local car shop guy told me i should sell/get rid of my XXX 18?

[audioholic 5,000+ posts]

Oh, and to the OP, you dont even seem to be in the ballpark for understanding the driver's needs in a sealed box are. I know you are going ported (good choice), but for a sealed box id punch the t/s specs into a box designing program and aim for somewhere near a .707 alignment. Leave the guessing, like is it 4 cubes or 9 for 'better bottom end', to the noobs. There is a science to this stuff guys. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Beautiful choice on a sub. If your 'knowledgeable' friend only knew...

Cheers.

 

[Immacomputer 10+ year member]

theoretically 3db increase going from sealed to ported. a noticeable gain.
sealed will be flatter, ported peakier. my tastes have always been ported, dont know about you.

I know you're trying to help but you're really steering him in the wrong direction with this advice. Sealed will NOT always be flatter nor will ported ALWAYS be peaky. This is very much dependent on the sub, the vehicle, and the alignment chosen.

You keep telling him to port the sub based on generalizations of the sub or compared to the 05 version. This is a terrible generalization and in this case could really end up sounding terrible.

Please take a look at the T/S specs of the 06/07 XXX; this is a VERY different sub than the 05 and was designed completely different; they're not even remotely comparable. The new 18" XXX has a very high Qes value as well as a mid placed Qts. Both of these would really lead towards the sub being sealed. Then, when you couple that with an extremely low Fs and Very high Vas, you should really only plan on sealing this sub. Porting it will lead it to sounding pretty terrible around tuning and peaking higher than tuning and dropping off in either direction in the frequency domain. The efficiency bandwidth product (EBP) is also VERY low for this sub which also screams "SEAL ME" and that it will sound pretty raunchy in a ported alignment.

This sub has a theoretical -3dB point of about 21hz in a 9 cube enclosure and is pretty much flat down to about 25hz. Because of it's high xmax, it should also be very loud as it gets down there. I would bet a pretty large sum of money that it would be much louder sealed over a spectrum than the ported enclosure would be. The ported enclosure MAY peak higher on a meter but the sealed will definitely sound louder and drop MUCH lower than the ported counterpart (assuming we're talking about the 9 cube @ 32hz).

You may cry all day that it's theoretical and that things will change when you put it in a vehicle and I will agree with you every day. But, the transfer function will still be applied to that system that you have before hand; which basically means that if it's peaky before the transfer function, it will be peaky after cabin gain. Also, while these theoretical values won't come to life exactly as modeled, they do give a great idea of how the sub will function in the possible enclosure.

Oh, and to the OP, you dont even seem to be in the ballpark for understanding the driver's needs in a sealed box are. I know you are going ported (good choice), but for a sealed box id punch the t/s specs into a box designing program and aim for somewhere near a .707 alignment. Leave the guessing, like is it 4 cubes or 9 for 'better bottom end', to the noobs. There is a science to this stuff guys. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
Beautiful choice on a sub. If your 'knowledgeable' friend only knew...

Cheers.

Shooting for a butterworth alignment for this sub probably wouldn't be a good idea seeing as the high Qes and high Vas will lead it to be around 25+ cubes. The 9 cube alignment is around .94 Qtc or so and yet it still has an F3 around 21hz.

 

[BreakingBad]

I know you're trying to help but you're really steering him in the wrong direction with this advice. Sealed will NOT always be flatter nor will ported ALWAYS be peaky. This is very much dependent on the sub, the vehicle, and the alignment chosen.
You keep telling him to port the sub based on generalizations of the sub or compared to the 05 version. This is a terrible generalization and in this case could really end up sounding terrible.

Please take a look at the T/S specs of the 06/07 XXX; this is a VERY different sub than the 05 and was designed completely different; they're not even remotely comparable. The new 18" XXX has a very high Qes value as well as a mid placed Qts. Both of these would really lead towards the sub being sealed. Then, when you couple that with an extremely low Fs and Very high Vas, you should really only plan on sealing this sub. Porting it will lead it to sounding pretty terrible around tuning and peaking higher than tuning and dropping off in either direction in the frequency domain. The efficiency bandwidth product (EBP) is also VERY low for this sub which also screams "SEAL ME" and that it will sound pretty raunchy in a ported alignment.

