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TKsys 16th January 2004 09:56 AM

Replacement for MJE2955...
Hi Folk,

I've build the Rode Elliot P03a
Amplifier with good result. Now it
itches me to try some other output devices. Currently I use MJE2955 and MJE3055 in TO-220 cases.

So are there other devices out there, maybe faster ones or ones more dedicated to audio?

But I'm fixed to the TO-220 style for space reasons.

The schematic can be seen on Rods site:


Netlist 16th January 2004 11:12 AM

You could try MJE15030/31 or 15032/33 with a higher Vce and Hfe.

/Hugo :)

djk 16th January 2004 11:38 AM

SOA is really poor on the MJE15028....31 series above 15V.

At 30V the SOA on a MJE3055 is 75W, on MJE15030 only 24W.

At the junction tempertures likely to be encountered at 5A peak collector current (50W/4R peak), the gain will be higher on the MJE3055.

There is little difference in speed at 5A (about 1Mhz on the MJE15030). These scream at 1A, but drop like a rock above 2A.

The only thing I can think to try would be the 2N6488/91, a very popular device with the car stereo crowd. 80V, 75W, 15A, 5Mhz

Netlist 16th January 2004 11:59 AM

Thanks djk
I'm happy I succeeded in making you post.
I learned more as well now. :nod:

/Hugo :)

pjacobi 16th January 2004 02:10 PM

Sadly NPN-only...
... is the Sanyo 2SC4164, which is significantly faster. And has secondary breakdown limit of 4.5 A @ 30V. So while it doesn't melt, it will work.

English but old datasheet:

New Japanese datasheet:

Peter Jacobi

pjacobi 16th January 2004 02:53 PM

Sanyo Transistors
Now I've found the reference page:

These ones are fine:
2SB1683 2SD2639

TKsys 16th January 2004 03:57 PM

Thanks a lot.

But where can I get those in Germany?

I tried Reichelt, Conrad, Segor. Nobody
seems to have them.


pjacobi 16th January 2004 05:31 PM


Originally posted by TKsys

But where can I get those in Germany?

Ah, you quickly discovered the downside. Sanyo has some very fine BJTs, but is a pain to get them in small quantities.

I assume the types discussed won't show up in the catalogs of German mail order stores.

But some of them advertise to get 'any' parts on request. So you may want to contact them to check the truth in advertising.


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