Mpsa13 booster questions

[Groovenut]

Here's another quick design I just did that seems to work well with the MPSA13. It'll net you about 10dB of clean boost up to about 1VP input. Plenty of frequency range to accommodate bass as well. You could probably eliminate R1 and R7 if you weren't concerned about I/O current limiting. R2 is to minimize TB switch pop. C1 can be smaller if you're only using it for guitar or want to tailor the boost freqs. C2 as well.

I haven't built this but it sim-ed fine  (famous last words)

[brianq]

Fuzzhugger "Groundswell" uses a pair of mpsa13, Bazzfuss with right bias sounds awesome!!!maybe u should break out a breadboard & go 2 town on some schematics?

[Fndr8875]

i bought 20 mpsa13 s first order i made because i was all about the bazz fuss, i just thought sweet a ton of gain in a single transistor, no clue there were very few other applications it would be useful in. love my bazz fuss, but wish i woulda got 18s instead of 13s

[Kipper4]

What's the point in using a darlington just to decrease it's gain?

Re this
Because most of the gain would probably be unusable and guitarists like to turn it up to 11.

Thanks guys
I've got a couple of weeks to mull it over before they arrive.
Looks good Lawrence.

I can see the images now I'm at home. Thanks Dino.
Is the crybaby arrangement a darlinton buffer?

[nocentelli]

Here's another quick design I just did that seems to work well with the MPSA13......

I haven't built this but it sim-ed fine  (famous last words)

Works well on the breadboard.

[duck_arse]

I'll just leave this here,
http://www.diystompboxes.com/smfforum/index.php?topic=113571.0

and slink away, quietly. [a bearhug with 1uF for C2 is asking fer trubble.]

[Groovenut]

[a bearhug with 1uF for C2 is asking fer trubble.]

Agreed... I couldn't find the most recent version of the schemtaic here on DIYSB to link to, so I grabbed his original post. Just for reference

[Kipper4]

Haha

[Groovenut]

Here's another quick design I just did that seems to work well with the MPSA13......

I haven't built this but it sim-ed fine  (famous last words)

Works well on the breadboard.

Nocentelli, thanks for reporting back. Greatly appreciated! Glad to hear it worked well 

[PRR]

> limit the gain?

The essence of "good" (not fussy fuzz) amplifier design is to make gain a function of Resistors (which are nearly marked value), not tubes or transistors (value varies all over the place).

You can't build millions of TV sets sorting transistors the way you DIY a FuzzFace. (Though to be fair, millions of radios were built by sorting reject transistors into good, poor, and diode-only; sort-labor was very cheap.)

But this assumes you are going to *design* (or find) something just to use-up 49 one-penny transistors. Even if you have $9.95 invested, that doesn't buy much heavy thinking (or plagiarizing).

[Kipper4]

I have a cunning plan.

Thanks

[Kipper4]

Heres where I'm upto
My Grenade Booster 2

[Kipper4]

This is a super booster Lawrence. I have it on the breadboard now.
Thanks

I put a 1n4148 between R5 (470ohms) and Gnd (cathode to ground) It gives a nice dynamic crunchy drive to it on harder strums. Bare in mind i mostly play only with fingers.

Let me know if this is a bad idea.

[Groovenut]

So by adding the diode you raised the emitter voltage by the Vf offsetting the bias of the stage and allowing it to clip more readily. Works for me 

If you sub the emitter resistor for the diode you get the bias offset plus to AC signal the diode looks like a short giving full gain of the stage for AC.

By putting it in series with the 470R I think you've created a partial bypass scenario.

Still works for me 

[Kipper4]

I tried both the partial scenario and diode form E to gnd. I preferred the later.
Thanks for the info Law.
Works for me too. I might put it on a switch.

[LightSoundGeometry]

Or something like this? Might try it myself this afternoon. I suspect it it will get quite gritty as the 1k gain pot is turned up, but you could dial it up to where it starts to clip then back off a hair (or have it as a trimmer to set the "headroom") and replace the 220k with an output pot.

after building bears darlington pair circuits, I may take a stab at cascading the 2n3904's and see what I can get! awesome , thanks for the layout!

[Kipper4]

Lpd mpsa13 booster with mods demo
https://youtu.be/Fs6trPEXzg8

Sorry for saying your name wrong Law...... Doh

[Groovenut]

Lpd mpsa13 booster with mods demo
https://youtu.be/Fs6trPEXzg8

Sorry for saying your name wrong Law...... Doh

No worries Rich, you made me sound like I fell out of Hogwarts 

I like the mods and the way it sounds. Very nice!

[Kipper4]

Hogwarts. Do they make effects?
It saturates my amp nicely and those little thumbed harmonics sound great.
Thanks for a super design Law.
My layouts done and fits on a 7 x 12 board. I'll order some 9mm pots and stuff it in a 1590A.

[Groovenut]

Hogwarts. Do they make effects?
It saturates my amp nicely and those little thumbed harmonics sound great.
Thanks for a super design Law.
My layouts done and fits on a 7 x 12 board. I'll order some 9mm pots and stuff it in a 1590A.

I think they have a pot builder named Harry