Help me design a *Lowest* playing subwoofer

[eRiCdWoNg]

ok I've done some research on this forum and around the net and I'm trying to build a subwoofer that will be used from 15-40 Hz or so. So far, most woofers do not have the Fs low enough to accomodate my needs. This will be used as a "sub-sub" woofer to a existing commercially made, 400 watt, dual 10" subwoofer that plays to about 30 Hz.

Constraints:
I don't have a problem with an enormously large enclosure, so if it needs to be 20 cubic foot, then I will do it. I don't have a problem with power either, I have a 5000 watt amp at my disposal if need be. I don't need max SPL, as this project is for low extension rather then absolute SPL.

Where I do have a problem with is $, I don't want to spend more then $500 USA or so on the woofer(s) alone, so the Servo-Drive ContraBass is out. Turning the basement into a horn sub, as much as I'd like to, is out as well Cutting multiple holes in the wall/ceiling for IB is also out (until I get a different house).

I need recommendations on a specific woofer, and alignment/configuration.

The Adire Tumult is out, I used to have that woofer, but sold it. I can't seem to find the Stryke Audio woofer anymore. The next candidate is the Parts Express Dayton Titanic MKiii 15". It has a 19 Fs, but after modeling that, it seems I can get good response out of a 6-9 cubic foot enclosure, ported, tuned to approx 25 Hz or so. I'd like to go lower Modeling it in a sealed box using heavy EQ did not look pretty.

Input please

[simon5]

Acoustic Elegance AV15 (Stryke Audio) woofers are still available, but I don't know how much time it takes for them to ship it because they are handbuilt.
http://yellow.mynethost.com/~bv12636...8f891502b79fde

There's this:
http://www.partsexpress.com/pe/showd...number=295-190

Or this:
http://www.ascendantaudio.com/arsenal15specs.html

This would be perfect but afaik it's not available.
http://www.ascendantaudio.com/allliance_page.html

BTW I just checked with the Dayton Titanic MKIII...
9 cu.ft tuned to 15 Hz just look perfect to me. EBS alignment that will give flat frequency response in room.

[RobWells]

Can you get a plot of a sealed corner placed sub in your room ? You should be able to see where room gain kicks in, and choose the amount of drivers you'd need, and decide where you want the f3.

Kelticwizard posted this chart, which really helps work out whats needed for sealed boxes. If you know what room gain you get then you're almost there.

Volume Displacement For SPL Chart

Thats all for sealed boxes though...


Rob.

[mashaffer]

If the boxplot speaker design software is correct the following are reasonable candidates.

- DaytonTitanic12 in 3.36ft^3 sealed -3dB @ 19Hz Xmax 18.7mm $160
- DaytonHiFiSub12 in 4ft^3 sealed -3dB @ 20Hz Xmax 14mm $130
- PylePro PPA15 in 56ft^3 (IB) sealed -3dB @ 15Hz Xmax 6mm $48
- DaytonIB15 50ft^3 (IB) sealed -3dB @ 12Hz Xmax 14.3mm $120

All are available at Parts Express. Seems that the comercial sub wold be redundant with one of these on the job.

mike

[454Casull]

Sealed box with Linkwitz Transform.

[lousymusician]

Originally posted by eRiCdWoNg
The next candidate is the Parts Express Dayton Titanic MKiii 15". It has a 19 Fs, but after modeling that, it seems I can get good response out of a 6-9 cubic foot enclosure, ported, tuned to approx 25 Hz or so. I'd like to go lower Modeling it in a sealed box using heavy EQ did not look pretty.

Try modeling the Titanic with an extended bass shelf alignment, something like 12 ft^3 tuned to 16 hz. In WinISD I get -4 dB at 15.7 Hz with a steep roll off below. That low enough?

A 15" Dayton Quattro in 12 ft^3 tuned to 15-16 Hz would about match the Titanic in extension, but not SPL. The Quattro is cheap, though. Less than 1/2 the price of a Titanic. Two of them together (in 24 ft^3) would play about as loud as a single Titanic. A box that big with two 15's would make a real statement!

If you need to go lower than that, I'd probably agree that the LT with a studly sealed box woofer would be about the only way. I suspect the necessary driver(s) would break the budget.

[DeonC]

Hi Eric

I see three possible alternatives for you, but all are larger than you speced. You can have a look at them then decide for yourself. I modelled all three in Win ISD Pro.

