Not entirely true, unless you are using subwoofers up to ~300 Hz, and even then you can't totally control room nodes (which of course bass traps only ameliorate rather than control, but it's better than nothing)
Subwoofer / Low Frequency Optimization
- Thread starter amirm
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Not entirely true, unless you are using subwoofers up to ~300 Hz, and even then you can't totally control room nodes (which of course bass traps only ameliorate rather than control, but it's better than nothing)
I will disagree here a little, if you read the article he describes a situation where the bass modes are controlled using 4 subs
in optimum positions (not sure if the main speakers are being run full range and what the freq resp of the mains are), then the
processor adjust the bass response all before eq, after eq the bass response appears (based on the FR in the article) to be
very good without the application of bass traps (I saw none mentioned inthe article).
in optimum positions (not sure if the main speakers are being run full range and what the freq resp of the mains are), then the
processor adjust the bass response all before eq, after eq the bass response appears (based on the FR in the article) to be
very good without the application of bass traps (I saw none mentioned inthe article).
McIntosh; do they have a nice surround sound pre/processor with a very nice Auto Room EQ?
The MX151 with RoomPerfect from Lyngdorf. ...Any good? Any owners here?
The MX151 with RoomPerfect from Lyngdorf. ...Any good? Any owners here?
The problem with using dissimilar subs is not so much brand or model related. The sad fact is there is no standard. Different approaches within the same brand are not uncommon.
In Steves' case perhaps four 112's might be a better solution. IMO.
In Steves' case perhaps four 112's might be a better solution. IMO.
As I understand it the Lyndorf tries to optimize for more than 1 listening position.
I think the future for both Tact and Lydorf could be with licensing their technology. Emotiva has licensed the Tact technology for their new preamp/processor.
It sounds as if the JBL processor and the process described inthe article can allow the use of dissimilar subs.
What differences would be accessible? How would we account for siginificanlty sized woofers or different crossover slopes? Assuming that would pose a problem.
You are using the contribution of each driver to the bass response of the room, this
works below the Schrodinger freq of the room. Geddes has made the same point when using subs with his speakers in a multi sub arrangement. This may not be as applicable with a symmetric arrangements as per Welti.
Hi Kevin,
Yes, RoomPerfect from Lyngdorf will optimize (EQ) for more than just one listening position.
Some TacT systems EQ only for one listening position.
As for the Emootiva XMC-1 with a TacT system implementation (coming sometimes this summer/fall); it remains to be seen. Everything at this junction in time is pure speculation and means absolutely nothing.
Kal (Rubinson) reviewed the McIntoosh MX150 A/V Processor before right here.
...From his Music in the Round column of Stereophile.
Bests,
Bob
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Thanks for the link, I find this whoel area fascinating. IMO this sort of processing plus Cello Pallette program eq can help us get the most out of our recordings.
A lot of music i love are on poor recordings, which I tolerate because of the artistic values.
Well, they cannot make a poor recording sound better,
but they can make your room sound closer to optimal. :b
I had a chance to use the Cello Palette on a good system back in the 80's you'd be surprised how much a good tone control can do to help improve the sound of a poor recording a lot of problems arre FR issues, which makes sense since the behavior of the systemthe recording (and room acoustics) probably have little to do with the system we listen to the recordin on...
Think of the four subs being made into one unit. If one sub goes lower than the others, then it will carry the weight there. At the upper end, you would be typically using 80 Hz. Your mains should be able to handle that well and so would subs as the response is sloping down by then for both as to achieve unity gain. Speaking of unity gain, the JBL ARCOS software has a unique optimization where it will actually measure the mains+sub to make sure they all level out to unity. If not, it will readjust the subs again to get there. It won't always succeed but most of the time it does.
steve williams
Site Founder, Site Owner, Administrator
Amir that ARCOS software sounds amazing. Do you use it for your clients. Did Keith use it in the design of your show room theater
If I may Amir, in your thread; an hour podcast (with video) from the acoustician Bob Hodas,
who discusses the process of "tuning" recording studios and home-theater rooms, different types of acoustic treatments, measurements versus subjective listening, the importance of the phase relationship between speakers and a flat frequency response in a room, speaker and subwoofer placement, and more.
Here
who discusses the process of "tuning" recording studios and home-theater rooms, different types of acoustic treatments, measurements versus subjective listening, the importance of the phase relationship between speakers and a flat frequency response in a room, speaker and subwoofer placement, and more.
Here
We use them. Both my designer and I are "master ARCOS calibrators" although he has more experience under his belt than I. Kieth is also a master calibrator but since we are one of the few he trusts to do that optimization, we did the work
.
The issue with using different subs is that for this whole mode canceling arrangement to work (and that is what all multi sub techniques are based on) the subs have to be 'playing together' over the modes in question. Most modern subs have EQ below 50Hz and this creates phase shift, so the reality is that you cannot guarantee more cancellation to work below this frequency unless you use the same sub for all of your subs. Luckily a lot of the big modal issues are above 50Hz so you might be able to get away with different subs...but I still think that using the same sub is the 'correct' way to go about things and will ensure the mode canceling arrangement works down all the way to the room's lowest modal frequency.
On the subject of not needing to use bass traps...well if your room has nice flexible well damped walls then you might not need any but a lot of rooms have brick or stone walls. In this case I find mode canceling arrangements of multi subs to work well below 100Hz where the subs are in control, but above this when the LCRs take over then you may well need significant bass trapping to bring the modes under control, since positional flexibility is close to 0 for these speakers and you cant use multiple LCRs! Case in point, I managed to get things super well behaved in a brick room using two subs, very flat below 100Hz. Above 100Hz it was a mess...solution - lots of bass traps.
On the subject of not needing to use bass traps...well if your room has nice flexible well damped walls then you might not need any but a lot of rooms have brick or stone walls. In this case I find mode canceling arrangements of multi subs to work well below 100Hz where the subs are in control, but above this when the LCRs take over then you may well need significant bass trapping to bring the modes under control, since positional flexibility is close to 0 for these speakers and you cant use multiple LCRs! Case in point, I managed to get things super well behaved in a brick room using two subs, very flat below 100Hz. Above 100Hz it was a mess...solution - lots of bass traps.
FYI, this article went to print in widescreen review magazine after all. It came out in the current print issue (May/June). I added a couple more measurements showing the dramatic improvements Sound Field Management can provide. It was able to do this by applying a *filter* to subs.
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