I'm using a cheap car subwoofer crossover and it has three pins to supply power: ground, remote, and +12. The ground and +12 connections are obvious and I can figure them out, but I don't know how to use the remote pin. I'm guessing that it either pulls to +12 or ground depending on whether it's on or off, but I don't want to just try one for fear of frying the poor thing. The spec sheet says it connects to the "acc" lead terminal (on the head unit?) and, well, my setup doesn't have one of those. 
I'm planning on using this crossover in my home-brew PA rig, and running it from the regulated +12 supply in my computer. Can I do this? If so, how?
I'm planning on using this crossover in my home-brew PA rig, and running it from the regulated +12 supply in my computer. Can I do this? If so, how?
Dear all,
You can use remote pin to power on-off control of the crossover.
When you connect this pin to +12V, the crossover will be turned on and connect to ground or open circuit, the crossover will be turned off.
If you use computer power supply, the noise of electric fan in power supply will disturb.
You can use remote pin to power on-off control of the crossover.
When you connect this pin to +12V, the crossover will be turned on and connect to ground or open circuit, the crossover will be turned off.
If you use computer power supply, the noise of electric fan in power supply will disturb.
Normally these are designed inside to be connected directly to your V+ without any external components, except for in some cases, a fuse. If you're using a computer power supply, a fuse is not needed, you're not going to be melting wires if it should blow, as in the car with very high battery current capability.
On any amp or other car equipment I've worked on, there is normally a complete resistor network there to limit current so that it is enough to switch the system on without really drawing anything more.
Hope this helps.
As for computer power supply fans... These are always a big pain. I have run a computer SMPS without a fan, however, this is not a good idea because they won't be able to dissipate much heat. A good measure is to run the fan at either 7 or 5 volts instead of 12. To get 7, connect the fan + to the yellow wire, and the fan - to the red wire. This is the difference voltage between 12 and 5.
If 5 doesn't turn the fan over, you must use 7, but try 5 first because that's much quiter.
Now, to eliminate fan noise. This can be done with various filter circuitry. I would imagine that capacitor accross the fan leads of 100uF or more and an inductor in series before the cap would kill off the noise to an acceptable level.
I'm sure of the usual frequency of fan noise, so not sure what cap and inductor values would be most effective. Can anyone give an idea here? Perhaps one has had experience in filtering fan noise..
This should help solve the nasty computer fan problem.
On any amp or other car equipment I've worked on, there is normally a complete resistor network there to limit current so that it is enough to switch the system on without really drawing anything more.
Hope this helps.
As for computer power supply fans... These are always a big pain. I have run a computer SMPS without a fan, however, this is not a good idea because they won't be able to dissipate much heat. A good measure is to run the fan at either 7 or 5 volts instead of 12. To get 7, connect the fan + to the yellow wire, and the fan - to the red wire. This is the difference voltage between 12 and 5.
If 5 doesn't turn the fan over, you must use 7, but try 5 first because that's much quiter.
Now, to eliminate fan noise. This can be done with various filter circuitry. I would imagine that capacitor accross the fan leads of 100uF or more and an inductor in series before the cap would kill off the noise to an acceptable level.
I'm sure of the usual frequency of fan noise, so not sure what cap and inductor values would be most effective. Can anyone give an idea here? Perhaps one has had experience in filtering fan noise..
This should help solve the nasty computer fan problem.
Oh, you were talking about power supply noise killing the sound! No problem--I'm running my crossover on a separate rail from everything else.
Part of the problem is that there are, for no reason I can fathom, 2 fans in my PSU. I guess *real* computer geeks feel like more fans = better computer, or something like that.
I've been meaning to buy a quieter CPU fan (since that's where more of my noise comes from) and line the box with sound damping material, I just haven't got around to it. There's also the hard drives, which I can't do a whole lot about...
One of these days I'll finally get a chance to do something about all these annoyances, and then I'll let you know what I did about it!
Part of the problem is that there are, for no reason I can fathom, 2 fans in my PSU. I guess *real* computer geeks feel like more fans = better computer, or something like that.
I've been meaning to buy a quieter CPU fan (since that's where more of my noise comes from) and line the box with sound damping material, I just haven't got around to it. There's also the hard drives, which I can't do a whole lot about...
One of these days I'll finally get a chance to do something about all these annoyances, and then I'll let you know what I did about it!
I'm LAZY, and the computer happens to be in exactly the right place to usurp a 12-volt rail. (The whole thing is in one rolling cabinet that's 54" tall, 21" wide and 27" deep, containing amplifiers, computer, mixer, CD players... the works.)
Eventually, I'd really like to build my own power supply for my computer, that would operate without any fans at all (HA!) and be totally silent.
Thanks, everyone, for your suggestions. I've got it working how I want it now, thanks to you all.
Eventually, I'd really like to build my own power supply for my computer, that would operate without any fans at all (HA!) and be totally silent.
Thanks, everyone, for your suggestions. I've got it working how I want it now, thanks to you all.
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