The RNZ suffix of the 2SC828

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The RNZ suffix of the 2SC828

Postby gihaume » Aug 27th, '18, 17:45

I just discovered this: http://secretlifeofsynthesizers.com/the ... nd-tr-808/

Did you know ? What do you think ?
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Re: The RNZ suffix of the 2SC828

Postby jeroenbvo » Sep 7th, '18, 08:17

Interesting article Gihaume.

Although I don't really agree with their statement: " If you put a standard 2SC828-R into a TR-808 in place of the noise selected part the sound completely changes. "
I can say that mine sounds pretty damn close to an original. Maybe I accidentally, by luck placed a shitty 828 in Q35! :mrgreen:

I also doubt: "TR-808 is pure analogue and the transistors had to be carefully selected and matched, otherwise every 808 would have sounded different from each other, not at all a satisfactory state of affairs if every new TR-808 in a music shop sounded different from the others."

It is known that they all have slight variations in sound. It's an analog machine!

Anyway, still an interesting read!
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Re: The RNZ suffix of the 2SC828

Postby gihaume » Sep 7th, '18, 12:54

I also think it's overrated. There is to be a change as they stated to use it. But if we build clones without it and feels very satisfied, it seems weird to read that this part was essential to the point of discontinuing the production.

Also defining it as simply defect seems false. Maybe it was only a measure which didn't fit the datasheet for the original 828 but still was a selected range. Roland are known to have been use selected parts in various products, maybe this time the selection was in a range that the manufacturer qualified as defect as they used to throw them away. So it's only a language abuse.

It would interesting to measure a few -RNZ from 808s to try to discover what were the selection criterias.
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Re: The RNZ suffix of the 2SC828

Postby blotvard » Oct 23rd, '18, 21:33

Thanks for the update.

In part one I said that a perfect clone isn’t possible without a 2SC828-R NZ. All of the testing that I have done since writing part 1 of this article has however shown me that getting close enough is definitely possible with the right 2SC945P. The next step is to use a 2SC828-R NZ as a benchmark and to design a jig to select and grade some 2SC945P’s for the closest match.


2SC945P :)
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Re: The RNZ suffix of the 2SC828

Postby mex » Oct 27th, '18, 16:03

I did make the noise part in my Yocto 808 plugable, so the transistor and OpAmp is changeable,
also i have various means of connecting small capacitors to reachable pins, to play around with the sound.

Granted I often dont use the best of studio monitors to listen to the results, which maybe alters my comment useless :) since with electronic music it also depends on the speaker you listen with :)

But I use to alter listen and monitor audio waveforms on a 100 MHz oscilloscope, so I can be pretty sure about if and what I alter.

And the noise transistor doesnt make a noticeable distinction in my case, I tried plugin in jelly bean parts like the 2N3609 ( notice the different direction of base emitter collector so you have to bend the pins in order to plug them in )

soundwise the result was pretty much the same.

Although the more I think of it, I maybe have tested with a wrong supply voltage :)
But anyway, I like to add an electric engineers opinion (that would be myself) on such subjective stuff as rare transistors and how they alter the sound.
To put it simple, it simply doesnt, it wont automatically render your music better or worse, if you use a "wrong" transistor, as long as the current and voltage ratings fit you simply can try anything.

In the TB 303 there are also some "rare" finds, simply JFET in the output section, driving the diode ladder filter, this one also doesnt alter the sound to an extent one would suspect once reading thrugh different online sources.

But to put something positive at the end, it is always nice that there are still some people out there interested in the analog process of making music.
cheers
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