The first idea uses an Ascendant Audio Alliance 18” HT Subwoofer (see http://www.ascendantaudio.com/) at US$399.00 each. This driver was designed to be used in a sealed box, so that is how I modelled it. The Fs for this driver is very low at 14.6Hz, so it will go very low if suitably used. You can go for a ‘0.707 Max flat amplitude’ design (which some say has more punch), or a ‘0.507 Max flat delay response’ (which some say is more accurate). So let’s start with the ‘0.707 Max flat amplitude’ design.

For the ‘0.707 Max flat amplitude’ design the total box size will be 350 litres (or 12.36 cu.ft.). That is a large box, but not totally unmanageable. You can reduce the size by about half if you add a few aperiodic vents (Vifa call them “flow resistance vents’). The specs for this design is as follows:
-3 dB @ 26 Hz
-6 dB @ 20 Hz
-9 dB @ 16 Hz
-12 dB @ 13 Hz

For the ‘0.507 Max flat delay response’ design the box size will be 720 litres (or 25.43 cu.ft.) Now as you can see, this will be a monster! Once again you can reduce the box size by half by using aperiodic vents. The specs for this design is as follows:
-3 dB @ 25.5 Hz
-6 dB @ 18.5 Hz
-9 dB @ 14 Hz
-12 dB @ 11.5 Hz

The next option is a driver by Max Fidelity (see http://www.solen.ca/) called the PR21125, priced at US$439.53 (not sure what the price is in Canadian $). This is a 21” driver, and pretty efficient at 95dB/W. I only modelled one box for this driver, and that is a vented box. The box for this design is a 300 litre (10.6 cu.ft.) box tuned to 20Hz. There is no real way to reduce the size of this box. The specs for this design is as follows:
-3 dB @ 28 Hz
-6 dB @ 21.5 Hz
-9 dB @ 18 Hz
-12 dB @ 16 Hz

The only real advantage the Max Fidelity has over the Ascendant Audio is in maximum SPL, where it has an advantage of between 3dB and 6dB (in the low bass). This remains until down to 15.5Hz where the curves meet, and the Ascendant Audio has the advantage below that.

In terms of box size, the Max Fidelity will be only slightly smaller than the ‘0.707 Max flat amplitude’ design box (in standard trim) or the ‘0.507 Max flat delay response’ design box if you use aperiodic ports. My choice, if you have the space, would be the Ascendant Audio in the ‘0.507 Max flat delay response’ design box using aperiodic ports. I think this would be an AWESOME sub (even better if you build two), but is going to take up some serious real-estate in your listening room. I do however think it will be worth the cost of entry. The choice is yours…

Enjoy,
Deon

PS. There are probably other alternatives, but these are the only ones I could come up with in a short time.

[Nemophyle]

I would advise you to go with 6 of the ascendant audio assassin 12 subwoofer, in a sealed box with a linkwitz transform.

as you have to account room gain, LT is certainly the most flexible way.

i modeled that i winisd. If you put a linkwitz transform going to 10hz at .707 , and then if you put a 4th order highpass at 8hz to reduce extremes excursions, you have an F3 of 12hz, and a sub that reaches its max excursion at 12 watts, delivering 106 db flat to 15 hz (in fact in most real world cases this is overkill, because of room gain) . Of course this is an extreme example, but then you have a lot of possibilities along theses lines.

you could buy only 4 and put a LT at 20hz, wich would certainly be enough, for example

Originally posted by lousymusician



Try modeling the Titanic with an extended bass shelf alignment, something like 12 ft^3 tuned to 16 hz. In WinISD I get -4 dB at 15.7 Hz with a steep roll off below. That low enough?

A 15" Dayton Quattro in 12 ft^3 tuned to 15-16 Hz would about match the Titanic in extension, but not SPL. The Quattro is cheap, though. Less than 1/2 the price of a Titanic. Two of them together (in 24 ft^3) would play about as loud as a single Titanic. A box that big with two 15's would make a real statement!

If you need to go lower than that, I'd probably agree that the LT with a studly sealed box woofer would be about the only way. I suspect the necessary driver(s) would break the budget.

i would not do that, it seems like Group delay would be huge, and that sealed linkwitz is a better option imo

[saramac]

I have a 15"dayton titanic in an EBS alingment box, wich I originally made for a adire tempest. The box is 48" high by 24" wide and deep with two 4" precision ports@ full length. You wont be dissapointed by this set up. I think the plans are still on thier web site. If you dont want to do that much carpentry (and I couldn't blame you) use a sono-tube instead.

[RobWells]

What are the room dimensions ?

Rob.