How does SDA work

[ben62670]

I have been reading the schematics of the fifth generation SDA's, and I can not figure out how any signal from the left channel to the right channel is reaching the "dimensional drivers", or vise versa. The interconnect cable seems to essentially tie together the grounds of both speakers. The inductor presents a load of almost 3 ohms to the circuit between the negative of the dimensional speakers and the ground. The interconnect cable seems to take the higher frequencies that the inductor filters out via IC to the other channels negative dimensional array. I do not see how this currant would pass through the dimensional drivers. I have been told this is a gimmick by a man who owns a stereo store. And if you took your IC cable, and connected it to the ground you would have the same effect. If anyone knows how the currant flows through the dimensional drivers I am dieing to know!

Thanks Ben

[F1nut]

Matt Polk published a white paper that explains it much better than I can. Call Polk and ask them to send you a copy.

As for the shop owner, he's talking out of his ass and you can tell him I said so.

[ben62670]

Thanks F1
One of the things that I don't understand is how currant flows both ways through the one wire that is tied to the ground.
Ben

[heiney9]

As for the shop owner, he's talking out of his ass and you can tell him I said so.

Can I get an AMEN!!!

SDA is NOT a gimmick it's a proven phenomenon that can be electronically compensated for. Ben I have a PDF version of the white paper if you want it PM me your e-mail addy and I'll send it to you. Perhaps Raife will see this thread and respond as well.

H9

[heiney9]

Sorry Ben I just realized the white papper I have is for the Surround Bar, your still welcome to a copy if you want it. It might shed some light or not; it's been awhile since I've read it.

[McLoki]

Here is your white paper.... (http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf)

Michael

[heiney9]

Here is your white paper.... (http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf)

Michael

That's the same paper I have.........perhaps it does shed some light. I'll take some time today over morning Java to re-read it.

[ben62670]

I really apreciate your help guys. I have allways been one of those guys who is not interested in what something is, but why it is. I do have the SDA'2, so I have heard them.

Thanks much, Ben

[DarqueKnight]

Ben,

The best explanation is found in the SDA technology paper published in the June 1984 issue of Audio. It contains an exhaustive mathematical explanation of the SDA signals, how each speaker processes the signals, and what is heard at each ear. [See page 39, column 1 and page 40, figure 11 of the paper.] This paper is reprinted in Appendix 1 of the Compendium.

The signals carried by the SDA cable are the difference signals of each speaker. However, since each speaker (left and right) is presumably receiving a different stereo signal from the left and right channels of a stereo amplifier, the difference signal is processed differently at each speaker depending on how much difference there is in the content of the left and right stereo signals.

Now, if the speakers are fed a mono signal by the amp, there will be no SDA effect because the signals at the dimensional drivers of the two speakers will be the same and the signals at the stereo drivers of the two speakers will be the same.

It is easy to see where there could be some confusion regarding exactly what is traveling through the SDA cable. Consider how a telephone works. Two people can be talking to each other simultaneously over the same telephone circuit. In other words, person "A" can be transmitting words to person "B" at the same time that person "B" is transmitting words to "A". However, person "A" and person "B" ignore the words that they themselves are generating and only concentrate on hearing the words from the other person. This is the same type of simple bi-directional (duplex) communication that the left and right SDA speakers use to "talk" to each other.

[ben62670]

Thanks DK I do have your book and have enjoyed reading it. I have understood the theory behind crosstalk cancellation, looking at the wiring is what has been killing my brain. Being a computer tech your analogy of "duplexing" has really opened up another closed area of my mind. Phones do have to lines one is tip and one is ring.

Thanks much for the explanation
Ben

[hearingimpared]

Thanks DK I do have your book and have enjoyed reading it. I have understood the theory behind crosstalk cancellation, looking at the wiring is what has been killing my brain. Being a computer tech your analogy of "duplexing" has really opened up another closed area of my mind. Phones do have to lines one is tip and one is ring.

Thanks much for the explanation
Ben

Full duplexing allows both transmitting and receiving to go on simultaneously. Half duplex allows only transmission OR receiving at one time.