AC128K indentification

[Joncaster]

Hi All,
First post here, been reading a lot, great forum!

Was trying to identify where these AC128K's might be from.
They have a different heatsink, like a U instead of O.
Out of the 25 AC128K's I tested, only these ones were between 90-120 Hfe (RG's method), the rest were normal K's with no gain.

Thanks

[rainless]

Are you sure that's an "8"? Looks kinda like a "5"...

Also... Who's RG?

[R.G.]

Character from a mythological time before modern effects pedals. 

[rainless]

Holy shit! The man himself!

Anywho... This might help:

http://www.jacquesstompboxes.com/ac128.htm

[darron]

Are you sure that's an "8"? Looks kinda like a "5"...

+1 those look like AC125. even better maybe though

[PRR]

The mechanical sure is special. Probably somebody saw how to save a penny with slotting instead of drilling. (You could slot a whole jig of 'sinks in one pass; holes is more one-by-one or three-by-three. If the final assembly already has the screw in, slotting might save enough time to justify paying extra.)

I suspect the electrical is the same as other parts of that number (128?125?) made in the same place and time.

[Joncaster]

Thanks,
Yeah most of the markings are too faded, but one is definitely an 8, one could definitely be a 5, and another one had a printed sticker on it with an 8 (dead).

Anyway, will see how they sound!

[thermionix]

Clockwise from top left:

Looks more 8 than 5
Definitely 8
Unknown
Looks more 8 than 5
Looks more like a 5, but still could be an 8

That's my final answer, Bob.

[Joncaster]

 
Well, they sound great.
The pair i like best is at around 90 and 120 hfe (what a surprise), and the slightly lower ones (75hfe or so) i'll use for a less ferocious build. Have a AC153K that has a great harmonic vibe to it (45hfe), so thats another one to use in a boost or crunchy fuzz.

I really want to find more of these (found two more but havent bought/tested them yet), because they have leakage lower than 100uA and just nice and sturdy. ALL of the other normal O-heatsink types were bad, but i think they were left-overs from a previous few people testing through the batches.

All told, 5 out of 35 for about $24. I was actually expecting to sink that cash anyway in my first foray into germanium, so i'm happy.

So if anyone finds these, I would definitely try them out.

As soon as i stop messing around with component values in this fuzz face (probably never), i'll box it up...very exciting.
When you get that little circuit going for the first time and it's a screaming gob of amazing...very cool.

[BetterOffShred]

That's what this hobby (profession for some) is all about to me too man.  That feeling when you fire it up the first time, and shred that first riff.. and your wife/girlfriend/cat despises their life choices leading up to that point right there..   

Grats on the Germaniums too.   I've just recently gotten into stuff using them myself, and it's a whole different ball game, but very rewarding IMO.   I've sifted through about 100 now all Russians up to this point.   

Thanks for sharing
-Brett