Proper SDA functionality, tests?

xllr8

Hello all, also here by way of AK.

I recently found some "excellent" SDA 2's & I'm wondering what I should be hearing. I wonder if mine are properly functioning, or how I might verify. I've got them 3ish feet from sidewalls, about 10 feet apart.

Timbre (aside from that slightly spitty tweeter spike) is beautifully smooth, top to bottom. The imaging however is VERY hit & miss, then on well known recordings I'd swear it's "eating" sounds. They shine on "drier" vocals, & acoustic music (usually), however as the music becomes heavier on the effects they can be a bit "smeary".

Interestingly they sound pretty consistent "deep" in the center of the sweet spot, like almost parallel on the speaker plane.

I ran through the mono signal balance check.
- got dead dimensionals on center
- all drivers & one dimensional when fully shifted to either side.

The only problems then are: I couldn't get the difference signal to work. After unplugging the black terminals turning on my amp I got a loud "hum".

Other than that I'm not too electrically inclined/adept.

Thoughts?

honestaquarian

Possibly they are in need of crossover upgrades.

honestaquarian

Welcome to the forum btw

Schurkey

xllr8 wrote: »

They shine on "drier" vocals, & acoustic music (usually), however as the music becomes heavier on the effects they can be a bit "smeary".

I can only imagine what "smeary" means, but the first thing that pops into my head is: Is your amplifier CONFIRMED to be common-ground--as in, have you put an ohmmeter across the negative terminals and registered less than one ohm resistance?

xllr8 wrote: »

- all drivers & one dimensional when fully shifted to either side.

All drivers in one cabinet, plus the dimensional in the other cabinet?

xllr8 wrote: »

After unplugging the black terminals turning on my amp I got a loud "hum".

I'm not sure what that accomplishes, but I bet the amplifier is very unhappy about not having a complete circuit.

pkquat

You don't mention how far back your listening postion is or your room size. Unless it is a deep room too, your listening position could be effecting things. 10ft is a little outside the recommended range. Here is a link to the manual.
http://polksda.com/pdfs/SDA1C.pdf

xllr8

Possibly they are in need of crossover upgrades.

What might be crossover malfunctioning symptoms?

Schurkey
I've not physically confirmed the common ground amplifier, beyond asking my electronic repair specialist. It's a Harmon Kardon Citation 12, which he ran through.

As for smeary, some sounds seem to be lost in too much reverb. Others sounds just don't come into a dead center tight focus.

The negative terminal disconnect was to create a "difference signal" as per SDA Handbook. And, no my amp was not happy. What's this about an open circuit. I feel retarded now.

Thanks for the input & welcome.

xllr8

pkquat
Ah, I was wondering about the distance apart. I read someone mention a smaller distance elsewhere & remember the shop playing their SDA1s at maybe 6 feet.
Thanks for that link it mentions a few more things than I'd seen so far.

My listening position would be at an equilateral triangle point, but possibly to close to a back (reflective wall at that point). I imagine first/early reflections are playing a doozy with the sound. The room is a fairly rectangle loft of almost 600sq ft.

Has anyone else had luck with that difference signal?

Nightfall

Disconnect the dimensional tweeters.

honestaquarian

Bring the speakers at least two feet closer together. It is better if they are five feet from the sidewalls.
Yes the crossovers may be malfunctioning due to their age.
There could also be a problem with the amp/speaker interface.
(*meaning they are just not a good match*)
Try another amp that is capable of driving low impedance loads and is common grounded.

As for the triangle try making the distance from the speakers a bit greater than the distance between them.

Also don't forget that what kind of soundstage you will get will be largely dependent on what you are playing.
If you are playing some modern pop music or lossy compressed music (MP3's for example) you may not get much of an effect.

xllr8

Looks like I'll be getting some exercise tonight. Funny how "pairings" (speakers to amps), got me in this whole rabbit hole.

Experimentation begins tonight.

I'm thinking I could purchase and ohm meter & test the circuits; I feel like I saw schematics on here somewhere, but I'm not 100% sure which speakers specifically I have.

SDA 2: with single tweeters & dual sr142/17 midwoofers.

F1nut

Is your SDA cable the blade/blade or pin/blade version.

The poster above is the only person I have ever seen that claims Polk said 5 feet. The standard is at least 3 feet, but more will not hurt. Just don't think you have to have 5 feet.

Nightfall

Sorry, OP.

got dead dimensionals on center

As for smeary, some sounds seem to be lost in too much reverb.

This made me think you had the originals.

xllr8

F1nut
Oh, yes. I'd forgotten to note: it's pin blade.

Nightfall
No, problem. I think my mention of listening to SDA1s might have confused the issue.

honestaquarian
As for pairings, my underpowered Marantz still sounds so much more yum! the Harman is very smooth, yet clinical. Well suited for studio use.

I think the speaker moving might have to wait till the morning though. The bod is still reeling from the original moving exercise.

F1nut

In that case you have SDA 2B's.

