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Old 10th December 2012, 07:29 PM   #631
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Originally Posted by dazed2 View Post
ok ok, I was just daydreaming about a balanced version.... have no real aspirations for it anymore.

Standard 4pr version it is, I think its enough power already and plenty quiet if it mimics the regular F5.

AudioSan, what are your source resistor values? With the rails that you have, if you run 3A bias you should be able to get close to 150W.
If you use 0r47 then overall, V=IR your total bias voltage should be 1.41V right?
Then each FET should run at only 0.35V bias.
it is not to scear you it is possible. just do it right
about bias. that will be 2.5A. so 0.62-0.63A pr output. and i'm gonna run dual 1ohm 5W pr device. so 0.32V drop
i'd like to run higher bias. but with rail voltage of +/-50V the sinks can not handle more then 2.5A i think i will have a little more power in class A/B doh.

Last edited by AudioSan; 10th December 2012 at 07:31 PM.
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Old 10th December 2012, 07:46 PM   #632
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I bet it is not as quite as your 4 Pr standard version .....
Feels like your waiting on Congress, doesnt it
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Old 10th December 2012, 07:49 PM   #633
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yes. if you can get it working right and have current from hell and above. same with outputs. and maybe input J-fets
Is there any doubt we are in unsettling territory here?
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Old 10th December 2012, 07:58 PM   #634
a.wayne is offline a.wayne  United States
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Feels like your waiting on Congress, doesnt it
I hope not , they usually disappoint with bad schema ......
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Old 10th December 2012, 08:31 PM   #635
dazed2 is offline dazed2  Canada
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Originally Posted by AudioSan View Post
it is not to scear you it is possible. just do it right
about bias. that will be 2.5A. so 0.62-0.63A pr output. and i'm gonna run dual 1ohm 5W pr device. so 0.32V drop
i'd like to run higher bias. but with rail voltage of +/-50V the sinks can not handle more then 2.5A i think i will have a little more power in class A/B doh.

This is why I'm going for the bigger heat sinks. If there are only 2pr per sink (sort of like the regular F5). 3A bias, or about 0.38V (0.5ohm) should be no problem in fact, going into FAB territory, bias it all the way to 0.6V per FET or 4.8A bias should be ok .
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Old 10th December 2012, 08:42 PM   #636
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If you are runnning diodes, I would suggest against .600mV. 50V rails and 1A bias per fet is all i would push these things, personally. With a V3, you are burning 200W per sink. That is BIG heat, although twp per Heatsink USA 10.08 @ 8" Tall should handle it. If you want to push 1.2A through each fet, you need to lower the Rs value to .33(1R ll .47R). THis will give you a Vdrop of about 400mV, keeping you in reasonable territory for the diodes and still getting you the wanted current.

Make sure you got excellent ventilation in your case.
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Old 10th December 2012, 09:12 PM   #637
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Originally Posted by dazed2 View Post
This is why I'm going for the bigger heat sinks. If there are only 2pr per sink (sort of like the regular F5). 3A bias, or about 0.38V (0.5ohm) should be no problem in fact, going into FAB territory, bias it all the way to 0.6V per FET or 4.8A bias should be ok .
wow. diodes starts conducting at about 0.9-1A you must have the bias pr device below that.
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Old 10th December 2012, 09:13 PM   #638
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If you are runnning diodes, I would suggest against .600mV. 50V rails and 1A bias per fet is all i would push these things, personally. With a V3, you are burning 200W per sink. That is BIG heat, although twp per Heatsink USA 10.08 @ 8" Tall should handle it. If you want to push 1.2A through each fet, you need to lower the Rs value to .33(1R ll .47R). THis will give you a Vdrop of about 400mV, keeping you in reasonable territory for the diodes and still getting you the wanted current.

Make sure you got excellent ventilation in your case.
yes. that will work
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Old 10th December 2012, 09:34 PM   #639
dazed2 is offline dazed2  Canada
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Whoops checked some calculations. forgot to factor in that it running at 50V rails.... It will need some massive heatsinks for something like that at 4.8A

Yes Buzz 0.33R would work much better.
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Old 10th December 2012, 09:39 PM   #640
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yes you will almost on the edge of forced cooling
480W pr ch is not baby food
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