SDA-2 in a home theatre setup ?

mhw58 · August 2002

I just scored a pair of SDA 1-C's which I plan on using as
my front speakers in a HT setup. I'll be using SDA2's as
my rear speakers. Has anyone used 2 sets of SDA's in a
ht setup? Do you have the interconnect cable connected
on your rears as well as fronts? How does it sound?
Thanks, Mike

jrausch · August 2002

SDA does not work in a 5.1 setup. All channels are discrete and don't carry the normal stereo matrix. If you play the movies in 2ch stereo, you may get some imaging depending on the soundtrack.
Movies sound excellent even without the SDA effect. I personally unhook the SDA cable to make sure everything stays discrete and the delay timeing stays true.

mhw58 · August 2002

So if you are watching a 5:1 music or movie dvd you unhook
the cable and only connect the cable when you listen to
stereo? I'll have to try that.
Thanks, Mike

nascarmann · August 2002

I'm not much on HT, but I don't unhook mine watching a movie. I do 98% 2 channel though...

jrausch · August 2002

In order to get the best possible sound from your SDA's, you may want to consider getting a 2ch rig as well. There is a huge difference in the quality of 2ch sound on a dedicated system. Even some of the most expensive and best surrounding systems sound washed out in 2ch mode. Having a pair of front radiating speaker for surround is best for 5.1 music, but that selection is very limited. If you want the best possible sound for movies and concerts you should look into a pair of Di-poles/Bi-poles. Rear special effects need to come from a non-direct location i.e. Plane crashes and the roar of a crowd in concert. You will understand this more when you get your system up. I would use a speaker switch to move between the two sets of speakers; unless you have one of the nicer Denon's which has this feature built in. I am currently using 2.3's for fronts, Crs+'s for rears and Deftech C/L/R 2500 for center. My Lsi 15's have a dedicated 2/ch rig, that I will sometimes move the 2.3's into for better imaging. I plan on getting a pair of deftech surrounds because the tweeter they use complements the SDA's better.

marvelous · August 2002

I watch movies all the time. I have a pair of 3.1tl for my fronts and rear. I have never disconnected the interconnect cable. I am very satisified listening to music or watching movies. I do have a denon receiver that allows me to use rear surround (CRS) and side surrounds (fx300i). I use nad amps to pump the 3.1tl. I also have a definitive center (C/L/R 2300. I was also thinking about changing my side surround with definitive tech as well. I agree the deftech tweeter do complement the SDA's.

mhw58 · August 2002

I've been using my SDA 2's as fronts and had the cable connected. I was using non SDA's as rears. Now that I have
the 1-C's, I'll use them as fronts and move the 2's to the
rear. I was thinking I would use the interconnect cable
for the fronts but not the backs. I'll have to do some
experimenting. Do you have your rears connected with the
interconnect cable also?
Mike

nascarmann · August 2002

I will take the SDA cable since you will not need it.......:)

marvelous · August 2002

I use my interconnect cable on all my SDA speakers. Why deny myself that great sound and imaging.

Larry Chanin · September 2002

I have recently gotten into a similar discussion with an audiophile at an other forum who believes that a center channel speaker will interfer with the SDA phase cancellation and hurt imaging. I should point out that I use SDA-1Cs, with the interconnect, as my mains in a 7.1 dedicated home theater using a Lexicon MC-1 processor, and to me it sounds great.

However, since I respect this guy's opinion, and in theory it sounded reasonable, I starting doing some critical listening experiments using multichannel music.

So I used the Roy Orbison Black & White Night multichannel DVD. I sat in the "sweet spot" and turned the center channel speaker on and off repeatedly to see if I could hear any loss of imaging. I could hear no perceptible lose of imaging. Dispite the fact that Roy's powerful voice was coming from the center as intended, I could distinctly hear the lead guitar coming from the far left just as well with or without the center. The only difference that I could hear was the slight decrease in sound level as the center speaker was turned off.

As you may know there are electronic versions of the interaural crosstalk cancellation technique that is used in SDA speakers. Sunfire continues to make a digital version of its Sonic Holography effect in its flagship Theater Grand III processor, and Lexicon uses its highly regarded Panorama effect in my MC-1 processor. Both of these high-end processors are designed with multichannel home theater in mind. (By the way to avoid conflicts between the two interaural crosstalk cancellation methods, I have chosen to use the SDAs and not the Panorama effect. I am told that its sweet spot is wider.)

