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The Alpha Big Boy with Buttah (ABBB) 52w Class A Amp GB

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xrk971

xrk971

Founder of XSA-Labs
Joined 2012
etsy.com/shop/XRKAudio
Paid Member
Hi Meanie,
What is the delta-C/Watt rating of the Conrad? Each output device dissipates about 100w, your heatsinks might be able to handle 75w is my guess, but the bigger concern is the spreading of the heat flux from the small contact patch out to the rest of the sink. That’s where heat pipes on the CPU coolers come in - they conduct heat 100x to 1000x better than solid copper. You may have a local buildup of heat that will make the MOSFET hot, locally. You can try it - use the ceramic thermal spacer and good heatsink paste compound. Have an IR thermometer ready to measure temp of MOSFET. As long as it is below rated max safe operating temp (probably 150C?), it can work. That’s a lot hotter than we normally run MOSFETs but I think that’s how they run in some industrial devices. Those devices are actually pretty tough.

The heat pipe and CPU coolers on the other hand keep the actual CPU below 80C.
 
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gary s

Member
Joined 2002
Hi X, I have your pcb's, just about all the parts ( I don't start a project till I have all parts on hand, that way the build is quicker), I then will check all resistors, double check Fet matching. Just waiting on the Toroids which have been ordered. I then reread all the notes and printouts I have done from the thread with handy build and testing/biasing info, put all of that in logical order, in a folder, double check all parts against the latest BOM.

I have the enclosure ready to go, so anticipating my build on this project for early in the new year as I have a few things to finish first and make space on my bench - as well as a way overdue tidy up.
 
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gtose

Member
Joined 2009
I’m slowly working through soldering in between other projects. One question. Are there any components that require / would benefit from matching? From the original ALPHA BB thread it appears the KSA992FBU (V101, V105) should be matched? Of course, I just got done soldering these as I thought about it :)

Greg
 
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gary s

Member
Joined 2002
Hi X, I have been looking through this thread for the latest schematic with any updates and corrections after you built and tested the pcb. I found a few BOM's from various members - but do not seem to be able to find the as built and tested schematic. Could you post that again at your convenience, thanks.

I have been gathering parts and want to make sure I have everything as required to build my stereo pair of pcb's, thanks again.

Regards,

Gary..
 
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gary s

Member
Joined 2002
Thanks X, you showed a schematic at post #1, but that was before any pcb's were made, so I was hoping there is a final as built schematic some where that I can compare the various BOM's to. I am sure that will help other members who are going to complete this monster :D

Cheers,

Gary..
 
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