Enclosure recommendations

[BrianJ]

Hi all, this is my first post. I thought I registered years ago but I guess not.

Ive been doing alot of research but am still a bit lost on determining enclosure sizes. Im looking to build a forward firing vented/ported enclosure using a Dayton 12" Titanic TIT320C and using a BASH 300 rear mounted (3.5"deep). Box size is not a real issue, although I would like to keep the depth to a max of 22" if possible, which leaves me only 18.5" for the enclosure after the amp space.

Any help or direction you can point me would be great.
Thanks,
Brian

 

[riverwolf]

There's really no "best" enclosure. WinISD Pro will let you quickly model and compare various alignments to see the tradeoffs.

Running some quick models, I like 3 to 4 ft^3 tuned to 18Hz with the BASH300. The 3 ft^3 port might be a bit of a problem at 4"x32"...4 ft^3 shrinks it to 4"x23" for the same tune. 4 ft^3 only gains you about 1.6 dB at 20Hz, less the higher up you go (virtually identical >30Hz) so there's really not a huge performance advantage realized from the increased box size.

To model the BASH300 in WinISD, on the EQ tab, choose Highpass/SOS user defined/Q=1,Fc=18.

-Brent

 

[BrianJ]

Im beginning to think I should step up to a 15" Titanic based on the fact I just measured my living room and its around 4200cu.ft and open to my kitchen which is all of 2500 itself.

 

[Matt34]

Im beginning to think I should step up to a 15" Titanic based on the fact I just measured my living room and its around 4200cu.ft and open to my kitchen which is all of 2500 itself.

A ported Temptest X2 15" with a Bash 500w(I believe these are currently on sale at Parts Express) would be a good approach depending on the budget.

http://www.diycable.com/main/product_info.php?cPath=24&products_id=652

You can check out some other builds at HTS to get some ideas going.
http://www.hometheatershack.com/forums/ported-subwoofer-build-projects/

 

[riverwolf]

Im beginning to think I should step up to a 15" Titanic based on the fact I just measured my living room and its around 4200cu.ft and open to my kitchen which is all of 2500 itself.

Is the primary listening position in kitchen? How loud do you want to listen?

Room dimensions will determine when and how much room gain you get (along with construction methods). Distance from the sub to the primary listening position will be the major determinant of how much output you can expect.

Real world example. My comfortably loud listening level is around -15 below Reference. I have a single 315HO in 1 ft^3 sealed powered by a BASH300 in my living room system. For relevancy, living room is 22'x20'x9' with a 2 story foyer-open stair case-catwalk where one wall should be...easily something north of 8,000 ft^3 the last time I tried to calculate it. My primary listening distance to the sub is 14', according to Audyssey/tape measure. Even with the sub placed mid-wall (no corner reinforcement) and all of that acoustic space, that little sub is capable of going louder than my comfort level...which results in peaks around 100dB on demo level soundtracks. Now my idea of loud might be your background noise....YMMV and all those other standard disclaimers.

That said, the T15 will give you 3-4dB more across the board than a T12 from the same power and it'll also handle more power for an even greater difference in max potential output. The downside is you're looking at a 6 ft^3 box minimum, IMO...and 8 ft^3 would be much better.

-Brent

 

[riverwolf]

A ported Temptest X2 15" with a Bash 500w(I believe these are currently on sale at Parts Express) would be a good approach depending on the budget.

http://www.diycable.com/main/product_info.php?cPath=24&products_id=652

You can check out some other builds at HTS to get some ideas going.
http://www.hometheatershack.com/forums/ported-subwoofer-build-projects/

Kevin's a great guy and I love his drivers, but he'll be the first to tell you that you can't break the laws of physics.

In similar alignments, same f3, transfer function variance from 15Hz to 200Hz of less than 1dB...the Titanic15 and Tempest-X2 will have virtually identical output with 500 watts. By virtue of more available excursion, the Tempest is capable of slightly more total output if you feed it enough power since the Titanic will run out of excursion first. Unfortunately, I haven't seen any distortion measurements of either driver to be able to say if there's a clear advantage there. With P-E's current sale pricing, the differential is $110, just for the driver.