This sub has a theoretical -3dB point of about 21hz in a 9 cube enclosure and is pretty much flat down to about 25hz. Because of it's high xmax, it should also be very loud as it gets down there. I would bet a pretty large sum of money that it would be much louder sealed over a spectrum than the ported enclosure would be. The ported enclosure MAY peak higher on a meter but the sealed will definitely sound louder and drop MUCH lower than the ported counterpart (assuming we're talking about the 9 cube @ 32hz).

You may cry all day that it's theoretical and that things will change when you put it in a vehicle and I will agree with you every day. But, the transfer function will still be applied to that system that you have before hand; which basically means that if it's peaky before the transfer function, it will be peaky after cabin gain. Also, while these theoretical values won't come to life exactly as modeled, they do give a great idea of how the sub will function in the possible enclosure.

Shooting for a butterworth alignment for this sub probably wouldn't be a good idea seeing as the high Qes and high Vas will lead it to be around 25+ cubes. The 9 cube alignment is around .94 Qtc or so and yet it still has an F3 around 21hz.

if this is all true information, you are one smart dude.

rah. i'm gettin 50/50... half say ported, half say sealed.

my goal: a sub that will sound good hitting various notes, go extremely low and deep and sound great doing it. i don't necessarily need SPL setup with this sub, either sealed or ported this sub will be loud in my book.

i just am really curious as to whats the best decision for what i want.

 

[audioholic 5,000+ posts]

Shooting for a butterworth alignment for this sub probably wouldn't be a good idea seeing as the high Qes and high Vas will lead it to be around 25+ cubes. The 9 cube alignment is around .94 Qtc or so and yet it still has an F3 around 21hz.

Sounds like words of wisdom to me. Ive never looked into the new xxx specs.
What's their EBP?

 

[Ignatowski 5,000+ posts]

I have yet to meet a local dealer who knew what he was talking about.....Other than the junk they are trying to sell

 

[jeremiah 10+ year member]

sealed

 

[azbass 5,000+ posts]

if this is all true information, you are one smart dude.
rah. i'm gettin 50/50... half say ported, half say sealed.

my goal: a sub that will sound good hitting various notes, go extremely low and deep and sound great doing it. i don't necessarily need SPL setup with this sub, either sealed or ported this sub will be loud in my book.

i just am really curious as to whats the best decision for what i want.

how would it not be true? the numbers you see in the specs mean something. you don't go buying a big ass sub woofer because it looks cool, when you dont understand the specs behind it.

 

[mike11202 10+ year member]

just like the guy at the local audio shop in my town.. said hes installed every type of sub including my 9515 when the owner never saw one before //content.invisioncic.com/y282845/emoticons/veryhappy.gif.fec4fed33b4a1279cf10bdd45a039dae.gif

 

[Hundreth 10+ year member]

I know you're trying to help but you're really steering him in the wrong direction with this advice. Sealed will NOT always be flatter nor will ported ALWAYS be peaky. This is very much dependent on the sub, the vehicle, and the alignment chosen.
You keep telling him to port the sub based on generalizations of the sub or compared to the 05 version. This is a terrible generalization and in this case could really end up sounding terrible.

Please take a look at the T/S specs of the 06/07 XXX; this is a VERY different sub than the 05 and was designed completely different; they're not even remotely comparable. The new 18" XXX has a very high Qes value as well as a mid placed Qts. Both of these would really lead towards the sub being sealed. Then, when you couple that with an extremely low Fs and Very high Vas, you should really only plan on sealing this sub. Porting it will lead it to sounding pretty terrible around tuning and peaking higher than tuning and dropping off in either direction in the frequency domain. The efficiency bandwidth product (EBP) is also VERY low for this sub which also screams "SEAL ME" and that it will sound pretty raunchy in a ported alignment.

