Brian May Treble Boost

[Khas Evets]

I just breadboarded a BMTB and it sounds great. I find that it works very nicely with a high output humbucker, but is a little weak with my jazzmaster and strat. I want to add two controls to give more flexibility, gain and tone.

I would like to increase the gain, which I believe can be accomplished by increasing the value of R7 (or using a pot). What's the largest value that can be used before the sound starts to degrade? Also if I use a pot, should I connect the wiper to the output (making it a voltage divider) or set up the pot as a variable resistor replacing R7? Is there a higher gain transistor that may sound better than the BC182L?

As far as the tone control is concerned, I've experimented with different values for C2. While I prefer the default value, I like having some flexibility in the tone control. At first I thought about making R1 a variable resistor, but I think this disrupts the voltage divider with R3. So my next thought is to do a varitone (multiselect various caps for C2). The question I have is whether C2 is the only cap I need to consider for tonal control? Does C5 affect the tone? Should I adjust both caps together (i.e. .0047/.047 to .01/.1)?

[Alpha579]

Making R7 larger isnt the best idea...it will offset the bias, causing a gating effect if made to large. What is the collecter voltage? If it is more than 4.5v you could increase it and it would have more gain/more bias swing. Changing C2 will affect the volume as well as low end. Making it larger may overload the booster, causing distortion... Changing C5 will affect output as well as low end...

[Khas Evets]

I tried adding a 10K pot in addition to R7 last night, and you're right, it causes gating in the upper range of the pot. I also tried using only the 10K pot set up as a voltage divider and that seemed to work a little better.

I measured the collector at both 6.8K and 10K for R7 and it read 4.5v at 6.8K and 3.4v at 10K.

[Gilles C]

A Treble Booster has been in my projects list for the last 3-4 years at least, and every time I decide to build one, I find another circuit to build for some obscure reason...

Now, before I finally build one, I was wondering if adding a buffer would affect the way it sounds. Like a Fuzz Face for example that I think prefers a low impedance input.

Thanks

Gilles

[Steben]

A Treble Booster has been in my projects list for the last 3-4 years at least, and every time I decide to build one, I find another circuit to build for some obscure reason...

Now, before I finally build one, I was wondering if adding a buffer would affect the way it sounds. Like a Fuzz Face for example that I think prefers a low impedance input.

Thanks

Gilles

Well, with a low input impedance (with buffer) you will have less treble cut in the FF and Booster. But actually, the treble-cut in FF's is what most people like about the little wonder. With a buffer, you make it more like a distortion which, for some, could be nice.

[Torchy]

crp

[Doug_H]

a;lkj

[Gus]

Make R3 a 47K in series with a 100k linear pot(the pot wired as a 0 ohm to 100K variable resitor)


Have FUN !!!!!!!

[Alpha579]

Gus, that would affect the bias of the circuit, but as far as i can tell fro the collector readings, its biased into its most linear regon, so why would that help? i think that without biasing problems, or a complete circuit makeover, thats the most gain you'll get out of that circuit with a sweet sound...

[Doug_H]

a;lkjd

[Khas Evets]

Thanks for the great advice. I'm going to hit the breadboard tonight.

Doug_H, could you explain "blooming" a little further. It sounds like an interesting option. Also, I think I agree with you that changing the transistor, while increasing gain, will have negative effect on the sound. I may try it anyway.

I tried this circuit with my Jazzmaster and a SHO in front of it, and it was too crisp. My guess it something like the AMZ Mini Booster would work better.

[Torchy]

crp

[mlabbee]

I've compared the BC182 and the 2n222 and prefer the 2n222 for two reasons - first, the 2n222 gives much better gain; second, teh BC182 has a weird effect on very high notes - some unpleasant distortion that sounds almost like an octaving efect is going on, but not as nice. Overall, teh 2n222 seems to give a nicer, rounder tone, while still boosting the treble quite nicely.  I'd be curious to hear if you agree or have different feelings about the sounds in comparison.

[Alpha579]

i own a crispy cream treble booster. which is basically a copy of the brian may booster, and it has the BC182 trany in it. Sounds great, low noise, and has this really cool nasally sound that other treble boosters dont do...heaven when you crank it through a valve amp...

[Khas Evets]

Are there any differences between the Crispy Cream schematic and the one above?

[mlabbee]

Does the crispy cream get really brittle/papery sounding as you go higher  up the neck?  Also, the gain on the BC182 is really, really low compared to the 2n222, but the specs on the datasheets aren't that different (2n222 has a little higher gain, but not by a huge amount). Any thoughts?

[Alpha579]

No, the CCTB sounds great as you go up the neck...I looked at the circuit last night, and i found it differs from the original that instead of the 6.8K resistor on the collecter, theres a 10K pot to control output level. This might help with the gain problem....

[Doug_H]

a;lkjd

[Doug_H]

a;lkjd

[mlabbee]

One real nice transistor is the motorola metal can 2n2222. It sounds better than the RS plastic one to my ears. Have not tried it in the BMB but I used it in my axis fuzz and it is very smooth. Ammscray suggested this one a few years ago IIRC.

I'm using the metal can one - just happened to be the one I had lying around. Serendipity, I guess.  It really does sound good.