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Old 30th January 2013, 02:44 PM   #1551
6L6 is offline 6L6  United States
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Carsten - The photos are still not viewing, but your sample screenshot did have the photos...

?

Please try again, your project looks wonderful from the little I can see of it.
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Old 30th January 2013, 04:47 PM   #1552
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Hi,
ok, i think, i now where is the problem. I show these pictures in another forum and link it to here. Next try.

- Test building
Click the image to open in full size.
Click the image to open in full size.

-That is what i want ......
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

Hope now it is better. And more pictures i will show you when i am finished ....
How it sounds? ............
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Old 30th January 2013, 05:12 PM   #1553
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Quote:
Originally Posted by Earthloop View Post
Hoping to build a B1 buffer next but I was wondering if anyone knows,
A) What is the input sensitivity of the A40 for full output,
B) Can the amps run with approx +/- 40V rails (my transformer secondaries are 25V and I have replaced the JFET with 2N4392,
C) Could the output stage bias be increased to 2 amps. My speakers are 4 ohms and the A40 will move into class AB at 20 watts into this load.
Maybe these are really questions for Nelson Pass.
Earthloop: Nice work so far! I suggest asking your questions in a separate A40 thread (new or existing), as I get the feeling we're trying to keep this thread as a pics-only thread....
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Old 31st January 2013, 01:49 AM   #1554
bcmbob is offline bcmbob  United States
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Default Ugly Duckling in the Water

Here is a proof of concept project to incorporate water cooling for computers into a discrete power amp build. There was a successful build with a LM3886 project, but that is a big overshoot.
This type of amp might benefit more with this technique. To stay in the spirit of this thread I'll post subsequent developments and photos on that other thread.

The basic block is built from generic locally and widely available stock. The major element is 1/4" x 3" x 17" aluminum. Mine was cut from a piece of 3x3 angle but a company like Metals Depot has about all one would need. The 1/2" x 1/2 " channel was selected because it provided more "fins" per unit/mounting screw.

[IMG]Click the image to open in full size.[/IMG] [IMG]Click the image to open in full size.[/IMG]

The box is from a sheet of 3/8" Plexiglas cut on a table saw with connecting edges polished to 1600 grit wet sandpaper - then glued together with Plastruct Liquid Cement. Metal to Plexiglas meet with a thin automotive paper gasket with Goop on both sides. Blind threaded holes with 6-32 screws were used along with 1/16" x 1/2" angle for reinforcement. For safety reasons the cooling system must be self-contained and completely separate from the amp.

[IMG]Click the image to open in full size.[/IMG]

The power transistor mounting plate is attached with 8-32 screws into more blind tapped holes in the waterblock.

[IMG]Click the image to open in full size.[/IMG] [IMG]Click the image to open in full size.[/IMG]

The stilts were installed as I thought I would place the cooling system under the amp, but decided I needed to make sure it would work before going to all that trouble.

[IMG]Click the image to open in full size.[/IMG]

Success - Amp - cooler combination in full operation in a complete system.

[IMG]Click the image to open in full size.[/IMG]

These readings were done with simple IR gun (I bought a new meter with a thermocouple but I put that part somewhere I wouldn't loose it, and....) so they aren't exact or scientific. There is enough information though to warrant proceeding to the next phase as well as learning where the heat transfer can be improved. I suspect I'll be able to use a smaller pump and radiator/fan and still get the efficiency needed.

[IMG]Click the image to open in full size.[/IMG]

Readings



The air cooling readings are on the partially "de-feathered" ugly duckling with a few new parts and shorter wires.

[IMG]Click the image to open in full size.[/IMG] [IMG]Click the image to open in full size.[/IMG]

Sound wise - the new Audyn Plus input caps have produced a huge improvement in the brightness and stage of the amps. Several other parts upgrades will follow shortly.

[IMG]Click the image to open in full size.[/IMG]

BTW - the next phase will be cutting/folding the water block in half to avoid the 17" dimension for better placement (hidden) inside a chassis. Something like this:

[IMG]Click the image to open in full size.[/IMG] [IMG]Click the image to open in full size.[/IMG]
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Last edited by bcmbob; 31st January 2013 at 01:55 AM.
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Old 31st January 2013, 02:04 AM   #1555
bcmbob is offline bcmbob  United States
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The larger readings link is not working - try this.
Attached Images
File Type: jpg Readings.jpg (122.6 KB, 211 views)
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Old 31st January 2013, 02:58 AM   #1556
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Nice well thought out.

Not looking for a spoon feed on this question. Ill do a search if its a yes.

Has anyone done cooling using transformer oil?
I've got a ton of the light super nonconductive/high temp oil for cooling big transformers.
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Old 31st January 2013, 09:24 AM   #1557
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Quote:
Originally Posted by bcmbob View Post
concept project
Why go to all that trouble when a professional fluid heat exchanger plate can be had for little dollars, and superior in every way to your contraption.

Size and construction of your aquarium suggest little knowledge of fluids and thermodynamics.
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Old 31st January 2013, 09:42 AM   #1558
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Quote:
Originally Posted by jacco vermeulen View Post
Why go to all that trouble when a professional fluid heat exchanger plate can be had for little dollars, and superior in every way to your contraption.

Size and construction of your aquarium suggest little knowledge of fluids and thermodynamics.
He might like the building and learning process!

That said, what's sort of Comercial available unit would you propose for such a build?
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Old 31st January 2013, 10:19 AM   #1559
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Think I posted the following picture half a dozen times already.(up to 3-4ft length if so desired)
In Europe, at vendors as Burklin in germany.
In the US, think McMaster&Carr.

See If you can spot the significant differences between that one and bcmbob's cooler.
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File Type: jpg FluidC.jpg (90.9 KB, 308 views)
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Old 31st January 2013, 11:05 AM   #1560
bcmbob is offline bcmbob  United States
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Thanks sakellogg.

MASantos is right on point. It's all part of the DIY challenge. After about ten years of liquid cooling CPU projects, with a lot of Plexiglas and metal in the stash, I wanted to use what was on hand. Thinking it through is half the fun

jacco, if you look at the "LM3886 Project" link at the top of the first post you will see I did use something quite similar to what you are suggesting. I also considered pizio blocks but you still have to deal with removing the residual from the hot side. The 1/4" aluminum is an intentional overbuild as I had no prior experience with the reported high heat of a discrete amp. You know - "No matter how many times I cut it, it's still too short" The biggest problem was the thin walls on that cooler. One would still have to use a plate of at least 3/8", or a sophisticated clamping system for mounting the power transistors.

6L6 suggested if I had four power transistors I would be in the area of four 100W light bulbs. I did an initial test with a 500W halogen bulb to see if I was in the ballpark.

No doubt there are thousands of successful air cooled discrete builds, and some of the giant heat sink amps have a big aesthetic appeal on their own - just plain impressive in mass alone. This is just a trial of a different approach.

Here is a fun little video of the flow pattern:

Water Spread

Flows from canter, then side to side and back out the center. Not a perfect isolation but enough to hold uniformity across the plate.
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Last edited by bcmbob; 31st January 2013 at 11:32 AM.
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