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post #1171 of 1508 Old 10-05-2013, 07:57 AM
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"how would you go about doing this? Would you be relying on measurements to tell you when the drivers are in the right place? If so, what specific measurement would be useful for this?"

there is a little natural delay in the woofers relative to the mid/top because of the inductance effect of their larger voice coils, but more or less, just measure.

ideally, it would be measured acoustically in the same kind of way as your avr "chirps" to find the distances from your speakers to your listening position.

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post #1172 of 1508 Old 10-05-2013, 10:28 AM - Thread Starter
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Good point LTD, I hadn't even thought of that as an issue. I can measure when I do the testing, and an angled baffle for the top and bottom woofers wouldn't be the most difficult thing in the world to build. I would imagine I'd need to do quite a bit of testing with delays and converting that to the measurements of baffle details. Well, off to the garage to get some work done...I have about a one hour window, so I need to make some progress.
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post #1173 of 1508 Old 10-05-2013, 10:50 AM
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don't make it too complicated! the cabs are modular, so just move the outers ahead by a little. :-)

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post #1174 of 1508 Old 10-05-2013, 12:27 PM
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You can do it a few ways. I wouldn't be a afraid of using delay. You can do a chirp test. FR sweep and look at the impulse response. Or align phase by moving the cabs physically. Once summation is at its maximum, you're in phase. This is really the most sure way.
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post #1175 of 1508 Old 10-05-2013, 01:07 PM
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easy to flip polarity adjust for deepest null, then flip back for max summation marty.

...

just found something...interesting. that is an almost perfect overlay! :-)


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post #1176 of 1508 Old 10-05-2013, 01:11 PM - Thread Starter
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Thanks guys, that's what I'll do and see how it works...I meant angled cabs more for the final product if that's what works. Not much seost progress today, but here is a pic of the three baffles for fun..


Most of my hour of free time today went to this....building a single Dayton 18 with a Funk 800w amp for mom and dad in their living room


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post #1177 of 1508 Old 10-05-2013, 05:01 PM
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For time alignment just a simple impulse response is all you need. Measure impulse response and adjust until they occur at the same time. As a rough way to get phase right in the crossover, flip polarity and adjust to get the maximum null. Then flip back. This will get you close although it depends on the slopes and frequency used what the overall phase and summation will look like throughout that region.

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post #1178 of 1508 Old 10-05-2013, 05:44 PM
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What is the maximum null?
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post #1179 of 1508 Old 10-05-2013, 06:32 PM
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The maximum null is the point at which the cancelation between two drivers when wired out of phase is at it’s maximum. That means when wired in phase those drivers would have maximum acoustic summation.
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post #1180 of 1508 Old 10-06-2013, 04:53 AM
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Thanks for the reply Matt! Can phase be measured in REW? If so, how do you go about measuring phase in REW?
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post #1181 of 1508 Old 10-06-2013, 05:01 AM - Thread Starter
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Ltd, when talking about the different distances from each driver to listening position... 1/4 wavelength or less for proper summing is referring to wavelength of cover frequency of the top or bottom driver from the mid woofer next to it correct??
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post #1182 of 1508 Old 10-06-2013, 05:51 AM
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there are actually two effects.

effect #1. one is the center to center spacing from one driver to the next. when they are roughly 1/4 wavelength or less, they will more or less sum constructively. with 15" drivers, that is about 1.25 feet center to center. so 1/4 wavelength is 5 feet long, which is 1130 ft/s / 5ft = 226hz. so by crossing up around 450hz, the drivers will *not* be acting as a single source, therefore effect #2 is important.

effect #2. if the drivers are behaving as independent sources, but they are aligned such they are still no different than 1/4 wavelength in total distance from the listener, the sound arriving at the listener will combine constructively and no cancellations will occur. this is the effect we are trying to achieve by moving the outermost woofers forward physically (or pushing the center unit back synthetically by putting a little delay on it*). the difference in the distance that we are talking about in this case is the distance measured from the listening position to the center or each driver. when that distance difference = 1/2 of a wavelength, the sound will completely cancel out at that frequency because the sound from the two sources is arriving exactly 180 degrees out of phase.

so, it is ideal to have effect #1 (which can also be described as drivers being "line arrayed"). almost as good to have effect #2 (which can also be described as having drivers "time aligned").

delay by the way is typically measured in milliseconds, or ms. since the speed of sound is 1130 ft/s under typical conditions, each ms of delay corresponds to roughly 1130 ft/s / 1s = 1.130 feet, or very roughly 1 foot.

