Should I add a 2nd sub?

[Blaser]

bsoko2 wrote:

And just what is "tru subwoofing"????? Do you know what you are talking about?????

Bill

Bill,

I know what I am talking about, but it seems you just don't know who you are talking to... Let's have a nice talk and respect forum rules. You are willing to help and I am sure you are a nice guy . We may have different point of view but we should be nice to each other.

What I mean by "true subwoofing" is equal output at all frequencies starting from at least 20 Hz for a "balanced" experience.
Pls let us see your FR if possible, I would like to see the effect of your MBMs on FR.

Thank you!

[bsoko2]

blaser wrote:

Bill,

I know what I am talking about, but it seems you just don't know who you are talking to... Let's have a nice talk and respect forum rules. You are willing to help and I am sure you are a nice guy . We may have different point of view but we should be nice to each other.

What I mean by "true subwoofing" is equal output at all frequencies starting from at least 20 Hz for a "balanced" experience.
Pls let us see your FR if possible, I would like to see the effect of your MBMs on FR.

Thank you!

Check out the HSU sub charts and you will see the benefit of using a main sub and MBM-12: http://www.hometheatershack.com/foru...rer-model.html. Large rooms like mine (6000 cu ft.) benefit greatly by mutiple subs and also with the addition of mid bass subs. This concept is not new and is just now getting some popularity. It solves alot of room anomiles. Here is how I have the subs set up: Both my 3.3 (MO) and 3.3 Turbo set at 50hz (co-located near field, behind the couch). Both MBM-12's (one with each main) are naturally set for 50hz to infinity (dial all the way up) and the cross over on the receiver LFE set at 150hz. Reason for high LFE cross over is that the MBM's take the strain off the mains mid bass so the tweeters can get the full benefit of the 200 watts from the amps. It works and sounds detailed.

Enjoy the sand, Bill

[jakewash]

That sounds to me like you really only need bookshelf speakers and even at that small ones, as the mains don't get much of anything below 130hz.

[bsoko2]

jakewash wrote:

That sounds to me like you really only need bookshelf speakers and even at that small ones, as the mains don't get much of anything below 130hz.

The mains will always get bass no matter what the LFE setting is. LFE takes some of the bass from the mains, not all. Amember of the HSU forum did the same thing that I did and this post and links in the post will further explain the reasoning for my setup: http://forum.hsuresearch.com/showthr...ight=crossover).

Thank you, Bill

[jakewash]

But isn't the spec for LFE 80hz and lower for the audio tracks when mixed? If so that would mean your receiver is taking the extra frequenies away from the mains. I am surprised you can adjust your LFE XO that high. Otherwise you would be getting some dialogue out of the MBM's. Do you use an MBM with your center channel too, as it would seem to need that boost as well to equalize across the front and take that load off you amp.

I always thought the MBM was made to help with Hsu's bookshelf system have better upper bass/midrange capability.

[bsoko2]

jakewash wrote:

But isn't the spec for LFE 80hz and lower for the audio tracks when mixed? If so that would mean your receiver is taking the extra frequenies away from the mains. I am surprised you can adjust your LFE XO that high. Otherwise you would be getting some dialogue out of the MBM's. Do you use an MBM with your center channel too, as it would seem to need that boost as well to equalize across the front and take that load off you amp.

I always thought the MBM was made to help with Hsu's bookshelf system have better upper bass/midrange capability.

You can set your LFE xover to whatever you are comfortable with. 80hz is simply a THX spec. Anything above aprox. 120hz will localize your sub but in my case it there is no localization as my true sub is xover at 50hz. There is no dialogue from the MBM's. Others have done what I have done and they report no issues.

Bill

[jakewash]

I see, you were not talking about the specific LFE channel as set in movie soundtracks but the usual subwoofer crossover.

[Blaser]

bsoko2 wrote:

Check out the HSU sub charts and you will see the benefit of using a main sub and MBM-12: http://www.hometheatershack.com/foru...rer-model.html. Large rooms like mine (6000 cu ft.) benefit greatly by mutiple subs and also with the addition of mid bass subs. This concept is not new and is just now getting some popularity. It solves alot of room anomiles. Here is how I have the subs set up: Both my 3.3 (MO) and 3.3 Turbo set at 50hz (co-located near field, behind the couch). Both MBM-12's (one with each main) are naturally set for 50hz to infinity (dial all the way up) and the cross over on the receiver LFE set at 150hz. Reason for high LFE cross over is that the MBM's take the strain off the mains mid bass so the tweeters can get the full benefit of the 200 watts from the amps. It works and sounds detailed.

