Jbl Sub1500 15" Subwoofer 4 Ohm

[JuniorJBL]

Originally posted by Giskard


I looked at the numbers on this driver again and it will indeed match the old B212 in bandwidth when used in a 4.0 cubic foot sealed enclosure. Very impressive! A slightly smaller package than the old B380. All the bandwidth of the B212 with considerably more thermal and displacement limited power handling capacity and slightly higher sensitivity plus much lower distortion. What a deal!

Giskard would you mind posting a screen shot of your graph of SPL/Frequency responce impedance plots?
I would like to compare with speaker workshop. I show a bump of about 3db at 50 Hz and that does not seem right.
Thanks Shane

[johnaec]

I saw this at another site - does it sound accurate?

Measuring Vas (equivalent air compliance)
To measure Vas, use a good solid enclosure of known volume that's about a cube of the nominal speaker size. Determine the total volume, including the speaker cut-out and that trapped by the cone with the speaker mounted on the outside of the box for easy access. Measure the resonant frequency in this situation as well as the free air space resonant frequency.

Vas = Vb((Fb/Fs)^2 - 1)

where

Vb is the volume trapped by the speaker and box
Fb is the resonance frequency of speaker and box

John

[4313B]

"Giskard would you mind posting a screen shot of your graph of SPL/Frequency responce impedance plots?"

Ok


John,

Looking at the MLSSA page I posted
Fs = 21.47 Hz
Fb = 46.61 Hz
Vb = 47.20 liters

from your formula Vas = Vb((Fb/Fs)^2 - 1), Vas should be 175.25 liters which isn't quite the 181.22 liters JBL calculated.

[JuniorJBL]

It is in a 2.2 Cu Ft sealed box. 2.5 with bracing and stuff. It sounds GREAT for the amount of space that it takes up. A little EQ at about 30Hz from my rane sp15, crossover ashley 1001 24db per at about 65 Hz. This woofer ROCKS. But you already knew this because it was made by JBL!!!!!!

[johnaec]

'Just got my first one too! Here are some pics comparing the SUB1500 with a soft-dome E140:



Side view comparing depth is below:



In the next pic, notice the three little holes on the top of the magnet. These are vents covered with a very fine cloth mesh from the inside. The standard rubber protector surrounds the magnet:



In this last pic, notice the rectangular openings in the basket right below the magnet - these are vents filled with foam - six total. Then notice the hole in the cone right behind it. There are four of these, open to the dome underneath.



The rubber surround extends roughly 1/4" in front of the basket. And according to my bathroom scale, the E140 weighs 21 lbs. and the SUB1500 weighs 30lbs. There are some JBL numbering stickers in a couple places, and a circular white stamp on the basket that says (JBL Pro 29). The top of the magnet is labeled 1500 SUB. As near as I can measure, the mounting dimensions are standard for JBL 15" models.

The only cabinet I have available right now is 2.4 cu.ft. - I plan to drop it in this weekend, then test it both sealed and vented. Eventually, I hope to have them in ~4 cu.ft.cabs - 'second one is on the way...

John

[Mr. Widget]

[jims]

Dang, John Have you been sleeping with those things?

[4313B]

Nice photos!

PE said they sold over 120 of them yesterday.

[Niklas Nord]

For us living in Sweden or the rest of Scandinavia,
it would be interesting to buy direcly from JBL in Denmark.
IF thats possible...

[johnaec]

Originally posted by jims
Dang, John Have you been sleeping with those things?

Don't tell my GF - she'll disown me!!

John

[JuniorJBL]

I think I will try a vented box this weekend (unless it snows) to see just what kind of performance we can get, most likely about a 4 to 5 cu ft box.
It does work excellent in the sealed box though. And if you want space savings this is the way to go. Although not as efficient as my 2242 it is close!!

LF extension is awesome and it really does not require that much eq. I was amazed at its detail for a VLF driver. It does sound quite good. As most people would use this for a sub/sat combo I would say don't use it above about 80-90 hz max at 24 db per octave. In the sealed box it gets a little "ringy" up there. If you do want to use it that high, I found rolling off about 100Hz with a mid "Q" cut buy about 5-6db then you can use it higher. Most of this could be the box though. The box is braced very well with medium amount of fiber fill although it might still fair better with another layer of .75 MDF. I am thinking about using 4 of these instead of 2 18's. In the sealed box I still save about 6 cu ft per side.
I will keep you posted.
Shane

[Niklas Nord]

If you look at the plot on the details page on PE,
it shows to be nice up to 400hz approx..

it should be ok up to at least 200hz,
why dont you like it over 90hz ?

[JuniorJBL]

I don't care for subs to go above about 70-80hz mostly I prefer below 60hz because I think they get a little directional. Now if you have 2 and they are very near your mains then that is a little different. But remember that is ONLY my opinon. As we all know audio is a personal prefrence and if we let others tell us what to like.... Im ranting sorry. Anyways if you like subs at 150-200 hz then by-all-means have some fun. I am sure at about 200 hz these will rattle your brain
Have fun Shane

[jims]

Originally posted by johnaec
Don't tell my GF - she'll disown me!!

John

No problemo. She probably has some appliances
she hasn't told YOU about...

Jim

[johnaec]

John

Looking at the MLSSA page I posted
Fs = 21.47 Hz
Fb = 46.61 Hz
Vb = 47.20 liters

from your formula Vas = Vb((Fb/Fs)^2 - 1), Vas should be 175.25 liters which isn't quite the 181.22 liters JBL calculated.

Hmmm...I'll also have to check the numbers at the 25.4hz Fs PartsExpress states. I wonder how they came up with 128 liters VAS? I guess I'll have to calculate two designs, and see how different the specs are...

BTW - what does MLSSA stand for?

John