damn, i thought i had an easy solution! thanks anyway.
in the beginning i wanted to use a fan tunnel, actually, this exact one: http://accelthermal.com/modelf3x3s.jpg
but then i found a 3-space aluminum rackmount chassis i liked a lot, and the sides look perfect for mounting a pair of huge sinks to...as a result i think it would be pointless to use fans attached externally. i guess i have to keep looking.
in the beginning i wanted to use a fan tunnel, actually, this exact one: http://accelthermal.com/modelf3x3s.jpg
but then i found a 3-space aluminum rackmount chassis i liked a lot, and the sides look perfect for mounting a pair of huge sinks to...as a result i think it would be pointless to use fans attached externally. i guess i have to keep looking.
jacco wrote:Two 4" pieces and a derated fan would be enough for 1 channel.
Indeed is the original tunnel about 4" long with 4 heatsinks for 2 channels.
I am going to use such a tunnel for 1 channel so maybe the amp is not getting so hot.
But i have to go a long way to hear the first notes coming out of the clone.
Greetings, Loek
Indeed is the original tunnel about 4" long with 4 heatsinks for 2 channels.
I am going to use such a tunnel for 1 channel so maybe the amp is not getting so hot.
But i have to go a long way to hear the first notes coming out of the clone.
Greetings, Loek
good luck
Good luck with that pre. I can't wait to see another Krell with a fan controller, want to know how it works out for you.
Don't forget you can derive the 5VDC from the 12VDC supply, just toss in a 5V regulator at the output of your 12V regulator.
Also I suspect but have not verified that the fan controller will simply attenuate the 12VDC supply and provide the resultant voltage to its outputs. So if you don't want to go full out I am guessing that you don't really need 12VDC, you can have any value...but that's just a hunch. I should try this....since my 12vdc is variable.....
Good luck with that pre. I can't wait to see another Krell with a fan controller, want to know how it works out for you.
Don't forget you can derive the 5VDC from the 12VDC supply, just toss in a 5V regulator at the output of your 12V regulator.
Also I suspect but have not verified that the fan controller will simply attenuate the 12VDC supply and provide the resultant voltage to its outputs. So if you don't want to go full out I am guessing that you don't really need 12VDC, you can have any value...but that's just a hunch. I should try this....since my 12vdc is variable.....
No.
Even if you used your 60,000 uF+++ cap bank from 1 channel, I think the fan would drain them in less than 20 seconds. First, think about how much power you are wasting in a resistor or regulator by reducing the 37+ volts down to 12V or less (over .5 watts), and second factor in your fan load somewhere around 100 mA or so for about 1 watt.
It would be easier and better to have a separate power supply for your fan. The power supply is "always on" but the primary of the transformer passes through a Normally Open bimetal (thermal) switch (like this) mounted on a heat sink and set for say 45C as in the example switch. So the fan is continuously on when the temp exceeds 45C no matter if the amp is on or not.
When the amp is turned off, the sinks are hot (exceeding 45C) and the Normally Open switch is closed, powering the PS and fan. The power supply and fan will keep going until the temp goes below the cutoff (hystersis makes this less than 45-- about 40C). When this happens the Normally Open switch will open and the fan PS and fan will be disconnected from the AC mains. On the other hand when the amp is turned on the PS and fan will not operate until the sinks exceed 45C because the normally open switch has not closed yet.
This means your amp will reach its operating temp faster and take less time to warm up. It will also take less time to cool off when turned off. I suppose some would say that this rapid startup means you get the sweet sound of a warmed up amp sooner.
(You could put in some logic or something to bypass this thermal switch on turn-on, say if you used a DPDT on/off switch and had a free pole, but I have not really thought about that yet. EDIT- ok I thought about it for a second, you simply hardwire the thermal switch to the AC mains and then bypass the switch with your on/off switch extra pole of your DPDT on/off switch. When "on" the thermal switch is shorted out and doesn't matter how hot the sinks get, the fan runs. When "off" the fan runs till the temp drops below the preset limits as its no longer bypassed but still connected to AC through the thermal switch)
Even if you used your 60,000 uF+++ cap bank from 1 channel, I think the fan would drain them in less than 20 seconds. First, think about how much power you are wasting in a resistor or regulator by reducing the 37+ volts down to 12V or less (over .5 watts), and second factor in your fan load somewhere around 100 mA or so for about 1 watt.
It would be easier and better to have a separate power supply for your fan. The power supply is "always on" but the primary of the transformer passes through a Normally Open bimetal (thermal) switch (like this) mounted on a heat sink and set for say 45C as in the example switch. So the fan is continuously on when the temp exceeds 45C no matter if the amp is on or not.
When the amp is turned off, the sinks are hot (exceeding 45C) and the Normally Open switch is closed, powering the PS and fan. The power supply and fan will keep going until the temp goes below the cutoff (hystersis makes this less than 45-- about 40C). When this happens the Normally Open switch will open and the fan PS and fan will be disconnected from the AC mains. On the other hand when the amp is turned on the PS and fan will not operate until the sinks exceed 45C because the normally open switch has not closed yet.
This means your amp will reach its operating temp faster and take less time to warm up. It will also take less time to cool off when turned off. I suppose some would say that this rapid startup means you get the sweet sound of a warmed up amp sooner.
(You could put in some logic or something to bypass this thermal switch on turn-on, say if you used a DPDT on/off switch and had a free pole, but I have not really thought about that yet. EDIT- ok I thought about it for a second, you simply hardwire the thermal switch to the AC mains and then bypass the switch with your on/off switch extra pole of your DPDT on/off switch. When "on" the thermal switch is shorted out and doesn't matter how hot the sinks get, the fan runs. When "off" the fan runs till the temp drops below the preset limits as its no longer bypassed but still connected to AC through the thermal switch)
Hi Lgreen,
sorry, I mis-understood the point you were making.
Your separate transformer supply for the fan is a good idea and the way you have suggested for implementation has some advantage.
You could even use this extra transformer for other uses. eg. powering relays, standby power on and auto power off, low voltage opamp supplies, protection circuits & monitoring.
sorry, I mis-understood the point you were making.
Your separate transformer supply for the fan is a good idea and the way you have suggested for implementation has some advantage.
You could even use this extra transformer for other uses. eg. powering relays, standby power on and auto power off, low voltage opamp supplies, protection circuits & monitoring.