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Old 15th July 2005, 05:30 PM   #11
Bensen is offline Bensen  Belgium
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Which Crescendo 250W??

1) Crescendo mini with 1 x 2SJ50 and 1 x 2SK135, 45Vdc
2) Crescendo 1982 with 2 x 2SJ50 and 2 x 2SK135, 75vdc
3) "1Kw" Crescendo with 4 x2SJ50 and 4 x2SK135
4) Crescendo ME

5) And there is somewhere on a Italien site an article of a crescendo with 3 x devices that claims to have 350Wrms/4ohm?


I have of each of these amps the circuits. From the crescendo 1982 I have the total article in Dutch and from that italien one the article in Italien.
But all of these file's are to big to poste also in ZIP format.

I wouldn't build the crescendo 1982 with only 2 devices in parralel, in 4ohm, you are far over the SOA curve off these devices.

Greetz
Ben
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Old 15th July 2005, 06:30 PM   #12
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hi

i dont know how much this would help but we have driven the crecendo with 2 X 750 VA ie 1 750 Va per channel with a few mods as higher voltage rating input trannies and 1 with a seperate suuply for the original input trannies while the mosfet output was fed with 750 VA

We Had Used Only J 56 & K 156 , they yet rock after 13 years and are going strong as ever

we use these for testing drivers - have fed them all type of wave forms - short circuited the out - put - when our test drivers have blown !

no probs with the amps - rock solid

suranjan
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Old 15th July 2005, 07:11 PM   #13
AndrewT is offline AndrewT  Scotland
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Hi Bensen,
some like BJTs and others like lateral FETs, some even like vertical FETs particularly for their low cost and reliability. But I hear the problem with them is trying to obtain anything even close to a complementary pair. For this reason the VFET fans often choose to go Nchannel and develop circuits to try to get the best out of NVFETs. Lots of past threads to choose from. Good luck.
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Old 15th July 2005, 07:30 PM   #14
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Crescendo 1982 with 2 x 2SJ50 and 2 x 2SK135, 75vdc!!
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Old 15th July 2005, 07:30 PM   #15
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"1Kw" Crescendo with 4 x2SJ50 and 4 x2SK135

That is it I sad wrong the another time!!

This is it "1Kw" Crescendo with 4 x2SJ50 and 4 x2SK135!!
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Old 16th July 2005, 11:21 AM   #16
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It is the "1Kw" Crescendo with 4 x2SJ50 and 4 x2SK135 I men!!
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Old 17th July 2005, 03:04 AM   #17
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Quote:
Originally posted by AndrewT
Hi Bensen,
some like BJTs and others like lateral FETs, some even like vertical FETs particularly for their low cost and reliability. But I hear the problem with them is trying to obtain anything even close to a complementary pair. For this reason the VFET fans often choose to go Nchannel and develop circuits to try to get the best out of NVFETs. Lots of past threads to choose from. Good luck.
Kanwar, Quasi, Lars, and few others are NMOS VFET fans
PVMOS is really a hell with loads of disadvantages associated along with it.....
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Old 17th July 2005, 10:27 AM   #18
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Heres is the schema for the original elektor 70w mosfet amplifier
http://www.audiofanatic.it/Schemi/Ti...K135_2SJ50.jpg
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Old 17th July 2005, 05:10 PM   #19
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But this is 250w in 8 ohm!!
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Old 17th July 2005, 08:29 PM   #20
Bensen is offline Bensen  Belgium
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danne_linkinpar,

What do you mean by "this is 250W by 8ohm". Power supply is 45Vdc, you lose 9v (VDS sat + 3.9v from cascode) --> 36V --> 20.8Vrms --> 54Wrms / 8ohm.


greetz
Ben
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