Just an update that the Master layout artist JPS64 is on the case. He will make two layouts: the 20W board and the 55W board. I think the 20W made to allow compatibility with the DIYA Store’s UMS specification might be a good idea? Whilst the 55W is strictly CPU cooler territory. I don’t think anyone wants a passive heatsink that can handle 300w per channel.
So outputs will be three per side closely spaced to all fit on copper block of the Dell surplus workstation heatsinks good for 130w to maybe 150w per side. The Dell FD841 heatsink designed for Xeon 5500 cpu’s Is supposed to be good for 130w with heatsink at 41C. We can tolerate 55C heatsink temps so perhaps can push 150w or slower fans speeds.
Excited to see what JP comes up with for layouts. Having both boards at least having a mounting pattern of 10mm x 10mm (and multiples, obviously) would be awesome. I think that's part of the UMS standard, and all the inexpensive, readily available base plates for sale in the diyAudio store are 10mm x 10mm.
I just bought a few of those heatsinks.
A couple of quick questions.
Do you think those Dell heatsinks could handle ~50w output without the need for a fan?
IIRC, the ~50w version needs ~35v rails? Would a 28v or 30v transformer work? Something like:
AS-4430 - 400VA 30V Transformer - AnTek Products Corp
I have a couple extra diyAudio store universal power supplies with 8x 22000uF 50v caps, and fep30dp rectifiers, that I was hoping to use one of, if appropriate.
Thanks~
~Gable
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The 55w one is kind of over the top but that’s what makes it interesting. Over the top without breaking the bank. Nice for cold rooms in the winter. I kid you not, I have a cold barely heated room in the house for my office and I put my (70w total dissipation) Class A amp on the floor and rest my feet with socks on it (too hot for no socks) for warmth.
I envision that this amp will have kind of “Bladerunner” look to it with the exposed heatpipe radiators and fans.
I envision that this amp will have kind of “Bladerunner” look to it with the exposed heatpipe radiators and fans.
Ooohh, nice an antique motorcycle air cooled head (or even airplane engine head). I saw a guys use an aluminum wheel from a car. I have some old thick non stick aluminum fry pans that have lost their coating and destined for the trash/recycle. Drill and tap a few holes and you can have a coffee warmer perhaps?
I just measured the copper area of the Dell FD841 heatsink at 61mm x 42mm. TO-247 devices are 16mm wide, so 3 would fit quite comfortably.
I just measured the copper area of the Dell FD841 heatsink at 61mm x 42mm. TO-247 devices are 16mm wide, so 3 would fit quite comfortably.
I wouldn't build a preamp either that required 29 transistors.
If one of them decided to take a dump, it would be hell trying to figure out which one it was.
I wouldn't build a preamp either that required 29 transistors.
If one of them decided to take a dump, it would be hell trying to figure out which one it was.
Well, I will do it just out of sheer will power - once I get the will
I need to because I will also be building SuzyJ's 32 transistor 5w sub-ppm THD amp - as a headphone amp. She did not say any matching is needed though.Cascading diamond buffers - a cheap low THD 10W amp with TIP41C
I am going to do another headphone amp comparison thread so would like some super low THD options to compare the SE Class A amps against.
Hi X,
I'd have to clarify your statement on the hockey pucks, the SOT227 parts are active current production that offer higher power handling capability and superior junction to sink heat transfer compared to smaller packages. I feel it could be misinterpreted by others and create unnecessary misunderstanding.
You are right, perhaps I should be using these for this amp as it really does put out some heat.
90amps and 1.5kW dissipation - definitely heat pipe territory. You could use it as a heating element of a stove
$25 ea though.
https://www.mouser.com/ds/2/205/Viewer-738438.pdf
I wouldn't build a preamp either that required 29 transistors.
If one of them decided to take a dump, it would be hell trying to figure out which one it was.
It is actually together with shunt regulator power supply.
No global feedback at DC?
A quick look at the circuit. The Big Boy has no global feedback at DC? Could be interesting to see what happens to the offset at the output as the amplifier warms up. Might share some of that excess heat with the speaker.
And just to remind everyone, have a look at the Pass Aleph 5 schematic.
A quick look at the circuit. The Big Boy has no global feedback at DC? Could be interesting to see what happens to the offset at the output as the amplifier warms up. Might share some of that excess heat with the speaker.
And just to remind everyone, have a look at the Pass Aleph 5 schematic.
An externally hosted image should be here but it was not working when we last tested it.
Hugh may have a more concise answer, but yes, that was a conscious decision for moderate amounts of global feedback to be applied at only higher frequencies. Regarding the Aleph 5 schematic - that’s why attribution for this amp goes in part Mr Pass. But notice that the front end is very different. BJTs, no CCS, and a modified Lender topology with KSC1845 straddling the “long neck pair.” And the outputs are P-channel MOSFETs.