solid state amplifier obsolete ??

[SMourareau]

Well I'm trying to understand ... Let's consider for example 2SA1016 or 2SC2362 one of the best parts as differential input stage for 100/200W audio amplifier.
These parts seams to be almost impossible to find probably osolete or discontinued.
So may be the state of the art has change current audio amp design no longer needs differential input pair.
May be current design are based on integrated chips.
or May be there is now some thing better than 2SA1016 and very easy to purchase.
If some one has ideas let me know. Tell me which parts should I use as differential input pair to be in the state of the art.

[Jay]

Originally Posted by SMourareau

Tell me which parts should I use as differential input pair to be in the state of the art.

FET or BJT it should be matched pair, I prefer the 5-leg devices

[jaycee]

Nowadays suitable small signal FETs are too hard to get. However modern manufacturing means that getting low noise and closely matched BJT's is no longer impossible. Chances are if you buy 25 such small signal BJT's from the same batch you will find they are all pretty close already.

[unclejed613]

there are always suitable devices for input diff amps available.... many designs these days use 2SC3200 for NPN diff amps (stay away from KTC3200, as they tend to have a high failure rate).... can't remember off the top of my head what the PNP devices are...

[jaycee]

Unclejed, who makes the originals? I have only ever seen the KEC versions...

[unclejed613]

not sure yet who makes them. i 've been told by Yamaha, Denon and Marantz tech support to order the parts as 2SC3200 rather than KTC3200 to get the original ones, but i haven't got them yet to see who made them. i'll keep my eyes open to see what else is currently being used, there may be another suitable device to use to avoid getting the korean transistors.

[SMourareau]

Well it seams PNP is 2SA1268, I could not even find its datasheet, not a chance to find them at farnell mouser or digi key.
I would not be confident basing a design on such an exotic part.

I'm still looking for the widely availale reference that all audio designers are currently using to replace 2SA1016.

[jaycee]

Yes, sadly Sanyo discontinued the excellent 2sa1016/2sc2362 pair

[Urgon]

AVE...

May it seem a stupid question, but why these transistors are better than over 10k other low power transistors that are available?
Why these two transistors are considered superior to other ones?
Why not use for example pair of BC549C or BF245C?

[Jay]

Originally Posted by jaycee

Nowadays suitable small signal FETs are too hard to get.

If I had access to purchasing at e-bay/craig's-list, I would keep an eye for old amps using matched FET or BJT. Here I can buy 5$ used amp with 5-leg LTP devices (the matched pair costs around 5$ new). Many old integrated amps do not sound good enough to be expensive, mostly because of poor preamp. But the transformer and the matched pair is useful.