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Discussion Starter #1
Just finished a sub box for a pair of 8" Inf Reference subs, 250W/ea, 91dB, checked it out in my SUV (box is actually for another car this Spring), and it doesn't seem to perform any louder thans the single 10" 350W kappa sub that I normally use.

Box dims (OS) are - 0.35 cf per chamber sealed box - 27-3/4" L x 9-3/4" W x 7-3/4" D, all 3/4" MDF glued, scrfewed & caulked, 3/4" divider (sealed) in the middle, let sit for 24 hrs before installing the speakers. I'm pretty decent with my hands, I think the box is tight. I did glue a bunch of polyfill inside the box(es), used quite a bit of it. Amp is a Kicker 500W @ 2 Ohm, have it wired for two ohms, both sets of speaker wires landed in th +/- terms on the amp.

Any thoughts or am I asking too much for a pair of 8's in a sealed box??
 

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Any thoughts or am I asking too much for a pair of 8's in a sealed box??
This.

What were you expecting? At best you might gain 3db which is not much. Odds are the 8's are less efficient than the ten at the very least one compared to another. They probably roll off sooner than the 10.

It's those pesky laws of physics and also one of the main things that used to get preached here. Adding new equipment or a bit more power may not add anything appreciable to the end product. Other than a dent in the wallet.

If you have the material and time, try a ported enclosure for those 8's and see if there is a difference;)
 

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Discussion Starter #3
I had figured the single 10" has a sensitivity of 86 (or 88?) dB, and the 8's have 91dB, plus the additional 150W of power, was thinking I would hear an appreciable differece. Used the same amp/HU settings as the 10" when i hooked it up, thought it was actually a little worse in both SQ (which I expected) and dB's.
 

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Are the subs brand new? If so they need to break in a little and they will loosen up and play louder. Also you need to double your power and cone area to see a 3db increase in output. Maybe add a 3rd 8" and throw 250 at each and you will see 3-4db's
 

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Discussion Starter #5
Are the subs brand new? If so they need to break in a little and they will loosen up and play louder. Also you need to double your power and cone area to see a 3db increase in output. Maybe add a 3rd 8" and throw 250 at each and you will see 3-4db's

Yes the 8's are brand new, good point.

These 8's are planned for the trunk of a Civic with a set of Focal 165 VB front components (in hand), rear fill TBD, Sping build. My SUV could just about fit that Civic inside - so big difference in cabin size. Plus small trunk which is used a lot, so trying to keep the footprint small.
 

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Same here. I just put two 8's in a sealed box. .50 per chamber with polyfil. Sounded weak at first but when they loosened up....I had to turn down the bass!! Give them a chance. Let us know.
 

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I had figured the single 10" has a sensitivity of 86 (or 88?) dB, and the 8's have 91dB, plus the additional 150W of power, was thinking I would hear an appreciable differece. Used the same amp/HU settings as the 10" when i hooked it up, thought it was actually a little worse in both SQ (which I expected) and dB's.
That sensitivity spec is suspect. My gues is it isn't a 1m/1m thing and most sensitivity specs are taken at 1000 hertz which means fakk all for subs.

Are the subs brand new? If so they need to break in a little and they will loosen up and play louder. Also you need to double your power and cone area to see a 3db increase in output. Maybe add a 3rd 8" and throw 250 at each and you will see 3-4db's
Double subs on same power gains 3 db
double power on same sub gains 3 db
do both gain 6 db

In a perfect world.;)

Same here. I just put two 8's in a sealed box. .50 per chamber with polyfil. Sounded weak at first but when they loosened up....I had to turn down the bass!! Give them a chance. Let us know.
Breaking in a sub generally lowers the Fs a little bit. Maybe on one of those SPL based super stiff suspensioned woofs it would be jaw dropping, but we are talking a couple of 8's in a sealed box.

Not trying to be arguementative but again physics come into play here. Also not disputing what YOU heard in your system. The key on these things is measurement if you want quantifiable results. Simple as a Radio shack SPL meter.

Place it on the dash or someplace you can repeat the measurement. Brand new subs, gain set any eq functions documented. record volume setting on head unit. Play and measure.

2 weeks later with no system changes or whenever you feel like it. Do same test. It's not scientific but it will help remove some of that psychosomatic justification of spending the money to the results.:)
 

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That sensitivity spec is suspect. My gues is it isn't a 1m/1m thing and most sensitivity specs are taken at 1000 hertz which means fakk all for subs.


Double subs on same power gains 3 db
double power on same sub gains 3 db
do both gain 6 db

In a perfect world.;)



Breaking in a sub generally lowers the Fs a little bit. Maybe on one of those SPL based super stiff suspensioned woofs it would be jaw dropping, but we are talking a couple of 8's in a sealed box.

Not trying to be arguementative but again physics come into play here. Also not disputing what YOU heard in your system. The key on these things is measurement if you want quantifiable results. Simple as a Radio shack SPL meter.

Place it on the dash or someplace you can repeat the measurement. Brand new subs, gain set any eq functions documented. record volume setting on head unit. Play and measure.

2 weeks later with no system changes or whenever you feel like it. Do same test. It's not scientific but it will help remove some of that psychosomatic justification of spending the money to the results.:)
False

You will not gain 3db by doubling subs with the same amount of power

You need to double cone are and double power to see 3db increase

1- 12" 300 watts vs 2- 12" with 150 each will not gain any db's
 

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False

You will not gain 3db by doubling subs with the same amount of power

You need to double cone are and double power to see 3db increase

1- 12" 300 watts vs 2- 12" with 150 each will not gain any db's
Frequently Asked Questions

I was trying to be simple but you are incorrect. Doubling radiating area nets 3 db gain.

Wiring 2 subs (same model) parallel gives you 3 db for the area and 3 db for the "doubling" of power for a gain of 6db

Kind of why same sub motor but larger cone speaker families, the larger woofer is louder/more efficient.
 

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Discussion Starter #10
Good stuff...

I had some mtgs this afternoon and spent a couple of hours driving the SUV, I felt the 8's loosen up a little just in short that time. So there's hope!

But I still wonder if the 8's in this box will have enough balls for the trunk of the Civic unless I go ported. Or would it be better to go with a single high-power 10 or 12 in the trunk of the Civic (like an Alpine R) or do a ported set of 8's? Again, its a small car with a small trunk that gets used a lot, college stuff transported.
 

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Good stuff...

I had some mtgs this afternoon and spent a couple of hours driving the SUV, I felt the 8's loosen up a little just in short that time. So there's hope!

But I still wonder if the 8's in this box will have enough balls for the trunk of the Civic unless I go ported. Or would it be better to go with a single high-power 10 or 12 in the trunk of the Civic (like an Alpine R) or do a ported set of 8's? Again, its a small car with a small trunk that gets used a lot, college stuff transported.
If designed properly 2 8's ported will outperform a single 10 or 12 sealed
 

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Discussion Starter #13
These Infinities were a cheap test, i already had one new so just picked up a 2nd for $60 and made a box to check them out. I'm also looking at the Alpine and JL W3 8's as a possibility for better SQ, but figured the Infinites were a good start for the price of one sub and some 3/4 mdf.

On thing I noticed is the JL 8w3 can go ported in a 0.35 cf box which is a nice small footprint.
 
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