SDAs and Home Theater

westmassguy

What's the general opinion regarding SDAs integrated into a 5.1 HT system? I've been using my CRS+s for several months for the L + R front's, and now have a pair of 2As as well. The SDAs, in my room, with my components sound incredible whether in 2 channel or 5.1. In 5.1 I leave the interconnect attached. Can I use one of my pairs for the rear surrounds as well (I'm using monitor 5s now)? Was wondering if anyone has tried it. Seems like the SDA effect would enhance the suround channels in a 5.1 system.

leroyjr1

They're a good all around speaker.

westmassguy

leroyjr1 wrote: »

They're a good all around speaker.

I agree, but regarding use as surrounds, is that from 1st hand experience?

Marty913

When I got my SDA 1Cs several years ago I moved my SDA2s to surround sound duty as an experiment. I personally did not like it. The general consensus is that surrounds should produce a diffused (non-localized) soundfield. Unfortunately, the very thing that makes the SDA effect so appealing in the front makes them less than stellar as a "diffused" source. It worked for some movies but more often than not was pretty bad. Then again, everybody's likes, dislikes, and setup is different so your results may be different.

audiocr381ve

This has been covered several times. Some like it, some don't. I did not like the way they sounded in my system for HT.

leroyjr1

leroyjr1 wrote: »

They're a good all around speaker.

westmassguy wrote: »

I agree, but regarding use as surrounds, is that from 1st hand experience?

Good all around speaking meaning for Music and HT. Personally I would never use SDA's as surrounds because I like my surrounds above my head not on the floor.

westmassguy

I appreciate all the replies. My Monitor 5 surrounds are mounted above ear height when seated, as would the SDAs tweeters and woofers. I'll play around with it and see what the effects are.

Schurkey

SIDE surrounds = No.

REAR surrounds = Maybe.

westmassguy

Schurkey wrote: »

SIDE surrounds = No.

REAR surrounds = Maybe.

They would be rear for 5.1

newrival

I say definitely yes for rear surrounds. As was stated, this has been discussed several times, so you can search the forum for more in depth discussion. SDA is great for surrounds but you need to follow the same rules for placement in the rear as they do the front:
-dimensional drivers to the outside
-distance of listening position to front plane of speakers to be equal or greater than the distance between speakers
-speakers placed no closer than 3' from side walls.

westmassguy

newrival wrote: »

I say definitely yes for rear surrounds. As was stated, this has been discussed several times, so you can search the forum for more in depth discussion. SDA is great for surrounds but you need to follow the same rules for placement in the rear as they do the front:
-dimensional drivers to the outside
-distance of listening position to front plane of speakers to be equal or greater than the distance between speakers
-speakers placed no closer than 3' from side walls.

Thanks for the input. The normal left speaker would be the right rear for surround. I did do a search before asking, but didn't get anything.
Perhaps since this has been discussed several times, it should be posted as a sticky, with the pertinant facts along with the other SDA stickies.

cnh

You want to use SDAs as surrounds? Run them as a normal speaker no SDA I/C. Keep the correct hook up for L/R fronts. Problem solved. Of course they're NO longer an SDA in that mode. lol

cnh

westmassguy

cnh wrote: »

You want to use SDAs as surrounds? Run them as a normal speaker no SDA I/C. Keep the correct hook up for L/R fronts. Problem solved. Of course they're NO longer an SDA in that mode. lol

cnh

Why would I want to put SDAs in the rear if I wasn't planning on using the SDA capabilities. I have Monitor 5s there now.

Joe08867

I used 2b's as fronts and rears at one point. Phantom Center.

I preferred the look of the system, but the sound could get confused sometimes. I didn't always have great rear surround separation. Meaning I don't think things sounded exactly as they should. I did adjust my AVR to compensate by adding width that was not there and the issue went away.

It almost seems like a waste for these speakers unless you are really looking for Volume.

chandler9a

westmassguy wrote: »

Why would I want to put SDAs in the rear if I wasn't planning on using the SDA capabilities. I have Monitor 5s there now.

