[Fatawan]

I am getting two of the LMS-Ultra 15" drivers. I have been messing around with WinISD and had some questions. First off, I have a 12' x 26' HT, completely sealed, with superchunk bass traps, OC703 on front and back walls, and at first reflection points. My current subs (Rythmiks and Mael-X) show an ample amount of room gain(12 db at 20Hz, even more lower). Now, for the questions.

A 3 cf sealed box(Qtc of .514) with a 3600W max input(CE4000 on 220) will have 26mm cone excursion at 10Hz, and 10-20mm from 50Hz down to 20Hz. Is that accptable margin of safety? SPL shows 118db at 70Hz, and 108db at 20Hz.

To contrast, a LMS 15" with 2 of the AE 18" PR's tuned to ~16 Hz will have the same max SPL output, but will be still cranking out 114db at 16Hz. The question is, is it worth it? The 1600g PR's are on sale for $100 each, and then I would need some kind of filter. Are room gain db's sonically equivalent to PR dbs? Does room gain apply in the same manner to the PR box, increasing my headroom even further?

Two of the "high profile" LMS builds(Jai and Robert's) went with PR's. I would love some opinions on this sealed vs. PR topic. Thanks!

 

[Fatawan]

I don't quite understand your question, but a PR acts like a port... A PR will add low frequency extension down to the tuning point.

Let me ask that question about sound quality another way. Let's say a sealed sub in room has 12db of room gain at 20Hz, which takes its 100db output up to 112db. The same driver in a PR enclosure has an actual output of 112 db at 20Hz without the benefit of room gain. Would they sound exactly the same? The reason I ask is that those with PR subs comment about the extra "punch" or "slam" they get over a sealed sub, and I can't imagine there is any difference if the levels are the same.

Thank you for all the helpful responses.

 

[Fatawan]

Ricci:

I had one parameter wrong--your model is correct. I have to shrink my box to be safe--closer to 2-2.5cu. ft. Thanks for the bit about the filter in the CE4000. I should have two of them, so it would be 3600W potentially to each driver.

Thanks!

 

[Fatawan]

I got one done(except for painting that MDF edge black where the driver is recessed). It's sealed, 2.4 cu. ft. internal, with 3/4" baltic birch inside, laminated with 1/2" MDF(3/4" on baffle, which has a double BB thickness), and veneered in figured walnut.

 

[Fatawan]

That is very pretty. What do you think soundwise?

I have been moving it around the room to get a smooth response at my listening positions, so that has been ongoing before an extended listening comparison session. It can take the power for sure, and it's loud.

Noooice...:T

How is the damaged CE4000 issue going?

Thanks. UPS denied the seller's insurance claim, he is appealing that claim, and my credit card company is looking into my dispute. I wish you would have put your CE4000's up for sale before I got into this mess!