Treble-booster clone

[C Bradley]

I wired up a treble-booster from the Brian May boost schematic on Geofex using a 2N3906 transistor. I used the same cap values, but eliminated the 1n, the 120k, and the 1k resistor, as well as the power supply filter ( this was on breadboard).

Is this supposed to have a nasal tone to it? It sounds kind of like a wah pedal stuck at a certain position.

[vortex]

I am sure that the circuit uses a NPN transistor. Try a 2N3904. :oops:

It sounds similar to other treble boosters. Use it with a tube amp set to breakup or drive an OD with it. I built one this week and have a .005uF input cap in mine. I'm thinking I might increase it to .0068uF.

I think the BM boost is a good circuit and am going to tweak it a bit more.  However I am happier with the Rangemasters I have been building of late.  

[vortex]

Maybe toss that 1K back in the circuit too...

[C Bradley]

I did remember to reverse the 9V connections and the 47uF cap, so it wasn't a polarity problem. I tried it in front of my JCM 800 clone, both in the clean channel and on the high-gain channel. It sounds pretty good on the high-gain channel but it still has that nasal sound. I might try it with a 2N2222 and see what I get.

I simulated the circuit on my computer and can't see that the 1k, 120k, and 1n make any difference in the circuit.

[Doug_H]

Is this supposed to have a nasal tone to it? It sounds kind of like a wah pedal stuck at a certain position.

That's the sound, pretty much.

Doug

[spudulike]

Use a BC182L  :wink:

[C Bradley]

I tried the 2N2222 and got pretty much the same results. I'm going to build it with what I've got on hand, which is pretty much just 2n3906 and 2n2222 transistors, or what I've salvaged out of old audio devices.

[Doug_H]

I tried the 2N2222 and got pretty much the same results. I'm going to build it with what I've got on hand, which is pretty much just 2n3906 and 2n2222 transistors, or what I've salvaged out of old audio devices.

2n2222's sound really nice in a lot of these kinds of circuits. I esp like the motorola's (metal can). One of my favorite npn's.

Doug

[Stevo]

Seems like it calls for a 100-300 hfe transistor A 2n3906 is at the low end of the gain scale maybe try a higher gain transistor.......What would a 2n 5088 with up to 900 hfe sound like in there....I know that these transistors can really sock it to you with just one....I did an experiment with a 2n5089 almost the same..did like a lpb-1 with one man it is like a sustain circuit with a lot of noise though...

[MjS]

I simulated the circuit on my computer and can't see that the 1k, 120k, and 1n make any difference in the circuit.

What program do you use for that? Is there any freeware software that can do that?

[Khas Evets]

I simulated the circuit on my computer and can't see that the 1k, 120k, and 1n make any difference in the circuit.

The 1n creates the bootstrap. Search the forums if you're not familiar with it. It raises input impedance.

Removing the 120k pull down resistor is O.K. if you don't mind pops when you switch. Removing it will slightly increase the input impedance, but the bootstrap has a more significant effect on impedance.

I've also wondered if the 1k does anything, besides slight attenuation of the signal.

Input impedance is one area my spice sim falls short. I'm using LT Spice.

[C Bradley]

I'm using the student version of Circuit Maker, which I got when I bought a text book on digital electronics. There are several student versions of PSpice available for download from university websites.