-Brent

 

[BrianJ]

prmary position is in livingroom, which is about 23.5x 15.5 with 15'cathedral cielings.

I have 2 positions in mind for the sub. one is to the left of the tv which gives me about 8ft of open wall to move the sub along for tuning. the other is right next to the couch(main listening spot). which would put it in a corner with no room to move it around. However the spot next to the couch allows me to have a large box and still be hidden. this spot is about 26"wide x 33" deep and 26"high would put me just below the couch arm rest.

 

[riverwolf]

A ported Temptest X2 15" with a Bash 500w(I believe these are currently on sale at Parts Express) would be a good approach depending on the budget.

http://www.diycable.com/main/product_info.php?cPath=24&products_id=652

You can check out some other builds at HTS to get some ideas going.
http://www.hometheatershack.com/forums/ported-subwoofer-build-projects/

Wierd. I posted a response Monday evening that got flagged for mod approval, but has never appeared. I can't imagine what triggered the flag so let me try again.

I like Kevin's products, but he'll be the first to tell you that you can't break the laws of physics.

Using identical alignments, frequency response/output for the Titanic15 and Tempest-X2 are virtually identical up to the limits of the Titanic15 since it has a lower excursion limit than the Tempest. BTW, that limit appears to be around 900 watts using a 6 ft^3 box tuned to 20Hz. Keep adding power to reach the Tempest's limit in the same alignment and it peaks at 1300 watts...largest output advantage is about 2dB at 30hz...the gap is smaller at higher/lower frequencies.

Will they sound different? The Tempest may produce lower distortion across the board. It has a newer motor design with possibly more emphasis focused on lowering distortion. Unfortunately, I'm not aware of any measurements of either driver.

With P-E's current sale pricing, the Titanic is $110 less...as the man in my TV says, you make the call.

-Brent

 

[riverwolf]

prmary position is in livingroom, which is about 23.5x 15.5 with 15'cathedral cielings.

I have 2 positions in mind for the sub. one is to the left of the tv which gives me about 8ft of open wall to move the sub along for tuning. the other is right next to the couch(main listening spot). which would put it in a corner with no room to move it around. However the spot next to the couch allows me to have a large box and still be hidden. this spot is about 26"wide x 33" deep and 26"high would put me just below the couch arm rest.

Where do you cross your mains? 80Hz or lower and sub position usually doesn't matter. Higher than 80Hz and you probably want to keep the sub somewhere between your L/R mains to keep from being able to localize it as a separate source from the mains. Sitting nearfield (next to couch placement) is a great way to reduce the room's influence on peaks/nulls.

For me, the T12 would have enough output, but there's no downside if you've got room for the larger cabinet needed for the T15.

-Brent

 

[Matt34]

Wierd. I posted a response Monday evening that got flagged for mod approval, but has never appeared. I can't imagine what triggered the flag so let me try again.

-Brent

Not sure why buy your posts got flagged as spam. I went ahead and approved them, hopefully it doesn't happen again, if it does just PM a mod and we will get them posted.

 

[BrianJ]

For financial reasons I stuck to the cheaper route and I went ahead and ordered the 12" Titanic and BASH 300. I'm trying to finalize my Idea for a box design to match my TV stand. I'm looking in the range of 4cu ft. after subtracting bracing, speaker, port and amp volumes from the interior. My thoughts are 22W x 22D x 19.75H. These dimensions will help to somewhat mimic my TV stand.

 

[riverwolf]

Not sure why buy your posts got flagged as spam. I went ahead and approved them, hopefully it doesn't happen again, if it does just PM a mod and we will get them posted.

Thanks. That was my next step if today's reply to you didn't appear soon...it got flagged for mod approval as well (didn't notice you were a mod before). Yet my response to BrianJ right before it and a post over in DIY made it through umolested. I'm figuring either "Kevin" or "$" is the magic word.

