Speaking of meek, I had need to use a 3U chassis for my Aleph clone. There's no way 100W/ch of heat would have worked, so after a think I pulled an output stage out of my Aleph 30. I guess this makes it an Aleph 20? Bias is now just a hair under 1.5A
It works on the bench & doesn't get too hot. This mod bought another 2V of rail swing and maybe a tiny 10mA increase in bias. The DC offset if anything got a touch better.
It works on the bench & doesn't get too hot. This mod bought another 2V of rail swing and maybe a tiny 10mA increase in bias. The DC offset if anything got a touch better.
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PC liquid cooling.
Take your 5U chassii (2 of them). Bolt a 3U chassis on top of each. No need for heat sinks on the 3U chassis, just make sure it is fully ventilated.
Mount one of them big CPU coolers on each side, the inside of the heat sinks, for a total of two per amp.
Run the cooling pipes from the back of the 5U chassis to the heat exchangers in the 3U above.
It will look like the radio the Traitors of Earth used to communicate with Ming Of Mars... but it will be most impressive!
Nelson made his Borgs, you will make your Ming Of Mars version. Very apropos, IMHO.
You'll have to do the calculations, but the heat dissipation for a big i7 or i9 is pretty impressive. I figure you need about an additional 300 watts per 1.2 amp.
You will still have to deal with the power but a simple power supply should handle it, I think. You won't need no fancy multi speed stuff like they do in PCs. Just pump the heat out, baby... pump that heat out.
https://www.pcgamer.com/noctua-nh-p1-passive-cooler-review-benchmarks/
https://www.pcgamer.com/best-cpu-coolers/
Another possibility would be to change the 5U heat sinks with flat slabs of metal. On the outside, mount some big Xeon class CPU coolers... that will work, BUT will be a bit loud. So, I'd recommend the liquid cooling to passive radiators to absorb the extra heat load.
Or this
https://www.amazon.com/Receiver-amplifier-cooling-thermoswitch-multi-speed/dp/B0106LT6B6
Mount the fans on the heat sinks. Some amp manufacturers do just that... mount fans on their heat sinks. I used to cool my tube amps like this when I had them in a mostly closed rack.
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I made an Aleph Mini with a 18vac transformer. I suspect it was around 15-20 watts. It sounded very nice. Only 2 devices on the outputs though. I bet yours sounds great. That lightweight aleph amp is what inspired me to take an interest in this thread. I suspect after I get through a few projects, I will build another aleph. Maybe even monoblocks.
I think the only issue with non-standard "cooling" based on air flow is that we really don't know how much "heat capacity" that will create.
The heat sinks in the 5U chassis that Randy was quoting are a row of simple vertical fins, less than an inch deep (*). They get hot enough on a heat dissipation of 300 watts for an A2. The 1.2 dissipates 500 watts.
The Krell that has those nice, expensive fins in a way that you can flow air over them. Force air through them ought to be simple. A single fan, with the cooling fins in a "tunnel" will flow cooling air through them.
With Randy's proposed chassis, to properly cool an A1.2, with a fan, would take full coverage, the heat sinks will have to sink an additional 100 watts per side, 200 per chassis. So, either build a box on either side or mount three cooling fans directly on either side. Either way, it's gonna look like a monstrosity. The thing is already 18 inches wide.
Or, like the Audio Research cooling fans of yore: enclose the sides of the chassis with an aluminum plate so that the air flow across the heat sinks is vertical and mount a "pizza box" enclosure above it with the fans drawing air from above it so it flows over the heat sinks. The whole thing could be built as a single piece "shroud". The problem is that without empirical data we really don't know how much cooling can such a set up handle.
Or... put the power supply in one chassis and the amps in another chassis... Will the 300 watt capacity of each chassis suffice?
Or got with active CPU cooling via pipes to external heat exchangers. We know the rating of those devices, the only issue being how to mount those heat pipes to a secondary heat exchanger chassis.
All, I can think though.. is that a 10U single piece chassis, per side, makes me thing lovingly of a Purifi amp. :-D
(*) I just measured it 38 fins per side. about 1 inch deep and 8 inches high with a slight serration, not much. Two sets of them get REALLY HOT for a single A2. So, assuming 300 watts of total heat dissipation for an Aleph 2, that makes each side good for 150 watts of passive heat dissipation.
