BluesBreaker Prob: Gain Adjustment = Massive Volume Adjustment

[railhead]

I've been goofing with the BluesBreaker circuit over at GGG, and I really love the sound -- but there's a quirk that gets on my nerves: when you adjust the gain, it has a massive impact on the overall volume. I mean massive in the sense if I have the gain at 50% and roll it to 80%, I have to crank back on the volume big-time to try and get the volume set again. I know more gain = pushing the output, but none of the other dist/od circuits I've built (or bought) exhibit such a massive reaction.

Is there something I can do to keep the gain amount from impacting the overall volume so much? Is my question making any sense?

TIA!

[d95err]

Not what you wanted to hear, but - it seems like perfectly normal behavior for any distorsion pedal or amp.

[railhead]

Right, but like I said, this is more pronounced than others. For example, my BSIABII clone doesn't exhibit this behavior this bad at all, and it's  much higher gain unit.

[Zben3129]

+1, I am having the same issue

I have been trying to find a solution, but as of yet, I have not come up with one 

I wonder if the stock pedal does this?

We need to find some way to control the 2 somewhat inversely

Also, do you know of where to get a vero layout of this, I have 2 on PCB but I want a 3rd and dont wanna pay another 14 bucks.

[d95err]

The higher the gain (distortion), the less volume increase you'll get when you bring the gain up. A heavily distorted sound is so compressed it can't increase in volume any more. A low gain sound still has a little bit to go before it reaches full volume.

The BSIABII and Blues Breaker are very different designs, so it's possible they react quite differently to gain changes. My Tube Screamer clone on the other hand is fairly similar to the Blues Breaker (opamp diode clipper, low gain) reacts like you describe. If you turn the gain down, you'll have to crank the volume all the way up to get some boost.

If you want to experiment with volume compensation, try a dual 100k pot for Gain, and put the second half in series with the volume pot (so when gain goes up, volume goes down a bit).

[railhead]

Ahh, good idea with the dual pot...

[John Lyons]

Side note:
You don't need so much a solution as to understand what's going on. Although it may lead to you a fun and useful modification (er...solution)
Since the gain of the BB is not so high and the diodes are doubled up in that circuit, the gain control passes some straight volume as well as crunch. With the extra diodes come less compression and a higher threshold. Diodes limit the volume of a stage. Adding a diode in series (in each direction, 4 diodes instead or 2) will lessen the clipping, which will have less compression...which will have more volume when you crank it up.

Heavy distorters or circuits with diodes to ground (in in each direction) will keep there relative volume better because the diodes are limiting the volume boost when the gain is turned up. Adding more diodes in series will raise this threshold.

This is the same theory as using a rangemaster or boosterwith a semi distorted amp vs a clean amp.
The clean amp will just jump up in volume while the amp on the edge of distortion will compress with the gain boost and the volume will stay roughly the same as the gain/distortion/overdrive kicks in with the boost turned on.

Check out the simple tips and mods section in the FAQ, lots of nice tid-bits in there.

John

[frankclarke]

You could call it a feature, and have a DPDT boost switch to up the gain and down the volume if needs be.

[Zben3129]

good ideas. On a side note, does anyone know of a vero layout for this? I really love the sound but can't do any more perfs