4U300 should work for most of the 25 Watt designs, depending on the ambient temperature where you live.
I am a big fan of 4U400, as it provides some reserves to play with higher bias and the like. And it also works well with Aleph J, which is one of the hotter FirstWatt amps.
3U400 is also a nice form factor and should provide a bit better cooling than 4U300.
2U probably will not work.
Regards, Claas
I am a big fan of 4U400, as it provides some reserves to play with higher bias and the like. And it also works well with Aleph J, which is one of the hotter FirstWatt amps.
3U400 is also a nice form factor and should provide a bit better cooling than 4U300.
2U probably will not work.
Regards, Claas
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Unless you do all the thermal calculations, always err on the side of too large heat sinks.
Use the advice given here on diyAudio for that kind of info.
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One of the main advantages of the Deluxe 4U/300 case is the the set of pre-drilled and tapped holes in the heatsinks. There is also a set of mounting holes in the thick front panel.
Regardless, I more often use the deeper 400 mm cases for their ease of installing dual transformers and filter boards.
Regardless, I more often use the deeper 400 mm cases for their ease of installing dual transformers and filter boards.
I have built an F6 (incl. PSU) in a 80mm tall 300mm long chassis, although with 50mm long fins. Nothing melts.
Good idea is to put top and bottom panels on small spacers for better internal cooling
That's good to hear. Would putting the power supply in a separate enclosure have saved much heat, or is it mostly coming from the amplifiers?
Good morning,
most of the heat is produced by the MosFets in the outputstage. This is the reason why they are mounted to the heatsink.
As higher you bias your MosFets, as more heat will have to be transfered away.
ClassA-amps are 'heaters'. Some are very hot....
The PSU doesn't produce real heat. But a toroid , bridge rectifiers,....will also become warm.
If you want to go the route with seperated PSU and smaller cases - perhaps you will have to use fans for cooling or can't bias as high with bigger heatsinks.
Also importatnt is to have enough space around your classA-amp for good airflow. It is no good idea to put them into a tight rack with reduced airflow around the heatsinks.
Cheers
Dirk
most of the heat is produced by the MosFets in the outputstage. This is the reason why they are mounted to the heatsink.
As higher you bias your MosFets, as more heat will have to be transfered away.
ClassA-amps are 'heaters'. Some are very hot....
The PSU doesn't produce real heat. But a toroid , bridge rectifiers,....will also become warm.
If you want to go the route with seperated PSU and smaller cases - perhaps you will have to use fans for cooling or can't bias as high with bigger heatsinks.
Also importatnt is to have enough space around your classA-amp for good airflow. It is no good idea to put them into a tight rack with reduced airflow around the heatsinks.
Cheers
Dirk
Good morning,
most of the heat is produced by the MosFets in the outputstage. This is the reason why they are mounted to the heatsink.
As higher you bias your MosFets, as more heat will have to be transfered away.
ClassA-amps are 'heaters'. Some are very hot....
The PSU doesn't produce real heat. But a toroid , bridge rectifiers,....will also become warm.
If you want to go the route with seperated PSU and smaller cases - perhaps you will have to use fans for cooling or can't bias as high with bigger heatsinks.
Also importatnt is to have enough space around your classA-amp for good airflow. It is no good idea to put them into a tight rack with reduced airflow around the heatsinks.
Cheers
Dirk
So what I'm hearing is those big 4U heatsinks really are important for a class A amplifier. Got it. That makes sense.
As a thought... I wonder if you could sandwich the MOSFETS between *two* heatsinks, one outside the case and one inside (with proper internal ventilation). Mount the driver boards in the center and run wires to each MOSFET. If the power supply is in a separate chassis, there should be room for the additional volume.
(I'm just really into the idea compact boxes
)
Forced cooling will be easier. But by all means try and let us know
I have seen small heat sinks on FETs on the inside to aid cooling, would be fun to see a sandwich of two full heatsinks
I very much want to avoid fans if at all possible. I agree that forced cooling would be easier. Putting it all in a bigger case with normal heatsinks would also be easier
I think I'll go with the standard 4U Deluxe case for my first build, try branch out from there. I definitely want to try a super compact build at some point! Maybe twin monoblocks that share a separate power supply enclosure? Only my bank balance can stop me!
SoaDMTGguy:
I'm also a fan of the 4U/400 Dissipante chassis. In the past, HiFi2000 offered a Deluxe version of that chassis (i.e., with the UMS holes drilled). Now, it's no longer part of their standard offerings but is available as a special order. A 400mm deep chassis gives you plenty of space -- lots of elbow room. I'd recommend it and the UMS drilling as a special order -- well worth the price.
Regards,
Scott
I'm also a fan of the 4U/400 Dissipante chassis. In the past, HiFi2000 offered a Deluxe version of that chassis (i.e., with the UMS holes drilled). Now, it's no longer part of their standard offerings but is available as a special order. A 400mm deep chassis gives you plenty of space -- lots of elbow room. I'd recommend it and the UMS drilling as a special order -- well worth the price.
Regards,
Scott