ACA V1.5 Illustrated Build Guide

[Alan4411]

There are good days and there are bad days. I guess today was the later. I think I will let it sit for a day or two and search to find my mistake (or mistakes).

Please see responses on main thread.
Amp Camp Amp - ACA

 

[gridgway]

How hot?

I have just powered up for the first time to set the bias voltage. All good, with no smoke! Set the voltage ok.

I wasn't quite expecting the speed of the heat build up on the heatsinks! By the time I'd faffed around setting the bias, the heatsinks were hot - the temperature of hot water that is just getting too hot IYSIM! I'm thinking 60 degrees.

What is the normal running temp? I'm using a custom case, so I'm slightly nervous in case I have heatsinks that are not up to the job!

Cheers
Graham

 

[gridgway]

Having done a scientific experiment steaming milk with my coffee machine (putting my hand on the jug as the temp went up), I think I've over-estimated temp. It wasn't 60 degrees, but more like 45. But still too hot I think.

Can anyone help with how big the heatsinks need to be? How big are the ones in the case that comes with the kit?

Thanks
Graham

 

[spiggs]

Having done a scientific experiment steaming milk with my coffee machine (putting my hand on the jug as the temp went up), I think I've over-estimated temp. It wasn't 60 degrees, but more like 45. But still too hot I think.

Can anyone help with how big the heatsinks need to be? How big are the ones in the case that comes with the kit?

Thanks
Graham

I just finished an ACA build with a custom case using heatsinks from the Diyaudio store. The sinks with the kit are 200mm x 80mm, I went with 200mm x 120mm. Both have 40mm fin height. Mine lives in a cabinet and gets hot to the touch but not what I think unreasonably so, just a bit more than where you would want to leave your hand on the sinks. I think 50c for these is normal from my reading but I will let those who know what they are doing comment.

 

[Alan4411]

I have just powered up for the first time to set the bias voltage. All good, with no smoke! Set the voltage ok.

I wasn't quite expecting the speed of the heat build up on the heatsinks! By the time I'd faffed around setting the bias, the heatsinks were hot - the temperature of hot water that is just getting too hot IYSIM! I'm thinking 60 degrees.

What is the normal running temp? I'm using a custom case, so I'm slightly nervous in case I have heatsinks that are not up to the job!

Cheers
Graham

They are hot!
That is normal for Class A, each channel dissipates 36 Watts in heat.
Papa Pass test is if you can hold your hand on it for a couple of seconds after it has been on over half an hour, everything is fine. (55 to 60 degrees C depending on ambient temperature.)

If your heatsinks are much smaller than the kit versions and / or ventilation is restricted temps might be higher of course...

Go and enjoy, Alan

 

[gridgway]

Thanks for the help. Assuming the measurements are of the finned area of the heatsink (excluding any 'edge'). That's about 24 sq inches. Mine are smaller at about 18 sq inches. If they need the bigger size, mine are definitely marginal. I need to borrow an IR laser thermometer thing and see how they go.
Cheers
Graham