This sub has a theoretical -3dB point of about 21hz in a 9 cube enclosure and is pretty much flat down to about 25hz. Because of it's high xmax, it should also be very loud as it gets down there. I would bet a pretty large sum of money that it would be much louder sealed over a spectrum than the ported enclosure would be. The ported enclosure MAY peak higher on a meter but the sealed will definitely sound louder and drop MUCH lower than the ported counterpart (assuming we're talking about the 9 cube @ 32hz).

You may cry all day that it's theoretical and that things will change when you put it in a vehicle and I will agree with you every day. But, the transfer function will still be applied to that system that you have before hand; which basically means that if it's peaky before the transfer function, it will be peaky after cabin gain. Also, while these theoretical values won't come to life exactly as modeled, they do give a great idea of how the sub will function in the possible enclosure.

Shooting for a butterworth alignment for this sub probably wouldn't be a good idea seeing as the high Qes and high Vas will lead it to be around 25+ cubes. The 9 cube alignment is around .94 Qtc or so and yet it still has an F3 around 21hz.

Truth. People here seem to have that "f*ck specs, this is the REAL world!" attitude, but in the "REAL" world they are dumbasses.

 

[profundus-sanus 10+ year member]

I know you're trying to help but you're really steering him in the wrong direction with this advice. Sealed will NOT always be flatter nor will ported ALWAYS be peaky. This is very much dependent on the sub, the vehicle, and the alignment chosen.
You keep telling him to port the sub based on generalizations of the sub or compared to the 05 version. This is a terrible generalization and in this case could really end up sounding terrible.

Please take a look at the T/S specs of the 06/07 XXX; this is a VERY different sub than the 05 and was designed completely different; they're not even remotely comparable. The new 18" XXX has a very high Qes value as well as a mid placed Qts. Both of these would really lead towards the sub being sealed. Then, when you couple that with an extremely low Fs and Very high Vas, you should really only plan on sealing this sub. Porting it will lead it to sounding pretty terrible around tuning and peaking higher than tuning and dropping off in either direction in the frequency domain. The efficiency bandwidth product (EBP) is also VERY low for this sub which also screams "SEAL ME" and that it will sound pretty raunchy in a ported alignment.

This sub has a theoretical -3dB point of about 21hz in a 9 cube enclosure and is pretty much flat down to about 25hz. Because of it's high xmax, it should also be very loud as it gets down there. I would bet a pretty large sum of money that it would be much louder sealed over a spectrum than the ported enclosure would be. The ported enclosure MAY peak higher on a meter but the sealed will definitely sound louder and drop MUCH lower than the ported counterpart (assuming we're talking about the 9 cube @ 32hz).

You may cry all day that it's theoretical and that things will change when you put it in a vehicle and I will agree with you every day. But, the transfer function will still be applied to that system that you have before hand; which basically means that if it's peaky before the transfer function, it will be peaky after cabin gain. Also, while these theoretical values won't come to life exactly as modeled, they do give a great idea of how the sub will function in the possible enclosure.

Shooting for a butterworth alignment for this sub probably wouldn't be a good idea seeing as the high Qes and high Vas will lead it to be around 25+ cubes. The 9 cube alignment is around .94 Qtc or so and yet it still has an F3 around 21hz.

X2 Exactly what i was wanting to say reading through this but you beat me, obviously.

if this is all true information, you are one smart dude.
rah. i'm gettin 50/50... half say ported, half say sealed.

my goal: a sub that will sound good hitting various notes, go extremely low and deep and sound great doing it. i don't necessarily need SPL setup with this sub, either sealed or ported this sub will be loud in my book.

i just am really curious as to whats the best decision for what i want.

seal it up at about 6.75 cubic feet net.. the thing will be peaky no matter what you do ported, unless you go with a 4th order bandpass... but then your looking at about 16 cubic feet externally.

 

[newusername 10+ year member]

8-10 cubes sealed. You will have a rising bottom end and it will be tough to match your mains with it.

Do not go ported unless you're going to tune really, really low. Some people suggested 9 cubes tuned to 30-32 Hz: you are going to have a giant peak in your response after transfer function...and I mean giant. The only way a ported alignment is feasible is if you are tuning extremely low (like 15-20 Hz) and then you have to balance port area and length.

