Superfuzz with Russian trannies / diodes

[PMowdes]

Hi all

I'm in the throws of putting a Superfuzz together and was wondering if it'll be any better  / worse with some Russian hardware?  I have a load of KT3102em's and KD521V diodes.  Perhaps i'll socket them and have a play about.

Any recommendations on hfe values and which transistors need matching?

Thanks

Phil

[Beaker]

Hm, not used this transistor, but have loads of those diodes myself - one of my favourite diodes. A quick search for the tranny says it's a Russian equivalent of a BC109 (looks like one too). High gain! I know they are used in some Civil War Big Muffs, as are those diodes.

Should make a paint-blistering Superfuzz in my opinion, but just possibly too high gain?. The only transistors you need to worry about matching are the long-tailed pair - the ones in the middle of this schematic:



Try it and find out!

[Beaker]

A quick bit of reading suggests that they may indeed be too high gain, so pick ones at the low end of the gain range.

I've built a couple of spectactularly good Superfuzzes using metal can 2N2222 - sounded much better than with higher gain 2N5088.

[Travis]

Beaker is right, I would expect those transistors to be too high gain

Look for something around 200hfe

You want to match Q4 and Q5 and match the forward voltages of the clipping diodes for the strongest octave

[PMowdes]

I'll go with the 2N2222's and some russian diodes.  Cheers for the input.

[tabbycat]

of the three different trannies i tried in mine i found 2n3904 the dirtiest and roughest in a good way, 2n2222 gave a slightly tamer version which was roll-backable a bit (though why would you?), and 2n5088 were just not right, hard to nail why but just didn't seem to have the appropriate bloom or decay for the signature sf sound. i think i read on diy sb that 2n2222 are uspposed to be closest to the original spec.

diodes are a matter of taste. i think oa90/oa91 are in the originals, which worked best for me, closest to sound of original. 1n34a give more rasp, brightness and volume, which tends to cut through a thick mix better. 1n270 give a finer grit and darker mood, nice on own but struggles in a mix. silicon 1n4148 make it far harsher and get you somewhere between the superfuzz and the 4 tranny fuzz war, more volume still. 1n4001 too smooth, leds too baggy.

can't comment on russian but intersted to hear what you discover. if you try russian anything in the sf report back.

i have tried to understand what is going on with all the russian stuff but it overwhelms me a bit.
i think i came to the conclusion that the current price of anything that can be considered equal to the already known good germaniums is now equal to that of the already known good germaniums, so unless you are buying for appearance there isn't much point. a few years ago they would have been worth jumping on with good deals to be had, but now knowledge and prices have caught up. plus tolerances and consistency are a reputed to be a bit slacker so not so easy to be sure what you are getting.

btw has anyone seen a simple comparison chart formulated by a trustworthy diy type re russian/known equivalents? that would be interesting, even if subjective it would be a starting point.

re transitor matching, as beaker said, the long-tailed pair q4 & q5 (in the middle) are responisble for octave. the closer in hfe the more pronounced the octave. though that is not to say that you won't get great sounds by intentionally mismatching.

[Beaker]

There's not much mystery about the Russian stuff really Tabbycat, just like the West, they designed components to do specific jobs. As such, nothing appears to be a direct, exact equivalent (in other words they weren't just copied) to western parts.

Therefore, "similar to" or "roughly equivalent to" is about the best you can hope for, as certain parameters will be different.

There are still bargains to be had, and I think rumours about quality sliding off is just muck-raking. They have colossal stocks of parts still knocking around the USSR, and supplies are not going to dry up any time soon. it's true though that prices creep up with demand.

The KD521 diodes are used in the Russian Big Muffs, and are rippers. PM me, and I'll send you a few to try.

[Marbles]

Is there a difference in versions? I have heard about them, but have seen KD521a, v, g.

Was thinking of buying a batch to mess around with.

Thanks!

[Beaker]

I have A and V versions and to be honest, I've not really noticed an obvious difference between the two, but maybe that is down to the nature of the circuits I've tried them on so far.

