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 13th March 2010, 09:20 AM #191 EUVL   diyAudio Member   Join Date: Oct 2003 You divide peak VOLTAGE by root 2 to get Vrms. But it is also the same for current in resistive load. So power is divided by 2. Or am I still wrong ? Patrick
 13th March 2010, 11:21 AM #192 bobodioulasso   diyAudio Member     Join Date: May 2008
juma
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Join Date: Nov 2005
Location: Berlin
Quote:
 Originally Posted by EUVL You divide peak VOLTAGE by root 2 to get Vrms. But it is also the same for current in resistive load. So power is divided by 2. Or am I still wrong ? Patrick
Sorry Patrick, I don't know why I asked at all - absolutely unimportant because this calculation assumes pure resistive load and sinusoidal signal - pretty much useless in real life.
Peak voltage/current value might be informative - it determines the clipping limit, the rest is of no use, unless we want to go into really complex modeling...

 13th March 2010, 03:02 PM #194 EUVL   diyAudio Member   Join Date: Oct 2003 > Peak voltage/current value might be informative .... That we agree. And in post #189 I was working back from what Nelson quoted in post #186 back into, exactly as you said, voltage, current, and thermal dissipation. Patrick Last edited by EUVL; 13th March 2010 at 03:05 PM.
Blues
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Join Date: Sep 2003
Location: The Milky Way
Quote:
 Originally Posted by EUVL You divide peak VOLTAGE by root 2 to get Vrms. But it is also the same for current in resistive load. So power is divided by 2. Or am I still wrong ? Patrick
This is correct. The square of the square root of 2 is equal to 2...

Prms=(Vrms)^2/R

since Vrms=Vpk/sqrt 2 then:

Prms=(Vpk/sqrt 2)^2/R; this then equates to:

Prms=(Vpk^2/2)/R)=Vpk^2/(2*R) or the customary =(Vpk^2/R)/2

As an example with the known values Vpk=20V and R=8

Prms=(20^2/8)/2=25 watts
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 13th March 2010, 05:08 PM #196 EUVL   diyAudio Member   Join Date: Oct 2003 > Or am I still wrong ? It was not supposed to be a question. Patrick
 7th October 2010, 05:29 PM #197 gl   diyAudio Member   Join Date: Dec 2003 Location: Sierra Foothills - California Hi Nelson, I was wondering how this project was coming along. Have you had a chance to do any preliminary or even serious listening and if so can you share your thoughts on the sound? Thank you. Graeme
 8th October 2010, 12:47 AM #198 Nelson Pass   The one and only     Join Date: Mar 2001 At this time I have 5 pc boards completely stuffed, ready for action. Four of them perform as previously described, and one of them has a little extra distortion. I began searching for the bad device by measuring the THD at the Source pin of each of the 588 devices on the board, and I got half way through before I had to go work on other things for a while. In actual testing the best performance looks to be with supplies in the +/-15V area - battery operation is very feasible. To get the power up I can run two pc boards in balanced mode, and this looks like what I may do, creating one stereo pair at about 40 watts and a single board suitable for two channels at 10 watts or less. I may have it a BAF, then again I might have something else.
nar
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Join Date: Apr 2002
Location: near the sea
Quote:
 In actual testing the best performance looks to be with supplies in the +/-15V area - battery operation is very feasible. To get the power up I can run two pc boards in balanced mode, and this looks like what I may do, creating one stereo pair at about 40 watts and a single board suitable for two channels at 10 watts or less.
I think this project is awesomely insane
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 8th October 2010, 07:29 PM #200 Nelson Pass   The one and only     Join Date: Mar 2001 It's become the Beast With 2,352 Jfets.

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