SDAs as towers?

Airplay355

Is there a reason for having the SDA driver and regular driver next to each other or would it sound the same if one was on top of the other? Could SDA2bs be rearranged in an Lsi15 configuration without changing the way they sounded too much? Sorry if this is a dumb question.

thuffman03

I don't think it is a sound issue more than a space issue. One of the reasons the SDA's were discontinued was because people did not want large speakers and with the LSI having the woofer on the side it does not look very large compared to the SDA's.

Airplay355

Right, I don't have the room for the wide SDAs but a taller deeper tower (to preserve the original internal volume) would work. Which is why I'm wondering if SDA2bs would sound the same if their drivers were arranged as the drivers in an Lsi15 or do the SDA driver and the normal driver need to be horizontal to eachother.

cnh

Maybe I'm being stupid here. But how would that 'work'? First, the mid-drivers in the SDA 2Bs are 'different' and mirrored pairs? The SDA effect is designed to to have the drivers firing in delayed patterns the inner drivers firing a bit off the outer ones in timing? Aren't they designed to produce the SDA effect through this horizontally paired....not vertically arranged array?

I'm far from an expert on these, I've only read the white sheets and looked at the specs...but from a scientific point of view it would seem to me that a vertical alignment of the two drivers in the 2B would interfere with the EFFECT?

Anyone else?

cnh

Airplay355

I have no idea how the effect works other than one driver is different from the other (since I have 2b's there's only one SDA driver and one regular driver). Maybe it would ruin the effect, I haven't a clue.

cnh

A brief explanation and diagram are found in the manual attached here. This is why I don't think you can do what you are suggesting...but perhaps I'm wrong....

cnh

MillerLiteScott

The dimensional drivers on the 2B are the outside drivers and the receive signal from the opposite speaker to cancel the interaural (sp) crosstalk which gives the corrects the timing of the audio signal. It may work in a vertical alignment but I don't think they would be as good as the side by side drivers. The side by side drivers also mimic the distance between your ears.

Airplay355

In contrast,
SDA™ used a system of extra drive units placed at the same distance apart as the space
between your ears (also known as the Interaural Distance) as the basis for an acoustic
system of Interaural Crosstalk Cancellation. (See Fig. 2) The additional “SDA” drivers
received an inverted version of the stereo signal from the opposite channel. The
geometry and spacing of the drive units insures that this inverted Crosstalk Cancellation
Signal arrives at the ear at the same time as the unwanted Interaural Crosstalk and
acoustically cancels it.

It seems to me that it would work as long as I kept the original distance the same. Why would speakers have to be next to each other to cancel a signal? Am I not getting something?

heiney9

No.....there would be no SDA. The distance between the regular driver and dimensional driver is about the distance between a normal person ears. The inner aural crosstalk cancellation that is the whole idea behind SDA's would be severly diminished or not at all.

H9

Airplay355

So if I turned SDAs on their sides I would ruin the SDA effect too? What I don't get is why placing the drivers that way would effect the timing at which the signals from the two drivers reach your ears. If I conserved the distance between them, what does being next to each other have to do with when I hear the signal?

heiney9

Airplay355 wrote: »

In contrast,
SDA™ used a system of extra drive units placed at the same distance apart as the space
between your ears (also known as the Interaural Distance) as the basis for an acoustic
system of Interaural Crosstalk Cancellation. (See Fig. 2) The additional “SDA” drivers
received an inverted version of the stereo signal from the opposite channel. The
geometry and spacing of the drive units insures that this inverted Crosstalk Cancellation
Signal arrives at the ear at the same time as the unwanted Interaural Crosstalk and
acoustically cancels it.

It seems to me that it would work as long as I kept the original distance the same. Why would speakers have to be next to each other to cancel a signal? Am I not getting something?

It ALL has to do with the timing of those signals to your ears. There are different timing contraints on drivers that are on top of each other and beside each other. The idea with SDA is to get the opposite ears signal arriving at the same time, hence the distance between the driver that plays the regular signal and the driver that plays the inverted signal has to be as they are (about the distance between your ears 6-7").

