thanks richieooboy, thanks for the response. i also had an idea of replacing the mjw3281/1302 pairs in it now, with the mjl4281a/02 pairs. the hfe, voltage, wattage, are higher with these and i think, the ft is 35mhz being a little higher than the 3281's by 5 mhz. could these maybe be an upgrade? i also have the drivers that go with the 4281a's but the ones in there now, are 2sd2061's/ 2sb1369's with an ft of 8 mhz otherwise, close parameters every where else. but, i was concerned that the replacement drivers with ft of 35 mhz, might cause occillations and maybe, should just use the original drivers. what do you think? as i'm not to well experienced in this subject. your advice would be appreaciated thanks, crippledchicken 
I got MJL and MJW the wrong way round. MJL is the wider case, MJW is TO247 case.
I'd just leave the transistors be. The differences between the power devices are small and you run the risk of lifting pads trying to remove things. If the originals were TIP devices or something then maybe a small benefit could be had. There's also the possibility (as you pointed out) of upsetting stability.
I'd just leave the transistors be. The differences between the power devices are small and you run the risk of lifting pads trying to remove things. If the originals were TIP devices or something then maybe a small benefit could be had. There's also the possibility (as you pointed out) of upsetting stability.
Hi,
Crippled chick asks if "ft of 35 mhz, might cause occillations"?
Would the knowledgable out there please confirm if using faster output transistors increases the risk of oscillation or reduces the risk?
I believe that the faster transistor will decrease the phase shift and thereby improve the phase margin. Have I got it right?
regards and waiting to hear
Andrew T.
Crippled chick asks if "ft of 35 mhz, might cause occillations"?
Would the knowledgable out there please confirm if using faster output transistors increases the risk of oscillation or reduces the risk?
I believe that the faster transistor will decrease the phase shift and thereby improve the phase margin. Have I got it right?
regards and waiting to hear
Andrew T.
well, i tried the mjl4281a/02 pairs using original drivers because of the ft 8mhz, vs the ft of 35mhz difference. so far i have found no ill effects such as extreme heat or any bad hissing sounds etc. the sound for sure, has better tight sounding and better low bass along with smoother, more detailed full bodied sound. the original outputs when amp was new were 2sc5200/2sa1943 in an onkyo m-282 2 chl. amp rated 105 watts 8 ohm, and 125 watts into 6 ohms per chl. rms. the power supply had 2 10k uf nichicon gold tunes caps and i added another 12k uf gold tune per side along with replacing the 8 amp inline bridge rect. with 30 amp 600v. stealth diodes awhile back. i'll keep a close check for excess heat, or any strange background noises and hope it stays sounding like it does now. just thought i'd share this bit of info about the mjl4281a/02 pairs they do sound good! appreaciate all the valuable info. crippledchicken
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