why are SDAs left /right postioned ?

leftwinger57

I think I asked this before and I either do not remember anyone answering me this qusestion. Clearly these SDA-2Bs speakers are marked for left/ right orientation ,but why?The general topography for lack of a better term is exactly the same ,a high verticle mounted tweeter 2 mids about 3/4 up the board and then the passives all in the same place as each other.Now there are speakers that are called mirror imaged such the entier DMC Time Frame line of speakers which I also own the TF 350s and the very famous Dalquist D-10s and D-20s both which must be positioned as opposing speakers meaning if the left tweeter is facing inward the right then the right hand tweeter faces inward also. So since the SDAs are or as far as I know never called mirror imaged speakers why the exact speaker orientation.I think I read somwhere that the left hand side speaker has 2 x-overs in it for the effect but that really doesn't do it for me.

This might be a tad over my head but do try to explain I do own these after all.

Big Dawg

You need to get your read on regarding sda. The outer speakers are dimensional drivers designed to reduce crosstalk. They are positioned sorta like real time arrays to deliver the out of phase channel to the opposite ear in synch to produce the sda effect (assuming I said that correctly).

leftwinger57

I guess I will read up on the subject.The only out of phase project that I can remember were the special double microphones the Grateful Dead used for the Wall of Sound p.a. to not get feedback and not need front of house monitors .

http://www.dozin.com/wallofsound/

leftwinger57

Very little from Wiki looks like you quoted them directly. One line about the SDAs

http://en.wikipedia.org/wiki/Polk_Audio

westmassguy

SDAs work by canceling interaural crosstalk. In a perfect world, when listening to a pair of stereo speakers, your left ear would only hear sound from the left speaker, and your right ear from the right speaker. It's not a perfect world. Your left ear also hears sound from the right speaker, delayed slightly by the width of your head. Same goes for the right speaker. An SDA speaker has Stereo Drivers and Dimensional Drivers. The inner drivers are Stereo, and the outer drivers are Dimensional. The outer Dimensional drivers receive their signal from the opposite speaker. This signal is frequency limited, inverted, and delayed. This has the effect of cancelling the delayed signals from the opposite speaker, that reach your ears. It's like headphones, without the phones. Polk did it with additional drivers and specially designed crossovers and interconnect cable. Bob Carver did something similar electronically with his Sonic Hologram Generator.

GFOviedo

Interesting. The more I read about the SDA the more interesting they get!

leftwinger57

Westmassguy, Now that's something I relly can digest.Now the way you meticulously explained this makes sense even if it looks the same by far it is not. Thanks that's all I need.

leftwinger57

I forgot to ask this also.Now like I said before I have multiple sets of speakers in the same room which will be all keepers for now.
The DMC TF350s, the ADC 303ax, Polk SDA-2b all running through my Niles 6zn speaker selector. I happen to like the variety and they of course all sound way different w/ the ADCs having that famous East Coast almost AR2 sound, the DMC 350s w/ their phase line array sound and of course the Polks which are in their own world.Now to some this might sound plasphamous but I llike it and it works. My question to you is is there any device that I can go directly w/ the Polks into my Adcom and remove them from station #1 on the selector but still have others running through it. I already looked up angled banana plugs but these still only except 1 wire and offer only convienence w/ the angle.

westmassguy

leftwinger57 wrote: »

Westmassguy, Now that's something I relly can digest.Now the way you meticulously explained this makes sense even if it looks the same by far it is not. Thanks that's all I need.

You're welcome. You might want to get ahold of the SDA Handbook, for more detailed explanations, as was as the history of Polk, plus a lot of useful information for setting up your SDAs, and testing them.
http://vr3mods.com/uploads/SDA_Handbook_2011_Rev2.pdf

westmassguy

leftwinger57 wrote: »

I forgot to ask this also.Now like I said before I have multiple sets of speakers in the same room which will be all keepers for now.
The DMC TF350s, the ADC 303ax, Polk SDA-2b all running through my Niles 6zn speaker selector. I happen to like the variety and they of course all sound way different w/ the ADCs having that famous East Coast almost AR2 sound, the DMC 350s w/ their phase line array sound and of course the Polks which are in their own world.Now to some this might sound plasphamous but I llike it and it works. My question to you is is there any device that I can go directly w/ the Polks into my Adcom and remove them from station #1 on the selector but still have others running through it. I already looked up angled banana plugs but these still only except 1 wire and offer only convienence w/ the angle.

I'm not the person to ask for multiple speakers running off the same pre-amp/amp with a switch box.
My Polks do double duty for Home Theater and 2 channel. It all depends on how I set my Pioneer Elite AVR/Preamp. I can switch between Auto surround, which kicks in all the Dolby/DTS processing, or Pure Direct, which takes the output from the DACs str8 to the gain section, bypassing everything else, and out to my Carver amp.

leftwinger57

Thanks for the link ,way to much reading for now,but 1.1 pretty much states the theory behind the entire line. Somone else refered me to another link of mods but not the science behind it like this. I will get my read on I do appreciate this and in this world it's I guess it's better to be informed than walking around talking nonsense....Lew

boston1450

GFOviedo wrote: »

Interesting. The more I read about the SDA the more interesting they get!

Guy im not sure if you have some or not. But if you dont. Go and listen to some even if you have to travel just to spend some time to view them. They are very interesting. You wont be disappointed

leftwinger57

Oh I have them, I guess you missed my 1st post on picking the pair up for $50 at a moving sale. Then the refinishing job I did on the water stained tops.Then the final product w/ pix and all.Talk about getting a need to hear them I don't have to they are 9 ' in front of my face..You do have great taste and luck w/ c/l . We have the same amp just mine is rack face.See I do read also.LEW