Toole also tried Haas kickers and dismissed that, also tested in an anechoic room with speakers emulating the content. I can't say I agree with that point of view after my own experiments. I have no idea what was tested and how that was done though.
Geddes has been outspoken on the disagreement he has with Toole on those first reflections and their part in perception. His point of view is to avoid those early reflections. They do agree on pretty much everything else, but not that part.
Geddes has been outspoken on the disagreement he has with Toole on those first reflections and their part in perception. His point of view is to avoid those early reflections. They do agree on pretty much everything else, but not that part.
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I've tried both techniques for inter-aural cancellation; the Bob Carver "Holographic Generator" electronic method and the Polk acoustic method. They both work well enough, Polk might be better (but there were variables). They both required you to be perfectly centered and with side walls at least 3 ft away. They both had a weak center image, which is part of the reason I've designed and am building a 2>3 channel"extractor" (as I call it), which will put an L-XR stereo matrix in front of it, and have an L+R center speaker, so the hologram function will have a good solid center image. I'll report back when it's done. I have all the parts (supposedly) and am waiting for the PCB's to arrive by the end of the month. It could be very groovy... 
The whole issue regarding reflections is dependent on under what conditions the tests were performed. If you have a test audience compare having early side wall reflections to not having them, that is one kind of test. If you have them compare early side wall reflections to having later arriving reflections from the same direction, that is a different test altogether. While seemingly the former has been performed many times, I have never heard of the later one being performed ever.
Add to this that we dont know the overall acoustic properties of the environment these test were performed under. I would think that the results could be very different in a anechoic environment versus one where early ceiling, floor and rear wall reflections were present.
Add to this that we dont know the overall acoustic properties of the environment these test were performed under. I would think that the results could be very different in a anechoic environment versus one where early ceiling, floor and rear wall reflections were present.
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Several such tests have been performed and are summarized (with graphs and commentary) in Floyd Toole's book, chapters 6 and 7.
Late, strong, lateral reflections are preferred, but are implausible in small rooms without the use of surround channels (which is why Toole advocates for surround sound). Short first reflections (greater than 2-3ms) also have a positive effect. The two are not mutually exclusive, it seems.
Not true. This is what kickers are about and in my 16'x25' room (not huge), I have dual 25ms strong lateral reflections.
Perhaps, but with some very negative consequences.
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Oh that's cool! I was confusing them with wesayso's "reflection" channels. I better read your thread... sorry.
Just saw this and it looked very much like a full range array. "Wall of speakers"
The Vibration Speaker. Massively Powerful Surface Speakers
Could this conveivably be used as a full range array? Anyone heard these?
The Vibration Speaker. Massively Powerful Surface Speakers
Could this conveivably be used as a full range array? Anyone heard these?
Transducers. DML speakers. NXT, ....
Yes, there is a substantial thread here about flat panels being "excited" with transducers to produce sounds.
http://www.diyaudio.com/forums/full-range/272576-study-dmls-full-range-speaker.html
There was another, can't find it right now...
Lots of DIY, and a lot of trials and errors before achieving some kind of believable sound.
Yes, there is a substantial thread here about flat panels being "excited" with transducers to produce sounds.
http://www.diyaudio.com/forums/full-range/272576-study-dmls-full-range-speaker.html
There was another, can't find it right now...
Lots of DIY, and a lot of trials and errors before achieving some kind of believable sound.
I "believe" part what makes the line array of full range drivers work as well as they do is the little mass of the moving parts combined with the big SD area. You're looking at a 65 gram speaker with 15" to 16" of SD area with quite a bit of motor force behind it. Compared to big, low mass speakers these can actually play up high and combined they do the low notes as well. The CSD showed they can do it cleanly, once processed with FIR.
In comparison the vibration speaker will have a lot more mass to move, depending on what it's driving of coarse.
In comparison the vibration speaker will have a lot more mass to move, depending on what it's driving of coarse.
