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-   -   Should I add a 2nd VTF3 MKII or an MBM-12? (http://forum.hsuresearch.com/showthread.php?t=5352)

Lexx2004 March 10th, 2008 8:55 AM

Should I add a 2nd VTF3 MKII or an MBM-12?
 
I'm thinking of adding a 2nd sub to my set-up but I'm unsure of which to go with. I currently have a VTF3 MKII that I'm running with a Turbo Charger. I don't have the cash to pursue both options so it'll be one or the other. My system is used primarily for music and movies (about 70/30). I'm looking at the best possible option and would like some feedback from members who've tried one or both options (ie., adding a 2nd of the same subwoofer or a mid bass module). Pros and Cons of either option would also be welcomed.

My room is acoustically treated (bass traps in all 4 corners and acoustic panels at all reflection points). My room is approx. 15x20 with 9 foot ceiling (approx 2700 cubic feet). My system consists of JBL S310II (floorstanding mains rated down to 35 Hz), JBL S-Center II, and JBL S36II surrounds, Arcam AVR300 receiver, Shanling T-80 tube CD player etc.

So far I'm thinking that the MBM-12 will make things more complicated. I've already read a lot of information supporting the use of the MBM-12 - light driver and outrageous spl @ 50-80 hz, lower intermodulation distortion, and less chance for cancellation due to having two different subs handling the same frequencies while in two different locations.

There are still those who feel the MBM-12 is not need. For starters, it introduces a 2nd crossover into the equation thus making it more difficult to integrate. Also, the MBM-12 reproduces the same frequencies that another of the same subwoofer already would (albeit more effectively) but does not go quite as low as adding another of the VTF3 MKII w/Turbo.:confused:

Pete_Hsu March 11th, 2008 9:23 AM

Hi Lexx,

Does your room open to any other areas of the house?

Also, could you show me a rough sketch of your room?

Assuming that your 2700 ft^3 volume is enclosed, I would lean towards getting an MBM-12.

Sincerely,

Lexx2004 March 12th, 2008 6:39 AM

Quote:

Originally Posted by Pete_Hsu (Post 30172)
Hi Lexx,

Does your room open to any other areas of the house?

Also, could you show me a rough sketch of your room?

Assuming that your 2700 ft^3 volume is enclosed, I would lean towards getting an MBM-12.

Sincerely,

Hi Pete,

The sub is VTF MKII is located at the front left corner. There is an opening into the kitchen which is on the right side, close to the rear wall. The kitchen area is approx. 10x10 with an 8' ceiling (800 cubic feet).

What about any crossover problems that might occur with the MBM-12 as it introduces a 2nd crossover into the loop? I'm still pretty skeptical about the MBM-12. As far as I know, HSU is one of the only companies that encourage it. Most other sub manufacturers still belive in adding 2 of the exact subwoofer. Perhaps HSU knows something that no one else does.

bsoko March 12th, 2008 10:08 AM

Here is some discusson from another forum about my setup with 2 MBM-12's and a 3.3 Turbo. I hope that this clears things up for you about the MBM-12 -

Quote:
Originally Posted by craigsub http://images.avsforum.com/avs-image...s/viewpost.gif
You send the 150 Hz crossover signal to both the MBM's and the main sub. The MBM's are filtered below 50 hz by the amp. Then set the crossover of the main sub to 50 Hz.

The set up of running a pair of MBM's next to the mains, with a 120 Hz crossover seems a natural, especially with the dynamic limits of so many mains today.

It is the recommendation of putting an MBM next to one's chair that never worked for me - it was very easily located.


Quote:
Originally Posted by bsoko2 http://images.avsforum.com/avs-image...s/viewpost.gif
That's exactly what my setup is, and my mains are JBL E90's. Since my Pio '94 will not do 120hz, that is why I set it at 150hz. There is no issue with localization since the MBM's are with the mains and it ads to the mains in the mid-bass area. The bass is amazing when set up this way and my living room is over 6000 cubic feet wtih two large openings on the left side going to other parts of the house. Check out the sub tests done by Ilkka last year and see what the output is for the MBM and 3.3 Turbo when set up this way: http://www.hometheatershack.com/foru...rer-model.html.

Bill


That makes sense - you have one hell of a setup there bsoko2! One thing though, why then does Hsu and his team recommend the MBM near field, and the lower freq. sub in the traditional location? Your setup makes perfect sense to me, Hsu' recommendation (and demo of it when it first launched.. I wasn't there I read about it in a revew from Hsu's site) had it the exact opposite. And yes, I was wondering when I read it about localization, but since I dont' have that setup never really mentioned it and this is the first I've seen for a comment like that.

Craig - can't remember now in all these posts, but if I recall correctly, you never did measure or judge the combo setup, did you? An HO and a pair of MBM's would be around 2 grand delievered. I'll bet that combo would very hard to beat if setup correctly (like how bsoko2 has) for that price.
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Lexx2004 March 14th, 2008 8:23 AM

Thanks for the response Bill.

Pete_Hsu March 14th, 2008 10:31 AM

Quote:

Originally Posted by Lexx2004 (Post 30191)
Hi Pete,

The sub is VTF MKII is located at the front left corner. There is an opening into the kitchen which is on the right side, close to the rear wall. The kitchen area is approx. 10x10 with an 8' ceiling (800 cubic feet).

What about any crossover problems that might occur with the MBM-12 as it introduces a 2nd crossover into the loop? I'm still pretty skeptical about the MBM-12. As far as I know, HSU is one of the only companies that encourage it. Most other sub manufacturers still belive in adding 2 of the exact subwoofer. Perhaps HSU knows something that no one else does.

One big advantage of MBM is that it lets one position the deep bass subwoofer in a location that is ideal for deep bass reproduction, and the mid-bass unit in a location that is ideal for mid-bass reproduction. Also, there is much lower intermodulation distortion, and the MBM-12 lets one run a subwoofer in max extension mode without sacrificing any mid-bass punch and impact.

There is nothing wrong with using a second identical subwoofer, but a system with MBM-12 and a single true subwoofer would still have some natural advantages over using two true subwoofers, and vice versa too. The benefits of using MBM-12 (including lower intermodulation distortion, wider dynamic range, reduced room reflections, higher headroom, etc) far outweigh any potential complications introduced by an additional crossover in my opinion. That's why there are plenty of customers with dual VTF subwoofers who still end up getting a great improvement with MBM-12.

Sometimes it is not an easy thing to decide whether or not to add a second identical subwoofer or an MBM-12. If one is getting mid-bass response anomolies with a single true sub, and/or they don't have a very large space to pressurize, then I think it makes most sense to get an MBM-12. If one is looking for much stronger deep bass impact, then it makes most sense to get a second true subwoofer.


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