Question for BSIAB and Thor builders

[caspercody]

I just built the BSIAB2, and Thor and both work great. Just one question for those that have one, when you turn the gain to zero (on both) do you get no sound?

Thanks

[Ice-9]

thats correct with the way the gain pot works, one of the mods i made to the BSIAB is to place a resitor in series with the gain pot (from ground to the pot end that would usually connect to ground) this means that when the pot is turned fully ccw the centre lug doesn't go directly to ground but instead has whatever value resistor you put there allowing some signal through. Experiment with values that suit what you want. ie on my cirrcuit 100k resistor and the gain pot to min gives me a slight bit gain more than bypass.

[caspercody]

Thanks, I will try this. Is this for both pedals?

[B Tremblay]

Yes, for the Thor, place a 100k resistor between lug 1 of the Gain pot and ground.

[caspercody]

Thanks, I will try this for both pedals this weekend.

[Thomeeque]

 Hi!

By putting 100k there, you will loose almost half of Thor's original range (your minimal gain will act like 12 o'clock gain before)*. I'd advice you to use much lower value, like 10k (or set pot without mod to value where you want it's new range to start, measure central lug to ground lug resistance and use this value for the resistor**).

For BSIAB2 you would loose even more, since there is 500k/LOG pot.

T.

*1M/LOG pot is on 100k in half of it's range - check commercial log pot curve here.
** it's a little approximation (since final divider ratio will change a bit after putting resistor there), but you can ignore it IMO.

[liquids]

Yeah, something from as low as you can find it, say, 47R or 100R, and probably not higher than 1k here would be a better solution depending on your favored range for how you set that pot.  All you want is for it to not 'shut off' on minimum setting, so a very small resistor will do.  100k is a bad idea if you're not looking for a radical mod.

[MikeH]

My rule of thumb for this sort of mod is 10%.  If the gain pot is 100K I go with a 10K, if it's 1M I go 100K, etc.

[dschwartz]

another solution is not using the pot on zero.

[slacker]

That's what I thought as well, just don't turn it all the way down, problem solved.
The same thing would happen on a real Marshall amp, so you could just say it's Runoffgroove making an accurate simulation

[waltk]

I use a resistor as described in other posts.  On my last BSIAB2 build, it worked out to be 2.7k.  You can pick the level YOU want by temporarily inserting a trimpot (maybe a 5k multi-turn), adjust it to taste, then measure and replace it with a resistor.  ...or just adjust the real pot drive/gain pot to the value you would like to have as a minimum volume, measure, and put in a resistor of that value.

[Ed G.]

I've never really understood why this seems problematic for some guitarists, because the gain control on the bsiab works exactly like the gain control on an amp (or volume on a guitar, for that matter) and when you turn it all the way down, what do you expect? I rarely play with the drive that low anyway.

[MikeH]

another solution is not using the pot on zero.

Patient: "Doctor, whenever I move my arm like this it really hurts".
Doctor: "Well, don't move your arm like that".

[caspercody]

Thanks for all the replies! I was not able to try it this weekend, and now reading more I am not going to bother.

I just wanted to make sure that they were working the way they were suppose to, that turning it to zero and getting no sound was the way it was designed.

[waltk]

I've never really understood why this seems problematic for some guitarists, because the gain control on the bsiab works exactly like the gain control on an amp (or volume on a guitar, for that matter) and when you turn it all the way down, what do you expect? I rarely play with the drive that low anyway.

Ed - First let me grovel a bit (I'm not worthy )... The BSIAB2 is by far the best OD/distortion I've ever heard.  You have my sincerest thanks for creating and sharing it.

It's not so much that the way the stock gain knob works is a problem - it is DOES work exactly like the gain knobs on the amps I'm familiar with.  I guess I just would rather think of gain as something that is added to the original signal, so that when you turn down the gain all the way, you are left with your original signal (not left without any signal).

[philbinator1]

Wouldn't that be called something like parallel distortion or something?  Like the way some compressors
have a 'blend' knob which controls parallel compression...?  I think the Voodoo labs Sparkle Drive uses that.

[oldrocker]

They're both reading this thread?  B Treblay and Ed G......thanks for the great designs.  You guys rock.