Zach has used them more than me, so he might have an answer for you.

They are great sounding diodes though, and are perfect for fuzzes and distortions when you want or need a silicon diode.

[rocket88]

I knew you were talking about me beaker, my ears were burning. Could be that or that I'm running low on tea and could use some. Got any? Lol

There are some subtle, and I mean subtle, difference in tone between each of them. It's mostly how they break up, one may be a little smoother, or one a little rougher, etc. but you have to really listen to notice it. The KD521V are the rarest, and most expensive out of the three, so unless you really have to have that specific one, I'd grab the cheapest. Have to agree with beaker, the KD521 is one of my favorite clipping diode. It's why I have a stash of about 600-1k of each.

[Beaker]

Well I have less of these diodes in the house than tea bags - and I have a couple of hundred of each of the KD521.

If you need tea bags Zach, I'll arrange an air-drop for you.

[rocket88]

NICE!!! who doesn't want tea airdropped when needed?

[Travis]

Let's make a tea party!! Oh wait

[Frank_NH]

I made a superfuzz vero layout using the CA3046 transistor array.  Haven't built it yet, but it should work...

[Marbles]

Thanks!

From what I could find on ebay I can buy a batch of 100 KD521a for $10,20 and KD521v for $9,35.

KD521g 250 for $8,50.

Are those prices ok?


(sorry for hijacking the thread btw, I'll be gone after this haha)

[rocket88]

Lol. Those prices seem fair. They all used to be a lot cheaper. Lol

[Marbles]

Haha, yeah... I have that a lot.. I should experiment more and take a chance now and then.

Sometimes I think I should just stack up on the cheapest diodes and transistors from the weirdest country to ever produce it. Buy the whole existing supply, then build a simple overdrive around it and advertise it having a lot of mojo with parts that are unobtainable..

Or wait, that has been done before haha.

[Beaker]

A and V are used in the Russian Big Muffs, so prices are (relatively) high.

I don't know what the G version is used in, but if not used in a major league pedal, it would explain why the price is a lower, for twice as many.

Here's a datasheet:

http://lib.chipdip.ru/249/doc000249247.pdf

From the top:
KD521A
KD521B
KD521V
KD521G
KD521D

As you can see, the only difference is the max voltage rating - A is 75V, B is 60V, V is 50V, G is 30V.
D is only 15V, so not really suitable for 18V builds.

Based on this info, I would happily go for 250 KD521G for $8.00.

Hope this helps.

[Marbles]

Ah that's great! Thanks a lot!

Ordered them

[tabbycat]

Beaker wrote

There's not much mystery about the Russian stuff really Tabbycat, just like the West, they designed components to do specific jobs. As such, nothing appears to be a direct, exact equivalent (in other words they weren't just copied) to western parts.

Therefore, "similar to" or "roughly equivalent to" is about the best you can hope for, as certain parameters will be different.

There are still bargains to be had, and I think rumours about quality sliding off is just muck-raking. They have colossal stocks of parts still knocking around the USSR, and supplies are not going to dry up any time soon. it's true though that prices creep up with demand.

The KD521 diodes are used in the Russian Big Muffs, and are rippers. PM me, and I'll send you a few to try.

thanks for the explanation beaker.

i appreciate the principle but the detail seems more slippery, as with the variant of the KD521a, v, g. it may be down to the fact that rather than being a pro-builder looking for bulk parts at big discount, i'm just a one-off type, so the research-to-pay-off ratio is far reduced. as with mojo caps, there is a lot of pro and anti gossip, and i think i got forum fatigue and gave up. but i trust your judgement far better than most, so if you recommend something i will take that seriously.

re the quality, that notion may be buying into the popular western myth that late 20thc soviet era tech was shoddy and second rate. concordski etc. tolerances all over. durabilty questionable. but again, if you have these things and stand by their quality then myth busted.

will happily pay you going rate for a few to try in my superfuzz, blender, muff, war, to see how they compare. would never rule out crossing over, comrade. many thanks for the offer.



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