active system, first pictures

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first pictures of my new active system
2x21w8555-01 with Aleph 5
12m4631g00 revelator with A3
d9505/990000 revelator with a3

A5(mono) contains two seperate toroids (300VA) for each voltage rail, two bridges, 2x47000uF, 2.2mh(0,47R), 2x47000uF+12x4700uF
A3(mono) contains 470VA, 2 bridges,2x47000uF, 2.2mH, 20x4700uF
A3(mono) contains 300VA, 2 bridges, 4x22000uF, 2.2mH, 20x4700uF
total uF (stereo) will be 244400+188000+182000=614400x2=1.228.800uF!! So special care should be taken with switching on. The caps will be loaded with large 100R and after 1 minute full power will kick in. (with a programmeble timerelais)
Here are the first pictures
 

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today installed 3 Thermistors (5Ohm ntc)+10 ohm resistor to repress inrush current. After 40 sec's they will be bridged.
So far so good! Then installed 1 Aleph 5 en that worked as well!
Old speaker; and there was sound!!!! yes!!!
And you can feeeeel real power and control, Je**s this is nice!
No hiss, buzz or anything! And dynamic range:bigeyes: !
I like it, will continue building and will send some new pictures soon.
By the way, how hot can/should the heat sinks be after 1 hour?
What can be tolerated?
 
aaronboumans said:
By the way, how hot can/should the heat sinks be after 1 hour?
What can be tolerated?

Mr. Pass mentioned 55 C in one of his papers.
If the ambiemt temperature is only 20 C and the cooling elements 59 C they are probably a bit hot.
Every increase with 10 degrees means half of the life expectancy for the Mosfets, same story with electrolytic capacitors.
Evidence of that are a number of class A Mosfet amplifiers running very hot known to break down, eg : Musical Fidelity MA50 in the 80s.

But Hey : its better to burn up than to wither away !!
 
jacco vermeulen said:


Mr. Pass mentioned 55 C in one of his papers.
If the ambiemt temperature is only 20 C and the cooling elements 59 C they are probably a bit hot.
Every increase with 10 degrees means half of the life expectancy for the Mosfets, same story with electrolytic capacitors.

About El.Caps - yes, about the mosfets - I'm not agree.

Have a very good experience, using mosfets at 100-110C with 70000-80000 hours lifetime.

Also the 40000-50000 lifetime for El.Caps - using 105C rated LongLife Caps with not more then 85C of their case temparature)
 
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