They really wouldn't sound right as rears with the IC connected. I would stick with the 5's, I've done that with great success.

dudeinaroom

Well the CRSs are easy enough to move around, try it. Only you will know if you like it. And yes you would want to swap left for rigth and vise versa for the rears. Also you will want to keep them as far away from you as the fronts whit the same distance between them as you front's to start with. Which ever set you are closer to will more than likely sound more directional. You might be able to find that magic spot, but I believe you will need a rather large room to get the most out of it. Another option would be to use the 5's as surrounds and crs as a center, but you would want to rewire them so the sda's drivers are putting out the same as the stereo drivers, which would also mean a rework on the crossovers to keep the crossover points the same. Or you could use the 5s as a center. I have 2As in the front, 7s in the rear and a 350 in the center.

cnh

westmassguy wrote: »

Why would I want to put SDAs in the rear if I wasn't planning on using the SDA capabilities. I have Monitor 5s there now.

Good question. All I'm saying is that if you "must" run SDAs as surrounds you have no other option except to treat them as "ordinary" speakers, not SDAs (pretty much common sense, or else you just smear the sound back there).

As for why you might want to run speakers larger and more "full range" in the surround mode. There are some advantages there in terms of crossing over lower or even going without a sub(s). Gives you a fuller more sound. Many people run towers all the way around and seem pleased.

If you wanted to have an SDA effect in surround? All I can ask is "why"? Modern AVRs are more than capable of distributing and decoding surround info and SDAs are "strictly" stereo speakers--designed for that exclusively.

If I had "extra" SDAs, I'd take my "best" up front for 2 channel and run the others sans SDA cable as surrounds and I'd think that would work fairly well. Unless I had a hankering for a second SDA system. In which case I wouldn't go SDA all the way around and just set up a second SDA system in another room.

If you like the Monitor 5s back there, that's certainly good enough. I'm must addressing those of you who have more SDAs than anyone should (you KNOW who you are!).

cnh

chandler9a

I have two pairs of SDA's in the closet because there is no room for them anywhere else. I will probably sell the 2A's here soon because I just don't need them and could use the money. If I WERE to keep them, I would not be against using them as rears without the cable. I just think someone else could use them for better purposes.

westmassguy

I really appreciate everyones comments, insight, and wisdom on this subject. I'm new to SDAs, and have been blown away by their abilities. My CRS+s have been recapped, woofers epoxied, RDO-194s installed. My 2As have also been recapped, epoxied, and waiting for my new RDOs for them. My last upgrade will be the Dynamat, which should be here any day now. I'm going to play around with them once I finish everything. I know some feel it's a waste to use them as surrounds, and I guess I'll soon be known a a hoarder, if I snag yet another pair. I'll try them and see if I like the sound or not.

TennMan

westmassguy wrote: »

I really appreciate everyones comments, insight, and wisdom on this subject. I'm new to SDAs, and have been blown away by their abilities. My CRS+s have been recapped, woofers epoxied, RDO-194s installed. My 2As have also been recapped, epoxied, and waiting for my new RDOs for them. My last upgrade will be the Dynamat, which should be here any day now. I'm going to play around with them once I finish everything. I know some feel it's a waste to use them as surrounds, and I guess I'll soon be known a a hoarder, if I snag yet another pair. I'll try them and see if I like the sound or not.

How do your CRS+ compare to your 2As?

westmassguy

TennMan wrote: »

How do your CRS+ compare to your 2As?

The SDA effect is similar, now that the caps in both pairs are settling in, but the 2As have much more punch in the low end.
I've compared them both in 2 channel, and as fronts in my HT. With CRS+s, I still need my subs running whether 2 channel or HT. The 2As on the other hand, sound quite good in 2 channel, and acceptable in HT without the subs.

TennMan

Thanks!

vcwatkins

I'm currently trying out 2b's as rear surrounds. They're in the back corners about 2 feet further back from the listener than the fronts (SDA-connected SRS-2's), not SDA-interconnected, and set to "large" (full range, bumped +3db). There's also a Hsu sub crossed at 50ish (still tuning). This setup sounds amazing with full bass and incredible surroundscape. I can't imagine it sounding appreciably better, and don't foresee spending another dime on this HT.

Hope you give it a try, but I will say that I think the CRS+'s have gorgeous, lush SDA sound that's hard to beat for 2-channel, and even rival most big brothers.

