This month’s mod Dan’s uses a 500k linear pot, a 1.5H inductor (L) with a 0.039 µF (39nF) cap (C), and a 220k resistor (R) in parallel.
Don’t let the name fool you, this is a purely passive device—nothing is going to be boosted. In general, you can’t increase anything with passive electronics that isn’t already there. Period. But you can reshape the tone by deemphasizing certain frequencies and making others more prominent (so … “boost” in guitar marketing language). Removing highs makes lows more apparent, and vice versa. In addition, the use of inductors (which create the magnetic field in a guitar circuit) and capacitors will create resonant peaks and valleys (bandpasses and notches), further coloring the overall tone. This type of bandpass filter only allows certain frequencies to pass through, while others are blocked, and it all works at unity gain.
“You can’t increase anything with passive electronics that isn’t already there … but you can reshape the tone by deemphasizing certain frequencies and making others more prominent.”
All the systems I mentioned above are doing more or less the same thing, using different approaches and slightly different component values. They are all meant to be updated tone controls. Our common tone circuit is usually a variable low-pass filter (aka treble-cut filter), which only allows the low frequencies to pass through, while the high frequencies get sent to ground via the tone cap. Most of these systems are LCR networks, which means that there is not only a capacitor (C), like on our standard tone controls, but also an inductor (L) and a resistor (R).
In general, all these systems are meant to control the midrange in order to scoop the mids, creating a mid-cut. This can be a cool sounding option, e.g. on a Strat for that mid-scooped neck and middle tone.
Dan Torres offered his “midrange kit” via an internet shop that is no longer online, same with his business website. The Torres design is a typical LCR network and looks like the illustration at the top of this column.
Dan’s design uses a 500k linear pot, a 1.5H inductor (L) with a 0.039 µF (39nF) cap (C), and a 220k resistor (R) in parallel. Let’s break down the parts piece by piece:
Any 500k linear pot will do the trick, in one of the rare scenarios where a linear pot works better in a passive guitar system than an audio pot.
(C) 0.039µF cap: This is kind of an odd value. Keeping production tolerances of up to 20 percent in mind, any value that is close will do, so you can use any small cap you want for this. I would prefer a small metallized film cap, and any voltage rating will do. If you want to stay as close as possible to the original design, use any 0.039 µF low-tolerance film cap.
(L) 1.5H inductor: The original design uses a Xicon 42TL021 inductor, which is easy to find and fairly priced. This one is also used in the Bill Lawrence Q-Filter design, the Gibson standard Varitone, and many other systems like this. It’s very small, so it will fit in virtually every electronic compartment of a guitar. It has a frequency range of 300 Hz up to 3.4 kHz, with a primary impedance of 4k ohms (that’s the one we want to use) and a secondary impedance of 600 ohms. Snip off the three secondary leads and the center tap of the primary side and use the two remaining outer primary leads; the primary side is marked with a “P.” On the pic, you can see the two leads you need marked in red, all other leads can be snipped off. You can connect the two remaining leads to the pot either way; it doesn’t matter which of them is going to ground when using it this way.
Drawing courtesy of singlecoil.com
(R) 220k: use a small axial metal film resistor (0.25 W), which is easy to find and is the quasi-standard.
Other designs use slightly different part values—the Bill Lawrence Q-filter has a 1.8H L, 0.02 µF C and 8k R, while the old RA Gresco Tone Qube from the ’80s has a 1.5H L, 0.0033 µF C, and a 180k R, so this is a wide field for experimentation to tweak it for your personal tone.
This mid-cut system can be put into any electric guitar not only as a master tone, but also together with a regular tone control or something like the Fender Greasebucket, or it can be assigned only to a certain pickup. It can be a great way to enhance your sonic palette, so give it a try.
That’s it! Next month, we’ll take a deeper look into how to fight feedback on a Telecaster. It’s a common issue, so stay tuned!
Until then ... keep on modding!
Jeff Kollman is a lifelong gigging guitarist whose resume stretches from Deep Purple’s Glenn Hughes to Chad Smith’s Bombastic Meatbats. Since 2017, he’s been performing with famed engineer, producer, and songwriter Alan Parsons, who worked on Abbey Road, Dark Side of the Moon, and a host of other records that you’ve probably owned for decades. It should come as no surprise, then, that as a member of the Alan Parsons Project, Kollman’s gig is to sound great. And he does so with a quick-and-easy rig.
After getting into Nashville’s Ryman Auditorium from a sweaty gig from the night before in Georgia, the band got set up and PG’s John Bohlinger rolled in to catch up with Kollman about his simple road setup.
Brought to you by D’Addario.
Inspiring and Practical
Kollman has a pair of No. 1’s he takes on the road. The first is this all-stock SG Faded Special he picked up used for $560, which he points out is “really resonant” and “really woody,” with great sustain. “It inspires me,” he says, “and it’s inspiring, I think, to kids to know they don’t have to spend five grand on a guitar.”
The SG stays in Kollman’s drop tuning with the low E dropped to C and the A dropped to G. He keeps all his guitars strung with Ernie Ball Super Slinkys (.009–.046).
Surfy Strat
Kollman’s other No. 1 is a ’59 reissue Strat from Wildwood Guitars in Colorado. It features a Brazilian rosewood fretboard and John Cruz custom-wound pickups in the neck and middle. The guitarist isn’t entirely sure what humbucker is in the bridge position, but it’s low output, coil tapped, and he loves it. This Strat stays in standard tuning.
A Lucky Les Paul
Kollman received a tip from pal Greg Koch that this Les Paul, from a limited edition run of featherweight LPs built for Wildwood Guitars, is a “tone beast,” so he jumped on it. At 7.98 pounds, it came as advertised. Kollman loaded it up with an original vintage set of PAFs.
Easy Amp Recipe
Since the Parsons Project does lots of fly dates, Kollman needs a tone recipe for an amp he can find anywhere. He requests a Marshall JCM2000, uses both the clean and dirty channels, and says, “I can flop and go in 5 minutes and have my sound,” while showing off the EVH-style dirt and “ethereal cleans” he can dial-up.
Functional and Fun
Kollman rolls with a pair of pedalboards built by Japan’s Free the Tone. The first is his practical board that is loaded up with an Xotic EP Booster, SP Compressor, and a pair of RC Boosters; some signature gear he co-designed with Tim Jauernig that includes his F-Bomb 3, Kollmanation distortion, and a Zhingh-Whundh (which he says is on the down-low currently);
an Ibanez Tube Screamer TS-808, and a Vemuram Jan Ray dirt box. They’re complemented with a Free the Tone Flight Time Digital Delay and Ambi Space Digital Reverb, and it’s all kept in tune with a TC Electronic PolyTune. Kollman only steps on his Free the Tone Direct Volume and his Free the Tone ARC-3 Audio Routing Controller.
His second board is “just toys” and includes a DigiTech Digidelay, a signature Tim Jauernig Bombastortion, another TS808, a Free the Tone Tri Avatar Multi-Dimensional Chorus, Boss OC-2 Octave, an Octavia clone prototype built by Tim Jauernig, a DigiTech EX-7 Expression Factory, and an MXR Custom Audio Electronics buffer.
