I just built a double LPB1- A question about the gain

[audioguy]

I know it sounds like a dumb question... but how can I reduce the gain from the first unit going in to the second? It sounds great, but at the higher volumes it distorts nicely. I dont want to remove too much gain, just take the edge off.

Thanks!

Audio guy

[petemoore]

Does the first LPB have a volume control?

[audioguy]

it does, but it still gets pretty hot and distorts pretty early....

[petemoore]

Try a lower gain transistor for Q1 [or Q2]
 I've never done alot of this so I'm guessing...
 BY fiddling with the Emitter resistance to ground will change the Gain, IIUC the farther you lift it off ground [with a larger resistor] the less positive swing room it has before getting near the top rail or V+...
 I probably already stuck my foot in sombody's mouth...GEO has the articles about setting up gain stages.
 Oh of course...you could limit the input with a  series resistor...the Siliface article at ROG tells of their putting a resistor in front of the FF. Same thing but adjustable on the EZ Face w/ input gain mod. using a  pot.
 Might be interesting, anyone put a 470k with a 470pf paralleled between two LPB's?
 Put some diodes on the end and see if you can get: clipping/gain reduction....wait that's a fuzz box... :roll:

[audioguy]

Maybe I'll try changing Q1- I have some 2n7000's, 3904's, and 5485's... would any of these brig it down?

[B Tremblay]

Try Pete's suggestion of series resistance at the input of the second LPB.

You could use a 50k trimpot wired as a variable resistor.  Turn up the gain all the way, then adjust the trim until the gain is where you want it.  Now the maximum gain will have a preset limit.

[audioguy]

I'll try adding a resistor first then...  What value do you recomend I start with?

[B Tremblay]

Use the trimmer to find the best setting, then (with the power off) measure its resistance.  Then, replace the trimmer with a the closest fixed resistor value.

[audioguy]

Brilliant!

Thank you