In addition, I should point out that although SDA were invented for stereo, Polk Audio must have believed that they could be used effectively for multichannel home theater applications. After all didn't they release those monsterous Signature Reference Theater systems with huge SDA arrays and multi center channel and surround speakers?

Larry

mhw58 · September 2002

Larry,
Interesting post. I just got my 1-C's on saturday and I'm loving them. How many watts per channel does your Lexicon put out?
I have the Roy Orbison dvd and will check it out tonight. It
is amazing when you listen to 5:1 with the vocals coming
from the center channel and then you switch to stereo and
the vocals still come right at you from the center. Sometimes
I can't tell if I'm set for surround or stereo. How long have you
owned your 1-C's?
Thanks, Mike

Larry Chanin · September 2002

Originally posted by mhw58
Larry,
Interesting post. I just got my 1-C's on saturday and I'm loving them. How many watts per channel does your Lexicon put out?
I have the Roy Orbison dvd and will check it out tonight. It
is amazing when you listen to 5:1 with the vocals coming
from the center channel and then you switch to stereo and
the vocals still come right at you from the center. Sometimes
I can't tell if I'm set for surround or stereo. How long have you
owned your 1-C's?
Thanks, Mike

Hi Mike:

The Lexicon is a surround processor and it doesn't have any power amplifiers. I am using a collection of Parasound power amplifiers that put out about 200 watts per channel into 7 channels, but most of the SDA enthusiasts would recommend a lot more power. These can easily handle more than 750 watts per channel.

Yes, when sitting in the 'sweet spot" it is impossible for me to tell whether the center channels is on without putting my ear against the speaker.

I've had my SDA-1Cs for at least 13 years.

If you are interested in my setup click on my signature below.

Larry

mhw58 · September 2002

Larry,
I looked at your website, your setup is great. What kind of
interconnect cables do you use? I'm wondering about
optical vs. analog. From what I've read, you have to use
optical for dts dvd while others say analog is better for
music. Any opinions, Mike

Larry Chanin · September 2002

Originally posted by mhw58
Larry,
I looked at your website, your setup is great. What kind of
interconnect cables do you use? I'm wondering about
optical vs. analog. From what I've read, you have to use
optical for dts dvd while others say analog is better for
music. Any opinions, Mike

Hi Mike:

Thanks for the kind words.

Let's try breaking your question into two parts, 1)digital interconnects (which can be optical or coaxial) and 2)analog interconnects (which are coaxial).

For digital connections I find the decision frequently has more to do with how many digital source components you have, and how many and what type of digital connections are available on your surround processor or receiver. For example I have three digital source components, a satellite receiver, a standard DVD player and a Home Theater Computer (HTPC). Before I upgraded there was a time where my digital receiver only had three digital inputs, one optical and two coaxial, therefore I had no choice but to select the typle of digital connections that were available.

With regard to the quality of the sound, my ears can not tell the difference from the same DVD played on my standard DVD player which is connected via optical versus when that disc is played on the DVD-ROM drive of my HTPC, which is connected via digital coax.

With regard to whether you use digital or analog interconnects on your DVD player, I would think you need both, but for different reasons than you suggest. Now, I'm not an expert on all the available types of DVD players available, but on mine I have digital connections and a PAIR of analog connections for two channels. If you want to listen to multichannel sound (either dts or Dolby Digital) then you must have a digital connection, the two channel analog connection in all likelihood wouldn't work for digital sound. On the other hand, if you wish to play two channel CDs in your DVD/CD player you will need analog connections.

Perhaps some of the club members who are audiophiles can amplify on the general issue of digital versus analog. For instance, a battle rages among audiophiles regarding "which is better, vinyl versus digital for music?"

Larry

nascarmann · September 2002

On the other hand, if you wish to play two channel CDs in your DVD/CD player you will need analog connections.

I use one optical cable for both.....

mhw58 · September 2002

Nascarman,
What brand of optical cable are you using?I have a cd player and a dvd player and I also use 1 optical connection from each unit to my receiver. I can switch
between surround and stereo with my receiver. There are
some people who say analog is warmer for stereo but
I don't really know. I would like to hear more opinions.
Mike

nascarmann · September 2002

All my cables are AR Pro series.....

hoosier21 · September 2002

Larry

Your diagram of your HT says the rear center surround is usually off, why is that? Just wondering

Larry Chanin · September 2002

Originally posted by hoosier21
Larry

Your diagram of your HT says the rear center surround is usually off, why is that? Just wondering

Hi hoosier:

The rear center channel speaker and associated mono block amplifier is a remnant of a prior configuration in which I used a receiver with an add-on SMART Circle Surround decoder to produce a sixth matrixed rear center channel.

