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Discussion Starter #1
If I run a sub with only a quarter of the amp power it needs and I turn the h/u volume way up is it most likely going to sound like ass?

Feel free to send this to the dumb questions section.
 

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By turning the HU all the way up, you bet your ass its going to sound like "ass". The signal will be distorted and make your speakers and woofers sound like crap. I also dont think a woofer requires 100% of the rated/RMS power to use it or enjoy it. I have a few Cerwin Strokers and their rated at 1000watts RMS, but I've fed them 125watts and they sounded almost as loud as when I fed them 600watts each.

Just aslong as you have the gain on the amp set right (as low as possible is the key/goal) you should enjoy it and it should sound proper. Setting gains are easy, lower both volume and gain all the way down. Then start with HU turning it up until it starts to distort the back down a little. Then raise the gain from amp up until it starts to distort then back down a little. That will be the highest volume from both amp and HU that will have clean signal or distortion free.

Ofcourse dont expect any crazy SPL with less than recommended power.
 

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If I run a sub with only a quarter of the amp power it needs and I turn the h/u volume way up is it most likely going to sound like ass?

Feel free to send this to the dumb questions section.
Define power. How are you determining the amount of power being utilized, and how do you know how much the speaker "needs" ?

The point is, that it all depends on the relative strength of the signal coming from the source, the input sensitivity range of the amplifier, and whether or not you are clipping the signal before it ever gets to the amp to begin with - which is what will happen if you max out the volume setting on a typical source unit.

If the subwoofer (or any speaker) sounds good and plays loud enough, then you have enough power. If the SQ is poor and/or the output is too low, then you may not have enough power or a clean enough signal.
 

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raelly depends on the HU too. alot of the alpines have been scoped at 100% volume and still do not clip. so if you have your gains on the amplifier set correctly, it will not clip at all. as for how it will sound. that will greatly depend on the sub, the amp and how you have it set up. you dont need to max out a sub on power for it to sound good. a sub doesnt "need" more than a couple watts to make sound.
 

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Define power. How are you determining the amount of power being utilized, and how do you know how much the speaker "needs" ?

The point is, that it all depends on the relative strength of the signal coming from the source, the input sensitivity range of the amplifier, and whether or not you are clipping the signal before it ever gets to the amp to begin with - which is what will happen if you max out the volume setting on a typical source unit.

If the subwoofer (or any speaker) sounds good and plays loud enough, then you have enough power. If the SQ is poor and/or the output is too low, then you may not have enough power or a clean enough signal.
^^This. You need to know where the source clips and set that as your "max" volume no matter what. Then turn the amp gain up on your sub until it begins to distort and back off a bit. That is the maximum output you'll get from your sub.

If you are unhappy with it's output compared to the rest of the system, you can: deal with it, back the gains down on everything else till it matches (at a reduced output), get a different amp, or build an enclosure that increases the output.

Also, don't forget about the typical 12-18db boost of cabin gain you get starting around 80hz. I only have 300w available for my sub that can handle much more in my upcoming build. I've got 125w going to a L/C/R setup. Everything models at around 110db (used for realative loudness reference since it won't hit that in the real world and would KILL your ears if it did). In a sealed box my sub starts to roll off around 60hz and I SHOULD have flat response down to 20hz thanks to cabin gain. Unfortunately, flat response sounds "weak" to most people since we are less sensitive to low frequency. So I'm porting it to get flat down to 24hz. This means I will have a boost from cabin gain and should compensate nicely for the Equal Loudness Contour.

All of that was said to point out that output depends on several factors and you can get something that isn't optimal to sound good just as easily as you can make it sound bad...it all comes down to how you plan for it.
 

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nothing performs well at 100% for very long..... nothing
if you are talking about RCAs, if they dont clip, they dont clip. 2-4V with nearly no current is not going to heat anything up. just most preamps dont function at 100% at all.
 

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Discussion Starter #8
Ok.
I'll define the situation a bit more. This is in my garage. I'm bridging one side of a 4 channel Kenwood amp, it runs off a computer power supply. The sub, an Aurasound ns10-794-4a is getting about 90 watts. It's rated for 400 rms and the efficiency is low. I'm using a Sony home cd player and a kicker 2 way active crossover. The gain on the Kenwood is at a quarter. I use the gains on the kicker as volume control since there is no volume control on the cd player. When I try to make the sub get loud, it starts to distort and sound like ass.
I make it get loud by turning the gain way up on the kicker crossover, maybe 85 percent, Unless I do this, it just doesn't have enough output. Maybe this is the issue. I'm hoping when I put it in my car on 250 watts, it will sound ALOT better, because so far I am not impressed.
 

