volume Control of the Tone TwEQ as you only Volume instead of having multiple volume controls.

Drawing courtesy of Trom:

So many easy options to turn your Dirt or Fuzz pedal into a Boutique Superstar!


Go to this thread for more ideas based on the Tone TwEQ!

June 26, 2015 at 12:30 AM Flag Quote & Reply

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