Faultline Build transistors, charge pumps, etc

[claytushaywood]

so the faultline... can't wait to get this one done!  couple questions

the circuit takes 8 2n5457 transistors... I was about to just start throwing em in there, but I decided I should test them to make sure I'm using all working transistors.  I began testing their hfe in my multimeter to find some interesting numbers.
out of testing about 15 of them
most of my 2n5457's fall very close (like +/- 20) of 450 or 650  with some right around 500.  It's weird there's like 3 groups of values.

Anyways, i figure using all 450 would be quite a bit different than all 650 with there being 8 trannys and all.  Anyone done any testing, should I be rocking higher gain guys or what?  does it matter that much or is it all luck and personal preference?

Last time I placed an order road rage boards were out... So i've found a vero layout for a voltage doubler from tagboardfx

http://tagboardeffects.blogspot.com/search/label/Charge%20pump

It calls for the icl7660- but can I use a max1044 here?  i seem to have ordered a bunch of max1044's for some reason... I have no idea? 

I'd really like to get 18v goin here.  Any help would be wonderful! Thanks!

[stecykmi]

wow i never noticed but the faultline is no joke! 8 trannies wow.

however, JFET's are not BJT's and therefore the "hFE" parameter doesn't exist, so who knows if you're getting accurate results. The only accurate way is to test each for current and Vgs. JFET's are notorious for varying wildly in spec.

anyway, for maximum gain, put the lowest gain devices in Q3 and Q8 since those act as buffers rather than amplifiers. I'm not sure about the 3 mu-amp pairs, but I would probably work my way up so to speak... ie lowest gain devices in Q3/Q8, mid gain in Q1/Q2 and high gain in Q4/Q5/Q6/Q7. But who knows, that may sound like crap!

that said, it might be easier/faster just to try a few combinations to see if you can actually hear a difference (you may not, a lot of law of averages going on to balance things out, plus many transistor circuits are less sensitive to variation than you might think). then try a few more to choose a combo you like.

[claytushaywood]

Well I finished it up and tried it out running 9volts.  and it sounds good!  really good...  not as much gain as I thought it would have.  But i guess 18v operation will increase that.

this is an awesome circuit.  I'm getting all sorts of awesome ampeg sounds, from rolling stones to queens of the stone age (if I use a booster in front) cant wait to try it out on my bass rig!

Thanks for the help!  when i get around to building my jfet tester I'll give those suggestions a try along with as much experimentation as I can stand and list my reports for yall!

[TNblueshawk]

Funny timing on this. I have a board and was trying to decide whether to run on 9 or 18v.

The Max1044 won't run on 18v as the data sheet says 10 or 12v max. The TC1044SCPA handles at least 15v or more as I recall.