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Old 9th June 2004, 08:18 PM   #1
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Default driver upgrade question?

hi, i've replaced the 2sc5200/2sa1943 outputs with mjl4281a/mjl4302a transistors. the originals if i rember right, were FT=30 MHZ and the replacements are FT=35 MHZ. i also, replaced original drivers can't remember off hand what they were have them here somewhere. my main question is in reguards to the FT=8 MHZ on original drivers vs. the FT=30 MHZ spec difference on the replacements mje15034/mje15035. all sounds great! no components heating up, quieter background just wondering if there were maybe, some type of bypassing needed due to the differences in the FT specs, to reduce the posibility of oscillations and if so, how should i apply the bypassing? thanks, crippledchicken
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Old 12th June 2004, 05:48 PM   #2
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Default forget it

waste of time
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Old 12th June 2004, 06:39 PM   #3
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if any compensation need be done, it's usually an added pf cap from the base to collector. I personally try to stay away from added resistors to the base,...too lossy in my mind. If you can find transistors that fit to begin with in stock form, then great.

two things I try to do is to look for linearity in the current gain around the idle current , and also to use the one with the less interelectrode capacitance, ... not as much current flying around that way. Some curves on high FT devices are not impressive at all, so watch out.
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Old 12th June 2004, 06:41 PM   #4
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sorry, had to say something...
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Old 12th June 2004, 07:12 PM   #5
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thanks, it's been going great for about three weeks running most of the time beginning to sound really good. have to put ear right against speaker with no sig, volume all the way up on preamp and just barely, any hiss. also subbed opa627bp op amps to adcom preamp and replaced lt1010 buffers with buf634t along with other power supply mods and it seems to make a good combination with the onkyo power amp and, the gfp 565 preamp. i'll just keep a close eye on thermal conditions and, if no problems, i'll just leave as is since there is a substantial audible, improvement. appreaciate your help, crippledchicken
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