2SC3329 low noise transistor

Hi

A glance at the datasheet seems to show that this would make a pretty good front-end for a transformerless mic pre. Are there other transistors that get similarly close to zero dB NF @ these impedances?

Any suggestions where I can buy them? Borbely sells them, but I don't mind if I had a cheaper source!

Thanks!

Samuel

Heh Samuel the secret is out (see also the recent thread about ribbons in the Brewery "EH Ribbon ?!"). Yes the PNP complement is the 2SA1316. Otherwise the only part that is even close is a near-mythical Rohm part mentioned in Horowitz and Hill.

I got some the other day in a bulk purchase with another forum member but I don't know what his source was. However buying a bunch they were way cheaper than Erno---not that his onesy twosy price is outrageous. The man needs to pay for his operation.

If you want a few just PM me and I'll send you some. Again, no obligation and no salesman will call---I'd just like to see the Toshibans realize there is a continuing market for these and other swell parts, and also to stop conspiring with the Romulans ;-)

I don't know how they are making these---it's not just by scaling up the number of electrodes etc. because the capacitances are not in proportion to the reduced rbb'. Almost worth learning Japanese and tracking down the designer.

Just to confuse everybody: I recently opened my MX8ooo B*ringer Eur0desk and found that there are two of these near mythical Rohm parts (2SB737) in each mic pre. They're combined with 2N4401, though, not what would be the ideal complementary, the Rohm 2SD786. My mixer is an early grey model from the time before they cut the price by 50% and threw in a free meterbridge & an effects processor. The later models must have different transitors as those Rohm parts were discontinued.

Brad, you don't happen to have a datasheet for those Rohm transistors? I have never been able to find one on the net.

Well, as far as I know the 2SD786 IS the ideal complementary for the 2SB737... What would you use instead?

Yes, isn't that what I said? The 2SD786 would have been the ideal complementary type, but the 2N4401 was used instead in the MX8OOO. I also have an old Ultragain 2OOO that uses 2SB737 and (if I remember correctly) BC546. The BC546 doesn't look like a good choice as it's not really low Rbb. Nonetheless I actually prefer the Ultragain over the MX8OOO. But that's probably because of other components in the chain (opamps, caps etc).

Maybe the complement got unavailable (sigh).

The cascoding transistor does not have to be super-magically low noise like the input transistor. There is no point spnning wheels there as they do not contribute much to the input noise figure. So using a 2N4401 or a BC549 is just fine. You want to spend your money/effort on getting a really good input transistor instead.
I have been trying to source the 2SB737 for months without going to USBID. No luck so far.

Thanks TK, that's good to know!

I just took another look at Gyraf's drawing of the B*ringer ADA8OOO analog section.

They actually use the 2SA1316 in there. The other transistors seem to be simple SMD types.

Does anybody have datasheets for thos Rohm transistors? Or at least information on basic parameters such as Rbb and Hfe?

For the 2SA1316:
rbb = 2 ohms
En = 0.6nV
Hfe = 200 - 400 for GR bin
Hfe = 350 - 700 for BL bin

I've not seen a datasheet, but H&H mentions an rbb' of 4 ohms for the 2SD786 (see Figure 7.44 on pg. 437 of the 2nd Ed. AOE).

Rich May used to say that SD stood for Slow Dog, so the f sub t is probably a bit low, like for the 2SC3329/2SA1316 parts.

If you guys want a few freebie pieces of the Toshiba parts PM me and let me know. I suggested to Samuel that we might put together a group buy (I don't want to sell many of mine---I got enough to play with and do some matching of pairs and multiples, but I'm not interested in becoming a supplier). BTW the parts are the high beta code ones (BL, 350-700).

from Tamas: For the 2SA1316:
rbb = 2 ohms
En = 0.6nV
Hfe = 200 - 400 for GR bin
Hfe = 350 - 700 for BL bin

And that 600pV/root Hz is a blurb number with unspecified collector current. It can't be at the tabular noise spec value of 100uA, as this would violate the fundamental operation of the shot noise/r sub e component. But it could be for, say, about a 700uA Ic.

I just echoed the hype-sheet data. I think they used 1mA collector current for that noise figure.

"I think they used 1mA collector current for that noise figure."

That's plausible, especially if we're just on the beginning of the 1/f component. Toshiba is funny about this stuff---sometimes the blurb data for noise is actually at lower than 1kHz, perhaps the result of the intended use in phono preamps.

I'm going to have to fire some of these up and see. It's fun to have a part that should challenge my noise measurement capability, even with some circuit gain involved!

Here's a link for the full 2SA1316 datasheet

[quote author="Rossi"]Yes, isn't that what I said? The 2SD786 would have been the ideal complementary type, but the 2N4401 was used instead in the MX8OOO. [/quote]

Yes, that´s what you said. What´s wrong with me?? Doh!

No problem, I recently confused silicon with silicone. THAT's d'oh!

Thanks for the data, TK & Brad.

Yes, a group buy would be cool. Anybody else interested?

And seriously---let me send you a few if you like. I will try to get around to setting up a test circuit but I need to find my filter-amp first. I saw it somewhere the other day...

I would be interested in both 2sb737, and 2sd786

rafa I only have the Toshiba parts---but they should be even quieter.

PM me with an addy and I will send you some.