Help with questions about jbl 2241 and frequency response

[jblisbest]

Hi, I'm an amature when it comes to pa. And dj work so bare with me if I say anything stupid, IM just trying to learn.

I have been djing for a few years now and have recently bought a subwoofer system for my car. I noticed that the frequency response of my car suborder system is far flatter in the lower 40Hz and below range than my pa. Subs. I have several jbl 2241h drivers that I put into boxes I've made myself, so I understand that part of the problem could be that my box isn't properly tuned or something like that. I used the specs that jbl provides on the PDF sheet on there website to make the boxes as best as I could. I used the correct internal volume vent area and vent depth, and added fiberglass insulation.

My main question is, were the 2241 drivers ever meant to have a flat response under 40 hz?. were they ever meant to be used at frequencies as low as 31hz? The song that I was listening to when I noticed this was delusional by tech n9ne (probably not this forums favorite music genre I know), Im not sure exactly what frequency the bass drops down to but perhaps someone here who has a good ear could check it out on youtube.

http://www.youtube.com/watch?v=xb09HZhJNcs

Im not concerned about the lowest note on that song, because it seems to just rattle stuff in my car and is only barely audible. Im not concerned about these frequencies when IM running PA. but I think it would improve my dj system. Thanks in advance and please understand im an amature.

[agedhorse]

Car subs are operating in a cavity called the cabin, and cabin gain is responsible for much of the perceived low frequency extension. In fact, the 2241 in the proper sized and built cabinet (large enough to get good F3 tuning) and with proper DSP algorithems can exhibit a 3dB down point as low as 35Hz. Granted, it's a pretty large cabinet, but it's realistic and probably flatter and at much higher net sensitivity than your car stuff can ever hope to do.

[dboomer]

Here's what your song looks like ..

 

[Pro Sound Guy]

 

Jbl is recommending a 10 cubic ft cabinet for that driver

BTW that is a dam nice driver

Fs is kinda high @35hz

Here is a link for cab specs.

http://www.jblpro.com/pub/manuals/enclgde.pdf

By putting all the JBL/cabs together in one spot in front of your dj system you get what is called a coupling effect and you should notice lower frequency response

ALSO

Very important for you to know.

That model JBL 2241 has reverse polarity to most other loudspeakers

The black terminal on those JBL 2241 loudspeakers IS POSITIVE

 and the Red terminal on that JBL 2241 loudspeaker is NEGATIVE

My guess is you are running your cabinets out of phase to your main loudspeakers

Reverse the connection to those JBL subs and you should have proper polarity and an increase

in bass response as well.

Cone Transducers: the following models are negative: 

LE8T-H 2105H

2118H, J 2123H, J

2202H 2206H

2220H, J 2226H, J

2235H 2240G, H

2241G, H 2245H

 

 

 

 

[agedhorse]

With a 15 CF box, and a 2241 driver, I was able to achieve an F3 of 32Hz and an F10 of 26Hz with good average sensitivity. That's about the best you can do with this driver.

[sibyrnes]

"Jbl is recommending a 10 cubic ft cabinet for that driver"

 

Interesting!  That is just about exactly the volume of my 4718 cabs.