Sub certainly feels underpowered.. which of these could be the reason?

[VS Omega]

Hi guys,

Just trying to work out why my sub feels severely underpowered (and then it distorts).. which variable is the main cause or is it a number of these:

The sub is a soundstream rubicon 12" with a 500w RMS power rating
The amp is an fusion encounter am-3002 (2ch 300w)
Running bridged across the two channels
Headunit is a Pioneer DEH-2950MP

- Sub is designed for a sealed enclosure but mine is ported
- Amp is 300w and the sub is 500w
- Amp is of an inferior brand or specification
- Sub is of an inferior brand or specification
- HU isn't up to the task
- Wiring isn't good (ran RCA's on opposite side to power)

Other possible reasons?

I'm prepared to get a new amp and just keep this one for splits (would it even be good for that?), what do you guys reckon? Don't bother? Sealed box? Could it make that much difference? How about what to replace this amp with, 1000w? Brand makes much difference, just want to drive the sub, not after competition quality or anything fancy

Even this other crappy MTX roadthunder 12" didn't feel very well powered

[| evaN |]

the amp is only rated at 180 WRMS Bridged so thats probably the problem. not enough grunt for the subwoofer. get a monoblock and it should stop the distortion. when buying audio gear make sure you compare with watts rms instead of max or peak

[daron]

fusion theres 1 of ya problems
yes do as evan says monoblock all the way
your just way underpowered and thats the quickest way to kill sub

[garfa]

Hi guys,

Just trying to work out why my sub feels severely underpowered (and then it distorts).. which variable is the main cause or is it a number of these:

The sub is a soundstream rubicon 12" with a 500w RMS power rating
The amp is an fusion encounter am-3002 (2ch 300w)
Running bridged across the two channels
Headunit is a Pioneer DEH-2950MP

- Sub is designed for a sealed enclosure but mine is ported
- Amp is 300w and the sub is 500w
- Amp is of an inferior brand or specification
- Sub is of an inferior brand or specification
- HU isn't up to the task
- Wiring isn't good (ran RCA's on opposite side to power)

Other possible reasons?

I'm prepared to get a new amp and just keep this one for splits (would it even be good for that?), what do you guys reckon? Don't bother? Sealed box? Could it make that much difference? How about what to replace this amp with, 1000w? Brand makes much difference, just want to drive the sub, not after competition quality or anything fancy

Even this other crappy MTX roadthunder 12" didn't feel very well powered

i would also make sure the box its in is the size size and type.

[RUN41T]

i would also make sure the box its in is the size size and type.

Agreed

New amp + Check the box

[commsirac]

Dont know anything about the amp in question, but even at 180W rms continuous, Id of thought that would be enough to make a decent racket. If you double the power, its only going to be 3dB louder anyway...Im sensing that you that you'd like a rise of a bit more than that.

One possibility is that the level of signal going to the sub is not high enough. Does the HU have a dedicated sub out and is its level adjustable and/or have you adjusted any gain control properly that may be fitted to the amp.

[VS Omega]

Thanks for your responses guys, I wanted to get a new amp to run future splits/co-axials anyway, might as well just get one to run the sub instead..

The HU doesn't appear to have sub controls (would be handy, running speakers off HU atm and sub off amp), and only one pre-out.. Although not the reason why; I can't tell the HU to do low frequencies without it going to the stocko paper speakers as well (i hear them crying in pain when I try), once I repurpose this fusion amp I'll make it high pass, use new amp for low pass and I shouldn't have any more issues like that. I played with all the settings on the amp, set it to LP and played with the cut off and gain, still can't get it sounding right..

What RMS watts should I be looking at? 1000? 500? And a monoblock; would a powerful enough 2ch be able to do the job?

Again many thanks all!

[commsirac]

So are you feeding a full bandwith signal to the sub, or has the amp actually got a filter to let through only the low frequency sub frequencies?

Another possibility is that the lineoutput from the headunit is no good. If you have another device which you could substitute as you input to the amp for testing purposes you could rule this out. A portable CD player or ipod would suffice.

[benjiaka]

Personally, I don't know much about Audio gear, But buying a new BIG AMP for the SUB and keeping your other for the speakers sounds good to me. because my boot setup has a 4-channel 400W Cadence AMP for the speakers and a 1000W Cadence Ultradrive for the 2x 15inch soundstream SPL subs. and my Music is crystal clear aswell as the bass hits hard and doesnt distort. My driver seat feels like a massage chair.. :O image the backseat!