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post #1183 of 1508 Old 10-06-2013, 06:03 AM - Thread Starter
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Ok, I understand center to center spacing in general, I think.....In the vertical quad stack, if the top and bottom woofer are only playing up to 150hz or so, wouldn't we be even closer without compensation?? Or are you thinking that the vertical stack should be done with all four woofers playing all the way up to 450hz?? I was thinking the vertical would be done with the top and bottoms running 150hz down, the two woofers nearest the waveguide to 450 and then the coax from there. Based on that logic, I was thinking that 150hz was the wavelength to worry about.

On a side note, I am going to run out today at some point to get a couple of books as well, hopefully to get a stronger base and then just need some help to interpret the details. I'm sure it will take some time and experimentation.

Edit..after reading and thinking more, this means that my MTM even needs some delay correct?? The above still confuses me with regard t the outside woofs crossing much lower and still needing it though.
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post #1184 of 1508 Old 10-06-2013, 09:03 AM
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Yes if only playing together at those lower frequencies the degree of phase error will be smaller because the wavelengths are longer, however getting them perfectly in line would still require the same amount of delay. If doing shaded woofers the alignment (through physical or electronic delay) would have to be adjusted anyway because the different low pass frequencies between the inner and outer woofers would cause differing amounts of phase shift in the crossover.

There also needs to be some creative EQ also so that you don't end up with a broad 6dB peak from 60hz or so up to 150hz, though some of the extra output in that range should be left in so you get that nice midbass kick you are looking for.
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post #1185 of 1508 Old 10-06-2013, 10:21 AM
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^^ +1.

that is why i was kind of hoping the 'semi-horn' hoaded side-by-side would do what i was hoping, as it would make integration that much easier. once you've got good components, the game then turns to integration as far as achieving ultimate performance.

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post #1186 of 1508 Old 10-06-2013, 10:32 AM - Thread Starter
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Great, I actually understand now, thanks for taking the time guys biggrin.gif

LTD, I am anxious to try the angled side by side too. In the end, it will be nice to try a few things and see what works out best. I am really anxious to fire up the dual version that Matt is perfecting. I bet they're gonna blow my mind.
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post #1187 of 1508 Old 10-06-2013, 10:53 AM
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Another option for the vertical configuration is a shunt cap across the upper and lower drivers. (Wire the upper and lower drivers in parallel, parallel the inner pair, the two pairs in series, cap across the outer pair.) This provides some adjustment of the vertical pattern without adding bass boost.

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post #1188 of 1508 Old 10-06-2013, 11:48 AM
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i think he got another amp and so has active control over both sets of woofers independent of each other.

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post #1189 of 1508 Old 10-06-2013, 12:10 PM - Thread Starter
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Yes sir I do. I actually have a few xtras now, just because of the deal I got them for.
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post #1190 of 1508 Old 10-08-2013, 07:34 PM
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Quote:
Originally Posted by ChopShop1 View Post

Ladieeees and Gentlemennnnnnn....

The SEOSR 215C.....yes I make up silly speaker names too biggrin.gif

The SEOSR 415T.....the super speaker



Keep in mind, these are just for show, pre bracing, even pre port cutouts...I just knew a few people wanted to get an idea of the size of them, so I stacked them in position. For scale, I'm 6'2", about 235-240lbs...

Yeah, they're big:D
That speaker looks nice there, in your bedroom!

We presume that's where your wife makes you sleep? wink.gif

Symmetry pleases the eye, but it usually offends the ears where low frequencies are concerned. -Yoda Fitzmaurice
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post #1191 of 1508 Old 10-09-2013, 06:23 AM - Thread Starter
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biggrin.gif

She'd like to for sure some days, but very blessed to have her, she's super understanding most of the time.

