BSIAB2 output question

[Govmnt_Lacky]

Has anyone figured out a way to get an output from the BSIAB2 without having to adjust the Volume AND Gain settings?

Could I just put a resistor from Lug 3 of the Gain pot to ground so that I would get an output with the Gain pot at minimum and ONLY adjusting the Volume?

[darron]

i'm still confused (:

[Ice-9]

Has anyone figured out a way to get an output from the BSIAB2 without having to adjust the Volume AND Gain settings?

Could I just put a resistor from Lug 3 of the Gain pot to ground so that I would get an output with the Gain pot at minimum and ONLY adjusting the Volume?

yes you could put a resistor to ground from the gain pot, the size of the resistor will alter the gain at minimum (gain pot) redistance. I have 1 of mine set up like this so that if i turn the gain right down i still have about the same amount of volume at the output as i would if it was ib bypass (output pot at full). try experimenting with different size resistors to get the results you want. 10K is a good starting place.

[Govmnt_Lacky]

I have 1 of mine set up like this so that if i turn the gain right down i still have about the same amount of volume at the output as i would if it was ib bypass (output pot at full).

This confuses me. What do you mean by " the same amount of volume at the output as i would if it was in bypass?" Does this mean with the Gain all the way down, and the volume all the way up, you pass a unity signal?    So your pedal provides no volume boost beyond unity?

[Ice-9]

Only when the gain is at minimum. When the gain pot is turned up you get normal volume and gain increases. just try it and you will see what it does, mess with different value rsistors until it suits your  needs.. Basically all you would be doing with the resistor you mention is not allowing the gain pot to reach 0 resistance thus providing a little gain at minimum pot setting.

[Govmnt_Lacky]

Only when the gain is at minimum. When the gain pot is turned up you get normal volume and gain increases. just try it and you will see what it does, mess with different value rsistors until it suits your  needs.. Basically all you would be doing with the resistor you mention is not allowing the gain pot to reach 0 resistance thus providing a little gain at minimum pot setting.

Ok. I dont think that is what I am looking for. When I turn the Gain pot, I DO NOT want a volume increase. I only want the Gain too change. The way my BSIAB2 works (and others as I have read), is that the Volume goes up as the Gain knob is turned. A minimum volume increase (as with most other OD/Distortion pedals) is OK but, when you turn the Gain on this beast..... the volume goes WAY UP! 

[ayayay!]

Can you link to your schem, please? 

[Govmnt_Lacky]

Can you link to your schem, please? 

Sure... Its the GGG schemo. 

http://www.generalguitargadgets.com/pdf/ggg_bsiab2_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

I did include the Contour mod. This entailed swapping R7 with a 5K6 resistor in series with a 100K pot.

Apparently, this is a common "problem" in the BSIAB2. Lots of volume increase when you crank the Gain pot.

[Ice-9]

All overdrive/ distortion pedals increase the volume if the gain pot is increased, some more than others. The BSIAB is a really high gain circuit to start with so it will be more obvious.
Sorry if this isn't really answering you question properly.

[Govmnt_Lacky]

All overdrive/ distortion pedals increase the volume if the gain pot is increased, some more than others. The BSIAB is a really high gain circuit to start with so it will be more obvious.
Sorry if this isn't really answering you question properly.

No worries!  I think I may have stated my original question badly. Here goes again:

When I have the Gain at minimum (or off), as I adjust the Volume pot I get NO OUTPUT. Only when I adjust BOTH pots do I finally get an output. Is there a way to get an output by ONLY adjusting the Volume?

[ayayay!]

When I have the Gain at minimum (or off), as I adjust the Volume pot I get NO OUTPUT

Well, yeah because when it's turned all the way down, even though you have your signal hitting C6, you're still shunting the signal to ground.  This is a very basic way to run it.  Adding a couple parts should get you 90% to all the way of what you're wanting.  

If it were me, I'd take a look at some other schems of your favorite OD's & Distortion's and see how they have their gain pots and nearby resistors and caps set up.  This isn't in a feeback loop, so look at some designs like it.  ROG's Double D for example.   