[garfa]

So are you feeding a full bandwith signal to the sub, or has the amp actually got a filter to let through only the low frequency sub frequencies?

Another possibility is that the lineoutput from the headunit is no good. If you have another device which you could substitute as you input to the amp for testing purposes you could rule this out. A portable CD player or ipod would suffice.

i would more be putting down to the box mate, esp. since its ported and not designed for the sub at all. it sounds like the tuning and size could be wrong causing the sub to over excurse past f3.

[bezz]

grab a monoblock capable of 500w rms at 4ohm. Also check your sub specs and build a box for it close to recommended specs. Also, sound deaden! Boot lid, boot floor and doors will do wonders! Also check your gains and your lpf settings and adjust accordingly. I doubt there will be much, but check on your amplifier terminals if there was any voltage drop between it and the battery using a multimeter.

To the guy that said doubling the power only produces 3dB increase, what are you basing this on? dB is measured exponentially, its relation to power is not linear. It also depends on many other factors, like those i mentioned above...

[commsirac]

grab a monoblock capable of 500w rms at 4ohm. Also check your sub specs and build a box for it close to recommended specs. Also, sound deaden! Boot lid, boot floor and doors will do wonders! Also check your gains and your lpf settings and adjust accordingly. I doubt there will be much, but check on your amplifier terminals if there was any voltage drop between it and the battery using a multimeter.

To the guy that said doubling the power only produces 3dB increase, what are you basing this on? dB is measured exponentially, its relation to power is not linear. It also depends on many other factors, like those i mentioned above...

Rubbish, dB is evaluated logarithmically: using the log of the power ratios of the sound form and multiplying by 10. ie dB increase when doubling the power = 10log2 =3dB
For goodness sake, look it up b4 you take me on.

Ive offered the advice of substituting a small portable device to test for a possible problem with the HU, because it is a possibility and it will cost NOTHING to test. Buying a 500W monoblock and finding it wasnt the problem is going to cost!

[bezz]

Regardless of whether its a log or exponential (good job on that, looks like you looked it half way through your post), there are too many other factors to take into account to base perceived loudness solely on power output. What about losses due to the car itself? Hence why i suggested sound deadening. Sub placement can also effect perceived loudness through constructive/deconstructive interference. Box design can impact hugely as garfa pointed out. Those are just a few among many others.

Not once did i question your advice of using a small portable device to test for problems so I don't know why you're bringing it up. That would be one of the first things I'd do also.

Now I hope your ego is satisfied, any moron can google dB and copy and paste.

[VS Omega]

Thanks all for the responses, got an Infinity Reference 600w amp today, does the job exceptionally well, so the issue was with the previous amp not giving the sub enough power.. now I need to seal off the enclosure, it feels like a fan blowing air though the port hole.. then it will be happy.. also need to figure out a way to mount two amps to the back seat of the vs (on the folding down section in the middle), thinking of building a shelf.. don't want to mount them upside down!

So are you feeding a full bandwith signal to the sub, or has the amp actually got a filter to let through only the low frequency sub frequencies?

The fusion and now this amp both using a built in low pass filter to block out the high frequencies, HU isn't very advanced in this field!

i would more be putting down to the box mate, esp. since its ported and not designed for the sub at all. it sounds like the tuning and size could be wrong causing the sub to over excurse past f3.

Next thing to fix, along with mounting the amps and powering the stocko speakers for now (just want to get the bass out of them, high pass on low gain should do).

Just another question (I'm a pain I know!), is there such a thing as a non-powered highpass filter which I can use (instead of a third amp as the fusion amp is only 2ch), so I can run the parcel shelf speakers off the HU (without exploding them due to bass)?

grab a monoblock capable of 500w rms at 4ohm. Also check your sub specs and build a box for it close to recommended specs. Also, sound deaden! Boot lid, boot floor and doors will do wonders! Also check your gains and your lpf settings and adjust accordingly. I doubt there will be much, but check on your amplifier terminals if there was any voltage drop between it and the battery using a multimeter.

Sound deadener sounds good, my whole car sounds like it's going to snap in half from rattles.. I want to perform the "hot earth" mod from the technical manual in the latest SC mag. to help stabilize voltage

C'mon guys chill out, there's lots of factors that can make things sound bad, all your points are valid!

