[Mike]

I am planning on picking up a pair of LMS 18" and was planning on just making a pair of sealed enclosures. I did consider making larger enclosures with a pair of 18" VMP's per enclosure but am trying to keep the costs down. I did read somewhere that I could use a single 18" VMP which would help to lower the tune and that would fit better in my budget. The pair would be for a home theater setting in a 4500 cuft room that has 2 large openings. I want the best music presentation first as a pair should provide more than enough SPL given that I don't blast my system past -10 on my THX pre-pro. I only want to go with VMP's to lower the F3 naturally while increasing sensitivity so I can avoid any boost down low and the added watts needed.

What I am asking here is what are the advantages and disadvantages between a dual VMP set-up VS a single? Would I be better off with a sealed alignment? I am also not crazy about having to run a pair of QSC PLX3402's if I go sealed but will a single 3402 be enough for a pair of VMP'ed 18's?

[Kyle]

Mike, on 26 July 2010 - 03:36 AM, said:

I am planning on picking up a pair of LMS 18" and was planning on just making a pair of sealed enclosures. I did consider making larger enclosures with a pair of 18" VMP's per enclosure but am trying to keep the costs down. I did read somewhere that I could use a single 18" VMP which would help to lower the tune and that would fit better in my budget. The pair would be for a home theater setting in a 4500 cuft room that has 2 large openings. I want the best music presentation first as a pair should provide more than enough SPL given that I don't blast my system past -10 on my THX pre-pro. I only want to go with VMP's to lower the F3 naturally while increasing sensitivity so I can avoid any boost down low and the added watts needed.

What I am asking here is what are the advantages and disadvantages between a dual VMP set-up VS a single? Would I be better off with a sealed alignment? I am also not crazy about having to run a pair of QSC PLX3402's if I go sealed but will a single 3402 be enough for a pair of VMP'ed 18's?

One VMP will give you more output than just the sealed box, of course two will give you better performance at high power when one might otherwise compress. I would say the QSC RMX5050 is probably a better amp for subs than the PLX. If you don't mind the weight the RMX5050 works very well with two LMS's and we have used that before. If you want lightweight i would spring for the PL's or maybe the new itech's but they are very expensive.

[Mike]

Kyle, on 26 July 2010 - 05:43 PM, said:

One VMP will give you more output than just the sealed box, of course two will give you better performance at high power when one might otherwise compress. I would say the QSC RMX5050 is probably a better amp for subs than the PLX. If you don't mind the weight the RMX5050 works very well with two LMS's and we have used that before. If you want lightweight i would spring for the PL's or maybe the new itech's but they are very expensive.

I could get rid of both my PLX3402's and just pick up a RMX5050, maybe I will just use a dolly instead of picking it up though.....oh my aching back.

I am trying to keep each box to a reasonable size. I did talk with Thilo over the phone the other day and he mentioned about 5.5 cuft. for a PR set-up. I suppose he was talking about a dual VMP but what would be the recommended size for a single VMP set-up? I was thinking the sealed could be in the 3.5 to 4 cuft. range.

I don't need to plummet into the low teens, 15hz to 18hz and above is fine as I have some serious room gain here which will extend it even further. My current TC-3000 with dual 15" VMP's in a 5.5 cuft. needs about a 3 db cut at 16hz in this room to be flat and that is with a 17hz hpf.

What would you do in my situation Kyle? I like the VMP route so that I don't need any boost down low but in my room in a large enough enclosure the sealed may only need a little boost, just a guess on my part.

I just want SQ for music to be the first priority as the SPL for movies should be a given considering I would be using 2 LMS 18" and I don't crank it at reference levels.

[Mike]

Just modeling the LMS 18" in WinISD Pro with a single or dual 18" VMPS in a 5.5 cuft. box doesn't seem to yield a big difference. I can't seem to reach the limits of the xmax with 4500 watts either, am I doing something wrong?

If I am not planning on running anything more than a pair of bridged PLX3402's at the most or more likely a single RMX5050 will I ever get to the point of compressing the single VMP?

Is the better performance with dual VMP's you mentioned limited to high power handling or would sound quality come into play even at lower volumes?

[Kyle]

I think it will be about a dB in terms of sensitivity difference between 1 VMP and 2, but its not much. You could also use two EP4000's and save a lot more money on amps and still yield about the same output as a simple RMX5050. I did not realize you already had the PLX's -you could try those first and see how they do.

[Mike]

I got a selection of amps to choose from including a EP4000, the PLX3402 pair and a pair of Face Audio F1200 which are actually pretty nice. Once I figure out which I like best with the LMS 18" pair I will sell of the others or sell them all and get a RMX5050.

What size would you recommend for a single and dual 18" VMPS enclosure?

I am in California too so if I order from Parts Express does it drop ship from you guys or would they be coming from Ohio? I plan on placing my order within the next week or 2 but am trying to decide if I should add the VMPS to that order and if so how many.

Thanks for all your help.

[Kyle]

Comes from Ohio, but all orders before 4pm (their time) ship that day. about 6 cubic feet works really nice for a low tune.