• Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
    Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.

Calling all Electrical Geniuses

D

D3v1an7

[H]ard|Gawd
Joined
Oct 22, 2003
Messages
1,256
My Brother in Law gave me a dual 10" speaker box with this amp
http://www.kenwoodusa.com/product/product.jsp?productId=2481

I want to hook this up to my home theater and replace my existing sub with it.

My question is this, will the 12 volt rail on a PS supply the correct amperage to get this thing working properly?

I know that the amplifier has a 40A fuse in it and I know that one of my extra PS doesn't put out nearly that amount on the 12 volt rail.

I guess I need to know if what the working amperage is on a 12v car battery and if the PS can closely replicate that source.

Thanks and sorry to mods if this is outside the realm of this particular forum.
 
See what the 12V rail on the PSU you're planning to use is.

Wattage = I^2 * R

So if it's rated at 10A then 100 * 4ohms(typical) = 400 watts.


As long as you keep that thing working under 25% or so if that 1000watt capacity it should work but no guarantees.
 
I have a generic POS sitting here that has 12A on the +12 volt rail.

My electrical mathmatics is more than a little rusty. Do you think it will be enough?

Also, what is the oporational amperage of a car battery? Knowing this could help me determine if this will work or not. I have searched on google for it but all I can find is Cold Cranking Amps and not normal amperage.

thanks
.
 
12A is not enough. P = I*V. 12V * 12A is 144W. You could run the amp on it if you kept the volume low, but I wouldn't even bother. If you really want to use PC power supplies, find like 5 cheapie ones (AT will be best since you can switch them on w/o bothering with an ATX connector) and run them in parallel.

But still, I wouldn't do that for a permanent setup... Get a real HT sub. This is supposed to be a great budget sub: http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=300-632&ctab=6#Tabs

Edit to add: car batteries can put out several hundred amps, some over 1000
 
Yeah, they put out a ton of amps but this amplifier has a 40 amp fuse so I shouldn't need to generate more than that.

If a PC PS isn't going to work, are there any OTC solutions that would work? All I can find are adaptors to plug your car cell phone charger into an AC outlet.



I have a home theater sub and it's not bad, I just want it to be able to feel the base in my bones when the sub hits.
 
It's more like he gave me the 1000 watt amp with the speaker box and rather then go out and spend several hundred for a Home Theater amp I would like to find a way to make it work.

Thanks for the help.
 
Speakers are a notoriously difficult impedance problem. As the freq changes, the impedance bounces all over the place. This requires huge headroom in the amp to handle the current spikes. I would be very leery of using a PC PSU to drive a 1000W amp. THD numbers are provided for a continuous load, which is usually 1/2 or less than the transient load. That 1000W is going to get used. Especially if the speakers are not very efficient.

Do you have an old stereo receiver lying around? You could feed the .1 channel to it and use it as a dedicated amp.
 
The power supply should be capable of putting out about 50% more than the fuse rating of the amp IMO. So a 12V 50-60A supply should be good (most car amps are rated for about 14.4V, so at 12V, your wattage and thus input current will be a bit less which is why I say 50A should be ok)
 
I've done this in a pinch for amp testing, and couldn't get it to work. During bass hits, the transient current can cause a power supply (even an Enermax 561) to latch off.

If they're car subs, they probably won't sound that good in a house - car subs tend to rely on your car's cabin gain to amplify low frequency stuff, and in a large room they won't produce much subbass at all. I'd sooner pick up a real home theater sub.

But if you reallyreallyreally want to use these subs, pick up a plate amplifier from apexjr.com or partsexpress.com
 
In that case, you would want to use a quarter or half farad capacitor (farad would probably create too much of a load for a crappy PSU)....But, again, it's better to just not use a car amp.
 
You must log in or register to reply here.
Back
Top