Clean boost suggestions?

[jfrabat]

OK, here is the deal; I am looking for something to boost the signal so that when I go into a solo or something, the volume is increased, but once done, I can bring it back down.  I gonna build this one, but I had trouble sourcing the 2N5457 locally (I live in Costa Rica; not everything is available!).  The transistors I do have on hand are:

2N5087 (PNP)
NTE451 (JFET)
BC327 (PNP)
2N3904 (NPN)
2N7000 (N-channel enhancement mode field-effect transistor)

Now, me being the neub that I am, I have no idea what the difference beteen a JFET, MNOSFET, NPN, PNP, etc is...  I know a bit, but not enough to know what I need or not.

I also saw this one online:



But I was wondering if I can replace the 2N5088 with 2N5087...  Of course, I would add a protection circuit, but this being a fairly simple schematic, I really like it, so if these are replaceable, I will go in that direction...

I also have a bunch of OpAmps (741, LM833, JRC4558D, NE5532, RC4558P, RC4559P, TL071, TL072, TL082, etc.) in case you have a clean booster that I can build with an OpAmp instead of a transistor...

So, what do you recommend I build?  By the way, my idea is to put the booster after the OD pedals in the chain.  Is this correct?

[dschwartz]

for clean clean i would use an opamp..
avoid 1 transistor boost if you want clean or transparent

search for mxr microamp DIY on the net, plenty of info available..

other nice ideas:
-a jfet buffer into a NPN booster..should be loud and transparent
-just the jfet boost.. not very loud, but nice clipping, needs a trimmer..

[Plexi]

I agree 100% with dschwartz
I would go for op-amps instead single transistor.
But, due the boost/pushing an Od function...I would focus more in mid/high freqs than volumen.
The one you post, is almost the beloved LPB 

I would add:
- maybe two Jfets cascaded; like Keeley Katana
- feed with 18v, and trimmer bias as more headroom as possible: the trimmer that has mentioned I supose is the one from source to ground.
- Adding to dschwarts Jfet and then transistor idea: I tried with a huge succes Echoplex preamp and then LPB1.
Get the preamp from the first, and boost the volume from the LPB.
If you push too much the LPB1, it will distort.
Avoid the 2N3904 in this situations: there's not too much headroom on them.
- With the 2N7000 I tried to use it in the EQD Black Eye (great modified SHO: master volume and classic "crackle" pot used as bias to reduce distortion), and back to the BS170. The 2N has a LOT of gain in this situation.
- LM741: of course, MXR Microamp
- With the TL071 I would try the BBE Boosta Grande: almost an MXR microamp
- With the RC4558P you could try the Jack Deville Boost Tiger
- In case you have TL081: DOD BiFet Preamp 410

(Cualquier duda, a tu disposición :-) )

[DrAlx]

But I was wondering if I can replace the 2N5088 with 2N5087...  Of course, I would add a protection circuit, but this being a fairly simple schematic, I really like it, so if these are replaceable, I will go in that direction...

The 2N5088 is a NPN, so you would need to substitute another NPN, not a PNP.  I would try the 2N3904 that you have.

[GibsonGM]

AMZ Mosfet Boost.  That's what I use...after a dirt box, before the amp.  Works great.

[Mark Hammer]

Is the intention to simply boost the level without changing the tone at all?

Maybe the "solution" is not a boost but a cut.  That is, a simple box with a preset volume drop.  Step on the switch and you get full volume.

[moid]

For what it's worth I can recommend the Mr Black Boost Tiger - it's so simple that even I can build it, and it outputs nice clean loud signal - the only issue is that the minimum volume on the circuit is unity - you can't make it quieter than that (without modifying the circuit).



and the vero version

[davent]

Use the 2N7000 to build either the AMZ Mosfet Booster as already mentioned or a SHO or both. The pinout of the 2n7000 is a reverse of the BS170 but nothing else needs to be changed. Breadboard to see which you prefer, very similar but different, low parts count and you already have the part that might be difficult to source.

dave

[robthequiet]

Just a note, if you make your image tag like

Code Select Expand

[IMG WIDTH=800]*url*[/IMG] it fits.

[jfrabat]

I finished breadboarding the LPB-1 using the 2N3904 instead of the 2N5088, and it sounds just fine.  I was gonna breadboard a couple of boosters to choose from, but this is exactly what I am looking for, so I built this one for permanent use.  I used this schematic:



And I added Ben Lyman's circuit protection:



And polished a Hammond 1590B case, and called it a day.  It's already on my pedalboard (the top left one):



I actually designed a sticker for it, and I tried to to finish the pedal today complete with sticker, but I ruined it putting it on...  so I threw the sticker away.  Here's the design:

[Plexi]

LPB-1 never fails.
I used one inside my tester box.. before output.