Shin-ei Companion. WOAH!

[superferrite]

I finally wired up a mostly salvaged parts version of this thing with the mid scoop mod, and I nearly peed my pants.
Holy smokes, this thing is INSANE!  

Had all kinds of room in the giant box, so I popped an old guitar 250k pot on the front to bias it for different pickups before I boxed it.

Any transistors sound "better" than any other ones in this?!?!?

I might even have an old Japanese stereo at work to tear up for parts.

[Quackzed]

i believe i've seen some "twin t" "notch filter" mods, i think mark hammer wrote up a few things about modding a twin t notch filter in different ways...
i think the shin-ei uses that type of filter,not sure if its the same as the mod you mentioned...
other than that q2's collector reistor is a good place to 'tune' different transistors you might try, basically its like the bias resistor in a fuzz face so you could always raise/lower it a bit and see if it sounds better etc...

[glops]

I would say definitely socket transistors in this one.  I've built about 8 of them.  When it sounds right, it's amazing.  I like to try different salvaged caps for the fuzz section.  They all sound slightly different and yields a variety of coloration.  The best units I built were with salvaged transistors.   2N3904s sounded really horrible compared to the others I've tried.  I also have bumped the feedback resistor in Q2 down to 470k and have gotten great results.  A wonderful fuzz, indeed....

[superferrite]

I popped 2N3904s in it because I had them lying around.  Really farty but pretty cool anyway.   I can't wait to improve on it.
Yeah, almost all the capacitors are ceramics from sixties and seventies stereos.   Nice and nasty.

The old Sanyo tuner I just destroyed has lots to transistors with hFes from 110 to 500, but their pinout is BCE.   I guess I'll bend the legs and forge ahead.
Thanks guys.

[glops]

Bend the legs!  I tried 3904s and it was too farty and not buzzy enough.  I like this circuit when its buzzy.  If you like this sound, check out the other 60's fuzzes that share the same topology.  It's a great simple interesting family....

[Mark Hammer]

Yep, with a bit less scoop, it has a really nice sound, doesn't it?  Throaty!!

I adapted the circuit to make a bass fuzz for a good friend who is a bass player.  I doubled the values of all the caps in the signal path (including the ones feeding the Fuzz control), and replaced the stock midscoop filter with a 3-position toggle and 2-pole lowpass filter. 

Finally, the collector of Q2 is fed V+ via a 100k and 47k resistor in series.  A .047uf cap is in parallel with the 100k resistor.  If you vary where the .047uf cap "joins up with" that 147k path, you can alter the bass content and "body" of the sound.  Between the Body and Filter controls, it could go from a very thin bright sound, suitable for guitar, to a much fuller and rounder sound, suitable for bass.

There are several ways to do that.  For example, I used a 100k pot and 2 fixed resistors (that all added up to 147k), one on either side of the pot.  The cap gets connected to the pot wiper and V+.  So, as you rotate the pot the cap joins up with that path at points where there is less than 100k between V+ and wiper, or points where there is actually more than 100k.  You could probably decide to use different value caps, but I kept it simple.

Another approach, for those who like it simple, is to replace the 147k total - with, say 33k -> 68k -> 47k - and use the toggle to connect the cap to either the 33k/68k junction, or the 68k/47k junction, for two different "body" settings (or whatever variations you like).

[superferrite]

One question:   Does this circuit like a high gain Q1 and a low gain Q2 like the Fuzzrite and Orpheum?   I'll try a bunch anyway, but it's nice to know where to start.

[Mark Hammer]

I still have an original, and the 2SC536F transistors are pretty darn normal, I have to say.  I probably posted it here somewhere, but I recall their hfe as being in the 230-250 zone.  So, nothing you couldn't do with a C828 or 2N3904.

[LucifersTrip]

One question:   Does this circuit like a high gain Q1 and a low gain Q2 like the Fuzzrite and Orpheum?   I'll try a bunch anyway, but it's nice to know where to start.

There was a thread a short time ago on the Shin-ei & Orpheum also with comments from Mark, glops & I.
http://www.diystompboxes.com/smfforum/index.php?topic=89458.0

For ge Orpheum I did best with Q1 hfe 100-120, Q2 hfe 30-60
For Shin-ei, I got excellent results with the 2SC536 hfe ~ 280

For Shin-ei, I subbed 50k & 100k pots for both the 10k & 15K in the scoop to give me an insane range of tones from the
original to harsh metallic.
http://fuzzcentral.ssguitar.com/schematics/shineify2schematic.gif