water cooled zen amp.

[firezab]

hi all,

I am trying to build a zen amplifier. I would like to use a water cooled heatsinK that they use in a PC system.

My plan is to used a large radiator and stack them if it is not enough. The cpu waterblock will be mounted directly behind. if it is not enough i can add another waterblock to remove more heat. The fans for the radaitor will be controlled by a fan controller with a temp sensor and also i can control the fan noise level.

Have anyone tried this method as i think it can reduce the amount of heatsink to be used.




Anthony Koo

 

[Raoul]

There are a few threads about water cooling. For example:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=41086&highlight=

Try searching for water cooled or water cooling. You will probably have to dig through a lot of threads, though.

edit: Nelson also posted a motor controller circuit somewhere in the Pass Labs forum.

 

[BillH]

Hi, Anthony.

I haven't tried water cooling an amplifier, but have water cooled my PC for about two years. The best source for technical information on water coling I've found is the forums at Procooling.com. It's aimed at PC cooling, but it applies to your amplifier as well.

If noise is an issue, you could use a passive radiator with no fans. I'm using an 8' length of 3/4" diameter copper tube on the floor as a radiator with no fans other than one 120mm fan on a speed controller in the PC case. The CPU it's cooling dissipates ~70 watts and the radiator keeps it at about 40° C.

Good luck on your project, and let us know how it turns out.

 

[firezab]

hi ,


Thanks for your reply. I am going to start buying the part.
and for the casing, i will be using a spare tower server case that i have.

one more question, I cannot find the 2 MH inductor coil in the MCM website. I do not know if i can get that locally in singapore. Any other replacement that i can use ??

 

[carpenter]

Ok, so my amp is the F4, not the Zen, but water cooling is what I'm interested in.

My question: does the water conduct enough voltage to become problematic between fets should I decide to not use mica isolators?

I will daisy-chain plastic tubing between fet cooling mounts--the mounts will be some type of brass plumbing fitting from Home Depot that accepts compression connectors.

John

 

[Magura]

Unless you got somewhere like a pond in the garden, a huge radiator or the like, where you can dump the heat.....the point of water cooling is moot. But you already knew that, didn't you?

The math behind cooling is fairly simple. You got X watts of energy, and you got Y surface area to loose that energy from, which results in Z temperaure rise per watt. All you have to add to this simple math, is the thermal resistance figures for the path from the device to the finns of the heatsink.

Now if you mount the devices in need of cooling directly on the heatsink, or you put a heat transfer system in between the device and the heatsink, makes only one difference, and that is the thermal resistance of the heat transfer system, that being water or just a plain lump of aluminum. So you actually need to ADD heatsink if you use water to transfer the heat from the device to the heatsink, in order to keep the device at the same temperature as if it was just bolted onto the heatsink.....bad business!
The reason to use watercooling in a computer, is the space constraints, you have no such when building an amplifier, so you can just bolt the devices directly onto the heatsink.

There are options that can lower the working temperature of the device, like a copper heatspreader, or even better, a carbon heatspreader, but we are talking details here, not something in an order of magnitude worth considering generally.

Magura

 

[carpenter]

Hi Magura,

My primary concern is that voltage may carry through the water to the other fets if I don't use mica isolators.

For the sake of simplicity, I prefer not to use isolators; I'd rather physically separate--and isolate with plastic tubing--the water cooled fet mounts.

At low voltages, I'm inclined to think that voltage transference through water will be negligible; just wondered if anyone else had experimented with this concept.

John

Yes, I realize that there must be a means of extracting waste heat from the coolant.

 

[Nelson Pass]

My primary concern is that voltage may carry through the water to the other fets if I don't use mica isolators.

If you are using resaonably pure water, there should be no
problem. Sea water would probably conduct too much.

 

[carpenter]

Thanks Nelson, now that's what I was hoping to hear.

Check: no seawater!

 

[Magura]

Check: no seawater!

The water will become contaminated over time no matter what you do. However there is another solution that looks somewhat more attractive.
If you use oil you will largely be able to ignore the issue of conductivity of the coolant.


Magura

 

[MJL21193]

, and that is the thermal resistance of the heat transfer system, that being water or just a plain lump of aluminum. So you actually need to ADD heatsink if you use water to transfer the heat from the device to the heatsink, in order to keep the device at the same temperature as if it was just bolted onto the heatsink.....bad business!
The reason to use watercooling in a computer, is the space constraints, you have no such when building an amplifier, so you can just bolt the devices directly onto the heatsink.

