Subwoofer not getting enough power?

masscrazy

masscrazy

masscrazy

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I have a JL Audio JX500/1D amp rated at 500watts power at 2-Ohms. I have a 2-Ohm JL Audio 500watt subwoofer.

I've set the output in vots to 31.6V based on the reading from a voltmeter. This is what the manual recommends. However it just doesnt handle many songs with a decent amount of bass at around 80% volume. The sub woofer struggles, either the bass sounds muffled or just doesnt even bother with handling it.

I previously had it at quite a bit higher power, maybe 15% more than recommended, and it sounds a lot better, sounded solid and punchy and loud. Didnt ever sound distorted or 'clipped' anything, in my opinion.

Therefore, if i've set the right amount of power going to the sub, should i be looking for changing something else? Because I'm pretty sure that the sub can handle a lot more than it does at the recommended settings. Any thoughts would be appreciated :D
 
joeyjojo said:
Where did you get 31.6 V from? The specs are listed at 14.4 V at
http://www.jlaudio.co.uk/jx500-1d-car-audio-jx-amplifiers-99400
and
https://www.crutchfield.com/S-fXhFrOVrBra/p_136JX5001D/JL-Audio-JX500-1D.html

Amp should be good for 35 A so maybe you've got the voltage too high and it can't swing that much?

P.S. hope you've got some thick cabling, that's a lot of current :eek:
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Cable is 4gauge. Have a look at Appendix A. - it said set input sensistivity target AC voltage - 31.6V.

And like i say i think this is way too low, and having previously had it at higher it sounded better without being distorted at about 75/80% volume.
 
Is the amp earthed properly? Back in my yoof I had a sub/amp setup and the amp had 2 earthing points, I had to use both.

Also might be worth looking at a power cap?
 
masscrazy said:
Cable is 4gauge. Have a look at Appendix A. - it said set input sensistivity target AC voltage - 31.6V.

And like i say i think this is way too low, and having previously had it at higher it sounded better without being distorted at about 75/80% volume.
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Ah thanks, thought you were talking about output voltage or something.

You could try turning the sensitivity up but the manual does say "! IMPORTANT Do not increase any "Input Sens." setting for any amplifier channel or channel pair in the system beyond the maximum level established during this procedure." :p

You double checked your test tone (50 Hz, 0 dB)? Will throw off the DMM measurement if wrong.

Also it doesn't say anything about sub sensitivity - maybe your sub is just less sensitive than average?

Obvious thing to do is just use the bass boost to put the levels up a bit.
 
Maccy said:
Is the amp earthed properly? Back in my yoof I had a sub/amp setup and the amp had 2 earthing points, I had to use both.

Also might be worth looking at a power cap?
Click to expand...

Got it installed from a reputable place, assume its all done correctly, earth cable is 4guage also. Seems to be done right.

joeyjojo said:
Ah thanks, thought you were talking about output voltage or something.

You could try turning the sensitivity up but the manual does say "! IMPORTANT Do not increase any "Input Sens." setting for any amplifier channel or channel pair in the system beyond the maximum level established during this procedure." :p

You double checked your test tone (50 Hz, 0 dB)? Will throw off the DMM measurement if wrong.

Also it doesn't say anything about sub sensitivity - maybe your sub is just less sensitive than average?

Obvious thing to do is just use the bass boost to put the levels up a bit.
Click to expand...

Hmm, I'll try running th test tone again, maybe from an SD card to avoid the phones audio software changing the desired tone.

I did try the bass boost but it sounds terrible, really boomy and not clear.

I think I'll just remove all the cables, re-add them, and do the test tone process again. Hopefully that fixes it, otherwise I'm gonna just increase the gain.
 
masscrazy said:
otherwise I'm gonna just increase the gain.
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I think the reason it says not to do that though is it will clip, because the amp can't swing enough voltage. You either need an amp with more voltage swing or a sub with higher sensitivity. You're best asking the installers though tbh as I'm guessing.
 
joeyjojo said:
I think the reason it says not to do that though is it will clip, because the amp can't swing enough voltage. You either need an amp with more voltage swing or a sub with higher sensitivity. You're best asking the installers though tbh as I'm guessing.
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I know what you mean, that is what they say. I did say above that I had it at about 10/15% higher gain before I decided to 'properly' tune it. And with the higher gain it sounded much better without at all any noticeable clipping or distortion. And the reason to properly do it was to prevent damage to the woofer, but it seemed like it was easily able to handle the extra volts (in my opinion anyway).

Anyway, i'll try retuning with 50hz test tone on an sd card, see if that yeilds any increases.
 
What head unit have you got?
The reason i ask is that Alpine head units require the subwoofer level to be set at the highest level to achieve maximum pre out voltage.

I personally use a cheap pocket oscilloscope to set the gains.
 
Its an Audi A3 car 2013, with an inbuilt head unit.

So I set the gain to about 20% more and it sounds a lot more powerful not buckling or sounding weak and under powered.

The amp is rated at 500watts at 2Ohms, and the input sensitivity/gains dial is just over half way. Does this mean the power being supplied is just over 250watts to the sub? (probably not I know, i imagine its not that simple).
 
No it doesn't work like that but setting it to half way is generally a good starting point. Just set the gain by ear, if it sounds good and there is no distortion or other odd sounds then i would not worry.
 
masscrazy said:
Does this mean the power being supplied is just over 250watts to the sub? (probably not I know, i imagine its not that simple).
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No way. The amp probably has a high input impedance, so the current (and therefore power) going in is small (much less than 1 W). For the line level it probably just takes the signal, for the high level it probably attenuates with a resistor first.
 
I had the same problem using a convertor, i got an adjustable one for a tenner from ebay and now works perfect.

Ebay number 331348757495 is the one i use
 
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