Bass cancellation in Camry

[fredberg]

I've been playing around with (10" sealed subwoofer) box placement in the trunk of my Camry. I found the best-sounding location and the most practical. Unfortunately, they are 2 separate spots.

1) box against rear seat, sub facing rear. this is the setup which looks the cleanest and leaves a lot of trunk space left over. but I get some bass cancellations there.

2) box in the rear corner, near tailight, sub facing to rear. I found this to be by far the best-sounding set up. good output at all frequencies.

the most common setup is #1. but i have some bass loss in the upper region from 90Hz and up. i have no problem with low bass, 80Hz and below. i say this becuz i use a bass tone test CD. also, songs that have a bass drum beat (like in rock) are hardly audible.

with setup #2, i get good bass output at all frequencies, anywhere from 60Hz to 110Hz. i prefer the sound at this setup, but the box takes up practical space in the trunk.

does anyone else have this problem? if so, how do u solve it, if possible?

[Black95Cam]

run more power. =D

i have mine like how you describe in #1 and i was able to go a 139.6 Dbs with 500 watt rms.. sealed box plus a 10 dont tend to hit as low as a 12+ in a ported box. you can switch to a ported box but when playing rock, it wont respond as fast. you win some and you lose some.

ported is for deep bass.
sealed is for quality.

[fredberg]

Originally Posted by Black95Cam

run more power. =D

i have mine like how you describe in #1 and i was able to go a 139.6 Dbs with 500 watt rms.. sealed box plus a 10 dont tend to hit as low as a 12+ in a ported box. you can switch to a ported box but when playing rock, it wont respond as fast. you win some and you lose some.

ported is for deep bass.
sealed is for quality.

thnx 4 the input, Cam. i know i can always run more power, but my problem wont be solved. for example, i'll be playing a song with a bassline or badd drum that goes all over the place. it will sound inaudible around 90-110Hz, but then it will sound overpowering when it hits lower, like at 80Hz or below.

with more power, the response will still be terribly unequal.

these r the times when i wish i had a hatchback

[Mr Marv]

It does sound like you have some cancellation going on and I have a few questions if I may..
Do you have any way to check actual output such as a Radio shack SPL meter or computer based RTA?
What do you have for midbass and where/how are they mounted?
Where are your crossovers set between mid and sub?
Does your headunit have time alignment for the sub?

[Black95Cam]

maybe it just how the sub/box comb is. for example, i had 2x 15s in a sealed dual chamber box and it sounded okay. so i switch to what i have now and it sounds soo much better. also try giving it a tune. adjust your your mids and highs then move on to the sub. after getting it set on the HU then go adjust the gain/boost control on the amp. remember under powering subs and with too much gain cause it to clips and will blown the sub(s). one of the mistake people make.

[fredberg]

Originally Posted by Mr Marv

It does sound like you have some cancellation going on and I have a few questions if I may..
Do you have any way to check actual output such as a Radio shack SPL meter or computer based RTA?
What do you have for midbass and where/how are they mounted?
Where are your crossovers set between mid and sub?
Does your headunit have time alignment for the sub?

Mr Marv, i hav a simple setup. but no, i have no RTA analyzer.

all i have is a pair of Alpine 6X9's in the doors and Kenwood add-on tweeters in the sail panels. they'r running off the (Alpine) HU power and playing the full range of music, no crossover. i get good midbass with them. also, i have no rear fill. i took out the rear speakers to let bass get into the cabin better, which actually works.

the sub is crossed over at around 110Hz. like i said earlier, when the sub is "corner loaded", i get great bass throughout the whole range, even the higher bass notes. with the sub against the rear seat, using the same test songs, those same notes disappear.

i guess i'm at the mercy of the trunk acoustics.

[Black95Cam]

also do you have a lot of stuff in the trunk? if your not running a high power system its better to face them into the cab. cause since it not moving much air by the time it get to your ears its have been reduced. if running a bunch of power, the air need room to roll around and spread out.

[Mr Marv]

Originally Posted by fredberg

Mr Marv, i hav a simple setup. but no, i have no RTA analyzer.

all i have is a pair of Alpine 6X9's in the doors and Kenwood add-on tweeters in the sail panels. they'r running off the (Alpine) HU power and playing the full range of music, no crossover. i get good midbass with them. also, i have no rear fill. i took out the rear speakers to let bass get into the cabin better, which actually works.

the sub is crossed over at around 110Hz. like i said earlier, when the sub is "corner loaded", i get great bass throughout the whole range, even the higher bass notes. with the sub against the rear seat, using the same test songs, those same notes disappear.

i guess i'm at the mercy of the trunk acoustics.

Cancellation occurs when sound waves interact in a "destructive" fashion instead of a "constructive" fashion. The fact that the sound improves with the enclosure closer to the rear of the trunk tells that the waves are arriving closer in phase than when the enclosure is near the rear seat (the position of the sub/enclosure has more to do with it than the enclosure/sub combo itself). As you mentioned we are at the mercy of the vehicle's trunk acoustics however there are a few things you can try to improve on everything "blending together" and reducing the cancellation. The first thing I would do is set the high pass on the 6x9's at around 80 hz instead of having them play full range. Next I would lower the crossover point on the sub to around 80 hz as a starting point since 110hz is too high for a trunk mounted sub IMO. Next I would reverse the polarity on the sub and see if that helps. Try these and let me know if you get any improvement. Also, do you have time alignment on your headunit?

BTW, an RTA is not necessary. I just thought maybe you were using some measuring device since you stated specific frequencies that were affected.

[fredberg]

Originally Posted by Mr Marv

Cancellation occurs when sound waves interact in a "destructive" fashion instead of a "constructive" fashion. The fact that the sound improves with the enclosure closer to the rear of the trunk tells that the waves are arriving closer in phase than when the enclosure is near the rear seat (the position of the sub/enclosure has more to do with it than the enclosure/sub combo itself). As you mentioned we are at the mercy of the vehicle's trunk acoustics however there are a few things you can try to improve on everything "blending together" and reducing the cancellation. The first thing I would do is set the high pass on the 6x9's at around 80 hz instead of having them play full range. Next I would lower the crossover point on the sub to around 80 hz as a starting point since 110hz is too high for a trunk mounted sub IMO. Next I would reverse the polarity on the sub and see if that helps. Try these and let me know if you get any improvement. Also, do you have time alignment on your headunit?

BTW, an RTA is not necessary. I just thought maybe you were using some measuring device since you stated specific frequencies that were affected.

Thnx again, Mr Marv 4 ur knowledge. i'll try ur recommendations. i can high pass the 6X9's at 100Hz with my active EQ. i will lower the X-over point of the sub to 80Hz. then i will play around with the sub polarity. i have a feeling i'll be missing a huge chunk of bass around 80-100Hz, but its worth a shot. oh, and my HU does not have time alignment. i'll read up on that as to what that feature is. thnx again!