The SMART decoder is still in place because it provides a convenient means of connecting a subwoofer dedicated exclusively to the surround channels. However, since I have upgraded to a Lexicon MC-1 surround processor (7.1 channel) that has two surround back channels, the use of the SMART surround decoder would interfere with the proper imaging of these channels, so it is turned off most of the time . The only time I use the rear center speaker and amplifier is when the Lexicon is in the Party mode. In this mode there is no surround processing however, the same unprocessed signal is sent to all speakers.

Thanks for your interest.

Larry

Larry Chanin · September 2002

Originally posted by jrausch
SDA does not work in a 5.1 setup. All channels are discrete and don't carry the normal stereo matrix. If you play the movies in 2ch stereo, you may get some imaging depending on the soundtrack.
Movies sound excellent even without the SDA effect. I personally unhook the SDA cable to make sure everything stays discrete and the delay timeing stays true.

As I mentioned in an earlier posting this subject came up in an other forum. What I didn't say was that it prompted me to send an email to Matthew Polk via Ken Swauger. Here's the complete exchange starting with my question and ending with Mr. Polk's response.

Larry
====================================

Hello Larry,
Here is Matthew's reply:

" Ken -

Larry's impression that the phantom center image sounded better than the actual center channel shared by many listeners and is not limited to SDA systems. The primary reason for this is that the center channel signal is usually a band limited signal or is otherwise degraded in the decoding processed as compared to stereo reproduction. Center channel quality is notorioulsy poor in Pro-Logic. In Dolby Digital the center channel has the potential to be of excellent quality but the recording techniques used to improve voice intelligibility often degrade the signal from an absolute quality point of view. However, things seem to be improving. When Pro-logic is played back in stereo some of the steering artifacts of the processing are eliminated. When Dolby Digital is forced to stereo it is frequently an entirely different track on the disc having an entirely different mix. In addition, there are certain psychoacoustic advantages to phantom center images which arise from the way we perceive the direction of sounds.

As regards SDA, multi-channel is actually one of the best uses of the technology. However, it is not as dramatically different as it is in a 2 channel setup. The big benefit of SDA in multichannel systems is its ability to create strong lateral images far to the left and right. A normal 5.1 speaker setup cannot do this. As Larry has noticed, a stereo pair of speakers can create a very convincing center image when the listener is seated facing the speakers, but if the listener turns 90 degrees to one side, the phantom image collapses. Because of the way we hear the direction of sounds two speakers in front of us will create a phantom image between them, but two speakers located left front and left rear will not create a phantom image directly to our left. This is the situation in a surround sound system and is the reason why surround effects that move from front to rear tend to collapse towards the listening position as they move from front to back. An SDA system, however, has the ability to create strong lateral images and, with SDA speakers front and rear you can actually pan the image from front to back at a realistic distance from the listener.

-msp"
I hope this is helpful information.
Regards, Ken, Polk

Original Message
From: [email protected] [mailto:[email protected]]
Sent: Friday, August 30, 2002 8:58 AM
To: Swauger, Ken
Cc: [email protected]
Subject: SDA Speakers for Home Theater and Multichannel Music

Hi Ken:

I wanted to thank you again for your help last month in coordinating a response from Mr. Polk regarding measuring frequency responses for SDA speakers.

I have an other SDA-related question that I was hoping you could assist me with.

A very knowledgeable audiophile suggested to me that SDA speakers are not really well suited for home theater if a center channel speaker is used. As the name Stereo Dimensional Arrays suggests, these speakers were designed for stereo applications before multichannel movies and music was invented. In addition, it would seem logical that sounds coming from a center channel speaker could adversely counteract the signals coming from the SDA drivers and smudge the imaging.

Before this question arose, I remember listening to music with and without the center channel. At the time I though the 2-channel version sounded better, but I attributed that to the fact that my SDA-1Cs were simply better speakers than my f/x500i. Sitting in the sweet spot I was amazed by the realism of the phantom center speaker. I had to literally put my ear next to the center channel speaker to confirm that I hadn't inadvertently left it turned on.

I'm thinking that because the dialog is so important in movies, and to accommodate other listeners not seated in the sweet spot, that I should continue to use the center channel for movies and accept some degradation of the imaging. With multichannel music, which is usually a solitary listening experience, I'm thinking that I should turn off the center channel, but leave all other channels on.