On a side note, I think I'm having withdrawls...I have worked on these in a couple of days.
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post #1192 of 1508 Old 10-09-2013, 07:09 AM
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ChopShop,

I'm a bit late in joining this party, however:
This is AWESOME - thanks for sharing these photos!

Cuzed2
Check out a video of my theater here
CuznEddy Cinema
Officially Hanesamatized on 8/1/09

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post #1193 of 1508 Old 10-09-2013, 08:34 AM
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I was led to this forum by LTDO2..

DAMN!!! Those are looking like THE speakers to have... I can't wait to see the finished product...

If I got it right, you're going to have 4 18inch woofers for each channel? And the same compression driver in the Noesis?? How low will the woofers go?
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post #1194 of 1508 Old 10-09-2013, 09:06 AM
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4 x 15" drivers on the three main channels, 1 x15" driver in each surround channel, and at least 16 x 18" drivers for the subwoofer channel.

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post #1195 of 1508 Old 10-09-2013, 09:41 AM
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Quote:
Originally Posted by LTD02 View Post

4 x 15" drivers on the three main channels, 1 x15" driver in each surround channel, and at least 16 x 18" drivers for the subwoofer channel.

Now, this is what I call a man's speaker system.. haha..

If after all that it still doens't sound as good as the Imax I go to, then I don't know what to say...
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post #1196 of 1508 Old 10-09-2013, 09:45 AM - Thread Starter
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Yep, as LTD02 said...once the dual 15 version is tweaked in, then the for 15 will get tested in different arrangements and whichever iteration sounds best will stay. The seos24 BMS4594 (I'm also probably going to grab a single Radian 951Be to test out and see how it stacks up to the BMS) and single 15TDM seos12 surrounds with the dna360 CD. The Dayton 18s will start numbered at 16 and see what the room ends up "needing" to keep up with the mains and let the lf section loaf along as well. Some subs behind the sreen and others in columns as the room dictates.
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post #1197 of 1508 Old 10-09-2013, 09:50 AM
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"Some subs behind the sreen and others in columns as the room dictates."

since you have the luxury of building the theater from the ground up, putting all the subs in the front wall and putting some big time absorption on the back wall will allow for pretty much perfect room response.

the subs mounted on the front wall will launch a bass wave the size of the entire front wall like a plane, aka a plane wave, it will pass by all listeners without vertical or horizontal room modes. if then absorbed by the rear wall, response will be virtually perfect.

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post #1198 of 1508 Old 10-09-2013, 10:00 AM
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Quote:
Originally Posted by LTD02 View Post

"Some subs behind the sreen and others in columns as the room dictates."

since you have the luxury of building the theater from the ground up, putting all the subs in the front wall and putting some big time absorption on the back wall will allow for pretty much perfect room response.

the subs mounted on the front wall will launch a bass wave the size of the entire front wall like a plane, aka a plane wave, it will pass by all listeners without vertical or horizontal room modes. if then absorbed by the rear wall, response will be virtually perfect.

Assuming do you this, putting subs from floor to ceiling, side to side, then place the LCRs in front of them, wouldn't the LCR's block the 'wave' of sub-sonics? There is only so much in one wall...
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post #1199 of 1508 Old 10-09-2013, 10:01 AM
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the idea works like this, each time the sound reflects, it creates a "virtual" source. if positioned properly, that wall of virtual sources completely cancels out the horizontal and vertical interferences.

the white is what you actually see on your front wall. the grey are all the virtual sources based on reflections and is what you will actually hear (well, technically, it extends out to infinity, but to keep it simple...). of course, this only shows 4 sources on the front wall and you will have many more, but it is to convey the idea.



paul put all 18 of his 15" subwoofers in his front baffle wall for this reason.


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post #1200 of 1508 Old 10-09-2013, 10:03 AM
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"Assuming do you this, putting subs from floor to ceiling, side to side, then place the LCRs in front of them, wouldn't the LCR's block the 'wave' of sub-sonics? There is only so much in one wall..."

one would start at the 1/4 distance in from the wall and the ceiling/floor for the first four sources, ideally, and work out from there.
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