I've changed R1-R2 because they slightly affect the idle current of the amp (the lower their value Io gets higher), also with MY system setup the amp sounds a bit better with these values, but you can build them with 0.47 ohm too, no problem.
The value of C4-C5 is not critical, they are on-board supply rail bypass caps, anything between 10 and 100 uF will do, but they should be low ESR types.
The value of C4-C5 is not critical, they are on-board supply rail bypass caps, anything between 10 and 100 uF will do, but they should be low ESR types.
wouldn't it be wise to put a small input capacitor to bias the jfet gate's voltage, so that the feedback network resistors could be of higher value, hence allowing for a better lower value capacitor (the one located at jfet gate)?
also it would allow for a broader range of jfet type like 2sj74 and so on?
I'm not an electronic expert, so take it with a «pinch of salt» ....
also it would allow for a broader range of jfet type like 2sj74 and so on?
I'm not an electronic expert, so take it with a «pinch of salt» ....
The problem is the bias and high frequency drive requiremeents of Q1 combined with the bias of Q4 needed to get the output to zero Volts. A 2SJ74 would likely require the impedance of the feedback network be even lower. If Q1 was changed to a lateral MOSFET or a low threshold V-Fet, that would allow the feedback network impedance to be raised.
dragonweed,
what are the advantages of 2n5461 and what characteristics are important here?
Loudthud suggest it's closely related to the feedback loop and Q1( on your schematic)
i currently have at home:
P-CH: 2sj74, 2sj103,j271
or for a completely reversed polarity amp....
N-CH:bf245, 2n5457,bf862,2sk170,2sk117,2sk369,j111-112-113...i think thats all.
Also, Nelson suggested to take a look at Wensan designs....i couldnt find any schematic....maybe they are better sounding( i could mail him...)?
what are the advantages of 2n5461 and what characteristics are important here?
Loudthud suggest it's closely related to the feedback loop and Q1( on your schematic)
i currently have at home:
P-CH: 2sj74, 2sj103,j271
or for a completely reversed polarity amp....
N-CH:bf245, 2n5457,bf862,2sk170,2sk117,2sk369,j111-112-113...i think thats all.
Also, Nelson suggested to take a look at Wensan designs....i couldnt find any schematic....maybe they are better sounding( i could mail him...)?
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