basic understanding of sda

superjunior

OK, I feel really dumb asking this question, but as I tell my workers the only dumb question was the one never asked so here it goes. Can someone please take a few minutes and help me understand the basic concept of the sda. In plain English please, or in a way that folks un-familiar with these speakers can understand. I've read publications like this http://www.polksda.com/srsreview.shtml
and I still don't fully understand. something about the extra drivers canceling out the interaural crosstalk on the other speakers drivers? is that what the ic is for? what is interaural crosstalk? I just don't get it, at least not in the complex technical way that its usually explained. Can someone dummy up the definition of the sda a bit to make it a little more understandable for those of us new to the technical aspects of audio. I'm trying to better understand sda's (my 2b's for starters). I'm not sure exactly what the 'sda effect' is so I'm not even sure what to listen for. I'm sure this has been gone over before, but to me at least, an open discussion is a lot more interesting and beneficial than pulling up some info from an old archive. thanks for any help
Dan

Pycroft

Good post and good question. I know I had no clue from reading those types of informational posts geared toward people who know more than I do. I didn't understand until George talked to me about it, but I wouldn't dare try and repeat for a fear of messing it up. I'm sure someone will be able to do it justice! It may be nice to be a sticky: SDA Effect Defined - For Newbies, or something like that.

James

nooshinjohn

the basics are that one set of drivers(either the inboard or outboard column) cancel out the cross-talk distortion of the main drivers in the oposite speaker. This restores the true stereo image that arrives to the listener.

heiney9

That review is about as simple as it's going to get. Do you have a specific question? Do you know what interaural crosstalk is?

Our ears are seperated by our skull. When you have a L and R stereo speaker with sound coming from both sides the signal from the Left speaker is delayed reaching our right ear because of the distance between our ears. Same goes for the Right signal reaching our left ear. That's interaural crosstalk. What a very simplified answer about SDA's is this: The outside driver array on SDA's plays a low level signal from the opposite channel (the Left SDA has low level signal info from the Right channel playing in the outside driver array which many refer to as the "dimensional driver") same is true for the Right channel

By playing this low level signal from the opposite channel in each dimensional array the delay (interaural crosstalk) is eliminated and it opens up the sound like no other speaker I know. This is not a gimmick it's an aural phenomenon. This is what headphones sound like. Of course proper placement and room dimensions, etc can lessen or increase the effect.

One of the main keys is the regular drivers (the inner drivers) and dimensional drivers (outter drivers) are spaced approx the same distance from each other as our ears. That is the short and skinny idea behind SDA's

Hope this helps

H9

BAD ASP

Maybe this is one way of thinking about it. If you consider that each speaker has a "cone" of sound coming from it and the sda effect simply makes both speakers act as a single "cone" thereby producing such a large sound stage. The interaural sound waves that cross over are cancelled out.
Just my way of taking it down to the most simplistic understanding that I have that I can put into words.

Schurkey

Headphones have no (or extremely little) interaural crosstalk. What comes out of the left earpiece is heard by the left ear, but not the right. What comes out of the right earpiece is heard by the right ear, but not the left.

Ordinary loudspeakers have LOTS of interaural crosstalk--you hear the left speaker with both ears, and you hear the right speaker with both ears. There's phase, frequency-response, and amplitude cues that make the sound at the "opposite" ear different from the sound at the "direct" ear.

In both cases, folks have "improved" the sound by manipulating the signal to a "middle ground". Apparently, SOME crosstalk is good, but no crosstalk and lots of crosstalk are both "bad".

SDA (and Carver's Sonic Holography) use reverse-polarity sound to cancel some but not all of the crosstalk from loudspeaker listening.

Headroom's headphone amplifiers use a blending circuit to add some crosstalk to headphones.

superjunior

so far everyone that has posted has taken me one step farther in better understanding sda's. before this I had no clue what inter aural crosstalk was. So from what I gather thus far the ic is to send a low level signal to the outside drivers (dimensional drivers) of the opposite speaker? creating a sound that more represents a single sound stage as opposed to sound coming from two different locations? Is that what is considered the sda effect? How would the speakers respond without the ic? I really do appreciate everyones input. I gotta run though, I'll check back later. thanks again
Dan

nooshinjohn

^^^DING DING DING^^^

we have a winner!

Schurkey

superjunior wrote: »

How would the speakers respond without the ic?

There's no harm done by not using the interconnect cable. You won't damage the speakers or the amp by NOT using the cable.

My 1Bs sound almost exactly the same without the cable, except that the soundstage collapses to the area between the speakers instead of encompassing a space extending to each side beyond the speakers. (Further left than the left speaker, further right than the right speaker.)

Apparently, other SDA models may not have the same tonal balance with or without the cable; at least that's what I've been told. No direct experience with anything but the 1B here.

JohnLocke88

heiney9 wrote: »

That review is about as simple as it's going to get. Do you have a specific question? Do you know what interaural crosstalk is?

