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Old 21st March 2014, 10:21 PM   #1
domyboy is offline domyboy  Scotland
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Default Watercooled HEXFET Power Amplifier

Some pictures below of my watercooled power amplifier. OTT I know but I just wanted to build it.


I created a video of the build here:

https://www.youtube.com/watch?v=WGpau-raMho

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Last edited by domyboy; 22nd March 2014 at 12:46 PM.
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Old 21st March 2014, 11:26 PM   #2
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Tnx!
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Old 22nd March 2014, 09:59 AM   #3
AndrewT is offline AndrewT  Scotland
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Is the fan sucking through the cooler?

The cooling will work better if you can get the fan under the cooler and get it to blow through the cooler.

The fan will also run cooler when it is out of the warm air stream.
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Old 22nd March 2014, 12:25 PM   #4
domyboy is offline domyboy  Scotland
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Quote:
Originally Posted by AndrewT View Post
Is the fan sucking through the cooler?

The cooling will work better if you can get the fan under the cooler and get it to blow through the cooler.

The fan will also run cooler when it is out of the warm air stream.
Andrew

The fan is pulling air through the radiator.

Yes I agree. Originally that was my intention. I thought about mounting the radiator vertically with a push pull with fans on low speed but it caused problems with the loop arrangement because I had limited compression fittings. The same problem occurred when I mounted the fan underneath to push air through the radiator.
If I was to build another there are many things I would change in this design. a few of the main changes would be; waterblock mounted onto case horizontally, transistors mounted at the edge of the PCB, no through hole bolting, vertical radiator, TO264 transistor packages, combined auxiliary power/Main power PCB and last but not least getting a machine to drill out the copper waterblock!

Kind Regards
Dominic
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Old 23rd March 2014, 02:13 AM   #5
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You may already know this but a small spacer between the fan and the radiator improves fan noise and cooling performance by a usually worthwhile amount. Though those particular fans are very quiet already.
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Old 23rd March 2014, 09:32 AM   #6
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Originally Posted by mt490 View Post
...a small spacer between the fan and the radiator improves fan noise and cooling performance...
I'm using an old defective fan after removing motor and blades. With the right shape such a spacer allows you to make use of the centrifugal force developped in any axial fan: https://www.google.de/search?q=swift...w=1024&bih=612
Dominic, in this thread (#8) and the related links you'll find some hints about building a water cooling system. Do you use a pump to improve the water flow? (Is it that acrylic piece in the pictures, or is it just a expansion vessel?)

Last edited by franzm; 23rd March 2014 at 09:37 AM.
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Old 25th March 2014, 01:25 PM   #7
domyboy is offline domyboy  Scotland
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Quote:
Originally Posted by franzm View Post
I'm using an old defective fan after removing motor and blades. With the right shape such a spacer allows you to make use of the centrifugal force developped in any axial fan: https://www.google.de/search?q=swift...w=1024&bih=612
Dominic, in this thread (#8) and the related links you'll find some hints about building a water cooling system. Do you use a pump to improve the water flow? (Is it that acrylic piece in the pictures, or is it just a expansion vessel?)
Hi Franzm

Yes the arylic peice is a small reservoir with a pump at the bottom. Mounted with rubber anti vibration mounts. It runs from the 12V auxillary supply with its own 7812.
I usually use a shroud with radiators to help with the airflow but unfortunalty in this instance raising the fan any higher would cause it to clash with the IO connectors on the back panel.
Whilst this is my second amplifier build (i built my first 10 years ago) i have built many watercooled systems (mainly computers) over the years.

Thanks for those links though. Great for some lunchtime reading


Quote:
Originally Posted by mt490 View Post
You may already know this but a small spacer between the fan and the radiator improves fan noise and cooling performance by a usually worthwhile amount. Though those particular fans are very quiet already.
Yes but it would clash with the IO connectors on the back panel. On future projects i will be mounting the radiator and fan verticaly to save space and allow a fan shroud. Yes those Noctau fans are very quiet, just a shame about the terrible colour scheme lol.

Kind Regards
Dominic

Last edited by domyboy; 25th March 2014 at 01:28 PM.
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Old 2nd February 2016, 05:58 PM   #8
domyboy is offline domyboy  Scotland
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Smile Update

Just an update for everyone. I re-designed and built a new version of the original amplifier. Better board layouts and components as well a superior grounding system. I created a build log again https://www.youtube.com/watch?v=n_uH9kESMlU

Some general Info;
PCB manufacture
PCBs are created using UV exposure method and culpric chloride for etching. I then drill them and solder all copper on the underside. After soldering all the copper I clean with IPA and spraypaint top layer black.
Case
Is a standard black 4U rack case made by RS components.
Transformer
The main toroidal transformer is VTX rated 160VA with 30V twin secondaries.
Main PSU
Main power supply uses capacitance multiplier with active feedback to correct rail voltage for altering load impedances. Nichicon 10mF filtering caps are used in a first stage CRC filter then 4.7mF Panasonics are used for the capacitiance multiplier. Main regulating transistors are Tip35c/36c.
Amp Modules
Amplifier modules are based on a (VSSA) symetrical CFA topology with MJE340/350 for VAS stage and IRF240/9240 for output stage.
Aux PSU
Auxillary power board provides 12Vdc and 5Vdc for the water pump, radiator fan, protection board and input volume attentuator. All outputs use LM7812 and LM7805 regulator ICs.
Protection Board
Protection board detects DC offset on the outputs using a common RC filtering circuit and turns off solid state relays (TO-247 IRF044N) to protect loudspeakers.
Volume Control
Volume attenuator is based on the optocoupled method using NSL-32SR2S.
Water circuit
Custom made copper waterblock is used to transfer heat from transistors and out through the RS120 radiator. Reservoir and pump is an EK combined unit.

Any questions just ask.
Cheers Dom

Last edited by domyboy; 2nd February 2016 at 06:00 PM.
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