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Old 18th June 2013, 12:08 PM   #21
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Borys,

Could you post your current schematic showing your bootstrap arrangement?
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Old 18th June 2013, 08:18 PM   #22
borys is offline borys  Poland
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There you go - schematic with double bootstrap for vas stage.
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File Type: pdf BG2-fet schematic.pdf (14.6 KB, 833 views)
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Old 18th June 2013, 08:41 PM   #23
shaan is offline shaan  India
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Old 22nd June 2013, 08:03 AM   #24
Tomq is offline Tomq  Poland
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Presently I am making basic version form first post. Yesterday I made pcb, but I see it will be much work with drilling - I made 6 chanels for active speakers

I think amp is so simple i look so good on measurements so its worth it do it


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Old 25th June 2013, 08:24 AM   #25
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Quote:
Originally Posted by smartx21 View Post
Nice!
I've got some N-channel IRFP250N only.
Could anyone draw a variant of this circuit to fit only N-channel hexfet outputs?
Thanks!
In that case it will not be symmetrical, and one of the important aspects of this design is symmetry.
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Old 25th June 2013, 08:44 AM   #26
wiljj78 is offline wiljj78  Philippines
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Quote:
Originally Posted by borys View Post
There you go - schematic with double bootstrap for vas stage.
Very nice! I'm excited to hear the result of this amp my friend...
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Old 25th June 2013, 08:53 AM   #27
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Quote:
Originally Posted by borys View Post
I am not able to compare sq at the moment but I must say that irfp version sound excellent, only one think I can notice is that bass is bit different.
I must admit that HexFets, although considered unsuitable for audio, sound excellent to me. In fact, I am tempted to say that I like their sound even more than the sound of BJTs and even Lateral Mosfets. In this particular circuit their tendency to oscillate (with catastrophical results concerning loudspeakers tweeters) is prevented in good measure by current feedback topology. The only drawback is that amp must be somewhat more complex because of the bias servo.
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Old 25th June 2013, 11:21 AM   #28
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Bellow results:

THD
Measurement is allways with amplitude 20V just to compare ....

Artifacts notwithstanding these are very nice results congrats
20volts - is that rms, peak or pk- pk ?
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Old 25th June 2013, 12:15 PM   #29
borys is offline borys  Poland
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Quote:
Originally Posted by kasey197 View Post
Bellow results:

THD
Measurement is allways with amplitude 20V just to compare ....

Artifacts notwithstanding these are very nice results congrats
20volts - is that rms, peak or pk- pk ?
20V is output amplitude (p-p voltage).
Bellow not tested 3 pairs board (you can cut off few o/p transistors with scisors anyway).
Currently I am working on BJT output version.
Need some time to show the results.
Attached Files
File Type: pdf BG2-fet 3pary top (1).pdf (59.9 KB, 321 views)
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Old 25th June 2013, 10:15 PM   #30
borys is offline borys  Poland
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Updated files for builders.
Attached Files
File Type: zip FET-hex v3.1 ZIP.zip (544.7 KB, 411 views)
File Type: zip FET-hex v6.1ZIP.zip (631.8 KB, 501 views)

Last edited by borys; 25th June 2013 at 10:17 PM.
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