Can too many woofers on 1 amp blow it?
04-06-2008, 11:33 AM
#11
1000 Watt CAFz'r
Join Date: Aug 2000
Posts: 1,113
The emf from one speaker is certainly not the same as 36 speakers when you present that load with another load, IE:the amps outputs. Every amplifier must overcome the back emf given off the subwoofers motor(fixed magnet/coils moving makes AC volt's and amps) Normally the back emf is so little it is a non issue so that is why you never hear about it.
But when you present that wall of woofers with resonance(sound waves that they will have the most simpathetic vibrations from) that 36 motors can turn out some voltage and some nice current. Now who knows if that current was enough to overdrive the amps current output but I have seen it before. Without actually seeing what failed on the amp we can only guess as to what caused the failure.
Do this as a small test, place a sealed enclosure with a Q of .7 in your cabin with a 15 or 12 and play the note that resonates your subwoofers the most(visually) then take a multimeter and measure the output at the 36 subs speaker wire that the amp was connected to. You will see X amount of volts, you then place a resistor across those 2 wires that has the approx impedence rise of your amp/sub box then measure current output. Try it its kinda fun
But when you present that wall of woofers with resonance(sound waves that they will have the most simpathetic vibrations from) that 36 motors can turn out some voltage and some nice current. Now who knows if that current was enough to overdrive the amps current output but I have seen it before. Without actually seeing what failed on the amp we can only guess as to what caused the failure.
Do this as a small test, place a sealed enclosure with a Q of .7 in your cabin with a 15 or 12 and play the note that resonates your subwoofers the most(visually) then take a multimeter and measure the output at the 36 subs speaker wire that the amp was connected to. You will see X amount of volts, you then place a resistor across those 2 wires that has the approx impedence rise of your amp/sub box then measure current output. Try it its kinda fun
04-07-2008, 04:14 AM
#12
50 Watt CAFz'r
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Join Date: Dec 2007
Posts: 189
normally if the load is supposed to be 1ohm I'd expect to see around .7-.8 ohms DCR, 1.1 seems high (but whatever, thats not the problem)
If the amps are known to be stable at 16v+ and half an ohm I really don't see the problem...
The amp could have just gave up the ghost.... or maybe you've got an intermittent short going on somewhere ? (tinsel leads are notorious)
was it the power supply or output fets that smoked ?
If the amps are known to be stable at 16v+ and half an ohm I really don't see the problem...
The amp could have just gave up the ghost.... or maybe you've got an intermittent short going on somewhere ? (tinsel leads are notorious)
was it the power supply or output fets that smoked ?
04-07-2008, 06:26 PM
#13
50 Watt CAFz'r
Join Date: Aug 2007
Posts: 487
The emf from one speaker is certainly not the same as 36 speakers when you present that load with another load, IE:the amps outputs. Every amplifier must overcome the back emf given off the subwoofers motor(fixed magnet/coils moving makes AC volt's and amps) Normally the back emf is so little it is a non issue so that is why you never hear about it.
But when you present that wall of woofers with resonance(sound waves that they will have the most simpathetic vibrations from) that 36 motors can turn out some voltage and some nice current. Now who knows if that current was enough to overdrive the amps current output but I have seen it before. Without actually seeing what failed on the amp we can only guess as to what caused the failure.
Do this as a small test, place a sealed enclosure with a Q of .7 in your cabin with a 15 or 12 and play the note that resonates your subwoofers the most(visually) then take a multimeter and measure the output at the 36 subs speaker wire that the amp was connected to. You will see X amount of volts, you then place a resistor across those 2 wires that has the approx impedence rise of your amp/sub box then measure current output. Try it its kinda fun
But when you present that wall of woofers with resonance(sound waves that they will have the most simpathetic vibrations from) that 36 motors can turn out some voltage and some nice current. Now who knows if that current was enough to overdrive the amps current output but I have seen it before. Without actually seeing what failed on the amp we can only guess as to what caused the failure.
