Ah, what a pity. two of the seats are next to each other, but the other is 2 meters away. No good way to make this work? Short of just getting lucky and managing to optimize both spots individually?
Nobody will care because he (Harman) has the patent. Who said life's fair
They don't have a patent on what I do.
The reduction in spatial variation isn't limited to a small listening area. The averaging effect of having multiple distributed bass sources extends throughout the room.
You crack me up Earl.
By the way, I can believe you find plate amps totally unreliable. That is quite a blanket indictment. Considering I have been building subs with (inexpensive) plate amps for over 10 years and never seen a failure I would say maybe it is somewhat over stated.
You crack me up Earl.
And I don't understand a lot of your comments = like this one.
Maybe a bad batch, but I bought a bunch of them from Parts Express - 5 - and I had problems with all of them and two of them failed outright. Don't know about other brands, so yes, I should not over generalize.
That is what we're all dreaming of but unfortunately that's not true. DBA/CABS is a different story.
Best, Markus
Well first you said Todd is doing what you do then you said they don't have a patent on what you do although - to my knowledge - SFM is patented by Harman.
The only difference between the two approaches is that you match the subs "by hand" and Todd uses a computer.
Best, Markus
Markus, in order for your claim to be true, there would have to be some acoustic effect that restricts the averaging interaction of distributed multiple subs to a small area. There is no such restrictive acoustic effect.
audiokinesis
From all I know multiple subs are only capable of reducing the variance in a continuous, spatially limited area. Todd never published data of the sound field outside the listener area. Maybe Earl has some data.
Anyhow, SFM might be able to find good solutions for spatially unconnected listening spots because of its flexibility and the huge number of variations that can be tested.
Best, Markus
From all I know multiple subs are only capable of reducing the variance in a continuous, spatially limited area. Todd never published data of the sound field outside the listener area. Maybe Earl has some data.
Anyhow, SFM might be able to find good solutions for spatially unconnected listening spots because of its flexibility and the huge number of variations that can be tested.
Best, Markus
Well, however much the effect may or may not be, I'm certainly intrigued by this concept, and I've decided to do a few experiments myself. I'm ordering four MCM 55-2185s to each put into a smallish vented box to randomly move about my room and see what happens. Worst case is I'm out 15€ per box, and the 20€ each drivers can certainly be used in other projects.
Won't have time until mid march, but I'll report back on what kind of effect it has.
Double Bass Array, see AES paper "Controlled Acoustic Bass System (CABS) A Method to Achieve Uniform Sound Field Distribution at Low Frequencies in Rectangular Rooms" by Adrian Celestinos and Sofus Birkedal Nielsen
Klankymen, I build a commercial system that is similar in concept to what you're planning. Here are my suggestions:
1. Use a fairly steep-slope lowpass filter so that you are free to position subs well away from the main speakers without them betraying their presence by passing audible lower midrange energy.
2. In the modal region, the output of multiple distributed subs will combine in semi-random phase, and below the modal region they will combine approximately in-phase. Also, boundary reinforcement will tend to boost the lower bass more than the upper bass. Take these lowbass-boosting effects into account as you design and tune your bass enclosures, so that you don't end up with too much low bass energy in-room.
1. Use a fairly steep-slope lowpass filter so that you are free to position subs well away from the main speakers without them betraying their presence by passing audible lower midrange energy.
2. In the modal region, the output of multiple distributed subs will combine in semi-random phase, and below the modal region they will combine approximately in-phase. Also, boundary reinforcement will tend to boost the lower bass more than the upper bass. Take these lowbass-boosting effects into account as you design and tune your bass enclosures, so that you don't end up with too much low bass energy in-room.
Adjustable gain helps
By the way, do you have data that shows how your solution minimizes variance throughout the whole room and not only over a limited listening area?
Thanks, probably going for a 24dB/oct filter at 100Hz, hoping that will be fine. Subs are to cover 36 to 100Hz or 30 to 100Hz, depending a bit on the volume I build.
Hence the larger of the two enclosures I simulated, with a gradual decline before the bottom corner, seeing as I'll be getting cabin gain below 50Hz or so.
Thanks for sharing your experience with the topic.
...you think of. That's why we do measurements.
I would like to know more about your solution: how many subs does it use and how does the in-room optimization work?
Well Marcus, I don't do time-consuming measurements on a quest to find problems that I do not believe exist, and for which there is neither evidence nor theory.
I have found Earl Geddes to be a very reliable source when it comes to small room acoustics. Earl on the subject at hand: "The spatial variations, and to a certain extent the frequency response variations, will go down (get smoother) as 1/N, where N is the number of independent sources."
My system, the "Swarm", uses four small subs wired in series-parallel and driven by a single amplifier. In the vented version, the frequency response curve of each of the subs slopes downward by about 3 dB per octave from 100 Hz down to the lower 20's before taking room effects into account. I recommend asymmetrical placement, with no more than one in a corner. Elevating one above the midpoint of the room would be beneficial but is usually impractical outside of a dedicated mancave. The amplifier includes a single band of parametric EQ, but to the best of my knowledge none of my customers are using it. Room optimization consists of setting the frequency and level controls on the subwoofer amp, with the phase and parametric EQ controls standing by in case they're needed.
I've gotten a bit of positive feedback on this approach:
"I’m 54, musician, assistant engineered & programmed synthesizer at the Sausalito Record Plant, been doing this since a teenager.... [the vented Swarm] equals or exceeds the best sub performance I know of."
"I am now enjoying the best bass, both in quality and quantity, that I've ever heard anytime, anywhere, in nearly 40 years of audio experience."
Links on request.
I am using the asymmetrical multisub approach with Earl's permission. Though he hasn't sought to copyright or patent it, it is still his idea. I never would have come up with it on my own. Any success that I have with my asymmetrical multisub systems reflects the competence and validity of Earl's brainwork.
I have found Earl Geddes to be a very reliable source when it comes to small room acoustics. Earl on the subject at hand: "The spatial variations, and to a certain extent the frequency response variations, will go down (get smoother) as 1/N, where N is the number of independent sources."
My system, the "Swarm", uses four small subs wired in series-parallel and driven by a single amplifier. In the vented version, the frequency response curve of each of the subs slopes downward by about 3 dB per octave from 100 Hz down to the lower 20's before taking room effects into account. I recommend asymmetrical placement, with no more than one in a corner. Elevating one above the midpoint of the room would be beneficial but is usually impractical outside of a dedicated mancave. The amplifier includes a single band of parametric EQ, but to the best of my knowledge none of my customers are using it. Room optimization consists of setting the frequency and level controls on the subwoofer amp, with the phase and parametric EQ controls standing by in case they're needed.
I've gotten a bit of positive feedback on this approach:
"I’m 54, musician, assistant engineered & programmed synthesizer at the Sausalito Record Plant, been doing this since a teenager.... [the vented Swarm] equals or exceeds the best sub performance I know of."
"I am now enjoying the best bass, both in quality and quantity, that I've ever heard anytime, anywhere, in nearly 40 years of audio experience."
Links on request.
I am using the asymmetrical multisub approach with Earl's permission. Though he hasn't sought to copyright or patent it, it is still his idea. I never would have come up with it on my own. Any success that I have with my asymmetrical multisub systems reflects the competence and validity of Earl's brainwork.