Beavis LPB-1 Mods

[audiolife]

Going to try a few builds soon. I'd like to tackle this one next:

http://www.beavisaudio.com/bboard/projects/bbp_LPB1.pdf

Any cool mod ideas? I'm fairly a noob...

Thanks!

[Buzz]

It's a pretty simple circuit and what you can do with it pretty much spelled out in the link.

Why not, while you are on the breadboard, try two in a row? See how it sounds.

You could try adding a pair of clipping diodes between 1 and two ( from the output of #1 to ground, one going each way ) and brew up your own distortion.

Breadboards are fun, that's the sort of mucking 'round I do on them. For the uneducated, like myself, sometimes works, sometimes doesn't.

Finding out why is the fun, enjoy!

[smallbearelec]

There are many, many good riffs out there on the basic common-emitter boost. The Ursa Minor is mine. You can breadboard it:

https://www.smallbearelec.com/HowTos/BreadboardUrsaMinor/BreadboardUrsaMinor.htm

tweak it a million ways until you have something you really like, and then re-use most of the parts in a professional-quality soldered build:

https://www.smallbearelec.com/Projects/UrsaMinor/UrsaMinor.htm

in a really cool enclosure.

[audiolife]

So I breadboarded this little guy and tested it with my Strat into my Vox Pathfinder. All I can say is WOW!

When cranking the volume on the LPB it gave a great sounding distortion and a really good volume boost. I'm pretty damn happy with this as-is.

Are there any other resistors in the circuit that I could use a pot to control?

[GibsonGM]

You could mess around with R5, the emitter resistor. Maybe slap a 5K pot in there.   You could try putting a cap in parallel with it, too (maybe 1 or 10nF to start, go ahead and play with values to your heart's content), see if you notice any 'tonal changes'! 

Changing R2 will vary the bias.  330k to 1M might be fun to play with...altho, being such a simple circuit, the in/out caps and other mods mentioned really are about all you're gonna get!  )

[davent]

There's a modified LPB-1 in the middle of the Brontoboost, you can try the component values shown in that schematic, (ignoring the PNP transistor being used there).

http://www.aronnelson.com/gallery/main.php/v/tungngruv/J-Gagan-NVN-Schematics/BrontoBoostv3.gif.html

[LucifersTrip]

to OP, here's a little "warning" if you're using modern 2N5088's (check the collector voltage).
http://www.diystompboxes.com/smfforum/index.php?topic=104730.0

also, remember, you need to have it after a buffer or it sounds sounds muddy & distorted (see "edit")
http://www.diystompboxes.com/smfforum/index.php?topic=104730.msg940320#msg940320

the simple mod that Buzz suggested is a quick way to get a little more distortion out of it....and is very usable.  you don't need a 2nd one to boost the signal after the diode clipping. the vol will be lower, but easily past unity. 

[smurfedelic smurfberry]

With old 5088's i saw no reason for mods whatsoever

[jishnudg]

In Smallbearelecs Ursa Minor, what are the functions of the diodes D1 and D2?

[Mark Hammer]

They provide clipping when the gain is turned up enough.  Think of it like one stage of a Big Muff without an input booster to push it.

[rutabaga bob]

The dual LPB-1 has been done...check out pinkjimiphoton's 'Lardacious Phat B***ard'.  I think Frequency Central's 'Assassin of Silence' is also a dual LPB-1.