Burns treble boost schematic

[taku0319]

recently I acquired this pedal and traced circuit.
different from other boost circuit and sounds quite good.

[kaycee]

Thats a very nice looking unit. Runs at 18 volts?

[taku0319]

yes, originally this unit is calibrate by V.T 4 battery x 2. which means 18v I think.

Here is a quote from Beat Instrumental in August 1965

"In the past, the general idea of a treble booster was obtained by cutting the bass in half, and giving the treble more volume. Burns, however, have developed a new principle which leaves the bass exactly as it should be, and just boosts the treble. The sound is really fantastic. It is run from two V.T.4 batteries, which will last for a year. The surface noise is practically non-existent, and the whole unit costs 6 gns."

[PRR]

[pacealot]

Just wanted to revive this thread to say that I breadboarded this circuit, and it's really quite good — does exactly what it says on the tin, as it were. It doesn't provide much of an overall level boost if at all, but the pot gives a very nice and useful range of treble cut and boost. I played with the voltage dividers at the base and with the pot value, with equally good results either way (I ended up with 470K/68K on the base instead of 100K/33K, and I found a 5K linear pot worked best for the boost control, but stock was very similar as well, with just more treble cut with the 10K pot).

It's very clean (depending on transistor choice), unlike my experiences with Rangemaster types. I tried it with an OC71 (hFE ~95, leakage ~240µA) which I had squirrelled away for future RM experiments, and with an NKT212 I had left over from a Buzzaround build (hFE~50, leakage ~120µA), and the NKT212 was significantly less noisy and seemed to provide just as much boost, so I think it's getting the nod here. I primarily ran it at -18V as indicated, although it also worked well at -9V, with perhaps a slightly reduced peak at maximum boost (which may be a good thing, as full-on at full voltage gets a smidge icepick-y).

Anyhoo, anyone looking for a more controlled/controllable Ge treble boost might benefit from giving this one a shot...

[nightraven]

I've played two original Burns TBs over the years (and still own one of them), and the circuit is very lacking in the 'boost' department. Both of the ones I've played didn't even go above unity gain. They were both pretty useless when running at the full 18v, but I was able to get some crude distortion sounds from running it at only 9v.

[pacealot]

Thanks for that confirmation that the originals also didn't get above unity. It definitely doesn't function anything like a Rangemaster or any of the other common treble boosters!

I do still find it a very useful tone control, though — it might make a nice alternative to something like the Big Muff tone control stage for some top-heavy fuzzes. I shall continue to play with it in various contexts and see...

[iainpunk]

i think its a bit like the VOX directly in to the guitar plug boosters (bass and treble units) that were designed with unity volume in mind as to not overdrive the amps used.

the distortion booster is the oldest version of what we call a fuzz face, the middle two boosters were near unity gain EQs (less than 3dB of boost) and the bottom one is unfamiliar to me.

cheers

[pacealot]

The Ge version of that Distortion Booster circuit is another one of my favourites as well (albeit in a well-tweaked form). It makes a great template for a lower-gain, thinner fuzz with some very musical gating to it, particularly with lower hFE germ trannies (I used ACY50s that I think were around 30-35 hFE and low-ish-to-medium leakage).

You can squeeze some extra output from it, but I prefer it to only kick over unity enough to not appear to have a drop (the iteration I built is more aggressively high-passed at the front end than stock). Again it comes down to personal preference and whether pushing the front end of one's amp harder is integral to how one uses fuzz and/or boost...

[Electric Warrior]

i think its a bit like the VOX directly in to the guitar plug boosters (bass and treble units) that were designed with unity volume in mind as to not overdrive the amps used.

the distortion booster is the oldest version of what we call a fuzz face, the middle two boosters were near unity gain EQs (less than 3dB of boost) and the bottom one is unfamiliar to me.

cheers

The early Distortion Boosters were actually based on the FZ-1. Not sure if they released the fuzz-face-ish versions before or after the Tone Bender MK1.5 hit the market.



They tweaked the circuits for the american versions of the boosters, so I guess the british made versions with germanium transistors may have a little more boost?

[pacealot]

That 330K connecting the collectors is a unique wrinkle — I don't have enough EE understanding to know what role it's playing here, but I assumed it was part of what made this circuit behave differently from an FZ-1/Mk I-type... (feedback? maybe positive feedback???)

Where I modified my version was in the ratio of the 1K/33K resistors between Q2C, -9V and the output cap — I raised the 1K significantly to increase the output (I think to 3.6K, if I recall correctly) and subbed in a 25K pot with (I believe) a 15K series resistor, in order to adjust the bias and control the gating to taste. Worked a treat...