my first NPN SI/Ge easyface

[joegagan]

i built a very simple fuzzface derivative today using a cool npn sanyo germ i found in my surplus store.

the heart of the tone is this Sanyo SD187 as Q2

2.2 uf input cap following a 100k bourns ( cermet or plastic, can't tell) hi quality pot for input gain,

2k and 47uf to ground off Q2 emitter - no fuzzpot!

33k Q1 collector resistor feeding a Si Fairchild 2N5551 with an hfe of 181

75k feedback resistor, 2.2 uf input cap.

390ohm Q2 series resistor before a 20ktrimpot to set the 4.5v bias on Q2. a 10 k resistor would have worked perfect as it turns out

.082 output cap feeding a 100k volume pot.

just sounds like a really gainy hot fuzzface with excellent transition to OD then nearly clean guitar tone as the volume on the telecaster is turned down. took about 20 minutes on the experimeter's board, mostly because my shop is in transition, couldn't find things too fast.

i am gonna go snatch up the other 50 of those sanyo trannies

i will post a pic of the internals of one of those bourns pots to see if anyone here can help determine if it is cermet or plastic trace, my internet research lists this series as having one or the other. i found that standard type pots add a lot of hiss when turned down even a little bit as a fuzzface pregain pot. thanks puretube for the suggestion a few years ago!

[Dragonfly]

Like this Joe ?



Nice trick on the 75K feedback resistor...I got that from Gus, IIRC, but it definitely "ups it a notch" for the fuzz level. The 187's are nice transistors. I've still got my old Easy Face from a few years ago...I built it NPN too...nice design/set of mods you came up with. Nice o see you around here again.
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I did a similar one a couple years back that was inspired by the Colorsound One Knob Fuzz ...easy to build, and sounds great !

[joegagan]

wow dude you nailed it. that is exactly the circuit as built. good job,


i had to go to work, didn't have time to draw it up ha!

[joegagan]

this is the amazing turnaround of this forum.
built at 1pm, new schematic at 6pm same day by another member, woah.

of course it is 'only' a fuzz face ' but you don't often hear hotrodders bemoaning the small block chevy motor they just build it and drive the hell out of it.

[Dragonfly]

.... you don't often hear hotrodders bemoaning the small block chevy motor they just build it and drive the hell out of it.

AMEN, Brother Joe !

[Dragonfly]

A note for people building...

I'd recommend a 1M or larger pulldown resistor before the input cap...

also, if you're going to use a power jack, a 100 ohm resistor from +9v BEFORE the junction of the 33k/390, and a 47U cap to ground, positive side away from ground.

Joe...I'm curious about your findings on the pregain pot type...care to expand on your thoughts ?

[Dragonfly]

Also, Joe...

If you get a chance, try out this mod to the bypass cap...it essentially gives the fuzz a frequency range control...

[joegagan]

one of the 'bugs' of the dinosaur fuzz as it went out to the public was a fair amount of hiss when the gain (pregain) was anything less than 100% full up. i also have heard this hiss on regular easyface circuits WITHOUT the tone cap blend at input. this is when

when i talked about this a few years ago on this forum, ton suggested a plastic trace pot , non conductive.
i tried a bourns 3859, i researched this part number. it is discontinued, and apparently was available in either plastic or cermet trace.
it solved the hiss problem, but i can't find them here in surplus in my preferred 250k.
i am gonna start another thread now that i took some pics of a disassembled one.

[John Lyons]

Andy
The 2uf cap side of the fuzz range is boosting treble right?
I know in amps that .68 (marshall value) is a pretty good lift in the high end.
So with a 2uf cap that's more like a mid.high lift and with the 22u or even 47u it's amplifying full range.

How audible/subtle is this tweak?

BTW. I have all those boards you wanted made. When I get your parts I'll see what to add for you. Thanks!

John

[Dragonfly]

Andy
The 2uf cap side of the fuzz range is boosting treble right?
I know in amps that .68 (marshall value) is a pretty good lift in the high end.
So with a 2uf cap that's more like a mid.high lift and with the 22u or even 47u it's amplifying full range.

How audible/subtle is this tweak?

it goes from "rangemaster-ish" (though not as cool) overdrive to all out fuzz...

BTW. I have all those boards you wanted made. When I get your parts I'll see what to add for you. Thanks!

John

Cool...they should be there any time ! Just send what you feel is fair...

[joegagan]

andy, i did a similar mod to quite a few fuzzes, but i never tried it as a mix control, i simply added (via 1kpot) a 47uf along with the 2 uf which was in circ at all times.,
i thought the tone the way i did it was not very pleasing as a low gain sound, kinda fizzy

i will try it your way tonight.

[Dragonfly]

andy, i did a similar mod to quite a few fuzzes, but i never tried it as a mix control, i simply added (via 1kpot) a 47uf along with the 2 uf which was in circ at all times.,
i thought the tone the way i did it was not very pleasing as a low gain sound, kinda fizzy

i will try it your way tonight.

I don't like it much at the lower ranges, but the variability is nice...you might also try a 4u7 or even 10u in place of the 2u2 cap.

[soulsonic]

Hmmm.... some interesting ideas here. Good conversation, guys! Looks like some neat stuff to consider for future builds.

[joegagan]

I don't like it much at the lower ranges, but the variability is nice...you might also try a 4u7 or even 10u in place of the 2u2 cap.

that is the problem with giving the public a knob. they expect it to sound good no matter where they set the knob, i guess this a pretty good expectation tho ha ha

[DougH]

Harumph... 

(This works pretty good on the NPN Boost.)

[Dragonfly]

Harumph... 

(This works pretty good on the NPN Boost.)

I remember that one...i actually got the idea from RG or Jack, iirc.... it was mentioned i a thread about making the AMZ Mosfet Boost into a treble booster !

[DougH]

Well, to be completely honest, I got the "range control" idea from Jake, of "house of Jake" fame. 

[Dragonfly]

Well, to be completely honest, I got the "range control" idea from Jake, of "house of Jake" fame. 

we're all just "borrowing" and hopefully "improving and finding new uses" for other peoples ideas !