Our ears are seperated by our skull. When you have a L and R stereo speaker with sound coming from both sides the signal from the Left speaker is delayed reaching our right ear because of the distance between our ears. Same goes for the Right signal reaching our left ear. That's interaural crosstalk. What a very simplified answer about SDA's is this: The outside driver array on SDA's plays a low level signal from the opposite channel (the Left SDA has low level signal info from the Right channel playing in the outside driver array which many refer to as the "dimensional driver") same is true for the Right channel

By playing this low level signal from the opposite channel in each dimensional array the delay (interaural crosstalk) is eliminated and it opens up the sound like no other speaker I know. This is not a gimmick it's an aural phenomenon. This is what headphones sound like. Of course proper placement and room dimensions, etc can lessen or increase the effect.

One of the main keys is the regular drivers (the inner drivers) and dimensional drivers (outter drivers) are spaced approx the same distance from each other as our ears. That is the short and skinny idea behind SDA's

Hope this helps

H9

Well written. I remember when I first got into Polks I had nary a clue about this.

Slinger182

Very cool and informative thread. Thanks! Someday I'll get my ears on a rig with SDAs.

nooshinjohn

Slinger182 wrote: »

Very cool and informative thread. Thanks! Someday I'll get my ears on a rig with SDAs.

You are welcome to drop by anytime!:):cool:

Slinger182

Be careful what you wish for..:cool:

F1nut

SDA is not an effect, regular stereo is. SDA corrects the stereo effect.

nooshinjohn

Slinger182 wrote: »

Be careful what you wish for..:cool:

bring it!!!


The danger of hearing SDA is trying to live without it afterwards. Be prepared to need to spend money to achieve it.;)

Slinger182

Sounds like a plan I'll definitely take you up on your offer one of these days.

BAD ASP

Slinger182 wrote: »

Very cool and informative thread. Thanks! Someday I'll get my ears on a rig with SDAs.

you are welcome here anytime as well. I live near O'hare airport.

lightman1

SDA is a gimmick for ignorant lemmings..........

Tony M

But combined with Bob Carvers' gimicky Sunfire amps they make one solid sound.:D

mmadden28

Try this video from the source:

http://www.youtube.com/watch?v=BVkYNUbuSLY

nooshinjohn

tony millard wrote: »

But combined with Bob Carvers' gimicky Sunfire amps they make one solid sound.:D

PLus 1000 Tony... how's things man!


Give me a call sometime.:)

dpowell

Here's an SDA Diagram scanned from my SRT manual.

superjunior

lightman1 wrote: »

SDA is a gimmick for ignorant lemmings..........

oh go lay an egg, do lemmings lay eggs?

ESavinon

nooshinjohn wrote: »

bring it!!!


The danger of hearing SDA is trying to live without it afterwards. Be prepared to need to spend money to achieve it.;)

So true, Oh so true.

xj4094dg

mmadden28 wrote: »

Try this video from the source:

http://www.youtube.com/watch?v=BVkYNUbuSLY

SDA defined. And it only took one post. Awesome.

Hypnotoad

SDA effect is awesome even to ignorant lemmings.

lightman1

Put the lemmings in your pants and eat cheeto's while listening. It enhances the SDA effect. superjunior told me so. It is gospel.

nooshinjohn

lightman1 wrote: »

Put the lemmings in your pants and eat cheeto's while listening. It enhances the SDA effect. superjunior told me so. It is gospel.

And this coming from the man that told Richard Gere that gerbils and hamsters are loads of fun.:rolleyes::D

cnh

Between Brock's verbal description and dpowell's schematics I think you get the picture.

EVERYBODY who has ever logged on to this site has been 'confused' by these Polksters constant jabber about SDAs and their 'effect'. I know I was. The easiest thing to do is use the search engine...or NOW...just read this thread. BUY a pair.....and you'll know.

That all enveloping space is pretty magical. When you first get it right and get a good recording that highlights the effect, you keep looking for the extra speakers in vain!

And some people even decide to just go 2 channel for HT because the effect (so-called and rightly so by f1nut, above) is just that GOOD!

Enjoy...good thread!

cnh

superjunior

lightman1 wrote: »

Put the lemmings in your pants and eat cheeto's while listening. It enhances the SDA effect. superjunior told me so. It is gospel.

its chease PUFFS Russ, c'mon man your slackin..

superjunior

cnh wrote: »

Between Brock's verbal description and dpowell's schematics I think you get the picture.

EVERYBODY who has ever logged on to this site has been 'confused' by these Polksters constant jabber about SDAs and their 'effect'. I know I was. The easiest thing to do is use the search engine...or NOW...just read this thread. BUY a pair.....and you'll know.

That all enveloping space is pretty magical. When you first get it right and get a good recording that highlights the effect, you keep looking for the extra speakers in vain!

And some people even decide to just go 2 channel for HT because the effect (so-called and rightly so by f1nut, above) is just that GOOD!

Enjoy...good thread!

cnh

thanks C, I know this thread has helped me out a lot. I am stoked now with this bit of knowledge for my next sda session and thanks for everyones input. How does one go about making a sticky out of a thread? I think the basic understanding of sda might just be worthy of that.