John Curl's Blowtorch preamplifier part III

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Aside from all other problems in audio, I have come up against another one that I can't easily fix. HEAT! Trying to make a 400W+ amp makes for hot heat sinks, IF I want any significant Class A region. My latest power overheated (I biased it high) after a few hours, AND it heated the room. Maybe OK in the winter, but maybe a 300W amp would be more appropriate. '-)
 
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Aside from all other problems in audio, I have come up against another one that I can't easily fix. HEAT! Trying to make a 400W+ amp makes for hot heat sinks, IF I want any significant Class A region. My latest power overheated (I biased it high) after a few hours, AND it heated the room. Maybe OK in the winter, but maybe a 300W amp would be more appropriate. '-)

Without a fan, lots of efficient heat sink area. and plenty of ventilation below and above. what else is there?


-RM
 
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The JC-1 size heatsinks are not really small, but they do heat the room as well, uncomfortably, even at idle, not necessarily at medium or high power. The REAL problem is the amount of CLASS A region available with +/- 100V supplies. 10W might be hoped for with a mono amp, much less with a stereo amp.
 
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Inspiration for George and other omni fans... :)

Thanks. It is a functional sculpture.

Find it quite intriguing with its combination of omni and close proximity placement of these speakers on each side of the listening position, spacious airy earphone effect? Got to try it out some day.

This concept has been served in the past (all small floor standing or table top)

RCA 150X
Zenith Circle Sound
PIONEER CS-06
LMS1011
Canon S-30, S-35

George
 
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Good old Seymour Cray did liquid cooling in the 1960's by brazing copper pipes to the PCB card racks and running chilled Freon through the pipes. {CDC-6600 supercomputer, delivered to Livermore in 1965}

Then he did liquid cooling in the 1970's by including stainless steel pipes in the card racks and running Freon from those pipes into a refrigeration unit located directly below the computer (in the basement). Each circuit board was bonded to a copper plate, which was clamped to the racks where the coolant flowed. {Cray-1 supercomputer, delivered to Livermore in 1975}

Then he did liquid cooling in the 1980's by submerging the entire computer in liquid coolant, a very expensive liquid called Fluorinert. {Cray-2 supercomputer, delivered to Livermore in 1985}
 
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Good old Seymour Cray did liquid cooling in the 1960's by brazing copper pipes to the PCB card racks and running chilled Freon through the pipes. {CDC-6600 supercomputer, delivered to Livermore in 1965}

Then he did liquid cooling in the 1970's by including stainless steel pipes in the card racks and running Freon from those pipes into a refrigeration unit located directly below the computer (in the basement). Each circuit board was bonded to a copper plate, which was clamped to the racks where the coolant flowed. {Cray-1 supercomputer, delivered to Livermore in 1975}

Then he did liquid cooling in the 1980's by submerging the entire computer in liquid coolant, a very expensive liquid called Fluorinert. {Cray-2 supercomputer, delivered to Livermore in 1985}
Yes, I was there for some 23 years from 6600 onward ( to the early '90's) and actually saw the whole pcb with processor in liquid running just fine. we watched the demo thru clear window (plastic? Glass?)
The more semiconductors and denser the circuitry is, the more heat produced and harder to get rid of it fast enough. That one big pcb was running 300A thru it! Big buss bars to it and into the solution. This solution to the heat issue was developed at LLNL.

But it was the robotic photo storage library (called Elephant) that really took my breath away.

Today this is used --> News | Lawrence Livermore National Laboratory

For stock pile stewardship.... hahahaha... sure. Still doing design as usual, I'm sure.


THx-RNMarsh
 
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Which dominates? CM or DMode?


-RNM

Are yo asking what is the dominate enoise on the AC line, or if the filter is dominate for CM or DM?

The filter with the Comoco is neat because you get CM and DM filtration. The DM filtration is significant. The smallest one has up to 1000uH DM.

Where as using the Bourn's 8120/8121 units are primarily CM. Their differential leakage is approximately the amount of DM filtration they offer, which isn't a lot.


From the AC line it's a mix. CM is fairly strong from what's in the air. But you'll get DM particularly from other things in the house. So there's a lot of factors. But I must point out that a lot of the DM is very hard to filter at significant current levels for amplifiers and such. The cost become prohibitive for many - largely because a lot of it is lower in frequency, too. Where as CM is actually rather useful for helping reduce shared enoise among your equipment. The high capacitance in small transformers for sources and maybe SMPS (not enough personal testings to comment on too much with SMPS) form CM noise, which the CM filtration assists with. So they work to help isolate the equipment from each other, or at least in a more controlled manner if the grounding schemes are decent.
 
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I talked with him a few minutes ago, mostly about the LXmini crossover,
full range Seas drivers in sealed boxes, the group delay figures of the
bass EQ network in the first Thiel loudspeakers in '77, and the good old
days when we had the time to drink beer and watch the channel 2
monster movies on a Saturday afternoon....

He is in good spirits, but tires easily.
 
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