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Old 9th January 2010, 05:46 PM   #21
a.wayne is offline a.wayne  United States
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Thanks for the respond gents , but i need more specifics .


Jack ,

Are you suggesting using an LM4702, LME49811 etc to replace the whole flat amp or just the driver transistors .

Sakis,

I have an situation , due to how the amp is being operated , i would like to have a stronger driver stage . Can i just upgrade to stronger drivers ?


regards,
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Old 9th January 2010, 06:10 PM   #22
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My Pioneer SX-838 which was a 50W design from the early 1970's now sports an LM4702 driving lateral MOSFETs -- I bought the receiver new from Harvey Electronics on 45th St. in NYC when I got my first job out of grad school.

I boosted up the power supply caps as well, redid the power wiring with teflon. This amp was always blowing the output transistors. I did one remake of the preamp/tone control section but wasn't quite pleased with the results -- I've got to get a bipolar supply in there!

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LM4702 meets the Pioneer SX-838
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Old 9th January 2010, 06:28 PM   #23
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Quote:
Originally Posted by a.wayne View Post
Thanks for the respond gents , but i need more specifics .


Jack ,

Are you suggesting using an LM4702, LME49811 etc to replace the whole flat amp or just the driver transistors .

Sakis,

I have an situation , due to how the amp is being operated , i would like to have a stronger driver stage . Can i just upgrade to stronger drivers ?


regards,
basically it would be wise to make a new thread regarding this issue this thread is to disscus the manual

then again if you state in trhis new thread your problem and your approach you can have my opinion

in a few words if you remove MJE340 /350 yha operate inside one amplifier and replace them with MJ15032 for example almost nothing is going to happen beyond the charcteristics of the specific transitor that might change the sound of your amp for best or worst ( which i dont think that you can hear ) then the only diference will be that 15032 is capable of more curent

how you drive those transitors and what do they have to drive makes the all diference

how your amplifier works , what is exactly your problem or approach , your drivers will have to be stated in some other thread to get some answer

regards sakis
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SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr
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Old 9th January 2010, 08:10 PM   #24
a.wayne is offline a.wayne  United States
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^^^ Thanks ...
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Old 12th July 2010, 07:22 PM   #25
rmyauck is offline rmyauck  Canada
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Sakis,

Thanks very much for link to this thread!

Randy
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Old 31st May 2014, 09:42 PM   #26
stank0 is offline stank0  United States
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Quote:
Originally Posted by picopos View Post
i have an amp here that was originally 4700ufx2 on the pwr with 2 output transistors per channel(x2)
right now after changing the driver stages to transistors that perform at 1.5A(before it was 1A) ,it has 4 transistors per channel(2sc5200 2sa1943) and 22x4700uf the transformer it's 500va 40 0 40 and it works fine(not to audio sonics extremes)just more power to drive tight and clean bass to 15" black widow(peavey) speakers,.....originnaly the fuse was 4A at 120volt and it's actually the same fuse right now,i play bass guitar on it and it's just fine...for sure the 22 capacitors are a waste but.....they're cheap(63v 4700uf nichikon 3bucks each),so.....
fans,bigger heat sink,
it match
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Old 2nd October 2014, 07:22 PM   #27
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I wish i could edit or add a few things more to this thread . 5 years passed after i placed it so in between i have actually repaired a few thousand amplifiers more so there is a lot to tell !!!

Kind regards
Sakis
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