With the room modes, you'll also have cancellation and addition somewhere. It's possible to get most of the room correct though, with a double bass array. It works excellent in rectangle rooms but it's also very effective on L-shaped rooms. Other room shapes are less effective to not improving.
The downside is, you need double/quatruple the number of subwoofers without adding more loudness, you need more amp channels and a dsp and the loudness isn't declining with the distance.
The downside is, you need double/quatruple the number of subwoofers without adding more loudness, you need more amp channels and a dsp and the loudness isn't declining with the distance.
For sure, multiple subs is a great move. Lots of evidence.*
But there are two sort of opposing theories on which those models are based. There is the wave-arithmetic theory (subs at opposite ends of the room) and there is the stochastic-diversity theory (the more the merrier).
I suspect the diversity theory is better because, as I have posted in this thread, working with phase is a hopeless exercise.
B.
* can't say as I've yet figured if mixed bass is better than stereo subs
Rick (and Ben too please) could you post a little diagram showing your room size & shape with the positions of speakers & listening (mike) positions too.
Rick, in your case, also the delay you use to each speaker and any EQ you apply SEPARATELY to the speakers. Otherwise, its all just noise.
To be honest I have not used the battery trick - but with the RYTHMIK system both coils would have to be reversed, which is within the realms of possibility. Never hurts to try. But I doubt that is the case, but I will try it.
The only point I was trying to make which someone classified as noise, takes a noisemaker to know one?
Trying everything is the key. AS soon as you think you "know" something you are in trouble. See it for yourself. There is much to learn about YOUR system and YOUR room. Do not assume that some textbook paragraph is going to get you anywhere. It will give you a start and that is all.
The simple fact is most people are too lazy and easily pleased to really find out how their speakers are playing their room, per Herb Reichert.
I wish I knew a fool proof method for making your speakers and room pleased with each other but there is nothing I could tell that would not mean more to you upon discovering it for yourself. And if you are not willing to discover for yourself - why are you reading about diy audio?
The comment about delay making the woofer work better out of phase - sorry - with or without delay the result is the same. The delay further smooths the response and the phase.
I think when one finds what can be done with bass with DSP they will want to take it system wide. I resisted it for years as a purist - I liked to call myself.
Funny thing is my system is far purer now. Polarity changes are more audible than ever - a rather subtle thing; now not quite as subtle. The xilica may be chocked full of 5532s, I have no idea, but it sounds quite fine to me.
I am using FW SIT1s on 2441s in John Inlow's Horns and FW J2 on a pair of old 75 hz Edgar horns with Great Plains 515ghps - which will be replaced when I can figure out what to replace them with. A pair of Edgar's Seismics with the mouth facing forward and the back chamber about 1/3 the size. No need for it to become a bastard infinite baffle since the Rythmik's handle the bottom octave. The seismics from about 50 to 125 hz. Nominally 450 hz crossover between 2441 and 515. The Seismics are infinitely better this way - no comparison and I have the measurements to prove it!
I could not be any happier with the xilica boxes. Easy to use and transparent to my ears.
I use simulation software and find that they can give an idea of trends once you do quite a few of them. But if you think a simulation can approach a REAL LIFE measurement ... oh, well ...
OF COURSE, the room is the problem! If it wasn't I would not have bought DSP boxes. But it is a given, it is what you are stuck with. There is nothing I can do to change the room. I have as much acoustic treatment as my ears tell me has not ruined the sound. The room is about 16 x 24 with a slopping ceiling starting at just over eight feel (speaker end) and rising to nineteen feet at the back of the room. Listening chair little more than halfway back with a Waslo inspired but further refined diffuser on the back wall.
Get going and measure your system. If you have DSP - don't be afraid of trying things and seeing what happens.
Thanks for this Ben.
If you could post a little diagram showing the room size and your mike & 14 sub locations. Some actual DATA is slo....o...w..ly trying very hard to emerge from the noise.
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An important point which we haven't mentioned yet.
At what frequency are you crossing over your Out-of-Phase subs to your 'normal' stereo speakers?
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Thanks for this Ben.
If you could post a little diagram showing the room size and your mike & 14 sub locations. Some actual DATA is slo....o...w..ly trying very hard to emerge from the noise.
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An important point which we haven't mentioned yet.
At what frequency are you crossing over your Out-of-Phase subs to your 'normal' stereo speakers?
I did not post these curves so everybody could have a detailed post-mortem examination of the idiosyncrasies of my music room. i have stated my purpose and your purposes are simply highjacking.
You are asking for an enormous effort on my part for a benefit which I can't imagine except to gratify your curiosity or to verify some universally accepted but vague propositions about acoustics.
I crossover somewhere around 130 to 140 and have done so since 1968. Changes from time to time and today with my wonderful DSP, the crossover is not the same for sub as for large ESL panels*. Is there something insightful about the data that you can share from learning that?
B.
