Active tone controls create a pretty hot signal and most guitar players love the full, mean and nasty range of sounds provided by active electronics such as the Eric Clapton Stratocaster Custom Shop Guitar. What is the difference you ask? To explain it in terms you understand without over simplifying the answer consider this:

In a passive circuit the crude signal generated by the guitars pickups is then filtered through capacitors and variable resistors eliminating unwanted frequencies. Therefore, when you turn the tone control counterclockwise you are removing a large amount of the high frequencies that are part of your overall sound (partials and harmonics). Sometimes a bleed capacitor can be used on the volume pot and it will help allowing the high frequencies at lower volumes, but the bottom line is a passive circuit works by filtering out unwanted frequencies.

An active circuit on the other hand, uses an electronic amplifier and filter system(installed in guitar) to boost or decrease selected frequencies and in most cases increase the output of the pickups, which results in a much taller signal to noise ratio and allows you to hear the harmonics and partials that might normally be lost otherwise. Your guitar amplifier receives a much hotter signal and you have much more control over tone. Active preamps built today are sometimes built right into the pickup itself and if any additional circuitry or switching, etc. is required special components must be used to facilitate the desired changes, and basically the sound they create is the sound you get.

Eric Clapton Custom Shop Fender Stratocaster with Active Circuitry

If you have a guitar with active TBX circuitry, you already know the beauty of having a hi-tech system such as this. The problem then for people with a passive circuitry setup. In a Fender Stratocaster you can use the exact same components they use to upgrade your guitar. The TBX Fender Pre-Amp Mid Boost Kit is perfect, allowing an increase of 25 DB. A complete kit contains the pieces below.
* 1 ea 0028617000 PCB ASSY Clapton Pre amp
* 1 ea 0021682000 Control 50 K Audio
* 1 ea 0028531000 Control 250 K Special Taper
* 3 ea 0016352000 Nut Hex 3/8-32×3/32 TK NI
* 3 ea 0022384000 Washer Lck Intrl 3/8 x .500 x .040 Ni
* 1 ea 0039432000 Jack Output OPN Stereo Urge
* 1 ea 0992052000 TBX Tone Control
* 1 ea 0057578000 Schematic Wiring Diag Mid Boost Circuit
* 1 ea 9903320000 Bag Zip Poly 10×13 2m

Many brands of guitars use active circuitry. I tend not to mess around with a system I like as much as a miner likes gold. If you have a different brand of guitar there are many places and styles of modified setups and kits for the other brands of guitars and personal needs.

Since my focus is on the Fender Stratocaster, my un-biased and the only choice for a Fender Guitar would come from the manufacturer of that guitar. Fortunately, Fender makes a Pre-Amp Mid Boost Kit 25 DB.

Note: This is such a popular upgrade that they are on back-order for a short period.

Obviously an Eric Clapton Custom Shop Guitar is a world class instrument and hard to match in any category. It’s also expensive. Personally, I have more than one Strat. My Mexican Strat featured, in an article on Strat upgrades, does not have an active circuit yet, I will use the EMG/SPC active circuit kit. I don’t hear the same full rich adjustable tones that come out of my Clapton Strat. I recommend reading that article since it goes into the virtues of upgrading a Mexican Strat, turning it into a great playing guitar on a budget. Honestly, getting it set-up by a luthier makes it extraordinarily enjoyable to play and doing the mods in the article are wonderful effective vibes, but adding an active circuit system is my next mod. and I can’t wait to report the results to you.

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5 Responses to Active Guitar Tone Controls or TBX Boost as in The Eric Clapton Strat.

  1. Never fully understood the difference between active and passive circuits. Thanks for the lesson!!

  2. I agree with JW. This article really clarifies some stuff about circuits for me. Nice photo of Bliss and Jimi!

  3. I’ve heard these guitars and they do sound great.

  4. Good information, thanks for sharing! I knew about this but your article clears some things for me.

  5. Hey’ Great article.
    I just installed a TBX Mid Boost kit in a Squire Strat and what a difference. The only thing is when you turn up the tone that would be in the Bridge & Mid you lose the high frequency. I guess that’s why they call it a mid boost.
    But it still does sound Great and it was a lot of work cutting for the circuit board and the stacked pot.
    But it was worth it love it.

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