Do this as a small test, place a sealed enclosure with a Q of .7 in your cabin with a 15 or 12 and play the note that resonates your subwoofers the most(visually) then take a multimeter and measure the output at the 36 subs speaker wire that the amp was connected to. You will see X amount of volts, you then place a resistor across those 2 wires that has the approx impedence rise of your amp/sub box then measure current output. Try it its kinda fun
that does sound interesting! might have to try that one for myself
04-07-2008, 08:12 PM
#14
DB Don... I was looking at the situation from the perspective of treating each woofer and it's enclosure as a resistor, capacitor, and inductor.... if we series/parallel 36 sets to 1ohm, I don't see the situation being much different from 4 drivers in parrallel to 1ohm...
of course power compression will be different, and thinking about it now the increased loading inside the vehicle would have to make a difference in the radiation impedance.. (increasing it)
but I just don't see a difference in the loads other then that ???
At anyrate.... if the psu Fets are what gave out, I would say that the amp could have been on it's last legs and probably didn't like the input voltage... I don't know how the amps were modded, but if it was only to disable the protection circuitry, well that does not necassarilly mean the amps will be rock solid on 16+ volts....
Don't discount the possibility of a short... you could have been drawing excessive amounts of current from amp, and the psu just happened to give out before the outputs.... clipping will also tax the psu...
of course power compression will be different, and thinking about it now the increased loading inside the vehicle would have to make a difference in the radiation impedance.. (increasing it)
but I just don't see a difference in the loads other then that ???
At anyrate.... if the psu Fets are what gave out, I would say that the amp could have been on it's last legs and probably didn't like the input voltage... I don't know how the amps were modded, but if it was only to disable the protection circuitry, well that does not necassarilly mean the amps will be rock solid on 16+ volts....
Don't discount the possibility of a short... you could have been drawing excessive amounts of current from amp, and the psu just happened to give out before the outputs.... clipping will also tax the psu...
04-09-2008, 09:55 AM
#15
50 Watt CAFz'r
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Join Date: Dec 2007
Posts: 189
Well I decided to just go for it after a few days of deep thought and good news is the amp is fine, no problems! The bad news is I decided to turn it on inside my garage with the van doors open and it knocked the garage door off of its track and now I have quite a project ahead of me putting it back on lol. Cant wait to show it to everyone at importfest
04-13-2008, 10:41 AM
#16
you should of called me. You also got to keep in mind your running bass race and your not playing 1 note. As your freq. changes that your playing so does your imped. You might be wired to 1 ohm but what is it all done just not connected to the amp? You might be at 4 ohms on one freq. but drop to .5 on another as the music plays. You have to becareful especially using small amps.
04-14-2008, 12:40 PM
#17
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Join Date: Dec 2007
Posts: 189
well my 500.1 broke. I have been using it for about a week with no problems and then I was powering it up (connecting the remote wire to my battery bank) and there were two popping noises and the amp clicked into protection and goes into protection everytime I turn it on. Im purchasing a 2nd 500.1 and im gonna run them at 2ohms each to see if that solves my problem, I sure hope so. Kenny, I gotta get the van out there for you to see it, I've just been crazy busy. Im going to the dmv tommorrow to reg. it and im gonna do the maintance on it over the weekend. Got the 1 alt in but the tensioner is siezed so I had to grab a new one. Its gonna be a bitch of a job putting it on. So as soon as its ready I will swing by. I will try to call you later tonite or tommorrow.
08-19-2008, 10:46 PM
#18
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Join Date: Aug 2008
Posts: 2
know this is a few months old, but I am considering trying a pair of xp1400ds .7ohms strapped on a single sub for music... 12v setup, to the best of my knowledge when running low ohms it's better to do lower voltage seeing as it's more stressing to do lower ohm and more stressing to do higher voltage unless the amp in question is a higher voltage design in which case it won't like lower voltage.. anyway. when you ran them .7ohms was it just burps or music too?
also it'll be a 4hp based sub so kinda high inductance from what I've read on termpro a few years back... and I think that directly effects backwaving voltage and current but I'm hoping to score decent regardless. we play music on peak hold, I have my own TL so I can tune no problem, just mostly checking how stable the amps are into this load. ran a search on goggle and came here been here before years ago trolling but I guess I never registered 
anyway, thanks for any inside in advance!
Tom
also it'll be a 4hp based sub so kinda high inductance from what I've read on termpro a few years back... and I think that directly effects backwaving voltage and current but I'm hoping to score decent regardless. we play music on peak hold, I have my own TL so I can tune no problem, just mostly checking how stable the amps are into this load. ran a search on goggle and came here
been here before years ago trolling but I guess I never registered anyway, thanks for any inside in advance!Tom
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