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Old 12th March 2010, 04:04 AM   #181
EUVL is offline EUVL  Europe
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May I ask what rail voltages (+/-15V) ?

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Old 12th March 2010, 06:42 PM   #182
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It's variable at this point. The absolute limit is about +/-20V.

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Old 12th March 2010, 06:45 PM   #183
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Distributed low power ...
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Old 12th March 2010, 07:09 PM   #184
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Quote:
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Distributed low power ...
I see it now. The Pass DLP amp ... patent pending!
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Old 12th March 2010, 09:53 PM   #185
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Quote:
Originally Posted by Nelson Pass View Post
It's variable at this point. The absolute limit is about +/-20V.

@5mA/jfet we have 100W/ch push-pull Class A? No heatsink required
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Old 12th March 2010, 11:04 PM   #186
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It would dissipate 100 watts. Output power would
probably be about 20 watts.

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Old 12th March 2010, 11:05 PM   #187
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Ghee butter, 588 JFETs per channel looks UFOddball enough.

588 at 6mA each is about 50W peak in 4.
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Old 12th March 2010, 11:28 PM   #188
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Quote:
Originally Posted by Nelson Pass View Post
It would dissipate 100 watts. Output power would
probably be about 20 watts.

still cool...
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Old 13th March 2010, 03:41 AM   #189
EUVL is offline EUVL  Europe
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20W is voltage limited at 8 ohm.

50W peak is 25W RMS. That would be something like 3.5A, 14V for 4 ohm. I max will be 12mA per JFET, which means V grade or some forward bias.

50W RMS at 4R requires 17mA per FET. You need to use V grade AND forward bias. And dissipation at the required 20V rail will be a bit high, so that the case temperature will be a touch higher than the reported 45°C.

30W rms at 6 R is 3A 18V. 180mW dissipation per FET.

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Old 13th March 2010, 09:01 AM   #190
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Quote:
Originally Posted by EUVL View Post
....
50W peak is 25W RMS. ....
Patrick, shouldn't that be: 50W peak is 25W average ?
My professors taught me that you get RMS value by dividing peak value with square root of 2 i.e 1.41. So 50W peak should be 35.46W RMS
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