[Ed G.]

Not sure why people ask for this mod. As far as I know, no one adds a resistor to the gain knob of a Marshall to do the same thing.
The BSIAB is not a tube screamer, it is more like a Marshall preamp with cascading gain stages and a pot wired as a voltage divider in between stages. As you increase gain, volume does increase. All similar circuits do this.

[Govmnt_Lacky]

Not sure why people ask for this mod. As far as I know, no one adds a resistor to the gain knob of a Marshall to do the same thing.
The BSIAB is not a tube screamer, it is more like a Marshall preamp with cascading gain stages and a pot wired as a voltage divider in between stages. As you increase gain, volume does increase. All similar circuits do this.

Thanks Ed. I know the BSIAB is a fantastic circuit. My only question is whether there is a way to pass a signal WITHOUT having to adjust BOTH the Volume and the Gain. Setting both of these pots to minimum and jacking in, I would like to be able to ONLY turn up the volume and still get a signal (all be it with minimum distortion/overdrive.)

As the signal works now, that cannot be done. That is why I am asking if putting a resistor between Lug 3 of the Gain pot and ground will solve this.

Thanks for everyones help. 

[ayayay!]

Not sure why people ask for this mod. As far as I know, no one adds a resistor to the gain knob of a Marshall to do the same thing.
The BSIAB is not a tube screamer, it is more like a Marshall preamp with cascading gain stages and a pot wired as a voltage divider in between stages. As you increase gain, volume does increase. All similar circuits do this.

With all due respect Ed, it's because this is not a Marshall amplifier that he's requesting this.  It's a pedal, not an amp, so it's not behaving like a typical preamp/amplifier in pedal form.  Volume doesn't increase on, say, a Dr. Boogey when the gain is turned up.  (It doesn't on mine at least)  And that's based off of a preamp w/ cascading gain stages. 

I think it's just interactivity that Govmnt_Lacky is trying to avoid.  Personally (and don't take this the wrong way please, Mr. G) I don't think it's too much to ask for the guy to do this one mod.  I don't think he wants you to change your process at all.  Yet I'm with this guy all the way:  If I tweak my gain on any pedal, I don't want to have to tweak the volume to correct the gain.   I know what you're saying, the circuit is what it is.  And if you changed the design so the gain wouldn't affect output volume, someone else may cry foul.

He's just looking for a simple mod. 

[John Lyons]

You have to look at the circuit though.
The BSIAB has two stages basically with a voltage divider between them.
(the third stage is volume recovery for the most part)
Turn down the first stage and it's going to affect the volume.
With the Dr Boogie you have 4 gain stages after the gain pot
so it's not going to make much difference in level. There is
so much saturation going on in that one that it mainy "de-saturates"
Notice how the Boogie still is pretty gainy even when turned down
compared to the BSIAB which cleans up a good bit more.

I don't really see an issue with the BSIAB. it's just how it is, nothing
you can do about it. It's got a good amount of gain but it's not as saturated so
it cleans up in volume as well as gain/distortion easier which is typical for
a lower parts count circuit of it's type.

[Ed G.]

Even though it is a pedal, it is still closer in form to the preamp section of an amp.
When the gain is down that low, there is not much saturation (and compression) going on, as John pointed out.
But crank the gain up to 50 percent. Then dime it. Not much volume change there because at 50 percent gain the jfets are starting to saturate and more gain just results in more distortion but not much more volume if any at all.
I have a 50 watt plexi clone with a post phase inverter master volume and the same thing happens. Set the amp clean and start to turn up the gain. The amp gets louder until it starts to get overdriven. Then past that point it just gets dirtier, not louder.
Possibly try some lower gain jfets like the mpf102 in q1 and q2. And maybe 2n5457 in q3 and q4. People who like to get cleaner more dynamic sounds like those fets there. Not sure if that will give you what youre looking for but it should give you more range to play with, so you don't have to turn the gain pot down so low. Just something to try.