Obviously I will continue to experiment to determine whether my untrained ears can hear any change in imaging, but it would be wonderful if Mr. Polk could share his thought on the subject of how to best to use the SDAs for multichannel movies and multichannel music. When I move I plan to build a new home theater. Would Mr. Polk recommend other Polk Audio speakers for a dedicated home theater and retire the SDAs to an other room for music?

Thanks very much.

Larry

burdette · September 2002

Originally posted by mhw58
There are some people who say analog is warmer for stereo but I don't really know. I would like to hear more opinions.
Mike

The digital signal is going to have to be converted to analog SOMEWHERE, correct? I mean, the CD player pulls the digital signal off the disk.. if the player's internal decoder does the work, then you get that analog signal out of the player's analog outs... but if you pull the original digital signal out of the player, then the decoder in the receiver will do the conversion... either way the digital signal has to be converted to an analog signal to be fed to the amplication.. isn't that correct, or am I having a major brain **** here??

If correct, then any differences - if indeed there were any or any that you could hear - would be the result of differences in the specific decoders in the specific equipment, and not something applicable to ALL players as compared to ALL receivers...? If the player and the receiver happened to use the same decoder from the same manufacturer... then short of a problem in some other part of the signal path (such as a problem with the player's analog outs), you should have the exact same analog signal reaching the amps... assuming you don't have an ungodly long analog feed from player to receiver...

Yes? No?

nascarmann · September 2002

Yes.....I agree. I use my receivers DAC's. I feel it is better...

mhw58 · September 2002

My thinking agrees with Nascarman. I have an Onkyo receiver,
and an Onkyo cd and dvd player. I figure the DACS are better
in the receiver than the cd player so I use an optical
cable from the cd and player to the receiver. I'm using a
Monster optical cable but I'm curious about the AR pro
stuff. Do you think AR is a lot better than Monster or are
all optical cables all equal since they are glass with no
metal on the ends?
Mike

nascarmann · September 2002

I will NOT debate wire and cables again......:D

mhw58 · September 2002

Originally posted by burdette

The digital signal is going to have to be converted to analog SOMEWHERE, correct? I mean, the CD player pulls the digital signal off the disk.. if the player's internal decoder does the work, then you get that analog signal out of the player's analog outs... but if you pull the original digital signal out of the player, then the decoder in the receiver will do the conversion... either way the digital signal has to be converted to an analog signal to be fed to the amplication.. isn't that correct, or am I having a major brain **** here??

If correct, then any differences - if indeed there were any or any that you could hear - would be the result of differences in the specific decoders in the specific equipment, and not something applicable to ALL players as compared to ALL receivers...? If the player and the receiver happened to use the same decoder from the same manufacturer... then short of a problem in some other part of the signal path (such as a problem with the player's analog outs), you should have the exact same analog signal reaching the amps... assuming you don't have an ungodly long analog feed from player to receiver...

An audiophile I work with says analog cables are better
because then you never have to convert it to digital and
back to analog which can cause distortion. He says use
only analog interconnects with cd players. Does this
make sense?
Mike

HBombToo · September 2002

I'll stick with digital all day.

mhw58
I bought the cheapest links that I could find at the time from CC which was the RCA brand, 3 ft for 20 bucks. Much like my radio shack 12 guage buck a foot wire... IMO there is a point of diminishing returns regarding both fiber and wire. If the light is coupled and decoupled then it works and if not its broke and buy new.

Paul Connor · September 2002

Here is a little something called the Vinyl Anacronist. Marc Phillips has spent quite a bit of time discussing analog vs. digital, especially the cd and newer digital formats. You might want to give it a look. I certainly prefer music on vinyl, but for some music, cd's sound great. Perhaps it's the Polks.

http://www.furious.com/perfect/vinyl33.html

jrausch · September 2002

Poor quality CD players that have a digital out are still affected by something called "jitter" that adds distortion to the wave as it sent from the pickup to the DAC. Jitter in digital audio equipment is usually caused by changes in the timing of bits and bytes in the digital data stream. A good quality DAC, ADC converersion and RAM buffer will help this, but a quality player in combination with the converters will yield the best results. Something with a jitter distortion of -130db would be considered an excellent quality signal. This would help you to achieve a more accurate signal. If you have quality converters in your player and tubes helping with the analog output stages, you would have even better results.

Mo money, Mo money
,Jer

SDA-2 in a home theatre setup ?

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