POWER QUESTIONS (Capacitor and Wiring) - What size wire for a 30amp amplifier?
03-02-02, 10:07 PM
#1
Racer
Thread Starter
POWER QUESTIONS (Capacitor and Wiring) - What size wire for a 30amp amplifier?
Thanks to all the great postings on both this and the SC forums, I am almost ready to upgrade the rear mid-ranges and woofer of my Nakamichi stereo on my 1992 SC400. That Vifa woofer Parts Express is selling (see other threads) looks like a bargain so I might get it if I discover my Nak woofer is shot when I open up my rear deck soon. In the meantime, I have a few more questions:
I have a Sony XM-5520 amplifier lying around, which is rated at 55 watts x 2 channels at 4 ohms. It has a switch for bridging to one channel, so I am assuming about 100 ohms total. Is it worth using this amp to drive my woofer, or does the stock Nak amp put out about that much for the woofer channel, anyway?
If it IS worth using, can I run it off the stock power cable? The amplifier's fuse is 30 amps.
I also have a few capacitors lying around- they are pictured below. I salvaged them from a PBX phone system power-supply a few years ago. Are any of them suitable for a car amplifier? I am guessing only the white one will come close to being usable, but maybe the volt rating is not that important.
I've seen some high-end capacitors sold with a feature that prevents the capacitor from draining the battery when the car is idle. Is this "drainage" issue only a factor if you don't start the car say, at least once a week? And if I should add some sort of circuit to prevent battery drainage, what does it consist of?
I'll save some additional questions for another thread. Thanks in advance for any information that members can provide. I'll be posting pics of my install, if anything noteworthy occurs.
I have a Sony XM-5520 amplifier lying around, which is rated at 55 watts x 2 channels at 4 ohms. It has a switch for bridging to one channel, so I am assuming about 100 ohms total. Is it worth using this amp to drive my woofer, or does the stock Nak amp put out about that much for the woofer channel, anyway?
If it IS worth using, can I run it off the stock power cable? The amplifier's fuse is 30 amps.
I also have a few capacitors lying around- they are pictured below. I salvaged them from a PBX phone system power-supply a few years ago. Are any of them suitable for a car amplifier? I am guessing only the white one will come close to being usable, but maybe the volt rating is not that important.
I've seen some high-end capacitors sold with a feature that prevents the capacitor from draining the battery when the car is idle. Is this "drainage" issue only a factor if you don't start the car say, at least once a week? And if I should add some sort of circuit to prevent battery drainage, what does it consist of?
I'll save some additional questions for another thread. Thanks in advance for any information that members can provide. I'll be posting pics of my install, if anything noteworthy occurs.
03-03-02, 12:39 AM
#2
Lexus Test Driver
Probably Not
Perry - I'm not sure ( Percy's the guru on advanced electronics here ) but I'm think that your capacitor would need to be engineered for a 12 VDC system. I also think U mean that your Sony would put out 110 WATTS mono into 4 ohms. Percy has the specs for the Nak system but I recall seeing something in the range of 100 watts dedicated to the sub so it'd almost be a wash to use the Sony amp. I've had (2) Stinger 1 farad caps in my system for over 2 years now & have left the car undriven ( & unstarted ) for periods of up to 2 weeks & the caps haven't drained my battery yet. If U plan on starting the car at least weekly then I'd think U have nothing to be concerned about.
03-03-02, 10:43 AM
#3
Moderator - Electronics Forum
Re: POWER QUESTIONS (Capacitor and Wiring) - What size wire for a 30amp amplifier?
Originally posted by PERRYinLA
I have a Sony XM-5520 amplifier lying around, which is rated at 55 watts x 2 channels at 4 ohms. It has a switch for bridging to one channel, so I am assuming about 100 ohms total. Is it worth using this amp to drive my woofer, or does the stock Nak amp put out about that much for the woofer channel, anyway?
***I'd use the Sony. Cleaner power and the amp isn't all integrated. That is, the amp itself (Sony) is actually using some REAL power transistors rather than having all of it's power from one single IC.
If it IS worth using, can I run it off the stock power cable? The amplifier's fuse is 30 amps.
***Nope. For 30 amps the recommended MINIMUM wire is 10 guage. But for the 15 foot run it takes to go from battery to trunk, I'd feed in a 8 guage. Doesn't hurt to go slightly bigger.
I also have a few capacitors lying around- they are pictured below. I salvaged them from a PBX phone system power-supply a few years ago. Are any of them suitable for a car amplifier? I am guessing only the white one will come close to being usable, but maybe the volt rating is not that important.