Enjoy the sand, Bill

Bill,

I am afraid you are not addressing my request. The link you gave is Ilkka's tests on differents subwoofers (that I already know by heart). What I need is your systems FR (at home) just to see how things look like. By the way, even HSU differenciate between an MBM and what they call a true subwoofer and therefore I can't understand why you were surprised by "true subwoofing".
MBM is unfortunately not the best way to correct room anomalies for 2 simple reasons:
- it is limited to 50 Hz
- it does not have a continuously adjustable phase setting (only 0 - 180), and while you might be lucky it works well in your setup, it might not work in another...
It also looks to me like you do not have very capable mains and therefore MBMs may be a good addition to your fronts, but again OP did not mention anything about the fronts if I am not mistaken.

[bsoko2]

blaser wrote:

Bill,

I am afraid you are not addressing my request. The link you gave is Ilkka's tests on differents subwoofers (that I already know by heart). What I need is your systems FR (at home) just to see how things look like. By the way, even HSU differenciate between an MBM and what they call a true subwoofer and therefore I can't understand why you were surprised by "true subwoofing".
MBM is unfortunately not the best way to correct room anomalies for 2 simple reasons:
- it is limited to 50 Hz
- it does not have a continuously adjustable phase setting (only 0 - 180), and while you might be lucky it works well in your setup, it might not work in another...
It also looks to me like you do not have very capable mains and therefore MBMs may be a good addition to your fronts, but again OP did not mention anything about the fronts if I am not mistaken.

Main sub xover is set at 50hz to down, the MBM is naturally set at 50hz to up - what is the problem with that? All you are doing is splitting the sub bass between two subs. This is not new! I have never ran any tests to track the room freqs. No need to, the ear is always the best and not all rooms or subs are the same.

Bill

[Blaser]

So you're definitely not addressing eventual room anomalies with MBM...By the way, if you're happy with your setup, that's fine...enjoy!

[jagman]

lexx24:

How's the move coming along? Have you had the chance to experiment with sub location? I'm really curious about having equal subs centered in the front and rear (the Harman alignment). If you've tried it, how does it sound?

I exchanged e-mails with the author of that paper and he said the front sub should be in phase with the mains, and that the rear sub's phase should be set so it fires at exactly the same time as the front suib (no delay). To me, what that means is the only way the front and rear subs would be "in phase" is if the seated position was exactly half way between the two subs. It seems kind of weird, but he wrote the paper. He also said the out of phase nature of not sitting in the middle is what allows the rear sub to fill in the valleys and drop down the peak in the in room frequency plot. Lastly, he said the central location (right to left) should minimize any localisation that occurs. But, a lot of that is theory... I've been told by someone else who's tried the two sub Harman alignment that localisation of the rear sub occurs above 50 Hz (probably due to proximity). Please comment! Thanks .

[lexx2004]

jagman wrote:

lexx24:

How's the move coming along? Have you had the chance to experiment with sub location? I'm really curious about having equal subs centered in the front and rear (the Harman alignment). If you've tried it, how does it sound?

I exchanged e-mails with the author of that paper and he said the front sub should be in phase with the mains, and that the rear sub's phase should be set so it fires at exactly the same time as the front suib (no delay). To me, what that means is the only way the front and rear subs would be "in phase" is if the seated position was exactly half way between the two subs. It seems kind of weird, but he wrote the paper. He also said the out of phase nature of not sitting in the middle is what allows the rear sub to fill in the valleys and drop down the peak in the in room frequency plot. Lastly, he said the central location (right to left) should minimize any localisation that occurs. But, a lot of that is theory... I've been told by someone else who's tried the two sub Harman alignment that localisation of the rear sub occurs above 50 Hz (probably due to proximity). Please comment! Thanks .

I just completed the move but I'm still a ways away from the set-up. I need to do some acoustic treatment first. I've read a few articles on dual sub placement and I'll likely go with the left and right locations (mid way in the room against the side walls). I'm not sure how phasing would work for that positioning though. Let me know if you have any thoughts on the phasing.

Thanks,

[Blaser]

lexx2004 wrote:

I've read a few articles on dual sub placement and I'll likely go with the left and right locations (mid way in the room against the side walls). I'm not sure how phasing would work for that positioning though. Let me know if you have any thoughts on the phasing.

If you use the same subs and amps, a spacing of 3-4 feet shouldn't generate any phase issues 80Hz and below. So, that's generally 1/3 and 2/3 rd front wall to accomplish that assuming a moderately sized room. That eliminates the lateral mode but not the axial. I wouldn't space subs too much otherwise you may need phase treatment, which many times won't produce good coupling at all frequencies...That's my 2 cent.