* I hope nobody takes a fit from hearing that bit of iconoclasm... but I just follow the where the plots lead me
Mod hat off.
C'mon Ben unless your mobility is limited, you are denying others what this site is all about. When you offer forth the posts you do, and are then not able to add more to the mix, why is it you posted in the first place? You're an intelligent man, you ought to realize you will need to offer more when the masses request. I don't understand your approach.
It is, since you can't hear any location in the bass unless you move and notice it goes louder in one direction ..aaaaannd.. practically of recorded music got no level/loudness difference in the sub area anyway. It's only bad if you cross them over too high, location starts ~100-120Hz. You can get away with a higher xo point sometimes if the subs are close to the speakers above that frequency.
Those are universally held beliefs that are largely true but vague. Like all long-held matters of "faith", ought to be re-examined from time to time. I thought I properly parodied those acoustic notions in a manner that was not dull and pedantic, as is this reply.
More substantively, on this forum there is a fast growing interest in OBs because of the great Toole-ambience - even for subs. But the room measurements of OBs is way off from the textbook wave annihilation diagram and the endless discussions of Linkwitz Transforms reflects this searching. Therefore, it really is time to think-through wave cancellation in real-world rooms.
Don't you think so?
B.
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That was not the intention.
I should have made that clear.
I thought when I changed the subject it would be more obvious than it was.
I guess I am confused by the subject of this discussion.
I assumed everyone knew that the levels change when you walk about the room. I would say measuring all of those points is rather academic more than pragmatic.
The only thing that matters is what is happening in the listening chair. Just like with a lens you can choose sharp focus at one spot or a blurrier focus that spreads the distribution of definition of the image wider and taller but never again is there a best position. There will be better positions than others, of course.
Does your room need to accommodate a number of listeners? Is this the reason for your approach?
Are you confusing me with another poster? Are you using the "King's you" (LOL)?
I don't know what approach you are talking about. I think you have me confused with someone else.
First, you should dispense with the dismissive "faith" proclamations. The science of room acoustics, while not fully settled, is fairly robust. If the average Joe gets some of it and misses some of it, that doesn't indict the science. My graduate engineering work was in acoustics -- it's complicated and I don't for a minute feel embarrassed that I still have plenty to learn.
Second, you are making proclamations that I suspect are rooted in your own perhaps meager measurement efforts, and subsequently using those to dismiss what might be solid theoretical underpinnings that have been poorly applied. I still can't figure out what your main argument is, but you sure seem resistant to explaining further.
Does that mean the phase of your Left channel is different from the phase of your Right channel below 130Hz?
Are your L & R channels in-phase above 140 Hz?
You'll excuse me if I ignore the noise, (religous, pedantic and/or often false). I'm trying to dig USEFUL FACTs out of this thread. I believe you said your original intention was to add FACTs to the discussion.
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I can't answer a question where the questioner is unaware that they must specify the location in the long path from the laptop to the ears (assuming face forward listening, of course) at which they wish me to evaluate the phase relationship?
Given that lack of grasp of basic principles, you can understand my reluctance to take a real long time to measure and draw a sketch of my room and speakers with all the features that have acoustic impact that you seem intent on seeing.
kgrlee - you posted "You'll excuse me if I ignore the noise, (religous, pedantic and/or often false)". Could you please provide just an example or two of these "often false" statements I've made so that I and all readers will be alert to these errors in the future.
B.
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Phase has nothing to do with which direction the listener is facing. It's kind of a basic principle.
Whatever are you talking about? Didn't you just post that you had a Master's degree in acoustics? Phase is always relative to some reference, duh.
And likewise for the relative phase of two acoustic sources depends on where you are relative to the sources. Relative phase of two sources is a function of where you stick your sensor(s). And as even the most naive of noobies would realize, it depends entirely on the frequency in question.
My little joke about "facing forward" was meant to illustrate that each ear would actually have a different phase relationship to the two sources unless you were facing the two sources (which of course isn't actually possible unless you were two-faced).
What a waste of time all the picky debating in this thread.
B.
B.
Oh, it was a "joke". Gotcha. Funny.
You're the one who is wasting everybody's time. You make false assertions and then "jaw-jaw" (your term) in a lame attempt to weasel your way out of your foolishness.
Let's put it this way: unless the measuring equipment (microphone, ears, whatever) actually perturbs the acoustic space in a significant way, the acoustic signals don't care if you're listening or not. Amplitude & phase exist independent of the measurement or the orientation of the measuring equipment.
Just stop.
You're the one who is wasting everybody's time. You make false assertions and then "jaw-jaw" (your term) in a lame attempt to weasel your way out of your foolishness.
Let's put it this way: unless the measuring equipment (microphone, ears, whatever) actually perturbs the acoustic space in a significant way, the acoustic signals don't care if you're listening or not. Amplitude & phase exist independent of the measurement or the orientation of the measuring equipment.
Just stop.
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