Very Simple Gain Question About a (sort of) EHX LPB-1

[Joe Hart]

Just a "yes" or "no" question. I've been messing around with the LPB-1 and was wondering: can it (however madly modified) ever get into DOD 250 territory? I mean, I played with the resistor from the emitter to ground (to increase gain), tried throwing a cap in parallel with it, tried adding soft clipping diodes and hard clipping diodes (like in the Electra Distortion), and played with the input and output caps and it's still very tame.  And the 250 isn't a ton of distortion to start with, but I can't get close.  And before you say, "well, just build a 250," I am actually looking to try something different but in the gain/distortion range of a 250, not replicate a 250.  I wouldn't mind it sounding like my BSM RPA Special Booster! Just slightly more grit. So, again: can a modified (in some way) LPB-1 ever get into DOD 250 territory?
-Joe Hart

[petemoore]

  The gain available with an opamp is more than what 1 transistor can muster.
  Two transistors or more seems to gain up similarly, but it's more parts.
  I'm trying to think of a multiple transistor design for reference with 'to ground clipping'...
  Two stages of BMP clips, but I don't think as fiercely as a '250'.

[Bad Chizzle]

I must agree, I think you need to have two transistors. I've achieved something like you're looking for by putting two Electra circuits together. Leave out the clipping diodes at the end of the first Electra section and boost the gain of the second transistor.You can also change the gain on the first stage for somemore fun results!

Hope this helps!

[Bad Chizzle]

Oh yeah,

Put trim pots from emitters to ground so you can dial in your gain stages!

[R.G.]

Just a "yes" or "no" question. I've been messing around with the LPB-1 and was wondering: can it (however madly modified) ever get into DOD 250 territory?

If I understand your question correctly, no.

Single transistor gain stages have limits on how much gain they can have, and multi-transistor circuits have more ways to make gain. You can limit the output swing with a diode clipper, but the amount of drive before the diodes is still limited.

Then again, "however madly modified" brings to mind the way to fix any car: you jack up the air filter and drive another car under it.

[Bad Chizzle]

@R G

Good one!

I hate to say no to people cause there's always that one guy who takes that old car and makes it do things I didn't think were possible. That's the great thing about building and trying circuits, there may just be some magic somewhere in them there components.
But, in this case, I couldn't see it happening.

[blooze_man]

Try running an lpb-1 straight into another one. I've heard it gets a nice overdrive that way

[Joe Hart]

Then again, "however madly modified" brings to mind the way to fix any car: you jack up the air filter and drive another car under it.

That's what I thought and that's why I decided to stop what I was doing and ask! My RPA sounds similar to a 250 gain-wise and I figured that since Mr. Blackmore has been rumored to use a Hornby Skewes treble booster (transistor circuit) and the Aiwa reel-to-reel reputedly had a transistor booster in it (it may have been more than one transistor, but I doubt it -- too much gain for a mic preamp), maybe I could get something similar (to the RPA) with a single transistor booster. It seems I may get closer with a 250-style circuit. Thanks everyone!
-Joe Hart

[Mark Hammer]

There is clipping that you get from a pedal which you would be able to hear running the pedal into the cleanest power-amp on earth, turned way way down.  And there is clipping you get from pushing the input (and sometimes output) stage of a guitar amp.  The LPB-1 can not, of itself provide enough zing in the signal to make diodes do any dirty work, but it WILL push your amp's input stage significantly and introduce clipping there.

I know it may seem somewhat straightforward to make a simple 1-transistor gain stage a clipping device on its own, but one should ot confuse the two sources of, and different approaches to, clipping.