A little off topic but relative to the above statement.......I have 50 tc9 drivers and my original intentions were to follow your design although much more basic as my woodworking skills aren't nearly as extensive as yours. I've been enjoying my VERY basic open baffle setup and thought just maybe I would start my line array journey with putting 25 TC9's per side in an OB of about 45-50cm wide. I would have low end support with a large OB woofer. My question would be how low can I push 25 of these to cross to the woofer? I have a pretty good idea how far I could push one driver but not sure how low 25 of them could be pushed in OB to meet the woofer. I'm sure efficiency would take a hit the lower I drive them but the woofer is already much less efficient than the array would be. I would prefer not to have to run the woofer much higher than 100hz. All else fails I go back to the sealed design.
Thanks,
Wes
I've read that with each doubling of the quantity of TC9's, you gain 3dB of acoustic power per unit of cone displacement (there are variables, but I think they're pretty small). If you make a decision on what one driver can do, based on acceptable SPL and lowest frequency desired, you can scale that SPL up accordingly.
I highly recommend reading everything on Roger Russel's website. He developed a line array that is very similar, although closed box. With open box or OB, I would design for minimal cavity effect on the rear (so no side panels - just a VERY rigid non-resonant baffle board - maybe an oak/MDF lamination an inch+ thick). An OB should sound good listened to from the rear as well.
The vert array drivers will need even more EQ than with closed baffles, which will be pretty extreme. I'd guess you'd need at least 4 times the cone displacement for open baffle vs closed. I doubt if it would work well below about 100HZ at about 80dB SPL, but that's just a guess by someone who has built a very successful OB with four 5 inch drivers per side going down to 100HZ with active OB EQ (6dB/oct. from 600HZ on down (based on baffle step)) and 24dB/oct cutoff rate at 100HZ.
For OB's, the Linkwitzlab.com website is the place to learn more. Don't try to do the EQ passively or you throw away most of the power amp power. I'd also make the baffle as narrow as is practical for best off axis response and imaging resolution horizontally. Multiple woofers distant from each other will often work much better with room acoustic issues (boominess). The nice thing about closed box woofers is that you can use active EQ ahead of the poweramp to make them acoustically flat down to 30HZ (with a fast rolloff below that), which sounds really good to my ears.
I highly recommend reading everything on Roger Russel's website. He developed a line array that is very similar, although closed box. With open box or OB, I would design for minimal cavity effect on the rear (so no side panels - just a VERY rigid non-resonant baffle board - maybe an oak/MDF lamination an inch+ thick). An OB should sound good listened to from the rear as well.
The vert array drivers will need even more EQ than with closed baffles, which will be pretty extreme. I'd guess you'd need at least 4 times the cone displacement for open baffle vs closed. I doubt if it would work well below about 100HZ at about 80dB SPL, but that's just a guess by someone who has built a very successful OB with four 5 inch drivers per side going down to 100HZ with active OB EQ (6dB/oct. from 600HZ on down (based on baffle step)) and 24dB/oct cutoff rate at 100HZ.
For OB's, the Linkwitzlab.com website is the place to learn more. Don't try to do the EQ passively or you throw away most of the power amp power. I'd also make the baffle as narrow as is practical for best off axis response and imaging resolution horizontally. Multiple woofers distant from each other will often work much better with room acoustic issues (boominess). The nice thing about closed box woofers is that you can use active EQ ahead of the poweramp to make them acoustically flat down to 30HZ (with a fast rolloff below that), which sounds really good to my ears.
I am not the right person to ask about the right cut-off frequency on an open baffle. Better to build one and measure it to see what it does different compared to a closed box array (or simulate it with a program you trust).
Cut of sharp below 30 Hz? I did try that for a while, I noticed I stated missing a lot of ambience queues, more felt than heard though. I roll off more gently now and ~17 Hz could be called my -3dB point. Steeper roll of below that though. The atmosphere it can bring is wonderful (if it's in the recording of coarse). Definitely word trying at least once!
