Note: I may be able to send out one of these immediately, but more often, I'll need anywhere from three to five days to assemble and test one. See the 'Ordering' page on the thaudio.com website for details.
The TH Audio N Boost is a Germanium treble/mid/bass booster with variable input voicing.
If you've never used a treble booster before, the idea is that it overdrives overdrive, specifically, by cooking the higher frequencies. In the 1960s and 1970s, guitarists started using treble boosters to brighten up darker-sounding guitar amplifiers and cut through a mix when needed.
Like most treble-boost units, the TH Audio N Boost uses a Germanium transistor, because Silicon transistors usually aren't nice in this context. The type of transistor varies, but it's usually a 2N388 or an OC140 if available. Each unit is biased, tested, and auditioned against a super-secret, invisible reference unit locked in a vault inside a fortress underneath a volcano guarded by gigantic mutant sharks.
Controls
Black knob Referring to the photos above, it's pretty obvious what the big chickenhead knob in the middle does: it controls the amount of gain. Actually, technically, it controls the output volume... which isn't really the same thing, but... hey lookit that bird!
Treble and Mid switches These three-position switches control the input voicing, in other words, the frequency range that is allowed through the circuit. A narrower frequency range will sound more 'treble-y' and a broader frequency range will sound more 'midrange-y'.
Treble middle / Mid middle: the most treble-y sound
Treble left / Mid middle: slightly more mid... can be hard to hear a difference
Treble right / Mid middle: noticeably more mid
Treble middle / Mid left: midrange-y
Treble middle / Mid right: very midrange-y and maybe even bass-y
Adding in Treble left/right with the Mid left or right positions can add slightly more of a midrange response.
By the way, the video shows what happens when the knobs are twiddled.
Tweakability
First of all, the N Boost arrives set up and ready to plug in. No assembly required.
But maybe you're a nerd and you want to swap out the transistor, you nerd. If you haven't already, you might want to read two articles on the GEOFex website:
Austin Treble Blaster: A Workalike of the Original Dallas Rangemaster by R.G. Keen
Picking Transistors for FF Clones by R.G. Keen
Referring to the closeup of the circuit board in the image gallery: at the top left of the circuit board, you'll see a trimpot (A). That is for biasing whatever transistor sitting in the socket (B). You'll also notice two small solder points on the circuit board (C) marked 'M' and 'MG'. Those points for measuring voltage and resistance with a multimeter.
- MG is ground (negative, since the transistor is NPN, not PNP).
- M measures at the collector of the transistor.
The N Boost ships with settings that are more or less compliant with the ones in Keen's Rangemaster article, calibrated thusly:
- With a transistor in the socket and power to the unit, the trimpot is adjusted until voltage between M and MG (ground) reads between 6.6 and 7.2 VDC.
- Unit is auditioned with a Fender Telecaster and a Gisbon Les Paul through a Dr. Z Jetta head into a Dr. Z 1x12" cabinet. Sometimes, minor adjustments to the trimpot are made.
If you want to replace the stock Germanium transistor with one of your own, just remove it (carefully, with audio and power jacks disconnected), put in another transistor, bust out a multimeter, and do steps 1 and 2 above (with your own choice of instrument and amp, of course).
Or you could just plug in the pedal and play guitar, you nerd.
For the N Boost, TH Audio likes low-leakage Germanium transistors with gains in the 60-70 range or sometimes a little higher. Some people like slightly lower gain, for less frying.
Note: The N Boost uses NPN transistors, not PNP. Both of the R. G. Keen articles referenced on this page emphasize PNP but do briefly discuss how to reorient for NPN (just flip everything over).
The N Boost features:
- True bypass switching
- Hammond enclosure
- Metal film resistors, 1% tolerance
- Mallory film capacitors
- Switchcraft jacks
- Heat-treated silkscreened graphics
All TH Audio pedals are handbuilt and tested in the United States of America.