-Brent

 

[riverwolf]

For financial reasons I stuck to the cheaper route and I went ahead and ordered the 12" Titanic and BASH 300. I'm trying to finalize my Idea for a box design to match my TV stand. I'm looking in the range of 4cu ft. after subtracting bracing, speaker, port and amp volumes from the interior. My thoughts are 22W x 22D x 19.75H. These dimensions will help to somewhat mimic my TV stand.

I don't think you'll be disappointed...definitely a high value system!

Consider 4 ft^3 (net after subtracting driver/bracing/port) tuned to 18Hz with a 4"x23" port. With the stock BASH300, you're looking at an f3=18Hz, f10=14Hz...ground plane. Your room could easily add 6dB or more at 20Hz and lower pushing your f3 a bit lower. With 300 watts, 1m ground plane output is 108dB@20Hz rising slowly to 110.6dB@100Hz...plenty for most without the help of any boundary loading.

-Brent

 

[TLS Guy]

I don't think you'll be disappointed...definitely a high value system!

Consider 4 ft^3 (net after subtracting driver/bracing/port) tuned to 18Hz with a 4"x23" port. With the stock BASH300, you're looking at an f3=18Hz, f10=14Hz...ground plane. Your room could easily add 6dB or more at 20Hz and lower pushing your f3 a bit lower. With 300 watts, 1m ground plane output is 108dB@20Hz rising slowly to 110.6dB@100Hz...plenty for most without the help of any boundary loading.

-Brent

That port is far too small and will have a vent air velocity of 40 m/sec. That will give huge port compression and chuff like a steam locomotive.

The optimal box for that driver is one of my designs on my web site. That driver needs a slot vent of 2" X 14" X 50"

 

[BrianJ]

That port is far too small and will have a vent air velocity of 40 m/sec. That will give huge port compression and chuff like a steam locomotive.

The optimal box for that driver is one of my designs on my web site. That driver needs a slot vent of 2" X 14" X 50"

Is it safe to assume that the width dimension of this box would be 14" internally? Also to get the slot to be 50" long it would probably have to wrap around 3 walls correct?

Whether it be a round port or slot port is there a industry standard for the minimum distance an inner port opening should be from an inner wall?

 

[TLS Guy]

Is it safe to assume that the width dimension of this box would be 14" internally? Also to get the slot to be 50" long it would probably have to wrap around 3 walls correct?

Whether it be a round port or slot port is there a industry standard for the minimum distance an inner port opening should be from an inner wall?

Yes the slot vent will need wrap around. The volume of the air in the port and the wood used for construction must be added to Vb. So your final box volume Vt is Vb + the port (air and wood) the volume of wood used for bracing, the air displaced by the driver, and the air displaced by and plate amp you mount in the box. Damping is allowed for and 50% of the internal surface should be covered.

 

[GranteedEV]

wouldn't a 50" port resonate with when using an 80hz crossover? That's what my gut tells me at least.

 

[TLS Guy]

wouldn't a 50" port resonate with when using an 80hz crossover? That's what my gut tells me at least.

Port resonance will be 132Hz. It is the almost the same as a 4' organ stop, the port being an open pipe.

So it will be fine with a fourth order low pass at 80 Hz. The driver will already be 3 db down at that point so by 132 Hz the driver will be 18 db down by port resonance frequency. So there will be little to excite port resonance. If he uses a 60 Hz crossover point there will be no excitation. This trade off is much better than having high port air velocity, and the port dimensions are as short as they can be compatible with little port compression and no noise.

 

[GranteedEV]

What exactly does a port resonance sound liek anyways? I've never experienced one so I don't know what it would sound like.

Is it basically the "Organ Stop" being excited when that signal is fed loud enough?

 

[TLS Guy]

What exactly does a port resonance sound liek anyways? I've never experienced one so I don't know what it would sound like.

Is it basically the "Organ Stop" being excited when that signal is fed loud enough?

The port is an open pipe so will resonate at frequency whose wave length is twice the length of the pipe. Even order harmonics will be generated. So a port resonance would result in nasty boom and or honk if excited. I the case of this port harmonics at 260 Hz and 520 Hz would be quite prominent, so there would be a degree of honk if you excited it.