A simple stereo Amp aroud a 2N3773

[mjarve]

I have four old Toshiba 2N3773 transistors (along with two new Motorola’s; six total 2N3773) from a 1970-s era Sunn Coliseum Lead guitar amplifier. I also have a pair of their PNP counterparts, the 2N6609 made by ON Semiconductor (Motorola?). In addition, I have any number of old 70’s-era Marantz and Pioneer receivers from which to scavenge parts from, and two 460VA transformers from a couple of early-1990s Technics integrated amps. I am thinking, instead of tossing ways a bunch of still good parts from old equipment, I would put them to use in a new, simple, clean sounding stereo amp. Obviously I would welcome any suggestions anyone might have, or some schematics of amplifiers that use the 2N3773 and 2N6609. It needn’t be pretty, but it does have to sound good.

[Greg Erskine]

I'm building one of these using 2N3773s

http://sound.westhost.com/project36.htm

[djk]

--------------------------------------------------------------------------------
And the Saga Continues ...
Now we have Toshiba branded 2N2773 power transistors. This in itself is interesting, as a search on the Toshiba site reveals that they don't even seem to make this transistor! It would be unusual for a Japanese manufacturer to make a "2N" device at all, but doubly so since this is a very old device now, and seems to be discontinued by just about every other maker.

Again, these have all the "earmarks" of counterfeits - and naturally enough someone was caught out, and his amp failed with these transistors installed. If you happen across any of these components, be afraid - be very afraid!

[slowhands]

These transistors were removed from an old 1970s amp. There was not much counterfeiting back then, if any. China had no semiconductor industry then. They are probably OK.

Most of the cost in an amp is in the power transformer, filter caps, chassis and heat sinks. The semiconductors are fairly cheap by comparison. You may want to consider using some better parts for improved sound quality and reliability since it really won't affect cost much. The 2N3773s are very slow and not capable of dissipating as much power as their modern counterparts. That said, I use them for repairing Dynaco 120s without problems.

[millwood]

Originally posted by slowhands
There was not much counterfeiting back then, if any. China had no semiconductor industry then. They are probably OK.

they did. they started to produce transistors in the mid 1950s.

[IanHarvey]

You could try this circuit:

http://www.users.zetnet.co.uk/avondale/NCC200Notes.jpg

which would use your four 2N3773's nicely. Wouldn't like to promise it would be stable with older/slower output transistors, but hell, if you blow them up replace them with nice new ones...

The full site is here:

http://www.users.zetnet.co.uk/avondale/

You can buy ready made PCBs; I've built an amp around these (with modern transistors) and it's very good.

Cheers
IH

[farjon]

Another option:

http://www.electronica-pt.com/circui...th-2n3773.html

[shreya]

can i give +/-50v to this circuit

Audio Amplifier 90-100W with 2N3773

[ostripper]

Originally Posted by shreya

can i give +/-50v to this circuit

Audio Amplifier 90-100W with 2N3773

Would last only a few hours/ or days. Would not issue a insurance policy out for 50V on that amp.
OS

[AndrewT]

Originally Posted by slowhands

The 2N3773s are ,,,,,,,,,,,,,, not capable of dissipating as much power as their modern counterparts.

How many other BJTs can guarantee, by 100% tested, that they can do 150W @ 100Vce?
List them for us.