Modified 4 Pi

[NWCgrad]

I've done a lot of searching here and around most of the other sites. I am in the planning stages of my next build. I currently am running Wayne Parham designed 4 Pi speakers as LCR in my home theater (JBL 2226H woofer, Eminence H290 + B&C DE250 CD). The speakers sound great but am wanting more bass for two channel music (I have plenty of subs for home theater usage).

I am thinking of building an enclosure around the inverted 4 Pi's (inverted so the waveguide is at the proper height) with a 2242 driver. Trying to get to 8 cu ft with a tuning of 25 Hz. Will use DSP to crossover with around 150 Hz.

The 4 Pi's roll off around 90 Hz, they are in a large open basement about 3 ft from the back wall. While I could just build stand alone mid bass modules I prefer the look of a larger tower speaker.

Am I crazy? I listen to a lot of music in stereo and would prefer not to run subs. For home theater I would run the current subs (Exodus Audio Maelstrom X 18" driver in sealed enclosure + dual Eminence Lab 12's in 200 L ported tower (tuned to 22 Hz). I have not had to much difficulty in getting a smooth frequency response down to below 15 Hz using miniDSP.

Is there a better JBL driver than the 2242 to get the 4 Pi's to full range without sacrificing sound quality? I love the 2226H's but they just don't dig deep enough on there own. Goal is flat to 30 Hz.

[dprice]

It sounds like you want to add subwoofer performance but don't want to call it a subwoofer ;)

I would look for a pair of JBL W15GTi. They will allow you to use a smaller enclosure but will require more power than the 2242....no problem since DSP implies an active setup with a dedicated amp for the woofer. If the budget allows for it, a pair of 2269H would do the trick. 2241 and 2245 are other options similar to 2242.

Good luck!

[NWCgrad]

:D

That is an apt description. If I add the word "subwoofer" then I get all the advice that subwoofers must be located based on physics and not aesthetics... By making a full-range speaker (coupled with subwoofers for home theater) I can avoid (or at least minimize) the negative aspects of a full range speaker.

I modeled the 2269H drivers, and they are pretty beastly! Seem hard to come by, I used the technical manual from a VTX product to get the JBL part number and they "seem" to be available on-line (I am not sure if the store will ask for S/N numbers when time to actually order). The W15GTi is quite a driver and would work well. I am not particularly fond of the aesthetics of the driver. Will be adding 4 large, low tuned subs using Stereo Integrity HST-18 for the low end requirement of movies. My taste in music, mostly late 60's to early 80's hard and classic rock (with a smidge of classical and jazz) should be fine with a response down to 30 Hz.

I attached some early drawings of what I am thinking, the 4 Pi is a standard build fully enclosed speaker internal to the larger speaker (only mode is increasing the external width by roughly 1.5"). Current size: 20" W x 60" H x 22.75" D, material will be Baltic Birch (hence the 60" height). I should be able to finalize bracing/vent volume to get right at 8 cu ft [25 Hz tune] which is the same size as the JBL Pro 4645C subwoofer. If I go with the 2269H driver I could make a half-sized 5628 sub. I really like the big JBL subs.

I will use the 4 Pi crossover and run the 18" driver only below 150 to 200 Hz depending upon in room response (will measure with REW). Basically the new speaker will be seen by the amp/DSP as a two-way crossed over at 150 to 200 Hz. Thinking of the QSC PLD-series amps, they have plenty of DSP/crossover horsepower for this project. If not, will get an Ashly Protea or DBX processor. Center channel will be a standard 4 Pi (except sealed, blessed by Wayne a couple of years ago and currently in use) driven by a Crown XLS1500 that is currently driving the left and right 4 Pi's.

Thanks for the feedback! I have been a long-time lurker on this site but obviously not an active contributor.

[NWCgrad]

Change of direction....found two 4645C subs for a price I couldn't pass up.