Thanks, bear. The idea, of course, is the opposite: to increase heat transfer per black-body theory (wood stoves for example). The paint coating would also fill some minor scratches and smooth sharp edges and thereby improve the looks.
Your logic is convincing to me, though, and I think I will pursue anodizing or leave it alone. I know how to paint but nothing about anodizing - another thing to learn - so I need to get off my lazy butt and figure it out.
With regard to Nelson's proprietary heatsinks, thanks Bobodioulasso and jacco for your answers, they make perfect sense. I posted this late last night, and then realized this morning (smack forehead!) that access to those heatsinks would also give the Pirates and Cloners and Persons of Loose Ethics and Primitive Sods Who Laugh at the Concept of Intellectual Property a big boost in trying to make fake First Watt amps.
I have read that black body radiation isn't really useful when applied to heat sinks. I think it appeared among a manufacturers 10 Myths list. Admittedly, I was surprised to read it.
I wonder if copper electroplating might be an option, though. At least it would look cool, I think. Copper is a superior medium to aluminum for conducting heat but is seldom used due to cost vs.performance. It was mentioned that aluminum is easy to extrude and copper wasn't.
I wonder if copper electroplating might be an option, though. At least it would look cool, I think. Copper is a superior medium to aluminum for conducting heat but is seldom used due to cost vs.performance. It was mentioned that aluminum is easy to extrude and copper wasn't.
burned out PA amp as enclosure
As I wrote earlier in this thread, I plan to build an F5.
I am low on budget and therefore I decided to ask around in local professional audio/event companies for a burned out PA amp 19" enclosure with big heathsinks on the left and right and offering some little money for it.
Some few mails later I got this very suitable enclosure from a shop very nearby for the price of ONE new heathsink:
It was a Hafler 550 Watt amp. Made in USA, not in China
It will be easy to add another frontplate, as I dont need any knobs on the front, just a LED.
The nice things are:
- mains connector, fuse and primary cabling, including thermistor, already installed.
- Output connectors already here
- also rectifiers are available
- heathsinks seems to be in a good size for 2 x 90W
Unfortunately, the trannie is not usable, as I was expecting it: it delivers after the rectifiers 50-0-50 VDC, twice.
Yes, there are two auxilliary secondaries, delivering 20-0-20VAC at 8 Ohm DC resistance.
But I doubt, they are powerful enough to drive an F5.
No problem, as I will go with the 20-0-20VAC torroide I choosed earlier.
Looking forward to build this amp!
Franz
As I wrote earlier in this thread, I plan to build an F5.
I am low on budget and therefore I decided to ask around in local professional audio/event companies for a burned out PA amp 19" enclosure with big heathsinks on the left and right and offering some little money for it.
Some few mails later I got this very suitable enclosure from a shop very nearby for the price of ONE new heathsink:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
It was a Hafler 550 Watt amp. Made in USA, not in China
It will be easy to add another frontplate, as I dont need any knobs on the front, just a LED.
The nice things are:
- mains connector, fuse and primary cabling, including thermistor, already installed.
- Output connectors already here
- also rectifiers are available
- heathsinks seems to be in a good size for 2 x 90W
Unfortunately, the trannie is not usable, as I was expecting it: it delivers after the rectifiers 50-0-50 VDC, twice.
Yes, there are two auxilliary secondaries, delivering 20-0-20VAC at 8 Ohm DC resistance.
But I doubt, they are powerful enough to drive an F5.
No problem, as I will go with the 20-0-20VAC torroide I choosed earlier.
Looking forward to build this amp!
Franz
Last edited:
One question
I have prepared mica isolators and silicone grease to install the power FET's.
But on this heathsinks, some isolation and synthetical thermal tape is already installed from the old circuit.
You can see it on the third picture.
Could I refurbish this "old" stuff and install the power devices directly to this stuff instead of using my micas and grease?
Franz
I have prepared mica isolators and silicone grease to install the power FET's.
But on this heathsinks, some isolation and synthetical thermal tape is already installed from the old circuit.
You can see it on the third picture.
Could I refurbish this "old" stuff and install the power devices directly to this stuff instead of using my micas and grease?
Franz
but a very nice one, UI core
take good care of it
aux 20Vac
if wires are same size as main secondary 36V they may be ok too
but with 20V you will have to go easy on classA bias
Due to rectifier/filter caps losses there can not be expected more than 25-26V rails voltage (with a full F5 bias) from 20V AC secondaries.
Your statement might be true. However, due to tight DIY budget, I do believe the followings:
1) The result mainly depends on circuit design;
2) If I could see from the F5 photo that 25V caps were used, why shouldn't I;
3) Cost-to-Benefit ratio is important to me and some DIYers. Better than industrial and exotic parts may be better. However, how marginally they are better?; and
4) Some DIYers think the higher the capacitance the better for filter caps. I wonder. High capacitance put more stress on the rectifier, CL60, and transformer ....