The skinny on Sanken 2SA1216 Epitaxials

[speaker]

I would appreciate it if anyone can lay out, in layman's terms, the advantage of using these devices or their drawbacks. I am curious as to why they are good or why they suck and can think of no better place than here to receive proper edification.

Profuse thanks in advance to all respondents!

speaker

[jacco vermeulen]

Sanken's 2SA1216, and its counterpart , the 2SC2922, are ring-emitter transistors.
They also used to be called multi-emitter devices.

Sanken also produces the 2SA1215 and 2SC2921, 150 watt versions.
Nowadays the planar epitaxial technique is solely connected to Sanken.
Sanken produces a great number of other planar epitaxial devices in MT200, e.g. the 2SA1494/2SC3858.
Toshiba produced ring-emitter devices for a relative short period: the 2SA1095 and 2SC2565.

Simply put, a ring-emitter device consists of a great number of transistors on 1 die.
Which translates in a large SOA with an unusual curving, and a very high bandwidth.
The 1216/2922 have a 40 MHz bandwidth, the 1215/2921 do 50 MHZ.
Toshiba's 150 watt 2SA1095/2SC2565 devices even higher at 60 MHz.
High bandwidth translates in high speed, in return this requires less feedback correction.
Less feedback is favorable for low TIM distortion.
Ring-emitter's have a high Hfe, which reduces the current capability of the driver devices, and consequently less current gain from the front end of the amplifier.

These devices are considered the best BJT's.
Besides many Japanese companies, a great many other audio companies have used the ring-emitter's for output stages.
Nelson Pass for a short period on Forte Audio models, Per Abrahamsen in Electrocompaniet power amps.
In Germany companies as Dieter Burmester in his Burmester 828, Reinhard Wachoviak in the Audiolabor Stark.
Here in Holland Johan Ketelaar on his 80's Active I and II, now in his prestige amp.
Best known now in the Zap modules.

Up till a number of years ago ring-emitter's and Sanken 2SA1216/2SC2922 were hard to get and price level was in accordance.
Audio designer/manufacturer Johan Ketelaar told me in the 80s he could only order large quantities of the Sanken's he used in his amps.
Currently prices for Sanken's are very low, seems to me that transistor price level is at the same level as 15 years ago.


http://www.jkacoustics.nl/AmpPrestigePowerAmp.htm

[jacco vermeulen]

Advantage in practice:
- quite rugged devices, confirmed by Eva here.
- high current capability.
- Sanken produces even higher voltage models.
- large sink area, low thermal resistance from case to heatsink.
- double mounting holes, which ensures mounting the device flat to the heatsink.

Downside:
- Mica insulators for MT200 are hard to get and very pricy.
- Up till now i have not seen AL2O3 or Kapton insulators for MT 200 casings.

[speaker]

^^^^^

A big thank you!

These were exactly the types of responses I was hoping for.

speaker

[Mr Evil]

If they're so good, then why don't I see them used more commonly? Specs look excellent and they are no more expensive than other high-end audio transistors. There must surely be some other disadvantage somewhere?

[jacco vermeulen]

I am currently building the extended leach of Jens Rasmussen with 10 Toshiba 2SA1302/2SC3281 in the output section.

If Jens goes through with redesigning the Super Leach for flatpacks i am doing that one too, trying it both with Toshiba 2SA1095/2SC2565 and with Sanken 2SA1216/2SC2922 in the output.

The front end boards probably will be exactly the same as for the "regular" extended Leach.
The chassis i am building will accept all three version device boards mounted on a separate heatsink as removable modules.
Besides the higher voltage there should not be any difference between the three except the voltage level and the number of output devices.

There seems to be an agreement here that the original Toshiba 2SA1302/2SC3281 that i am using are as good or better as the MJL1302/3281A versions or the Toshiba SA1943/SC5200 .
Reads as those are very popular ones.
To me, the 2SC2922 looks much more linear on its datasheet than the 2SC5200.

On the link i posted you can read the stats on the JK Ultimate amp.
I had the chance to 'hear' those amplifiers, 200 watts in class A on 14 Sanken's per channel, +350 in AB, tremendous current ability.
Nice amps, for a tadd over $20.000(in Holland).
But then, Johan really is a nice guy, so i am not going to put him down.

If you check the Metaxas site you can read that they still use extrem high bandwidth devices.
Same goes for the amplifiers John Curl designs, a few days ago i posted on his JC1 Halo, would not surprise me if the JC1 uses ring-emitters.
Maybe Mr Curl will be kind enough to tell a bit more of his designs some day. He is not going to write a book, he said.

[speaker]

Originally posted by Mr Evil
If they're so good, then why don't I see them used more commonly? Specs look excellent and they are no more expensive than other high-end audio transistors. There must surely be some other disadvantage somewhere?

Great question, can anyone else comment?

speaker

[Stuart Easson]

I tried to buy the really good sanken parts (2sa1216 etc) about 6 years ago, at that time I was told they were only available 'anytime' as samples and that larger quantity required a bulk purchase (5000+ pairs) or to wait for the next production run, then about every 4 months...a major pain in the derriere for small shops...plus no second source I could find...

my 2c

Stuart

[Stuart Easson]

...musical fidelity really liked these transistors, though I have no idea if they were used elsewhere...

Stuart

[jacco vermeulen]

I can come up with at least 20 brand model names, with proper cerebral massaging.

Quicky:
Rotel RHB10
The poweramp model with the Japan Red wooden sidepanels and closed chimney heatsinks.
200W/8 - 330W/4
Used 8 Sanken's per channel, two 1000VA toroids.

In Germany the Berendsen, Linear Acoustics, and Brinkman power amplifiers.
Islem in France.

btw:
Elektor did a 200 watt car amplifier design several years ago, with the 2SA1216/2SC2922 for outputs.
Including a very powerfull smps.