Cheers!
Craig

newrival

I am fairly certain that people saying to not have SDA for the rears are either improperly setting them up, or have not tried it. Arguing that the effect is good for the front speakers but not for the rear does not make sense. If AVRs are capable of doing just as good of a job in the surrounds, why would they not be for the front channels? Are they utilizing some other method? Rear surrounds in a 5.1 setup are utilized in a nearly identical manor as the front L/R. they, too, are used to create a phantom center and produce stereophonic information. And I'm not the only one who holds this opinion. Matthew Polk's reference theater system, the SRT Seismic rig, utilized the SDA equipped SRT speakers in both the front and rear L/R channels.

Still not convinced? How about directly from the words of a lead engineer at Polk during the development of SDA, Stu Lumsden?

Here is a post from him in the stick thread "Why were SDAs discontinued by Matthew Polk":

Dear ESWAROOP,
As VP of Engineering at Polk I suppose your question about SDA is aimed pretty squarely at me. I've been designing speakers at Polk for 33+ years now and I have been part of the SDA design work through all of its evolution which continues on even now.
So, let me answer your question about the continuing relevance of SDA and Interaural crosstalk cancellation. Yes, SDA is still relevant. I'm tempted to leave it at that since several other folks have stated the reasons quite accurately in this thread but you seemed unconvinced. The supporting reasons for SDA?€™s continued relevance are quite simple actually and perhaps it is the lack of complexity makes it all seem too easy. Matthew?€™s article on SDA, published in the Audio magazine June 1984 issue, "Polk's SDA Speakers - Designed-In Stereo" explains SDA in great detail and it is also referenced by other respondents to the question. I cannot provide that level of detail here so I advise a good of that article. http://www.polkaudio.com/downloads/w...WhitePaper.pdf
I can however provide a brief summary to address your questions.
It is a fact that when speakers L & R are played in a typical arrangement for stereo the sound from the left speaker reaches the right ear (about 0.5ms later than the left due to the distance between our ears) and vice-versa for the right speaker. Interaural crosstalk was understood to exist at stereo?€™s inception but given the great step forward offered by stereo encoding on vinyl as compared to mono and the lack of understanding as to just how much better it might be if Interaural crosstalk were cancelled, it was left unaddressed for about 30 years. Polk developed SDA to cancel this crosstalk acoustically by the specific arrangement of the drivers on the baffle and the signals they are fed. By adding a driver (or array) to each speaker (L&R), separating the drivers 5-7 inches laterally and feeding this ?€œDimensional driver?€? only the anti-phase least-correlated information between the L & R channels. A cancelation signal is therefore sent to each ear and, due to the offset position, arrives at precisely the same time as the crosstalk from the opposite channel and the crosstalk is cancelled. An in-depth analysis of the Hass or precedence effect that describes our ear<>brain computation for determining how we perceive the direction of a sound source was necessary in order to properly tailor the bandwidth and gain for these ?€œDimensional?€? signals. Matthew found, during this investigation, that Interaural crosstalk not only interfered with our ability to perceive the recorded soundstage, it also provided aural queues as to the location of the loudspeakers.
So, SDA has to do with the sound being played back from a set (or sets) of loudspeakers. The manner in which a recording is made does not affect SDA. SDA does not create or add any spatial ?€œeffect?€? to the recording. It simply removes a distortion in the payback chain. The effect of a well tuned system with SDA is to dramatically improve our perception of whatever soundstage the recording engineer has created in the studio. Sonic images become more stable and coherent. They remain stable as program levels and tonality change throughout a performance. The loudspeaker disappear as a sound source and instead of a soundstage that exists only between the loudspeakers, the soundstage fills the entire listening space. It is, to a much greater degree than with non-SDA, more like the performance is taking place in front of the listener which is the point of hi-fi after all.
Interaural crosstalk cancellation can be achieved electronically by deriving a cancelation signal and mixing it back into the original with the appropriate delays, but the electrically you can only fix the delay so as to account for a single listening position. Our acoustic approach as is more tolerant of listener position and head angle. As the listener moves closer or farther away the angle between the listener and the offset ?€œDimensional?€? drivers narrows or widens and thus the delay is adjusted accordingly.
In home theater setups there is the consideration for multiple pairs of speakers around the room. SDA will work for a pair of speakers in front or behind a listener. It is essentially benign for a pair of speakers located to the side. So, as a basic technology it is still a potential benefit in HT setups . We have sold SRT systems consisting of front and rear SDA stacks with the SRT center (the center is not SDA for obvious reasons) and this created an amazing degree of image accuracy. If you can find SRS or SRTs and have the room to set up 4 as front as rear I suggest that you do it. Use a center channel in the front and back and use the 6.1 mode for multichannel HT or music. It will sound amazing.
So, SDA is still relevant. The simple reasons that it fell out of favor for freestanding L & R traditional speakers is that a) it requires extra drivers and a larger front baffle and adds significant cost due to the extra drivers and crossover parts, and b) the retailer base needed to capably demo the product is near extinction despite my hope for resurgence. We continue to look for ways to employ SDA in a more compact and cost efficient format. We use SDA on the front channels in several of our current Surround Bars, both passive and powered, with great success.

