Nowater must be psychic - this was one of my original ideas. Since it doesn't involve cutting, I'm onboard with the 6ft tall tower amp - tipped back slightly.
I'm not sure what kind of base to make for it, though. It's heavy enough to kill my dog if he decides to play tug of war with the cables. I figured I'd make a small box at the bottom and place the PS and control boards in the box, then place the transistors in intervals along the back.
Any suggestions on the base / box size, or on how to mount something that large and heavy?
I'm not sure what kind of base to make for it, though. It's heavy enough to kill my dog if he decides to play tug of war with the cables. I figured I'd make a small box at the bottom and place the PS and control boards in the box, then place the transistors in intervals along the back.
Any suggestions on the base / box size, or on how to mount something that large and heavy?
Just $0.02 to agree with Jennice - the thermal resistance is not a linear function of length.
The Wakefield extrusion catalogue quotes everything in 3" lenghts and shows a de-rating curve for longer lengths. To halve the thermal resistance of a 3" length, with convection flow, you need a 12" length. So for maximum efficiency you should use lots of short vertical sections.
Also, don't forget the thermal resistance of the insulating washer. Dissipate the power you want over as many devices as possible - the temperature rise between sink and case will reduce by that factor. Though you are concerned about the heatsink temperature rise above ambient, don't forget about the device rise in temperature above the sink temperature.
Regards
13th Duke or Wymbourne
The Wakefield extrusion catalogue quotes everything in 3" lenghts and shows a de-rating curve for longer lengths. To halve the thermal resistance of a 3" length, with convection flow, you need a 12" length. So for maximum efficiency you should use lots of short vertical sections.
Also, don't forget the thermal resistance of the insulating washer. Dissipate the power you want over as many devices as possible - the temperature rise between sink and case will reduce by that factor. Though you are concerned about the heatsink temperature rise above ambient, don't forget about the device rise in temperature above the sink temperature.
Regards
13th Duke or Wymbourne
The thermaflo site numbers seem to be taking length into account:
If I cut this into 3" sections, each should dissipate 56W at 35C rise above ambient. Since I would have 24 of them, it could dissipate 1344W at 35C above ambient. But this would result in 240 linear inches of the material, so I'd have to find a creative arrangement to use that much (a stepped pyramid comes to mind), and it'd be a lot of cuts (I still haven't figured out how to cut it at all, let alone cleanly).
If I cut it into 36" sections, each should dissipate about 320W at 35C rise, for a total of 640W.
I can't get data above 48" sections from their site, but since 320W/36" section accomplishes my goal of 300W/channel dissipation, I'd say that's probably the way to go. Two 36+" high monoblocks would be lighter and easier for me to transport.
Something else the manufacturer's data seems to be taking into account (at least with the surface area) is the back side of the heatsink where the transistors will be mounted. This may mean that all those folks who are building vert fin amps with top covers may be sacrificing ~10% performance. Well-vented top and bottom covers might help this some, but certainly not completely.
If I cut this into 3" sections, each should dissipate 56W at 35C rise above ambient. Since I would have 24 of them, it could dissipate 1344W at 35C above ambient. But this would result in 240 linear inches of the material, so I'd have to find a creative arrangement to use that much (a stepped pyramid comes to mind), and it'd be a lot of cuts (I still haven't figured out how to cut it at all, let alone cleanly).
If I cut it into 36" sections, each should dissipate about 320W at 35C rise, for a total of 640W.
I can't get data above 48" sections from their site, but since 320W/36" section accomplishes my goal of 300W/channel dissipation, I'd say that's probably the way to go. Two 36+" high monoblocks would be lighter and easier for me to transport.
Something else the manufacturer's data seems to be taking into account (at least with the surface area) is the back side of the heatsink where the transistors will be mounted. This may mean that all those folks who are building vert fin amps with top covers may be sacrificing ~10% performance. Well-vented top and bottom covers might help this some, but certainly not completely.
Batee,
It sounds like you got yourself a plan
Two monoblocks seem much easier to build than a stepped pyramid. Also, it must be considered that a stepped pyramid will not be able to bring good cooling to the higher steps of the pyramid. The rising, hot air from the outer, low heat sink sections will block for fresh air to the higher sections. It would be vary inefficient.
Btw. If you were to place power transformers, caps, etc. on the base of a leaned-back amplifier, I don't think it will be that easy for your dog to tip over. The dog-proof version will simply have the cables exit at the base of the amp. Thus, the amp will be dragged along and not tipped over, if your dog sould be wanting to play.
Jennice
It sounds like you got yourself a plan
Two monoblocks seem much easier to build than a stepped pyramid. Also, it must be considered that a stepped pyramid will not be able to bring good cooling to the higher steps of the pyramid. The rising, hot air from the outer, low heat sink sections will block for fresh air to the higher sections. It would be vary inefficient.
Btw. If you were to place power transformers, caps, etc. on the base of a leaned-back amplifier, I don't think it will be that easy for your dog to tip over. The dog-proof version will simply have the cables exit at the base of the amp. Thus, the amp will be dragged along and not tipped over, if your dog sould be wanting to play.
Jennice
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