I'm sure with much less passive methods and more active methods like in the Surround Bar technology where it's almost all active processing you could get something................but IMO, not anywhere as natural as the passive SDA's of the past. The Surround Bar products are phenominal...........but they do fall short of the "original" SDA's. Plus, they are marketed and desiged for a different market and end result.

MillerLiteScott

H9. I would not say there would be NO SDA effect but I don't think it would be as much/dramatic as the side by side drivers.

Scott

heiney9

Airplay355 wrote: »

So if I turned SDAs on their sides I would ruin the SDA effect too? What I don't get is why placing the drivers that way would effect the timing at which the signals from the two drivers reach your ears. If I conserved the distance between them, what does being next to each other have to do with when I hear the signal?

Yes, absolutely.

You need to read the white paper on SDA's. It explains it all in there. I have answered it as simply as possible in the post before this one.

Airplay355

Why would the opposite ears signal arrive at a different time as long as I changed both speakers? Why can't the two drivers be 6 or 7" apart vertically instead of horizontally. The signal from the opposite channel would get to me at the same time regardless of the orientation of the drivers wouldn't it?

I'm not trying to be a dick, I just don't get it. I appreciate you explaining.

heiney9

MillerLiteScott wrote: »

H9. I would not say there would be NO SDA effect but I don't think it would be as much/dramatic as the side by side drivers.

Scott

I'd have to disagree. The timing of the 2 signals and how they reach the ears IS critical for the passive SDA system to work properly. I'm sure you'd sill hear some odd effects but nothing I would describe as what you'd hear when SDA's are set=up properly.

Now if your talking an active set-up like the Surround Bar........then perhaps some of the SDA properties would remain intact by virture of the DSP logorithims designed to "mimick" the passive properties.

Anyways that's my take on it after reading the white paper recently.

Airplay355

Is figure 3 in the white papers what you're trying to explain to me? I think I'm getting it now.

heiney9

Airplay355 wrote: »

Why would the opposite ears signal arrive at a different time as long as I changed both speakers? Why can't the two drivers be 6 or 7" apart vertically instead of horizontally. The signal from the opposite channel would get to me at the same time regardless of the orientation of the drivers wouldn't it?

I'm not trying to be a dick, I just don't get it. I appreciate you explaining.

All I can say is get ahold of the white paper (the orginal SDA paper not the current Surround Bar paper). There is no way I could go into here in a post without a very lengthy explanation................and frankly the white paper explains it better than I ever could.

Perhaps this review from Stereo Review might give some more insight about how SDA works.

http://www.polksda.com/sda1creview.shtml

They break down how SDA is supposed to work, maybe then you'll see why it won;t work layed on it's side or with the drivers on top of each other.

H9

heiney9

This explains SDA better than the other article and there is a diagram

http://www.polksda.com/srsreview.shtml

Airplay355

I think I get it now. Sorry for taking so long. Physics wasn't my favorite class and we flew through the sound portion in a week.

I guess I'm stuck with monsters for now.

Hillbilly61

Airplay355 wrote: »

I think I get it now. Sorry for taking so long. Physics wasn't my favorite class and we flew through the sound portion in a week.

I guess I'm stuck with monsters for now.

I'm late here, but yep you are stuck with the "monsters". To put it very simply, your ears are horizontally placed apart from each other. However, each ear hears what the other is hearing but at a sightly different time. This is how come we can locate the source of a sound.

SDA 2Bs attempt to create this 3D effect by sending nullifying sound to the ear just at the same instant the sound from the wrong speaker reaches there. This cancelation creates a sense of depth in what is being sensed by our brains. Relocating the 2 SDA speakers above each other destroys this effect.

jon s

if you really want to try it... lay down the towers flat on its side and see what happens...

Conradicles

Airplay355 wrote: »

I guess I'm stuck with monsters for now.

Many people would love to be "stuck" with those.:D

VR3

This is an easy fix...

Take the left speaker, bolt it to the ceiling by its side ---

Take the right speaker, bolt it to the floor - then suspend yourself half way up the back wall laying on your right side...

Should work great!