I hope this addresses your questions. Keep listening.

Stu

newrival

westmassguy wrote: »

Thanks for the input. The normal left speaker would be the right rear for surround.

exactly right, and vice versa

I did do a search before asking, but didn't get anything.
Perhaps since this has been discussed several times, it should be posted as a sticky, with the pertinant facts along with the other SDA stickies.

I just tested out the search function and seems to be a bit wonky at the moment. Even a search for "sda" turned up zero results, which we know is certainly not the case.

cnh

That's certainly interesting. But even the quote removes both the Center and the Rear center (6.1) from the SDA equation and would require back SDAs that are arranged in a pattern similar to the fronts.

If surround SDAs are "benign" as sides when placed in the normal surround position. Then that must mean that it's similar to running them without a cable. Hence NO SDA effect. No?

The above quote does not contradict much that has been said above about the limitations of the SDA effect as surrounds. And to be honest. Even running them as L/R can occasionally lead to some errors and confusion in 7.1 soundtracks because of the surround matrixing decoded by the receiver. And the SDAs need to create a "pure" Stereo only field of sound?

Don't see any new info in the post above! But it's certainly from the horse's mouth.

In any case, you're right--you should try it. I haven't always been "happy" when I tried SDAs as L/R fronts in a 5.1 configuration so Two channel it is for them!

cnh

vcwatkins

Cool. Thanks for the quote. Guess I'm making a long IC now. (sigh)

newrival

VC, is your IC not very long? the stock ones seemed like they were 100' long.

vcwatkins

I can pull them in to try with the original cable (20' maybe?), but will have to go underneath in the crawl space, requiring 35-40ft.

newrival

cnh wrote: »

That's certainly interesting. But even the quote removes both the Center and the Rear center (6.1) from the SDA equation and would require back SDAs that are arranged in a pattern similar to the fronts.

Not sure what you mean here. But yes rear SDAs must be set up just as you would for the fronts (ie. no toein, flat to rear wall, following spacing instructions for SDA, etc.). So this would not follow a THX style 5.1 setup, nor a standard install where the rears are side mounted just behind the lister.

If surround SDAs are "benign" as sides when placed in the normal surround position. Then that must mean that it's similar to running them without a cable. Hence NO SDA effect. No?

this is referring to surrounds in a 7.1 setup where the surrounds are on the side walls. Obviously SDA has no effect when they are in this orientation and firing directly at each other.

Even running them as L/R can occasionally lead to some errors and confusion in 7.1 soundtracks because of the surround matrixing decoded by the receiver. And the SDAs need to create a "pure" Stereo only field of sound?

I am not sure what matrixing you're speaking of that would effect SDA's effectiveness. L/R whether front or rear are mixed simlarly. They either have some or none of the opposite channel's info to create spatial cues and this is what SDAutilizes. even out of phase spatial recording effects are carried through and enhanced by SDA.

In any case, you're right--you should try it. I haven't always been "happy" when I tried SDAs as L/R fronts in a 5.1 configuration so Two channel it is for them!

cnh

The only thing I wasn't thrilled about with SDAs for HT was that they are so relaxed. Utilizing the original s2000 tweeters that some feel are "bright" was best, IMO. I had great success with 2b fronts (I prefered these over SRS fronts), CRS+ rears, and 10b centers. Although I later moved to CS1000p centers. The 10bs were the better match (timbral) but The CS1000p offered better clarity, and really it was a decent match, just not as exact. I also utilized 2 Dayton Titanic mkIII subs.

newrival

vcwatkins wrote: »

I can pull them in to try with the original cable (20' maybe?), but will have to go underneath in the crawl space, requiring 35-40ft.

How far apart are your rears?? remember, to get the benefit, the distance from the listening position to the vertical plane of the front of the speakers must be equal to or greater than the distance between the two speakers.