[roon_VR]

Sound deadener sounds good, my whole car sounds like it's going to snap in half from rattles.. I want to perform the "hot earth" mod from the technical manual in the latest SC mag. to help stabilize voltage

C'mon guys chill out, there's lots of factors that can make things sound bad, all your points are valid!

Yes, sound deadener will be an exceptional investment into your car audio build. I recommend edead sound deadener from ebay. You can grab 30 square feet of that material for $140 which is pretty good value compared to dynamat. Do the front doors and parcel shelf first and you should be doing somersaults. I know i did haha.

the hot earth mod is also a good idea. I'm yet to have a go at doing it, but I've heard some good stories.

good luck with everything,

[bezz]

Just another question (I'm a pain I know!), is there such a thing as a non-powered highpass filter which I can use (instead of a third amp as the fusion amp is only 2ch), so I can run the parcel shelf speakers off the HU (without exploding them due to bass)?
!

A passive hpf can be made simply by having a capacitor in series and a resistor in parallel with the speaker. In order to determine your cutoff frequency use the formula f = 1/(2pi*R*C) where R is the resistance and C is the capacitance.

Alternatively, simply chucking a capacitor in series can also effectively act as a hpf. In my old car i added 4.7uF caps in series with my tweeters, which gave it a cut off of about 10kHz. Probably a bit high but meh.

[commsirac]

Regardless of whether its a log or exponential (good job on that, looks like you looked it half way through your post), there are too many other factors to take into account to base perceived loudness solely on power output. What about losses due to the car itself? Hence why i suggested sound deadening. Sub placement can also effect perceived loudness through constructive/deconstructive interference. Box design can impact hugely as garfa pointed out. Those are just a few among many others.

Not once did i question your advice of using a small portable device to test for problems so I don't know why you're bringing it up. That would be one of the first things I'd do also.

Now I hope your ego is satisfied, any moron can google dB and copy and paste.

Exactly what stunt are you trying to pull here Bezz. You challenged my earlier statement that doubling the power will only increase the sound intensity by 3 dB and claimed that decibels was exponentially related to the power.................did you not?
Defending my post as correct is an ego thing....Im meant to let it pass by when someone jumps in and claims what Ive written is wrong....please!

I have in reply put the simple formula in front of you showing that indeed what I stated is mathematically correct, whether I needed to go to google to do that or not(no I didnt, its something I learnt at school about 30 years ago) is irrelevant, it is still correct. Perhaps even paste what I wrote into google and do a search, that would tell you where I copied it from........not

, any moron can google dB and copy and paste.

........
any moron?, well there was one person here that proved incapable of even being able to do that! You appear to be backing yourself as some type of audio guru, really, if you dont know this basic school boy stuff, its hard to consider anything else you say may have any merit at all.
It would be prudent that anyone recommending how much amp you need would have at least a rudimentary understanding of these basics. ie to achieve a 1dB increase in sound level(the level of threshold for humans to detect a difference in sound intensity) the power of the sound needs to be increased by 26%. ie if you have a 400W amp, youll need to go to at least 500W(all other things being equal) to be able to hear a detectable difference in loudness.

You are also accusing me of going back and editing the post in question after your reply accusing me of falsehoods? suggest you go back and carefully check that there has been no edit on the post where I gave the advice regarding power and dB........I'd like an apology thankyou.


No I wasnt referring to you when I defended my advice to substitute another device for the HU, sorry if it appeared that way, I should have made a specific point to address garfa who wanted to dismiss my suggestion.

In short, I didnt claim any one was wrong in suggesting that the enclosure for the sub or the amp were not the cause of the problem(as has now been revealed), just to approach the problem systematically for other faults before throwing any money at it.

[1991_Vn2nV]

Now now girls... Leave it for another thread or PM.

[bezz]

yea not worth the effort, sorry it got so heated I'm not trying to come off as some audio guru, just trying to add another opionion.

[Phreddy]

For what it's worth, I go along with Garth - using a driver designed for a sealed box in a ported box, you're shooting yourself in the foot straight away - especially if the port tuning isn't correct. You'll end up with cancellation at exactly the frequency you want it to work at!

If the driver has been designed for a sealed box, then it's best to go with the manufacturer and use a sealed box!

Just my opinion mind - although in 25+ years of working with audio and speaker systems wouldn't necessarily mean I'm any kind of expert.....