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I think your powersupply is the issue. how many amps will that supply put out? it would need at least 18-20 amps on the 12v line.

90 watts is plenty for a sub to make sound. you dont have to max it out for it to sound good. more power will run cleaner and give you more headroom though.
 

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Discussion Starter #10 (Edited)
for reference the ported jl12w0 I had hooked to the same setup slammed like nobody's business. I know a sealed 10 is not a ported 12 output wise but still, seemed weird that it would distort like that.
 

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Sounds like its because you are using a home CD player often they are 1v output. You should be able to gain the amp up high to make it work but sometimes it just does not work as well that way. Even older car HU are 2v output and that works with most things, 1v is a little weak.

Right the PC power supply is 12v possibly less with a big load and very likely it can't run that amp. Put a meter on the 12v and crank it up if it drops below 11.5v/etc you don't have enough power. Or if you have a car jumper pack or car battery, even jumper it from a car (not running) so you have a battery connected then try it max power will have at least 12v then.

Remember power is log to volume you hear in dB, that means 10w is twice as loud as 1w (what a common plain TV is), and 100w is twice what 10w is in dB. You need 1,000 to get twice as loud as 100w. That is why a sub will work on 1/4 the power its rated for. Sure it will go louder with more just not that much, usually to the ear more power sounds like more impact though that may be from the smaller amp clipping on peaks. On subs amps clip way before you think they do, you can check AC voltage and estimate the watts the amp is putting out.
 

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Discussion Starter #12
Sounds like its because you are using a home CD player often they are 1v output. You should be able to gain the amp up high to make it work but sometimes it just does not work as well that way. Even older car HU are 2v output and that works with most things, 1v is a little weak.

Right the PC power supply is 12v possibly less with a big load and very likely it can't run that amp. Put a meter on the 12v and crank it up if it drops below 11.5v/etc you don't have enough power. Or if you have a car jumper pack or car battery, even jumper it from a car (not running) so you have a battery connected then try it max power will have at least 12v then.

Remember power is log to volume you hear in dB, that means 10w is twice as loud as 1w (what a common plain TV is), and 100w is twice what 10w is in dB. You need 1,000 to get twice as loud as 100w. That is why a sub will work on 1/4 the power its rated for. Sure it will go louder with more just not that much, usually to the ear more power sounds like more impact though that may be from the smaller amp clipping on peaks. On subs amps clip way before you think they do, you can check AC voltage and estimate the watts the amp is putting out.
Well the amp was fine with the 12w0. I used to have a discman and it did get alot louder when I switched to the home unit. I guess we will have to wait and see what it's like in my trunk.
 

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You should notice a large difference between the two subs and shouldn't be using that as a reference point.

A ported enclosure is more efficient than sealed and therefore the JL should be louder (if it has a high tune/peak), should extend lower (if it has a low tune/extended response), or a combo of both off the same power.

It appears the JL sub is 3db more efficient per specs. As far as I know, a 3db gain is roughly equivilent to doubling the power.

A larger radiating area (12" vs. 10") should work less to match output (lower distortion) all else being equal.

Between the three changes and the fact you are likely clipping your signal, I would say that "quiet" and "crappy sounding" bass would be reasonable to expect. As far as how it will do off 250w in the car, it all depends. The extra power will give an audible difference (3db) but won't double the output (10db like sqs mentioned), and porting will give one of the two benefits mentioned above as well (if you choose that route). After you factor in cabin gain, it should be more than twice as loud in the car as it is now though.
 

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Discussion Starter #14
You should notice a large difference between the two subs and shouldn't be using that as a reference point.

A ported enclosure is more efficient than sealed and therefore the JL should be louder (if it has a high tune/peak), should extend lower (if it has a low tune/extended response), or a combo of both off the same power.

It appears the JL sub is 3db more efficient per specs. As far as I know, a 3db gain is roughly equivilent to doubling the power.

A larger radiating area (12" vs. 10") should work less to match output (lower distortion) all else being equal.

Between the three changes and the fact you are likely clipping your signal, I would say that "quiet" and "crappy sounding" bass would be reasonable to expect. As far as how it will do off 250w in the car, it all depends. The extra power will give an audible difference (3db) but won't double the output (10db like sqs mentioned), and porting will give one of the two benefits mentioned above as well (if you choose that route). After you factor in cabin gain, it should be more than twice as loud in the car as it is now though.
I'm hoping this is the case. I think it will be loud enough then.
 
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