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Old 9th July 2010, 11:09 AM   #511
Tea-Bag is offline Tea-Bag  United States
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Quote:
Originally Posted by cka3o4nuk View Post
dear Nelson Pass in f2j the SJEP120R100 are used only for q1 or q2 too?
best regards Max
I am not Nelson, but I retrofited my F2, It's Q1.

Additionally - From Nelson Pass
The F2's that I have updated with the JFETs need the
following changes:

R6 = 47k

C1 = 10 uF

Z1 removed

The potentiometer must be re-adjusted for minimum
distortion at 4.5 watts (symmetric clipping) and readjusted
after an hour..
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Old 9th July 2010, 01:17 PM   #512
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Tea-Bag thanx i plan to use the for power follower
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Old 9th July 2010, 01:54 PM   #513
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cka,
Generg and myself have had success using the BA-1 output stage as a power follower if you follow that thread. Same idea, put using R100's for output on top part of circuit. Leaving IRFP240's on top as Current Source.
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Old 9th July 2010, 02:06 PM   #514
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ssr100 on the lower part .....
Very easy to do, such a fun to hear.....
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Old 9th July 2010, 02:31 PM   #515
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Tea-Bag
will one ssr100 handle in follower 3a bias 33v from transformer?
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Old 9th July 2010, 03:01 PM   #516
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Quote:
Originally Posted by cka3o4nuk View Post
Tea-Bag
will one ssr100 handle in follower 3a bias 33v from transformer?
I would guess it would with plenty of sinking, but I would think a current source of IRFP240 would not. The IRFP240's are recommended to run less than 65c. The math escapes me on what the F2-F2j is doing for output. I think it's 65watts total per side, so that's roughly 33 watts a device? Someone else surely has a more precise answer.
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Old 9th July 2010, 03:54 PM   #517
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Quote:
Originally Posted by Tea-Bag View Post
I would guess it would with plenty of sinking, but I would think a current source of IRFP240 would not. The IRFP240's are recommended to run less than 65c. The math escapes me on what the F2-F2j is doing for output. I think it's 65watts total per side, so that's roughly 33 watts a device? Someone else surely has a more precise answer.
24w per chanel
but irfp240 only for ED
for curent source i use 2sk1530
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Old 19th July 2010, 07:14 PM   #518
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Some high praise here for XA100.5 and FirstWatt J2 from Tone Audio.

http://www.tonepublications.com/MAGPDF/TA_030.pdf

Check out page 158. I cannot copy text from it, must be protected.

Anyways, My first half-decent speakers were a gifted pair of Maggie MG-I's, restored by Magnepan.
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Old 19th July 2010, 09:38 PM   #519
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Quote:
Originally Posted by Tea-Bag View Post
Some high praise here for XA100.5 and FirstWatt J2 from Tone Audio.

http://www.tonepublications.com/MAGPDF/TA_030.pdf

Check out page 158. I cannot copy text from it, must be protected.

Anyways, My first half-decent speakers were a gifted pair of Maggie MG-I's, restored by Magnepan.
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Old 19th July 2010, 11:51 PM   #520
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Thank goodness for Snagit.
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