Pioneer m-25 power transistors info needed !!!!

McMarantz

Active Member
HI ALL
I NEEDED INFO ABOUT PIONEER M-25 POWER AMP POWER TRANSISTORS
WHICH TRANSISTORS I CAN REPLACEMENTH TO MN25 AND MP25 POWER TRANSISTORS?:scratch2:
Thanks
 
HI ALL
I NEEDED INFO ABOUT PIONEER M-25 POWER AMP POWER TRANSISTORS
WHICH TRANSISTORS I CAN REPLACEMENTH TO MN25 AND MP25 POWER TRANSISTORS?:scratch2:
Thanks

Those are to-3 cased ring emitter transistors, with a very high MHZ specification - 45 to 60 mhz.

these STMicroelectronics transistors are probably the closest available anywhere:

2ST2121 PNP to-3 250V, 17/34A 250W 35-160hfe 25MHz $3.00
2ST5949 NPN to-3 250V, 17/34A 250W 35-160hfe 25MHz $3.00


mouser.com
511-2ST2121 PNP to-3 250V, 17/34A 250W 35-160hfe 25MHz $3.79
511-2ST5949 NPN to-3 250V, 17/34A 250W 35-160hfe 25MHz $5.14
digikey.com
497-8739-ND 2ST2121 PNP to-3 250V, 17/34A 250W 35-160hfe 25MHz $3.79
497-6953-ND 2ST5949 NPN to-3 250V, 17/34A 250W 35-160hfe 25MHz not available

these ON-Semi devices are much slower, at 4 mhz:
mouser.com
863-MJ21193G pnp to-3 250v 16/30A 250W 8-75hfe 4mhz $4.07
863-MJ21194G npn to-3 250v 16/30A 250W 8-75hfe 4mhz $4.07
digikey.com
MJ21193GOS-ND pnp to-3 250v 16/30A 250W 8-75hfe 4mhz $4.56
MJ21194GOS-ND npn to-3 250v 16/30A 250W 8-75hfe 4mhz $4.56

either way, you will need to scope it to check for stability with the substitution.

The driver stages (q10,q12 / q11,q13 in darlington configuration ) DO have 56 pf of negative feedback caps collector to base to control the high frequency gain, so if I were working on one, I would do one channel with the 4mhz transistors and the other with the 25 mhz transistors. Then test the daylights out of it on a scope, distortion analyzer and other instruments to figure out which to use.

as a guide, pioneer does spec the amp with a frequency response of 5hz to 200,000 hz +0 / -1 db (distortion and power for THIS not specified)
with 0.008% distortion at 60w (5 to 30,000 hz)
and 0.01% distortion at 120w into 8 ohms (0.02% into 4 ohms at 20,000 hz)
 
Reviving this thread to see if there are any other alternatives to these? Mark any ideas? My amp is working great but wouldn't mind having some for any future issues.
 
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