Keep in mind that this sub has 54mm of Xmax. Even if we ignore it's Q factor for a minute, it doesn't make much sense to use it in any alignment that features a Helmholtz resonator. You're looking at 20-25mm tops of usable excursion in any ported enclosure under 10 cubic feet, whereas in a sealed enclosure you will actually make use of that linear throw; paired with less electrical damping, this is clearly a sealed candidate.

Either way, though, you will easily drown out your mains. But sealed will work the best.

 

[IgnoreMe 5,000+ posts]

I know you're trying to help but you're really steering him in the wrong direction with this advice. Sealed will NOT always be flatter nor will ported ALWAYS be peaky. This is very much dependent on the sub, the vehicle, and the alignment chosen.
You keep telling him to port the sub based on generalizations of the sub or compared to the 05 version. This is a terrible generalization and in this case could really end up sounding terrible.

Please take a look at the T/S specs of the 06/07 XXX; this is a VERY different sub than the 05 and was designed completely different; they're not even remotely comparable. The new 18" XXX has a very high Qes value as well as a mid placed Qts. Both of these would really lead towards the sub being sealed. Then, when you couple that with an extremely low Fs and Very high Vas, you should really only plan on sealing this sub. Porting it will lead it to sounding pretty terrible around tuning and peaking higher than tuning and dropping off in either direction in the frequency domain. The efficiency bandwidth product (EBP) is also VERY low for this sub which also screams "SEAL ME" and that it will sound pretty raunchy in a ported alignment.

This sub has a theoretical -3dB point of about 21hz in a 9 cube enclosure and is pretty much flat down to about 25hz. Because of it's high xmax, it should also be very loud as it gets down there. I would bet a pretty large sum of money that it would be much louder sealed over a spectrum than the ported enclosure would be. The ported enclosure MAY peak higher on a meter but the sealed will definitely sound louder and drop MUCH lower than the ported counterpart (assuming we're talking about the 9 cube @ 32hz).

You may cry all day that it's theoretical and that things will change when you put it in a vehicle and I will agree with you every day. But, the transfer function will still be applied to that system that you have before hand; which basically means that if it's peaky before the transfer function, it will be peaky after cabin gain. Also, while these theoretical values won't come to life exactly as modeled, they do give a great idea of how the sub will function in the possible enclosure.

Shooting for a butterworth alignment for this sub probably wouldn't be a good idea seeing as the high Qes and high Vas will lead it to be around 25+ cubes. The 9 cube alignment is around .94 Qtc or so and yet it still has an F3 around 21hz.

its not so much that i was comparing it to the 05. its more so the fact that i just am willing to sacrifice a flatter response for a more peakier but overall louder response. they are generalizations, of course, but then again ive never used a driver like the current XXX, so thats where the information im giving could be way off.

to the OP, yes "immacomputer", "audioholic" and "devildriver" are guys that will go by the specs, and have a much better idea of what SHOULD be a better alignment. they are (seem to be at least, since i dont know them in person) to be VERY well educated, and their response are defiantly something to think about.l

 

[Earthman 10+ year member]

Most commercial shops e.g. [ JL,mtx etc. ] don't know about underground products, hence all the B.S. he told you. They don't know any better, just ignore em. That's what I do when I go In to challenge them on their knowledge of products they usually haven't any experience of. They shure don't like to be shown up in their own field of work.

 

[IgnoreMe 5,000+ posts]

Most commercial shops e.g. [ JL,mtx etc. ] don't know about underground products, hence all the B.S. he told you. They don't know any better, just ignore em. That's what I do when I go In to challenge them on their knowledge of products they usually haven't any experience of. They shure don't like to be shown up in their own field of work.

i had some guy tell me 8 cubes net ported for my 2 15" RE sx's was WAYYY too small. i was like //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[BreakingBad]

so, for the sound i want it seems as if most people are saying sealed will probably be the best environment to go with..

9 cubes sealed...

and from what devil said, ported won't make use of the lows this sub can produce.. is that correct? or unless i tune the box super low... and even then it will be "peaky"?