[RMaddGT]

I have a relatively low space for trunk room but I want t ported enclosure and the recommended vented box volume is about 1.25 cu/ft for one sub and the sub is alpine type r-1221D and I wanted to know what would be the best box for dual 12''. The height cannot be more than 13.5" in so and the depth can't be much more than 13.5" so I can get it in there and possibly 33" wide, Perhaps I could angle the box or some manner... thanks for advice...

[155dB5.0]

Originally Posted by RMaddGT

I have a relatively low space for trunk room but I want t ported enclosure and the recommended vented box volume is about 1.25 cu/ft for one sub and the sub is alpine type r-1221D and I wanted to know what would be the best box for dual 12''. The height cannot be more than 13.5" in so and the depth can't be much more than 13.5" so I can get it in there and possibly 33" wide, Perhaps I could angle the box or some manner... thanks for advice...

Just shoot for about 1cuft per sub, mabey a little less if you like more SQ

Darren

[302stang]

For this sub a ported box of 1.25 cubic feet is pretty small, and you should not go under this. Going bigger would be even better, something like 1.5-1.8 cuft. The box has to have an even bigger internal volume than this to make up for the displacement of the sub and the port(s). The space that you said you have(13.5x13.5x33) is about 3.5 cubic feet and taking into account box wall thickness, port volume, and the displacement of the subs you should have enough room for around 1.25 cuft per sub.

Just shoot for about 1cuft per sub, mabey a little less if you like more SQ

For SQ with a sealed box, bigger is better, not smaller. Bigger sealed boxes will play lower, have a higher efficiency, and have a faster transient response than a small sealed box. For a ported box you want to use the recommended size otherwise either too small or too big will hurt SQ.

[155dB5.0]

Originally Posted by 302stang

For this sub a ported box of 1.25 cubic feet is pretty small, and you should not go under this. Going bigger would be even better, something like 1.5-1.8 cuft. The box has to have an even bigger internal volume than this to make up for the displacement of the sub and the port(s). The space that you said you have(13.5x13.5x33) is about 3.5 cubic feet and taking into account box wall thickness, port volume, and the displacement of the subs you should have enough room for around 1.25 cuft per sub.




For SQ with a sealed box, bigger is better, not smaller. Bigger sealed boxes will play lower, have a higher efficiency, and have a faster transient response than a small sealed box. For a ported box you want to use the recommended size otherwise either too small or too big will hurt SQ.

I beg to differ bigger boxs are sloppy and not as acurite as a smaller seald box. When i stated 1 cuft i asumed the distplacment of the sub would allready be subtracted. The best thing to do would be to get build a ported Box for the subs, it will be louder, more efficent and sound better in my opion.

Darren

[302stang]

Originally Posted by 155dB5.0

I beg to differ bigger boxs are sloppy and not as acurite as a smaller seald box. When i stated 1 cuft i asumed the distplacment of the sub would allready be subtracted. The best thing to do would be to get build a ported Box for the subs, it will be louder, more efficent and sound better in my opion.

Darren

This is a common myth but is wrong. Smaller boxes will increase the response in the upper bass frequencies and start to become peaky or boomy. As a sealed box gets smaller the Qtc value rises, which hurts its low frequency response and also increases the transient response of the speaker. With a bigger box the Qtc will get lower and the transient response and low frequency response will improve. Look at the following link to see how frequency response changes with Qtc. http://www.loudspeakers101.com/SealHelp.htm For the best sound you want the frequency response to be as flat as possible, which means about a Qtc of .707 for a woofer than plays up to several hundred hertz. For a subwoofer that will only play up to 75 Hz or so, you get the flattest response by having as low a Qtc as possible. And remember to lower Qtc you increase the size of the box and to maximize it you mount the sub infinite baffle.

Some people may prefer the sound of a small box because it plays midbass frequencies louder and their other speakers don't play these will. But a subwoofer should only play up to about 75 Hz because higher than this the sound starts to get directional, and to sound best these frequencies should only be played with the front speakers. Also since a car has a gain at lower frequencies because of the small interior, the loss in response by the subwoofer may be made up by, by the cabin gain.

[BBrinks]

Couple of questions,
How much power are you going to give it?
What's it going to be tuned at?
If you're not dead set on a vented box, the Type-R's have great SQ in a sealed box(1-1.25 cu. ft.), and will get pretty loud, too as long as you don't underpower them.
If you're set on a ported box, I'd recommend about 1.8-2 cu. ft. tuned in the low 30's.

[155dB5.0]

Originally Posted by 302stang

This is a common myth but is wrong. Smaller boxes will increase the response in the upper bass frequencies and start to become peaky or boomy. As a sealed box gets smaller the Qtc value rises, which hurts its low frequency response and also increases the transient response of the speaker. With a bigger box the Qtc will get lower and the transient response and low frequency response will improve. Look at the following link to see how frequency response changes with Qtc. http://www.loudspeakers101.com/SealHelp.htm For the best sound you want the frequency response to be as flat as possible, which means about a Qtc of .707 for a woofer than plays up to several hundred hertz. For a subwoofer that will only play up to 75 Hz or so, you get the flattest response by having as low a Qtc as possible. And remember to lower Qtc you increase the size of the box and to maximize it you mount the sub infinite baffle.

Some people may prefer the sound of a small box because it plays midbass frequencies louder and their other speakers don't play these will. But a subwoofer should only play up to about 75 Hz because higher than this the sound starts to get directional, and to sound best these frequencies should only be played with the front speakers. Also since a car has a gain at lower frequencies because of the small interior, the loss in response by the subwoofer may be made up by, by the cabin gain.

Ah this may just be me, but are you just reading this and copying it? A Seald box is not at all ideal to get a flat responce out of a speaker no is it going to be ideal for listening if you like loud bass.
You may be right about the bigger box for seald, yea it will go lower and the lows will sound better but thats because you are changing the box, your higher frequenseys will suffer, there is alweas a trade off.
I dont even run seald box's because they sound like crap and are not practical to develop good sound out of unless you have a speaker thats TS praramiters match well with it.
Oh, midbass is suposed to come from your midbass's, a sub is a poor excuse for a midbass driver.
What experiance do you have in the audio indrustys?

RMADGT, you would also be better facing the subs twards the back.
I can help you desgine a ported box if you would like also

Darren