Oops, recall you already posted toroid piccies long time ago at the homey front.
Good catch.
With four 1R emitter resistors at each output device, quiescent current is ~2.6A
With some voltage sag from the 650VA's (5.2A total bias current per rail), dissipation is at some 240W.
With heatsinks at 70C and silicon insulators, output device die temperature will be ~125C !
125C die temperature is a real serious problem, see A1216/C2922 datasheet graphs.
You might want to exchange the silicon sheet under the Sankens for Keratherm red foil, easy to order at Conrad.
The insulator swap will lower output device die temperature by ~15C minimum.
An easy way to drop heatsink and die temperature would be to take out one of the emitter resistors, which lowers bias current and dissipation by 25%.
Reducing bias level is not the best option though, lowering rail voltage is preferable (read Sander's lines about AB crossing and the local output stage compensation ), you likely have to do both.
As your Tauscher toroidals are potted, unwinding their secondaries is out.
What you could do is set up a CRC/CLC between the transformer and the rails, easiest would be to add another 33.000uF electrolytic per rail after the bridge rectifier, as input cap for a C-R-CC/C-L-CC, plenty unused space left in the case.
Thing to keep in mind is that efficiency of your heatsink arrangement goes down considerably if you drastically lower their temperature.
For the Modushop 5U heatsinks to be at 55C (for 25C ambient), it likely takes dropping the quiescent current level by a full 1A to 1.6A !
(my Bruno monaurals have high performance heatsinks, about 8kg the piece, with two 120mmx120mm fans on each, running in stealth mode. Barely get warm. Biased at 3.25A instead, btw)
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Hi Jacco,
Thank you for the suggestions. I will try to measure how hot the Sanken get during operation. You are right 125c is too hot but until now they are still "touchable" after an hour of operation; I doubt they get this hot. Off course this is not the die termperature but stil.......
By the way; the silicon sheets I used are Bergquist Silpad 2000; the highest perfoming pads I could find.
Scanspeakman
What an absolute monster...
I love it!!!
I'm often bitching about modern 7x150Wrms amps weighing a lot less than my 2x100Wrms amp.
I think you can beat my 18kg
Talking about monsters, I once owned a McIntosh MC2300, a real monster, weighting 128 lb! (a horrible amp, btw)
Cheers,
E.
Silpad 2000 has almost half the conductivity of the Kerafol, and can have up to twice the thickness.
Better insulator material than e.g. K-10, i haven't kept track of newer insulator material after EUVL's pointer to the Kerafol several years ago.
125C die temperature or a little under 120C makes little difference for the outcome though.
Dimitri,
ESL2905 (+ last revision classé omega preamplifier, assemblage dac)
In a small room, <250sqft, about as detailed, airy, and punchy as can be achieved in a home surrounding, imo.
(i'm not into low vibes, not even in concert halls, or any natural environment)
Still have to exchange the fans for Noctua NF-12B models, which do 10.5dB(A) at 76m3/hr, or ~2m/s, according to the datasheet.
The all-low distortion of the trio is more of a coincidence than planned, single item left on my list is a tone control
Jam,
i've posted several pics on the extrema build on multiple audio fora over the years, e.g. : http://www.diyaudio.com/forums/group-buys/133796-gb-rmi-fc100-parts-2.html#post1742589
Given the CNN like monitoring level of this forum at times, this is one design i do not feel like advertising for.
(Mr Stuart shouldn't be posting his home adress on the web, he's just asking for a confetti bomb letter)
Depends, on the projects, and which parts of them.
I've posted several construction pics over the years, examples ;
http://www.diyaudio.com/forums/pass...-more-boring-making-thread-3.html#post1388899
http://www.diyaudio.com/forums/pass...-more-boring-making-thread-6.html#post1413132
http://www.diyaudio.com/forums/pass...-more-boring-making-thread-6.html#post1414983
http://www.diyaudio.com/forums/pass...-more-boring-making-thread-7.html#post1422134
http://www.diyaudio.com/forums/pass-labs/52104-mosfet-a40.html#post610978
http://www.diyaudio.com/forums/pass-labs/52104-mosfet-a40.html#post776696
http://www.diyaudio.com/forums/pass-labs/52104-mosfet-a40.html#post776701
This place is like CNN, some things I'd like to keep to myself, I do not build stuff by the assembly manual, there's more to an amp than sticking a transformer and a PCB in a case.
Not meant to sound cocky, but I haven't invested close to 30 years of studying & measuring every aspect of amplifier design, to see a total-package clone image pop up at some familiar copycat site.
(I do sometimes post more detailed pics at other audio fora, less random accessable ones).
The wise guys at this forum never post assembly images, ever seen an AndyT production ?
(most just post SOB from a college textbook 5 times a day. If you're lucky, one of them fumbles a bit with a secondhand oldy commercial amp)
Long time ago I asked my professor at university if I could do my MSc graduation work on a subject I was interested in, guy told me I had to graduate at another professor if I wanted that, not with him.
A number of years later, a fellow student I had told the story to at the time, informed me he had just graduated. Inbetween the lines about the newbuilt home he bought in Amsterdam, and the company he started work for, he mentioned that he graduated on the subject of my idea, signed and delivered by the same professor.
Bumped my nose more than a few times, before and after the moment of that anecdote.
I've posted several construction pics over the years, examples ;
http://www.diyaudio.com/forums/pass...-more-boring-making-thread-3.html#post1388899
http://www.diyaudio.com/forums/pass...-more-boring-making-thread-6.html#post1413132
http://www.diyaudio.com/forums/pass...-more-boring-making-thread-6.html#post1414983
http://www.diyaudio.com/forums/pass...-more-boring-making-thread-7.html#post1422134
http://www.diyaudio.com/forums/pass-labs/52104-mosfet-a40.html#post610978
http://www.diyaudio.com/forums/pass-labs/52104-mosfet-a40.html#post776696
http://www.diyaudio.com/forums/pass-labs/52104-mosfet-a40.html#post776701
This place is like CNN, some things I'd like to keep to myself, I do not build stuff by the assembly manual, there's more to an amp than sticking a transformer and a PCB in a case.
Not meant to sound cocky, but I haven't invested close to 30 years of studying & measuring every aspect of amplifier design, to see a total-package clone image pop up at some familiar copycat site.
(I do sometimes post more detailed pics at other audio fora, less random accessable ones).
The wise guys at this forum never post assembly images, ever seen an AndyT production ?
(most just post SOB from a college textbook 5 times a day. If you're lucky, one of them fumbles a bit with a secondhand oldy commercial amp)
Long time ago I asked my professor at university if I could do my MSc graduation work on a subject I was interested in, guy told me I had to graduate at another professor if I wanted that, not with him.
A number of years later, a fellow student I had told the story to at the time, informed me he had just graduated. Inbetween the lines about the newbuilt home he bought in Amsterdam, and the company he started work for, he mentioned that he graduated on the subject of my idea, signed and delivered by the same professor.
Bumped my nose more than a few times, before and after the moment of that anecdote.
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