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You could always mount large heatsinks to the inside of the vacant areas of the heatsink and put a fan in the top plate. That should get you a little bit. little heatsinks on the mosfets instead of a washers. Through holes in the heatsink leading into the fins to blow air through them. Although that may get dusty.
https://www.amazon.com/AC-Infinity-Top-Exhaust-Receivers-Components/dp/B01LVUWOBX
Can you mount two of those under the top lid of the chassis? And then run the cooling pipes directly to the center of the heatsinks... ( problem being the split sinks..two per side...).
https://www.amazon.com/dp/B08YRN162...pcg-us-1205760531180124400-20&geniuslink=true
Can you mount two of those under the top lid of the chassis? And then run the cooling pipes directly to the center of the heatsinks... ( problem being the split sinks..two per side...).
https://www.amazon.com/dp/B08YRN162...pcg-us-1205760531180124400-20&geniuslink=true
I've been listening to it now in my main system for a couple hours. In short, detailed and smooth but with bass punch & control. Helpful as I tend to listen to a lot of junk from the 90's on CD & it cleans up some of the treble fuzz.
It likes being barely driven by an ACP+ and doesn't seem to mind the weird series crossovers in my 2-ways. There are no caps between the amp's input and my ears.
Shows some active cooling options and gives an idea of their performance
https://gdrectifiers.co.uk/products/category/heatsinks_and_hardware/force_air_cooled_heatsinks/
PSBF160bgives 0.12c/w for 175mm and is 82mm x 82mm. This with a 12v fan but doesn't state air flow rate/ fan speed.
So quite good performance for a compact package
https://gdrectifiers.co.uk/products/category/heatsinks_and_hardware/force_air_cooled_heatsinks/
PSBF160bgives 0.12c/w for 175mm and is 82mm x 82mm. This with a 12v fan but doesn't state air flow rate/ fan speed.
So quite good performance for a compact package
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PS260 over 300mm gives 0.07c/w with a 5m/s airflow. 125x135mm extrusion.
I've been looking lowering the heat of my Aleph 30. I thought I had 'asbestos' fingers as I can generally get hot plates out of the oven much to my wife's bemusement. But the Aleph sinks feel pretty damn warm to me. 5 seconds is a grimace! IR and K probe thermometers both agree on late 40s, early 50s however.
I've been looking lowering the heat of my Aleph 30. I thought I had 'asbestos' fingers as I can generally get hot plates out of the oven much to my wife's bemusement. But the Aleph sinks feel pretty damn warm to me. 5 seconds is a grimace! IR and K probe thermometers both agree on late 40s, early 50s however.
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We have one of them IR hand held probes too... On a hot summer day with inside room temps at 78F, I've measured 60C+ on the heat sinks of my A2s in Randy's specified 5U case. So, at 300w dissipation we are really getting those heat sinks very hot. Going to 500w is gonna make them REALLY HOT. I don't think the 5U case can handle 500w without going to forced air or some means of adding more heat sinks.
Since each sink is dissipating 150w at 60C (summer mode)... perhaps adding a 3rd heatsink to the front panel might take us close to the 500w under 65C or so? Can you shift some of the components to a 3rd set of heatsinks?
Could Giancarlo (that's his name?) come up with such a 1.2 designed chassis? it would take a special front panel.
The more I look at this, the more I understand Nelson Pass's Borg design for these amps. They really need lots of cooling fins. A few months ago I ran into an actual pair of XA160.8 in the flesh (metal). That thing is HUUUUUGE. The good thing about the original Aleph's Borg design is that when driving big Maggies you can hide them behind. Like I told my my wife. She said: "Ugh, they're ugly".. I replied "that's why the Maggies are so wide".
Randy, I fear you have reached the thermal limit for a single passive cooled case unless the Italians can build a Borg or a 7U case.
Or. one more thing... could different, larger, more complex heat sinks fit into the side of the case? The current fins are only 1 inch deep, perhaps deeper 2 inch heat sinks might do the trick? As it is, the chassis is 18" wide, so it would still come under 20inches. I think the XA160.8 is wider yet!
I'm afraid, though, that hanging wider heat sinks with built in fans will make the amp very wide unless you go to a completely different case layout.
Perhaps the active shroud idea with side plates directing the airflow might work... I don't know. I don't know how to calculate the heat dissipation. You will have to do some fabrication... or just get one of them cooling fan gizmos I gave you the link above, put it on top of the big F5 Turbo V3 and see how much it cools it.
Naturally, when going to such dissipations, you will need a red LED because these amps will run lot hotter than the cool running blue LED.
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XRK over on the Alpha Nirvana thread have good results with those cpu coolers you linked to Tony.... your last link...well not those exact ones but that form factor . There are some beefy Dell and HP ones available cheaply enough and coupled with a Noctua quiet fan....gives a good solution. Using 2 output devices per sink but probably quite a bit less bias than Aleph
But if I have two 50vdc rails on one mono I don't need some Room above 50V or will I be ok?