Bass Sounds Like It Is Coming From The Back

[Shojahan]

Heil everybody,

In just about all cars the subwoofer is placed in the trunk, way behind you. So at first I thought that naturally therefore the bass should sound like it's coming from the back, that's where the sub is placed after all.

But I just don't like it. I need that 12" sub bass, because the front speakers and 6X9's don't hit hard enough, yet it just sounds like the interior speakers are playing one bassless track while the subwoofer is some Mob informant I've locked in the trunk banging on the lid to turn the music down until I get some SQ

I figure this may be a common problem, and was wondering if anyone worked out a solution I could use? From previous discussions, I'm aware I need to get deadeners and seals for the front doors, but I still need to bring the sub bass up front right?

I'm confused as to whether I should turn the sub's LPF higher to try and take over some mid-bass, or in fact lower, to create more separation from the interior speakers, though I'm not sure how the latter would help. My understanding of how a bass signal gets produced is obviously not that well informed, is there an informant who can help me?

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[Why So Cereal? 5,000+ posts]

Few Questions:

What are your HPF and LPF frequencies?

Do u have any form of Time alignment on your HU?

Is your trunk deadened?

Are your doors properly sealed and deadened

What speakers, sub and vehicle?

 

[Shojahan]

In regard to HPF and LPF, I have tried different adjustments, and at the moment I have simply set them both to midpoints until someone offers helpful insight.

I don't believe there is any 'Time alignment' on the HU, it's a Kenwood KDC-MP239.

I haven't had any aftermarket deadening or sealing done. I'm not sure how I could even get some Dynamat behind the speaker baffles on the front doors, it was a miracle that I could get new speakers to fit, just.

The speakers are Pioneer, and the sub is Alpine Type-R.

About the car, it is a 89 Prelude (Acura). Europeans might classify it a sports car, but the Japanese marketed it as a GT. Therefore the luggage space in the trunk is cavernous with the massive fuel tank located mid-chassis. There is no partition between the cabin and trunk except for the backseat itself. This makes cabling, amplifier bay placement and rear deck speaker access quite a joy, but I've wondered if it affects SQ somewhat.

Good thing you reminded me about the car's design features, they may well be playing a role, but man I've really wanted it for a project so I'd like to keep it.

Also, even though I've duplicated this thread in the Advanced SQ forum, it's okay to just reply here, thanks.

 

[wenn_du_weinst 10+ year member]

edit: In threads like this I only read the first post as I don't want to sort through the misinformation that may have been given.

time alignment isn't you problem. this is a VERY VERY common problem. What is doing it is that subs don't play clean, they are loud intrusive and usually playing a high level of distortion. Bass it's self is not directional, what brings your ears to locate your subwoofer is usually one of these problems. The first and easiest way is to turn your lowpass filter down. The higher the freq the more directional it becomes. That is why you have to choose your tweeter location so thoroughly. If you, like me, have tried every low pass setting available and still have the bass being pulled back, then you come to another problem which is your not actually locating the bass. What you are doing is noticing the resonance and vibrations of your vehicle making it appear that your bass is in the trunk. It does this by making non linear sounds that are much easier to pick up on when played over a cleaner sound. The way to fix that is to get rid of all the rattles and resonance that you can. Then of course the one nobody wants to hear, Your sub could be high in distortion, this isn't your fault ALL subs will generate distortion to a certain level. The only way to fix that is, after you have done everything else I mentioned, is to use a different subwoofer. You are looking for transparency, a loud sub will be much easier to locate as they tend to have more distortion.

What exact equipment are you using and are you still at stock noise inhibition?

 

[Why So Cereal? 5,000+ posts]

In regard to HPF and LPF, I have tried different adjustments, and at the moment I have simply set them both to midpoints until someone offers helpful insight.
I don't believe there is any 'Time alignment' on the HU, it's a Kenwood KDC-MP239.

I haven't had any aftermarket deadening or sealing done. I'm not sure how I could even get some Dynamat behind the speaker baffles on the front doors, it was a miracle that I could get new speakers to fit, just.

The speakers are Pioneer, and the sub is Alpine Type-R.

About the car, it is a 89 Prelude (Acura). Europeans might classify it a sports car, but the Japanese marketed it as a GT. Therefore the luggage space in the trunk is cavernous with the massive fuel tank located mid-chassis. There is no partition between the cabin and trunk except for the backseat itself. This makes cabling, amplifier bay placement and rear deck speaker access quite a joy, but I've wondered if it affects SQ somewhat.