Hi,
In a hardcore, overclocked computer you need efficient heat dissipation. In a water cooling system, the heat transfer is helped by a circulation pump that literally pumps the heated water away from the CPU and replaces it with cool water. This system doesn't use a heatsink, it uses a radiator. Heated water enters the radiator and the heat is extracted. This can be helped by a fan, to move the air across the radiator (similar to a cars cooling system).

This is a very effective way to cool, but it's complex and expensive. Unless the radiator is passive, you have fan noise. If you can live with fan noise, it might be more worthwhile to actively cool a regular heatsink.

Big score on the bragging rights though.

 

[cviller]

Is this carpenters idea?

How long does the orange joints need to be in order to transfer the energy to the water at a given velocity? And how about thermal tracking between the fets, wouldn't that be a lot better if they were all mounted on the same lump of iron?
I doubt waters thermal conductivity is sufficient for such a setup...

 

[Boris_The_Blade]

My primary concern is that voltage may carry through the water to the other fets if I don't use mica isolators.

At low voltages, I'm inclined to think that voltage transference through water will be negligible; just wondered if anyone else had experimented with this concept.

It wouldn't be hard to test. Take a tube of water of whatever length and put it in a U shape with water in. put two copper leads in each end and hook up whatever the operating voltage is. If you see bubbles, then no go. Try some type of oil, as it is far less conductive.

I believe you can also get special liquids made for this from places like newegg. It will probably be far less corrosive to the copper sinks than water.

g'luck

 

[MJL21193]

Distilled water (available at most drugstores) is completely non-conductive.
It also doesn't corrode copper.

 

[carpenter]

Thanks for the replies, guys.

I like the idea of using a radiator! I have a deck just outside my listening room--I could mount it there.

Distilled water sounds like the immediate candidate.

 

[Magura]

Hi,
In a hardcore, overclocked computer you need efficient heat dissipation. In a water cooling system, the heat transfer is helped by a circulation pump that literally pumps the heated water away from the CPU and replaces it with cool water. This system doesn't use a heatsink, it uses a radiator. Heated water enters the radiator and the heat is extracted. This can be helped by a fan, to move the air across the radiator (similar to a cars cooling system).

This is a very effective way to cool, but it's complex and expensive. Unless the radiator is passive, you have fan noise. If you can live with fan noise, it might be more worthwhile to actively cool a regular heatsink.

Big score on the bragging rights though.

Now all you need is to tell us what the actual difference is between a radiator and a heatsink when it comes to dissipating heat?

Radiator= heatsink with liquid running through it....hence thermal resistance calc looks like this:

Thermal resistance from device to cooling block + thermal resistance from cooling block to liquid + thermal resistance from liquid to heatsink (radiator)......or you could just lay low and stick to thermal resistance from device to heatsink


Magura

 

[Daveis]

Is the slow heat up time desirable for audio amps?
It might take an hour to fully reach thermal equilibrium.

You'd need a pretty big radiator to dissipate 200-300 watts.
I'd guess a three by 120mm PC radiator system.
Cost would likely be $150 USD.

Likely the water cooling system would cost more money than big passive heat sinks. But it would have a cool factor in that it might be less weight and smaller.

I've wondered if you couldn't mount an Aleph with water cooling into a normal PC case. Since PC cases are pretty much commodity the cost might work out.

 

[MJL21193]

Now all you need is to tell us what the actual difference is between a radiator and a heatsink when it comes to dissipating heat? ......or you could just lay low and stick to thermal resistance from device to heatsink

Ever wonder why most car engines are water cooled and not air cooled? It's more efficient, that's why. Yes, there are more steps, more complication but it's worth it because it's more efficient.

Think about how quickly heat travels through an aluminum heatsink. Now think about how fast water can travel through a radiator. There's the difference. Got it?

 

[Magura]

Think about how quickly heat travels through an aluminum heatsink. Now think about how fast water can travel through a radiator. There's the difference. Got it?

I greatly respect your input, but in this case you need to do the math....it's a plain matter of radiating surface area. It is no problem to make the heat travel through the aluminum, as long as there is enough of it. The speed is of no importance in this aspect.


Magura

 

[Magura]

Ever wonder why most car engines are water cooled and not air cooled? It's more efficient, that's why. Yes, there are more steps, more complication but it's worth it because it's more efficient.

That is not the reason for watercooling in cars.
The reason is partly to reduce fan noise (read up on it at the Porsche website) and partly that watercooling can be distributed more even in a car engine.

Magura