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Old 29th April 2009, 03:03 PM   #2911
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for the FET can i use 2sk246/2sj103 insteed 2sk370/2sj108?

because in my place very hard to find those type FET.

thanks
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Old 29th April 2009, 03:28 PM   #2912
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by bakpaosiomay
will my speakear blow if i dont use any speaker protector?
nope - if you make amp properly



Quote:
Originally posted by bakpaosiomay
for the FET can i use 2sk246/2sj103 insteed 2sk370/2sj108?

because in my place very hard to find those type FET.

thanks

well ..... think of paralleling at least 3 of each , to replace original ones ;

is it possible for you to buy anything outside your country ?

that amp deserves that trouble , believe me .

any Papa's amp worths at least quadruple money , looking at price of his commercial products vs. other competitors .
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Old 29th April 2009, 07:18 PM   #2913
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If you have a source which can drive 5 Kohm and a couple hundred pF,
you can dispense with the JFETs altogether and simply drive the Gates
of the Mosfets.

A little more work, and you can use a single pair of Mosfets and raise
the impedances of the bias circuit, and then it would be about 22K and 70 pF.

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Old 30th April 2009, 07:25 AM   #2914
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Quote:
Originally posted by Zen Mod


nope - if you make amp properly






well ..... think of paralleling at least 3 of each , to replace original ones ;

is it possible for you to buy anything outside your country ?

that amp deserves that trouble , believe me .

any Papa's amp worths at least quadruple money , looking at price of his commercial products vs. other competitors .

Quote:
Originally posted by Nelson Pass
If you have a source which can drive 5 Kohm and a couple hundred pF,
you can dispense with the JFETs altogether and simply drive the Gates
of the Mosfets.

A little more work, and you can use a single pair of Mosfets and raise
the impedances of the bias circuit, and then it would be about 22K and 70 pF.


how about 2sk170 and 2sj74?

thanks.
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Old 30th April 2009, 07:28 AM   #2915
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Quote:
Originally posted by Nelson Pass
If you have a source which can drive 5 Kohm and a couple hundred pF,
you can dispense with the JFETs altogether and simply drive the Gates
of the Mosfets.

A little more work, and you can use a single pair of Mosfets and raise
the impedances of the bias circuit, and then it would be about 22K and 70 pF.


it is okay to dispense the jfet?.

it will not affect the sound?

if the quality of sound is decrease i will consider to buy those jfet in another country.

thanks
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Old 30th April 2009, 08:40 AM   #2916
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by bakpaosiomay


how about 2sk170 and 2sj74?

thanks.

they are same jfets as in original
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Old 30th April 2009, 08:47 AM   #2917
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Quote:
Originally posted by Zen Mod



they are same jfets as in original

okay i think i will purchase those j-fet overseas.

what do you think about f5 and f4.

what is the main difference?.

i realy confuse.

what is the strength and weakness?

thanks.
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Old 30th April 2009, 09:03 AM   #2918
cviller is offline cviller  Denmark
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Quote:
Originally posted by bakpaosiomay



okay i think i will purchase those j-fet overseas.

what do you think about f5 and f4.

what is the main difference?.

i realy confuse.

what is the strength and weakness?

thanks.
Main differences:
F4 has no gain
F5 has less power fets

Both are push pull, which is a good thing if this matches your speakers and you like the sound (I do).
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Old 30th April 2009, 12:19 PM   #2919
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Quote:
Originally posted by bakpaosiomay

what is the strength and weakness?

thanks.
F4 makes more heat!

I am going back to F4 from F5 -- now that I have an Impasse preamp!
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Old 1st May 2009, 12:06 AM   #2920
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What surprised me about the F4 is how much difference the preamp made. Just put my Pumpkin on them and they are a new animal. They probably are more neutral then most amps and more revealing of the other components. In any case have half the parts for an Impasse gathered it should be interesting the one I will prefer.

Bill
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