There's not a lot of loud tones or sound below 30 Hz, but there sure is a lot of added atmosphere there. If a note would be played at full power there I'd run out of excursion quick.
There's only a few songs that I stumbled upon that made me worry.
"A Perfect Circle" with "Lullaby" comes to mind. Can't play it too loud. (while the highest peak is at 35 Hz, there's still a lot of energy at 24 Hz and lower)
Cut of sharp below 30 Hz? I did try that for a while, I noticed I stated missing a lot of ambience queues, more felt than heard though. I roll off more gently now and ~17 Hz could be called my -3dB point. Steeper roll of below that though. The atmosphere it can bring is wonderful (if it's in the recording of coarse). Definitely word trying at least once!
There's not a lot of loud tones or sound below 30 Hz, but there sure is a lot of added atmosphere there. If a note would be played at full power there I'd run out of excursion quick.
There's only a few songs that I stumbled upon that made me worry.
"A Perfect Circle" with "Lullaby" comes to mind. Can't play it too loud. (while the highest peak is at 35 Hz, there's still a lot of energy at 24 Hz and lower)
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These comparison graphs think support wesayso's experience if we can trust REW waterfall, in below it seems target as low as possible 15Hz or less, it would pay back with first slices of direct sound not affected of booming delayed tail coursed by system high pass filter and clear up also into area of mids. Below being fullrange without any XO point as with wesayso's arrays, adding IRR XO point in low frq area to below example will add quite some new slices of tails unless XO is created or corrected somewhere with FIR filter.
Bob i also play electric guitar and below makes sense a situation i had in past when comparing a FENDER Super Sixty top verse a Fender Bassmann top driving same dual 12" celestion speaker box. Having both amps voiced close to same tonal balance they sounded nearly the same except all notes on deep E string and chords where Bassmann top was superior in resolution and details in lows, now looking at below plots think it makes sense that in being a dedicated bass amp its high pass filter frq point is set lower and makes a difference.
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There isn't often a low bass note that goes below 40-50HZ, but drums sound much more real when the speaker is acoustically flat down to 30HZ rather than barely making it down to 40 or 50HZ. I suspect that part of the reason the low freq. extension sounds so much better is because with real world program material, the envelops of the higher frequency energies will have spectra to very low freqs. My main system is actively EQ'd to be acoustically flat down to 20HZ, but I find that most recordings that actually have energy down that low have been mixed with the lowest freqs exaggerated, to work better with "typical" speakers. So now I go with 30HZ as a good place to call it quits.
I my experience there are way more songs that exaggerate the 40-50 Hz and surely not many that target the area below 40 Hz. I started missing the effects down low, even though the bass sounded as loud. It was a feel thing, more than hearing a difference. The plots BYRTT shows might have something to do with it. I'm not running separate subs and have it all time aligned.
I'm willing to bet that does make a perceptual change. No matter how the big boys feel about it, I do believe in phase having an influence on perception, I've heard both.
If you look at the B&O blog on the Beolab 90, they mention bad recordings. An example they mention is Eric Clapton's 1992 Unplugged. That one has low notes that are left in the recording. Feet pounding on the floor boards. The B&O guys think this is detracting from the experience while I feel it's adding something nice. More of a "live" experience. But the timing has to be correct for it to work. Those notes are obvious though, they are heard. But I can't understand why they think it's taking something away from the experience.
I'm willing to bet that does make a perceptual change. No matter how the big boys feel about it, I do believe in phase having an influence on perception, I've heard both.
If you look at the B&O blog on the Beolab 90, they mention bad recordings. An example they mention is Eric Clapton's 1992 Unplugged. That one has low notes that are left in the recording. Feet pounding on the floor boards. The B&O guys think this is detracting from the experience while I feel it's adding something nice. More of a "live" experience. But the timing has to be correct for it to work. Those notes are obvious though, they are heard. But I can't understand why they think it's taking something away from the experience.