View Full Version : Box for JBL 2245H

Niklas Nord
04-22-2003, 12:42 AM
What would be the best solution for the JBL 2245H 18"
driver, suited for Very low frequency playback.

A flat response (in room) down to 14hz-18hz is that possible?

Lets say, i have 4 JBL 2245 woofers.

they will play frequency up to 50hz approx

Will 4 of them do some nasty things with my home?

then from 50hz the 2234 will take ower...!!

has anyone been trying to mount the 2245 with an passive radiator, like the stryke 18" radiator, in a big box with 2 or 3 radiators the 2245 would go lower and higher spl i think, but how would the hifi get... im in simulationmode right now:)

:p :cool:

Ian Mackenzie
04-22-2003, 01:12 AM

It depends on what you are trying to do??

Box designs
Suggest you look at the article by Greg Timbers/ Lorr Kramer on the main site, it details all you need to know about the 2245H bass enclosures complete with drawings. I have seen other articles for Coffin style couplers at go very low also using multiple drivers.

I recall the 12 cu ft version is flat to 20 hertz, unless you live in a large living area anything below 25 - 30 hertz is wasted unless you sit over the top of the box a receive what is termed "global output " response which could result in a major bowel disfunction!

Matching to the System and the room
There are also problems with group delay using very low (ELF) subs crossed over low (50 - 80 hertz)and you will need to time align the cabinet for best effect, meaning the sub boxes will need to be positioned forward of the main system: See Drews Clues on the main site for setup and calibration of subs, Drews design uses the JBK 2242 18". Otherwise it will sound strange on musical program material.

I have not seen 18" passive radiators, but this would require more than one 18" passive per 2245 as there would be excursion limited output and compression of transients compared to a ported design.

Subs for Hifi
My 2245s are tuned to around 28 hz for -3db @ 32 hertz in a 9 cu ft box, as part of the complete composite system (JBL 4345) the results are outstanding in terms of bass extension and musical accuracy. With a Clair Bros Phase Linear 700 its also a killer for home theatre and in many respects sheer amp horsepower is a siginicant issue for sub woofers.

In most rooms there is significant 12 - 18 db room gain below 50 hertz so the issue of extension is not so crucial to me, more over the total response flatness and low distortion.

Please note I am by no means an expert, this is just what I have come across and learnt in practise.

I hope this helps


04-22-2003, 05:40 AM
Speaking of Drew, here's his 2245H solution:


Here's the other links:



04-22-2003, 08:38 AM
check this out for a diffrent point of view. ( Instead of refigerator sized cabnets)

Ian Mackenzie
04-22-2003, 01:45 PM
Hey Yeah,

Apparently he blew one of those 24" driver at a party!!! with an Xseries 1000 watt amp.

Why not consider the CLAW.