Replacement output transistors for 2SA747 and 2SC116 - Yamaha A-1

[Hifibythekg]

Need to replace a pair of OT’s on a Yamaha A-1.

Have a couple of recommendations but can anyone say which transistor pair is best suited OR has worked well in this particular amp (or both, of course!)

Would like to place an order today if possible, so all replies much appreciated.

Existing:
2SC1116/2SA747 140V, Ic=10A, Ib=4A, Pc=100W, Ft=15MHz

Possible replacements?:
MJ15022/15023 200V, Ic=16A, Ib=5A, Pd=250W, Ft=7MHz, mouser 23/1
MJ15024/15025 250V, Ic=16A, Ib=5A, Pd=250W, Ft=7MHz mouser 31/575
MJ21193/MJ21194 250V, Ic=16A, Ib=5A, Pd=250W, Ft=7MHz mouser 1176/737

Is lower Ft significant?
And should both channels be replaced whilst repairing the faulty pair.

 

[larryderouin]

The MJ21193/94G are pretty much one of the go to transistors for most any amp/receiver above 35W in a TO-3 pkg as replacements for the 1116/747 pair. You CAN use any of the 3 pair (from what I can see they are nearly identical or identical). All are overkill. Personally I'd replace both channels. The MJ21195G/96G are also recommended. Basically the same as the 21193/94G. ft should be ok as both are fairly slow. Now if you had 30mHz transistor and replace them with slow transistors, it'll muddy up the waters (so to speak).

Lot's of threads on the A-1 here on AK.
https://www.google.com/search?q=yam...oXBNQQrQIoA3oECBgQBA&biw=1525&bih=655&dpr=0.9

 

[Hifibythekg]

Hey Larry, thanks for the advice, much appreciated.
Do people ever say that they can hear a differnce with the originals, or even an improvement? Very subjective territory I'm sure.. but can't help asking prior to fitting..

 

[avionic]

MJ15022/15023 200V, Ic=16A, Ib=5A, Pd=250W, Ft=7MHz, mouser 23/1
MJ15024/15025 250V, Ic=16A, Ib=5A, Pd=250W, Ft=7MHz mouser 31/575
MJ21193/MJ21194 250V, Ic=16A, Ib=5A, Pd=250W, Ft=7MHz mouser 1176/737

Is lower Ft significant?

I'm afraid they are the only game in town for new legit TO-3 transistor.. Lower FT .. I can't hear the difference. But the point is mute..