Good thing you reminded me about the car's design features, they may well be playing a role, but man I've really wanted it for a project so I'd like to keep it.

Also, even though I've duplicated this thread in the Advanced SQ forum, it's okay to just reply here, thanks.

just realized you said this. my bad...

 

---------- Post added at 09:39 AM ---------- Previous post was at 09:39 AM ----------

 

Try flipping the phase on the subs. The reason you are noticing that the bass is coming from the rear likely has to do with a phasing issue.

This is why I asked about time alignment. T/A is a way to fine tune your phasing in such a way that the sound from the midbass drivers and subs hit your ears at the same time and all of the bass seems to come from the front of the vehicle. Flipping the phase is sometimes enough for some people, so I'd give it a try. Its easy and free.

The reason I asked about deadening the trunk is that even once the phasing has been corrected, if your trunk is rattling like hell, the bass will still be pulled to the rear so be sure to get that area as quiet as possible.

You'll want your doors properly sealed and deadened to get good midbass that allows you to get that upfront bass effect. Without a proper environment, your mids will likely not give you much in the way of midbass and your hopes of getting the bass to seem like its coming from the front will be very difficult, if not impossible.

Another thing to consider is that around... 70hz iirc, sounds start to get pretty directional and if this is coming from the subs and not the mids, then your bass could be pulled rear.

My suggestion to you is first try flipping the sub phase and see if it helps.

If it doesn't do what you want, you're looking at doing a few things:

1)get a HU with some kind of Time alignment so that you can get those drivers in proper phase with each other (like a Pioneer 80PRS, if youre looking to go new or you could go used)

2)deaden that trunk of all rattles

3)properly seal and deaden your doors to get strong, authoritative midbass from your front drivers (http://www.caraudio.com/forums/car-audio-build-logs-cars-trucks-suvs/516096-2005-scion-tc-sq-hertz-audison-pioneer-build-log.html

4)Play around with diff HPF and LPF frequencies but try and keep it no higher than 80hz at very most. 63hz worked for most my midbass drivers.

 

[maylar 10+ year member]

Turn your subs off. Then improve your front stage install to bring as much midbass to the front as possible. If you can get good output down to 70 Hz it'll make a world of difference.

Then turn the subs back on. Use 80 Hz as the cutoff point for LPF. Adjust the level so that the subs keep up with the main speakers but don't dominate.

 

[wenn_du_weinst 10+ year member]

80hz is usually to high, my car I have it set at 50hz because otherwise it's unbearable.

 

[Shojahan]

Thanks for the help Prince, but what do you mean by this operation "flipping the sub phase"? Is this something obvious which I am oblivious to? I can't see any kind of 'phase control' on my amp.

 

[Why So Cereal? 5,000+ posts]

Thanks for the help Prince, but what do you mean by this operation "flipping the sub phase"? Is this something obvious which I am oblivious to? I can't see any kind of 'phase control' on my amp.

swap the pos and neg wires at the sub amp.

Also, look into possibly turning the subs down as stated up above

 

[wenn_du_weinst 10+ year member]

yeah it just runs the sub backwards, this changes when the time it takes for the waves to reach the listening position.

 

[Shojahan]

Well I didn't realize that swapping positive and negative wires could make a difference, but I'm definitely going to try this first thing tomorrow, thanks guys. As for deadeners, I'll just have to off those door panels again, and get the Dynamat in, but I'm thinking door seals are a pro job?

 

[goingdef 10+ year member]

It sounds like the gain on your sub amp is too high causing the bass to come up before the rest of the music, do as someone suggested and cut the subs off adjust the highs and then bring up the subs to compliment the rest of the music.

 

[supermaxx123 10+ year member]

To get a proper blend you also want to match the levels of your mids and bass, in other words one shouldn't drown out the other. Most ppl listen to bass a lot louder but once you get it set up, even louder bass will not sound like its directly behind you. Never set your lpf past 80hz for the sub. Time alignment is also a big thing that'll help, but it is not a simple to set up. Getting things to sound right takes time and patience.

 

[supermaxx123 10+ year member]

Also if you're ever in Orange I'd be willing to help out

 

[Shojahan]

I appreciate that offer, if you mean Orange in Australia, not Orange County CA, I was in Orange once, I was also in Bathurst and Dubbo. Which high school were you senior at?