@Vunce In my case, the total area of the radiator will be about 1200 centimeters, which seems sufficient for dissipating 90 watts of power.
Μy setup for AN39 is 21.5 +/- rails at 2.6A= 56+56 total 112W
No problem with active fan .With a room temperature of 29-30 C degrees in summer I have a temperature on the body of the mosfet of 56C degrees and on the heatsink 44-46 C. No noise at all ....120mm fan.
I will follow your example regarding the 1.8K resistor.Thank you.
@manniraj I have had positive experience using the Hood 1969 amplifier with a switching power supply and a small case.
That's 8 watts amp...yes, that chassis can handle jlh amp. Built few versions of jlh into similar case. But AN is different beast. You were warned. Suit yourself.
@adason Yes, maybe I'm wrong, but I want to understand. You use the "4u400 modushop" chassis for two channels. In my case, these will be monoblocks. Then my question is, what radiator area is needed for one passive cooling channel at an ambient temperature of 24 degrees?
Yes, I agree. But JLH has 15% efficiency compared to 43% for AN and we are talking about one channel. I will conduct tests )))
Please do. I am not discouraging you from building AN39, its one of the best amplifiers i heard, got two, but it will need forced air cooling in that enclousure, even as monoblock.
Yurid,
Please listen carefully to the advice from Danny, Adason, Vunce, and Manniraj. All have built the AN39 and all know that dissipating 180W of low grade heat is a serious business. If you scimp on the heatsinking you will be melt your amp, and destroy your Class A expectations......
Furthermore, you live in Israel which experiences similar climate to Australia, where I live. Recently we suffered through a week of over 35C (95F) and one day was 39C in my Melbourne suburb. While you may not enjoy your amp on those hot days, you need lots of heatsinking.
The other option for you is a fan to force air over the heatsink and even at low speed fans the heatsinking capacity if more than doubled. This might change your plans, as a forced air cooling requires a different approach to passive heatsinks.
It is in the area of thermal management where you must start your plans for AN39. EVERYTHING about this amp comes back to heat. Make a mistake and you can waste a lot of time and money as the amp will fail.
Cheers,
Hugh
Please listen carefully to the advice from Danny, Adason, Vunce, and Manniraj. All have built the AN39 and all know that dissipating 180W of low grade heat is a serious business. If you scimp on the heatsinking you will be melt your amp, and destroy your Class A expectations......
Furthermore, you live in Israel which experiences similar climate to Australia, where I live. Recently we suffered through a week of over 35C (95F) and one day was 39C in my Melbourne suburb. While you may not enjoy your amp on those hot days, you need lots of heatsinking.
The other option for you is a fan to force air over the heatsink and even at low speed fans the heatsinking capacity if more than doubled. This might change your plans, as a forced air cooling requires a different approach to passive heatsinks.
It is in the area of thermal management where you must start your plans for AN39. EVERYTHING about this amp comes back to heat. Make a mistake and you can waste a lot of time and money as the amp will fail.
Cheers,
Hugh
Great post Hugh,
This is why I am waiting to continue with my AN39 build. I am building other projects first, gaining knowledge and building tips from other people on the forum. I have more than enough projects in the wings to build, experiment with, and gain valuable knowledge to carry forward to when I want to continue the AN 39 build.
Yurid, good luck with your build.
MM
This is why I am waiting to continue with my AN39 build. I am building other projects first, gaining knowledge and building tips from other people on the forum. I have more than enough projects in the wings to build, experiment with, and gain valuable knowledge to carry forward to when I want to continue the AN 39 build.
Yurid, good luck with your build.
MM
Its enough my friend if you put one mosfet per heatsink ONLY but long cables more capacitance....only if you put the main board on the center of the box so...the space its limited about the PSU then....ALL its the bias ... 1.8A? 2A? 2.6A? 3A? biggest heatsinks more comfortable but too expensive and soooooo heavy .
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Yurid,
As Hugh and others have already mentioned, the heat dissipation from the AN is still quite considerable, despite it's relative efficiency as a Class A power amplifier.
Around 90 watts to dissipate per channel, it is better to look for passive heat-sinks that are more like 300mm * 200mm (5U), or if you can get longer ones then go for 350mm * 150mm or 400mm * 150mm. Ideally, the "base plate" of the heat sink should be at least 8-10 mm, and the fin length 35-40mm (can be more).
If you plan to use a more compact chassis - even as mono-blocks, then use fans to help with the cooling.
As Hugh and others have already mentioned, the heat dissipation from the AN is still quite considerable, despite it's relative efficiency as a Class A power amplifier.
Around 90 watts to dissipate per channel, it is better to look for passive heat-sinks that are more like 300mm * 200mm (5U), or if you can get longer ones then go for 350mm * 150mm or 400mm * 150mm. Ideally, the "base plate" of the heat sink should be at least 8-10 mm, and the fin length 35-40mm (can be more).
If you plan to use a more compact chassis - even as mono-blocks, then use fans to help with the cooling.
And that's exactly it. Each mosfet has its own 300mm×90mm radiator with a fin length of 50mm.
You will be on the limit but it all depends on the current..Officially for 4 Ω speakers Mr Hugh gives 2.2A bias.
If you can fit everything inside, a main board amp - trafo 300/400Va - and power supply- SSR output protection-Soft start , it will be fine.If you have already purchased the boxes, go ahead. It's really great to put a fan in it. You'll see it in action.
If you can fit everything inside, a main board amp - trafo 300/400Va - and power supply- SSR output protection-Soft start , it will be fine.If you have already purchased the boxes, go ahead. It's really great to put a fan in it. You'll see it in action.
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Then ....you are very cool....if you can put all these above stuff in your box.
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