NP writes
Mental image: an Aleph5 running a single FET per bank mounted on 4 Athlon heatsinks ... these would easily fit inside a standard 19" rack case.
Hmmmm ..... add Nelson's idea above and this could be a little fun - and I've got a few spare FETs 🙂
cheers, mark
I've been thinking about this for a few weeks now. I recently upgraded my PC motherboard to an AMD "1.8" Athlon and the heatsink/fan assembly is really a neat unit.
Mental image: an Aleph5 running a single FET per bank mounted on 4 Athlon heatsinks ... these would easily fit inside a standard 19" rack case.
Hmmmm ..... add Nelson's idea above and this could be a little fun - and I've got a few spare FETs 🙂
cheers, mark
On the quiet fans thread for all you quiet fan fans out there.... here's some info from a friend in the components business: (thanks dude.....)
...............................
I noticed your answer on the passdiy last night about quiet fans. The really neat DC fans that are super
quiet are made by Sunon. Amazingly, Sunon has a patent on the "magnetic levitation" fan that I like.
Digikey had started to carry some of the Sunon fans but not sure if they carry all the models, regardless,
I think I'll be going back to a "real job" next week or so and should be able to get us a couple of samples
(although not sure if we need them for these amps)
.................................
...............................
I noticed your answer on the passdiy last night about quiet fans. The really neat DC fans that are super
quiet are made by Sunon. Amazingly, Sunon has a patent on the "magnetic levitation" fan that I like.
Digikey had started to carry some of the Sunon fans but not sure if they carry all the models, regardless,
I think I'll be going back to a "real job" next week or so and should be able to get us a couple of samples
(although not sure if we need them for these amps)
.................................
I have a friend here at Georgia Tech who is really into overclocking, and he bought some of those quiet Sunon fans (I believe he got some 80mm and some 120mm), and he has a total of 6 fans in his case (replaced the power supply case), and it does not sound that bad. Before he replaced them, his case sounded like an airplane taking off, and he had to turn it off at night, since he is living in a dorm room. I find it rather ridiculous to have 6 fans in a computer case... but to each his own.
Also, if you wanted to make the Sunon fans even quieter, you could simply supply less voltage, and you lose some output, which is not really needed for an amplifier if used right. I have a friend that used a fan to cool his leachamp, since he used small heatsinks, and he used it in a combination with a capacitor to slow it down. He has had no problems with noise.
--
Brian
gte619j@prism.gatech.edu
Also, if you wanted to make the Sunon fans even quieter, you could simply supply less voltage, and you lose some output, which is not really needed for an amplifier if used right. I have a friend that used a fan to cool his leachamp, since he used small heatsinks, and he used it in a combination with a capacitor to slow it down. He has had no problems with noise.
--
Brian
gte619j@prism.gatech.edu
I've successfully used Sunon fans (both 60 and 80 mm sizes), running them at 50% voltage rating (two in series) to lower their already low noise level even further.
Additionally, I only run them when needed using a thermal switch (at least for class AB they only turn on when on the test bench, not with actual music). I use those made by Selco, located in Orange County, California, model 802 Series (Close on Rise). This is packaged as a TO-220. See their web page at http://www.selcoproducts.com/cfm/ProductDetails.cfm?Action=Close&Crit=PCB&TN=PCB
Additionally, I only run them when needed using a thermal switch (at least for class AB they only turn on when on the test bench, not with actual music). I use those made by Selco, located in Orange County, California, model 802 Series (Close on Rise). This is packaged as a TO-220. See their web page at http://www.selcoproducts.com/cfm/ProductDetails.cfm?Action=Close&Crit=PCB&TN=PCB
Some if you maybe are looking for very quiet fans with thermatic options.
Well, Farnell has a number of super low noise fans ref page n724 of the 2000 catalogue.
The Papsel Range has a Brushless Super Slim 80mm 12/24 volt dc fan rated at 19.4 cuft/min with only 12 dba noise! It has Sb bearings and a price of $45.49 with speed sensor using a square wave output. (item 635-297)
There is also another 12 volt model with an external thermistor that controls spped /airflow relative to temperature with 12 dba noise @$50.72. (item311-1659)
Even with the Alpeh's lower heat output thee may still be applications for these for component longevity.
regards
macka
Well, Farnell has a number of super low noise fans ref page n724 of the 2000 catalogue.