***The volt ratings is EXTREMELY important! I know since I blew up a capacitor about 15 years ago due to overvoltage. It was something like 50 volts into a 35 volt capacitor. There's a certain smell (ozone like) and then you hear sizzling. After the sizzling you hear a loud POP and then the relief vent of the capacitor opens op and sprays electrolytic oil all over the place. It was literally a 7 foot spray of fine misty oil in the air...and from a little capacitor about the size of a quarter. All this happened within 5 seconds of powerup. The capacitor that is shown on top is rated for 7.5 volts DC. The alternator of the Lexus models will put out a very tightly regulated 14.1 volts. Even when completely loaded down the alternator will crank out 13.8 to 13.9 volts. Still about 50 percent over rated for the 7.5 vdc cap. As for the middle cap, it MAY be usable, but I'd still buy a dedicated cap or make an array of low ESR (equivalent series resistance) caps.
I've seen some high-end capacitors sold with a feature that prevents the capacitor from draining the battery when the car is idle. Is this "drainage" issue only a factor if you don't start the car say, at least once a week? And if I should add some sort of circuit to prevent battery drainage, what does it consist of?
***It's probably more than likely a remote relay turn on. If I remember right, the outboard caps have a remote wire to them. This tells them when to start getting a charge (when powered on) and when not to charge (when system is off).
I'll save some additional questions for another thread. Thanks in advance for any information that members can provide. I'll be posting pics of my install, if anything noteworthy occurs.
I have a Sony XM-5520 amplifier lying around, which is rated at 55 watts x 2 channels at 4 ohms. It has a switch for bridging to one channel, so I am assuming about 100 ohms total. Is it worth using this amp to drive my woofer, or does the stock Nak amp put out about that much for the woofer channel, anyway?
***I'd use the Sony. Cleaner power and the amp isn't all integrated. That is, the amp itself (Sony) is actually using some REAL power transistors rather than having all of it's power from one single IC.
If it IS worth using, can I run it off the stock power cable? The amplifier's fuse is 30 amps.
***Nope. For 30 amps the recommended MINIMUM wire is 10 guage. But for the 15 foot run it takes to go from battery to trunk, I'd feed in a 8 guage. Doesn't hurt to go slightly bigger.
I also have a few capacitors lying around- they are pictured below. I salvaged them from a PBX phone system power-supply a few years ago. Are any of them suitable for a car amplifier? I am guessing only the white one will come close to being usable, but maybe the volt rating is not that important.
***The volt ratings is EXTREMELY important! I know since I blew up a capacitor about 15 years ago due to overvoltage. It was something like 50 volts into a 35 volt capacitor. There's a certain smell (ozone like) and then you hear sizzling. After the sizzling you hear a loud POP and then the relief vent of the capacitor opens op and sprays electrolytic oil all over the place. It was literally a 7 foot spray of fine misty oil in the air...and from a little capacitor about the size of a quarter. All this happened within 5 seconds of powerup. The capacitor that is shown on top is rated for 7.5 volts DC. The alternator of the Lexus models will put out a very tightly regulated 14.1 volts. Even when completely loaded down the alternator will crank out 13.8 to 13.9 volts. Still about 50 percent over rated for the 7.5 vdc cap. As for the middle cap, it MAY be usable, but I'd still buy a dedicated cap or make an array of low ESR (equivalent series resistance) caps.
I've seen some high-end capacitors sold with a feature that prevents the capacitor from draining the battery when the car is idle. Is this "drainage" issue only a factor if you don't start the car say, at least once a week? And if I should add some sort of circuit to prevent battery drainage, what does it consist of?
***It's probably more than likely a remote relay turn on. If I remember right, the outboard caps have a remote wire to them. This tells them when to start getting a charge (when powered on) and when not to charge (when system is off).
I'll save some additional questions for another thread. Thanks in advance for any information that members can provide. I'll be posting pics of my install, if anything noteworthy occurs.
Percy
03-05-02, 08:11 AM
#4
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PERRYinLA
Those capacitors will NOT work. Let me put it this way you don't really need capacitor for 100W amp. (the amp already have large capacitors build in) and those capacitors your have, their value is too small (adding several 15000uF caps is like adding water in the sea, does not make any different, also, some of that cap is for AC application only)
Anh
Anh
03-05-02, 09:43 AM
#5
Racer
Thread Starter
Thanks Mean Gene, Percy and BananaGS - those capacitors are now on eBay!
Well, thanks to all the advice you folks gave me, I am certainly not gonna use them caps! In fact, the AC ones are now on eBay and I already got a bid!
http://cgi.ebay.com/aw-cgi/eBayISAPI...tem=1710831613
So my loss, is someone else's gain! (I'll of course advise the winning bidder NOT to use them caps for his car stereo!)
http://cgi.ebay.com/aw-cgi/eBayISAPI...tem=1710831613
So my loss, is someone else's gain! (I'll of course advise the winning bidder NOT to use them caps for his car stereo!)
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