Amplifier Transistor upgrade

[Hufsredo]

I would like to upgrade the transistor matching pairs from these: 2SA1169 & 2sc2773 to these 2sa1170 & 2sc2774 , the other two from these 2sa1209 & 2sc2911 to these 2sa1210 & 2sc2912 . The amp in question is the Yamaha R1000 . Anyone see a problem with this?
Also if this looks ok, can you make a recomendation on the manufacture brand

Thank you.
Anton

 

[SVI2004A]

Sanken 2SA1493 and 2SC3857 directly superseded these

You can go up to 2SA1494 and 2SC3858

 

[SVI2004A]

think Digi key and B+D are the 2 in USA that carry genuine non counterfeit Sanken devices

 

[Hufsredo]

think Digi key and B+D are the 2 in USA that carry genuine non counterfeit Sanken devices

Great, do you have a cross reference for the 2sc2912 & 2sa1210 in Sanken? I have an account at Digi-key, just noticed B&D is priced a little lower.

 

[SVI2004A]

Can't see anything in production ATM

Matsushita 2SA1112/2SC2592 (aren't sure if they're unobtanium)
2SA913B/2SC1913B (unobtanium now)

You'll want 180V-200V with fT 150mhz and hFE around the 200-25- nominal range (rank ranged from 100 - 400 for the 1210)

I'm sure ppl on here would know equivalents... it's extremely rare that I have to replace drive transistors or outputs based on Sanken MT200 output stage.

The voltage and ft freq narrow down pickings

 

[Hufsredo]

It's discouraging trying to find the 200v drive transistors, there is a seller on ebay claims to have the Toshiba 2sa1210 and 2sc2912 but you know how that goes. The drivers in their now are 180 volt, do you think I'll have any issues with that?

 

[FootFungus]

Its only a 100wpc unit, the original Sanyo 2SA1209/2SC2911 are more than enough for that.

 

[SVI2004A]

Just saw this in another thread... replaced 2912/1210 with these KSC3503DSTU / KSA1381ESTU

 

[Hufsredo]

I had faith that AK would would be of help. In stock at mouser!!!
Thank you.

Just noticed the collector current is 40 ma less, is this cause for concern?

 

[tranguru]

just a question: why do you want to do that?
I doubt the amp will sound better because you changed the power transistors.
you will then also have to check the drivers and maybe also bias circuit.

A lot of risk with low reward potential.

 

[Hufsredo]

Just looking for a comfortable head-room on the amps. My home made speakers are 5.6 ohm.

 

[OMGCat!]

I doubt changing the transistors is going to do much of anything. They had a better range of devices back then and spec'd those to match the rest of the amp.

 

[petehall347]

consider the power supply

 

[Hufsredo]

just a question: why do you want to do that?
I doubt the amp will sound better because you changed the power transistors.
you will then also have to check the drivers and maybe also bias circuit.

A lot of risk with low reward potential.

The risks would be?? The pre drivers and bias circuit could not get much better. The transitors mentioned above are the only different parts between the R1000 amp and the R2000 amp.
Ic412 was uppraded to the 3165 unit and the power supply and filter caps/rectifiers are in excellent condition.

 

[OMGCat!]

You'd have to look at power supply voltages between the two models if the layout is that similar.
The output transistors are just doing with the stage before is asking (as long as the power supply can keep up). A replacement transistor is going to do the exact same thing.

 

[tranguru]

risk:
getting the wrong xtors that might make it worse
bad maneuver that damage the amp
effort and no reward

Power supply might be worth looking at. some amps today sound lousy only because of the insufficient power supply (ex: harmon kardon surround amps - great amps section but very bad power supply)

 

[Hyperion]

The risks would be?? The pre drivers and bias circuit could not get much better. The transitors mentioned above are the only different parts between the R1000 amp and the R2000 amp.
Ic412 was uppraded to the 3165 unit and the power supply and filter caps/rectifiers are in excellent condition

So, what improvement are you expecting? - or have already experienced?

 

[SVI2004A]

I'm with you on this... jesus this thread needs thicker diff oil to eliminate the whine

1494/3858 and (if needed pre drive) transistors.... it adds a tad more lee way for 4 ohm loads....

 

[Hufsredo]

Yes getting the wrong parts or counterfeit ones, is a concern. I am looking for "robustness", not gain here. I have the Sankens 2SA1494 and 2SC3858 ordered from Digi-key. What about these pre drivers, 2sa1810 & 2sc4704? There readily available from trusted suppliers.

 

[Alan0354]

Why do you want to do that, I checked, one transistor is 20MHz, not that bad. From my experience, the power transistor affect the stability of the amp a lot, changing power transistor might cause the amp to be unstable. There are polls and zeros compensations in the amp, changing the transistor might need to redo the compensation.

If something goes wrong, you have the knowledge to fix it? When I change power transistor, I put my amp through the gauntlet to verify stability.

The transistor you have are the big one already, what make you thing you get more of anything with a better transistor? You cannot get any more headroom or power with replacing transistors like this, you need bigger heatsink, higher rail voltage to get more headroom and safely get higher power.