The Papsel Range has a Brushless Super Slim 80mm 12/24 volt dc fan rated at 19.4 cuft/min with only 12 dba noise! It has Sb bearings and a price of $45.49 with speed sensor using a square wave output. (item 635-297)
There is also another 12 volt model with an external thermistor that controls spped /airflow relative to temperature with 12 dba noise @$50.72. (item311-1659)
Even with the Alpeh's lower heat output thee may still be applications for these for component longevity.
regards
macka
Maybe of interest to many here:
Taken From <a href="http://www.abc.net.au/ra/elp/innovatn/inots574.htm">www.abc.net.au/ra/elp/innovatn/inots574.htm</a>
<i><font color=#400000>BLANCH : So describe how the jet fan improves on conventional fans.
DAY : With a conventional fan the aim of course is to move air from one place to another and there are various reasons why a conventional fan breaks down or doesn't perform as well as it should and usually that is, that there's a resistance to the airflow in a system, say in a computer, where air has to be pushed through convoluted passageways between electronics or in airconditioning ducting that might be in a supermarket or a high rise building where the resistance is being partly generated just by friction along the walls of the piping and so on, so all of these mean that the fan is being resisted by the system that it's attempting to push the air into. Now, what happens with a conventional fan is that at the blades, a stall occurs which is very similar to when you see, say a sailing boat, has its sail collapse. The work is no longer being done to pull the boat along by the wind and when it isn't stalling you see the sail nicely filled, well, in conventional fans the blades are working, in a way, very much in the same way. What we've done with the Jet Fan is to eliminate that stall so that we don't have conventional air foils rotating around and we don't have passage ways between the blades that can give us the turbulence that occurs with conventional fans whether they be, what we call, 'axial Flow fans, mixed flow or centrifugal fans' as in super charges or turbo charges.
BLANCH : So is this what makes Jet Fan unique?
DAY : Yes it does. It eliminates the stall common to all fans but not to the jet fan and when it comes to using it with water then, it means that it eliminates or dramatically reduces the cavitation that occurs, say for example with jet skis, jet boats and so on.
< snip >
BLANCH : Is it noisy?
DAY : No, because noise from a fan is produced by turbulence being generated by the blades and the downstream structures where the wakes from each blade collide with those downstream structures and the reason for that is, that the air through a conventional fan comes off the blading at high speed and is usually swirling. With a jet fan it produces the static pressure, meaning bursting pressure, as you would find on a balloon, right between the blades themselves and so the air comes off the fan (discharge side) at a high pressure with greatly reduced turbulence and so the noise is greatly reduced.</font></i>
<a href="http://www.angelfire.com/ak/egel/coanda.html">The "Coanda Effect"</a>
Regards
James
Taken From <a href="http://www.abc.net.au/ra/elp/innovatn/inots574.htm">www.abc.net.au/ra/elp/innovatn/inots574.htm</a>
<i><font color=#400000>BLANCH : So describe how the jet fan improves on conventional fans.
DAY : With a conventional fan the aim of course is to move air from one place to another and there are various reasons why a conventional fan breaks down or doesn't perform as well as it should and usually that is, that there's a resistance to the airflow in a system, say in a computer, where air has to be pushed through convoluted passageways between electronics or in airconditioning ducting that might be in a supermarket or a high rise building where the resistance is being partly generated just by friction along the walls of the piping and so on, so all of these mean that the fan is being resisted by the system that it's attempting to push the air into. Now, what happens with a conventional fan is that at the blades, a stall occurs which is very similar to when you see, say a sailing boat, has its sail collapse. The work is no longer being done to pull the boat along by the wind and when it isn't stalling you see the sail nicely filled, well, in conventional fans the blades are working, in a way, very much in the same way. What we've done with the Jet Fan is to eliminate that stall so that we don't have conventional air foils rotating around and we don't have passage ways between the blades that can give us the turbulence that occurs with conventional fans whether they be, what we call, 'axial Flow fans, mixed flow or centrifugal fans' as in super charges or turbo charges.
BLANCH : So is this what makes Jet Fan unique?
DAY : Yes it does. It eliminates the stall common to all fans but not to the jet fan and when it comes to using it with water then, it means that it eliminates or dramatically reduces the cavitation that occurs, say for example with jet skis, jet boats and so on.
< snip >
BLANCH : Is it noisy?
DAY : No, because noise from a fan is produced by turbulence being generated by the blades and the downstream structures where the wakes from each blade collide with those downstream structures and the reason for that is, that the air through a conventional fan comes off the blading at high speed and is usually swirling. With a jet fan it produces the static pressure, meaning bursting pressure, as you would find on a balloon, right between the blades themselves and so the air comes off the fan (discharge side) at a high pressure with greatly reduced turbulence and so the noise is greatly reduced.</font></i>
<a href="http://www.angelfire.com/ak/egel/coanda.html">The "Coanda Effect"</a>
Regards
James
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