W1500H Enclosure help

[stevem]

I am about to build enclosures for two W1500H subwoofers. I have a box program, and it's suggesting a 2.1 cu ft ported enclosure. I will be using these crossed over at about 80Hz, with an active crossover. Can anyone tell me what would be the optimum enclosure size and type for these drivers? I will really appreciate any suggestions. Thanks!

[4313B]

The HB 5000 is about 2.6 - 2.7 cu ft sealed. The 1500 Array is 2.8 - 3.0 cu ft tuned to about 30 Hz. The sealed one needs about 10 db of Eq and the ported one needs around 4 dB. They end up with essentially the same curve to 26 Hz below which, the sealed has more output.

Here's the voltage drive for the 1500 Array. You can build, or have built, the appropriate high pass bump filter. You might want to compare this voltage drive with that of the old BX63A.

[stevem]

Thanks, Giskard. Do you have a preference for the sealed or the ported?

[4313B]

I prefer sealed. But I used a staggered B212 type cut filter on the upper end of the bandwidth instead of a bump filter; Kills efficiency but it worked for my application.

Ported works better for higher efficiency mains and I suspect most people would like it better. +4 dB Eq is easier to come by too.

[matsj]

I have problems with my parameters on w1500h, something is wrong. I get too small boxes around 0.21 cuft.
Can someone show ported vs sealed box simulations ?

mats

[4313B]

3.0 cu ft sealed and tuned to 30 Hz

The red curve in the real life LEAP plot below is achieved with the voltage drive I posted above in #2

If I remember correctly JBL's large anechoic chamber is only good to ~ 25 - 30 Hz.

[4313B]

3.0 cu ft sealed with old B212 staggered "cut" filter. 12 dB loss of efficiency but the bottom end in a typical room is insane, basically flat to 10 Hz with typical room gain. No one needs this kind of bottom end for anything. Just stick with the JBL solutions I posted above in #2

[matsj]

How much does room gain add ? I think a 30hz port is a little to high. How about 22 hz ?

mats

[Mr. Widget]

How much does room gain add ?

Depends entirely on your room... the smaller the room the greater the gain and don't forget placement will also affect this.

Will your primary use be movie soundtracks, music from CDs and SACDs, or vinyl albums?


Widget

[matsj]

Cd and computer.

mats

[Mr. Widget]

Cd and computer.

So I guess you want deep bass, but not "subterranean bowels of a ship churning the ocean", movie bass...

Depending on your room size and placement, I would go with ported at 30Hz or sealed... I use mine sealed for music and the deep bass is substantial.


Widget

[matsj]

Correct. I want stuff to happend when i play: tchaikovsky 1812 overture for example.

I´m going to use W15Gti for movies with my K2/Array diy.

mats

[4313B]

How much does room gain add ? I think a 30hz port is a little to high. How about 22 hz ?

mats

Room gain is ~ 12 dB/octave. Like Mr. Widget said, where the gain starts depends entirely on your room. ~ 50 Hz for a "typical" automobile and around ~ 25 to 30 Hz for a "typical" room are probably reasonable guesses.

The 3.0 cu ft sealed box with the B212 filter I showed above in #7 is arguably too large of a sealed volume. Reduce the volume to move the roll off higher, from ~ 25 Hz up to something like ~ 30 Hz, easily scaled with something like BB6P. One can use the B212 cut filter and loose ~ 12 dB or use ~ 10 dB of boost like Greg did with the HB5000 or like Revel did with the Gem. Either way, one needs some decent power.

Remember that JBL designed the Revel 15 aka 1500SUB and the W1500H to survive in small sealed boxes with tons of power. They negate the need for huge boxes and eighteen inch drivers. That's the whole point of these beasts.

B212 schematic showing "cut filter" aka Passive Equalizer Network R4, R5, C1, C2: