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Old 6th October 2010, 12:46 PM   #791
frags is offline frags  Canada
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Quote:
Originally Posted by samoloko View Post
Gentelmen

what Is the current per FET
I'm using 1A. So 2A total bias.
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Old 6th October 2010, 12:47 PM   #792
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Quote:
Originally Posted by Yunick View Post
Well 60 deg C is the hottest spot on the heatsink. On the outsides the temperature is around 45 deg C. I dont worry to much about it. I use Peter Daniel's PCB and the mosfets are mounted pretty tight in the middle of the heatsink...

I did build it according to the original schematic from Nelson P but can't remeber what bias I ended up with.. I'll check tonight. it's been running 5-6 month now..

I remeber a few using these heatsinks to build Aleph 3/30 a few years ago...
I will use PD boards but think to place FETs at row on center at MF35-151.5
I have F5 which Is Push Pull and FETs In pair run at same current
I like to know Is It same with AlephJ which Is different
also how can I set bias
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Old 6th October 2010, 12:51 PM   #793
frags is offline frags  Canada
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Quote:
Originally Posted by bobodioulasso View Post
36°c above ambient is too much.
What about summer time?
It doesn't matter what temperature of heatsink is.
It does metter what temperatures of FET junctions are.
You may have cold heatsinks but high temperature in a FET because of crappy thermal interface between heatsink and FET
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Old 6th October 2010, 01:00 PM   #794
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Quote:
Originally Posted by samoloko View Post
how can I set bias
R27 sets the bias current.
R8 the output offset.
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Old 6th October 2010, 01:48 PM   #795
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Quote:
Originally Posted by Bill Fuss View Post
In an Aleph J the current through the speaker will never equal the algebraic sum, the bias must be subtracted. And because it is dynamically biased, the bias is constantly changing.
The difference is vanishing?
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Old 6th October 2010, 03:34 PM   #796
frags is offline frags  Canada
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Quote:
Originally Posted by bobodioulasso View Post
The difference is vanishing?
Poor Mr. Kirchhoff. He did not know that his laws would not work for Aleph J amplifiers.
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Old 6th October 2010, 04:45 PM   #797
flg is offline flg  United States
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Quote:
Originally Posted by bobodioulasso View Post
Quote:
Originally Posted by Bill Fuss
In an Aleph J the current through the speaker will never equal the algebraic sum, the bias must be subtracted. And because it is dynamically biased, the bias is constantly changing.

Originally Posted by Bobodioulasso
The difference is vanishing?
I think this is somewhat off thread and belongs in the "Favorite Threads and Posts in "Pass Labs"" thread Or???
Who's Poor Mr. Kirchhoff Anyway? Aaarghh!
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Last edited by flg; 6th October 2010 at 04:51 PM.
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Old 6th October 2010, 04:56 PM   #798
flg is offline flg  United States
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That reminds me of something. This is as good a place as any. Been reading some posts lately from a long time (DIY Time) ago. Who P#$%^d off GRollins? I just thought he'd be back next week, maybe next week, but he didn't come back? You can read his stuff on a few other sites, I'm sure you know, but, It's about time he showed his face(maybe that should be A$%^) here again...
Hi Grey
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Old 6th October 2010, 07:41 PM   #799
Yunick is offline Yunick  Sweden
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I did some measurements tonight..

My rails are +/- 22.5V and bias 1.22A.

Heatsinks are measured with a IR gun.
Fets are 60 deg C, sinks are 55 deg C behind the fets and 45 deg C at the ends..
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Old 6th October 2010, 08:01 PM   #800
Zen Mod is offline Zen Mod  Serbia
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yeah - good old Mr. Insomnia Ego GR ....

in any case - (that's) not worse than any of us , with incredible talent for helping other ppl

he got pi$$ed in pi$$ing contest Thread of Threads - Blowtorch Amongst Earthlings Again

who pi$$ed him - I mean it's thread itself ....... that thing is alive ..... like Anaconda



it's time for him to be back ...... long ago .
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