Try them 6 feet apart and 5 to 6 inches off the back wall, no toe in. Spikes will help....a lot!

honestaquarian

The reason why the ideal distance from the sidewalls is five feet has to do with the speed at which sound travels and early reflections off of the sidewalls and such. It is the ideal,however most people (*including myself*) do not have a room large enough to do that,so three feet is more realistic. The further the loudspeakers are from the sidewalls the more there is a reduction in the effect of early reflections which work to smear the image and reduce the effectiveness of the Stereo Dimensional Array.
Just because some people have never read this information does not mean it doesn't exist. This is something I came across in a review about the larger SRS series over two decades ago.

I work in an auto shop and I have had people come in and tell me with straight face that they've never heard of brands such as Goodyear and Michelin. They act like since they are the be all,end all these brands cannot be good since THEY have never heard of them.

TennMan

honestaquarian wrote: »

The reason why the ideal distance from the sidewalls is five feet has to do with the speed at which sound travels and early reflections off of the sidewalls and such. It is the ideal,however most people (*including myself*) do not have a room large enough to do that,so three feet is more realistic. The further the loudspeakers are from the sidewalls the more there is a reduction in the effect of early reflections which work to smear the image and reduce the effectiveness of the Stereo Dimensional Array.

Although five feet may be the ideal distance, my room proves it it isn't a huge factor in determining the SDA effect you will get. My 2B-TL speakers are 72" apart and 64" from each sidewall. They are 6-3/4" from the back wall. There are no obstructions to the sound waves from the drivers that would degrade the SDA effect. All dimensions are symmetrical right and left of the centerline of the room, including my seating position. The speakers pass all the SDA tests and are working properly.

With all that said, I don't get the SDA effect others claim to get even though my setup meets the ideal distance of five feet on the sides. The width of my soundstage extends to about where the red arrow indicates in the photo below. The distance from that red arrow to the side of the speaker is about six feet, which I think is a good soundstage, but it doesn't come close to what some member here report hearing. They hear sounds 90 degrees to the sides and sometimes coming from behind them. I don't hear that. BTW, the results are the same with my CRS+ speakers.

Don't count on distance from the sidewalls to guarantee a robust SDA effect.

honestaquarian

TennMan wrote: »

honestaquarian wrote: »

The reason why the ideal distance from the sidewalls is five feet has to do with the speed at which sound travels and early reflections off of the sidewalls and such. It is the ideal,however most people (*including myself*) do not have a room large enough to do that,so three feet is more realistic. The further the loudspeakers are from the sidewalls the more there is a reduction in the effect of early reflections which work to smear the image and reduce the effectiveness of the Stereo Dimensional Array.

Although five feet may be the ideal distance, my room proves it it isn't a huge factor in determining the SDA effect you will get. My 2B-TL speakers are 72" apart and 64" from each sidewall. They are 6-3/4" from the back wall. There are no obstructions to the sound waves from the drivers that would degrade the SDA effect. All dimensions are symmetrical right and left of the centerline of the room, including my seating position. The speakers pass all the SDA tests and are working properly.

With all that said, I don't get the SDA effect others claim to get even though my setup meets the ideal distance of five feet on the sides. The width of my soundstage extends to about where the red arrow indicates in the photo below. The distance from that red arrow to the side of the speaker is about six feet, which I think is a good soundstage, but it doesn't come close to what some member here report hearing. They hear sounds 90 degrees to the sides and sometimes coming from behind them. I don't hear that. BTW, the results are the same with my CRS+ speakers.

Don't count on distance from the sidewalls to guarantee a robust SDA effect.

@TennMan

The distance to the sidewalls is ONLY ONE part of a larger equation here.
Program material, ancilliary equipment,interconnects, overall room acoustics and even your hearing all serve to effect what you hear with ANY system. Not trying to put you down or anything like that,but your room (*which looks fabulous btw*) appears to be an extremely live and reflective room. Yes this can have an affect on the soundstage in ANY system. Certainly with Stereo Dimensional Array loudspeakers.

TennMan

@TennMan

The distance to the sidewalls is ONLY ONE part of a larger equation here.
Program material, ancilliary equipment,interconnects, overall room acoustics and even your hearing all serve to effect what you hear with ANY system. Not trying to put you down or anything like that,but your room (*which looks fabulous btw*) appears to be an extremely live and reflective room. Yes this can have an affect on the soundstage in ANY system. Certainly with Stereo Dimensional Array loudspeakers.

I don't feel put down at all. You are correct. My room is very live and reflective. It isn't the ideal situation but it is what I have to live with. I don't have a room dedicated to my sound system so there isn't much I can change. The warden won't allow it.

The main purpose of my post was to point out those who don't have a lot of room on the sides of their speakers that just moving to a room that allows more space on the sides may not make the SDA effect better.

honestaquarian

The room is the one component of our stereo system that is often overlooked.
My SDA's are three feet from the sidewalls and about six feet apart. I live alone and have been able to take measures to "deaden" my living room. Heavy curtains on the windows,a large rug on the floor,a tapestry like blanket on one wall and a large curtain on the ceiling. Just doing the last one removed the slap echo completely. Not everyone can take such measures and end up living with what they have.

F1nut

honestaquarian wrote: »

Just because some people have never read this information does not mean it doesn't exist. This is something I came across in a review about the larger SRS series over two decades ago.

A review that only you seem to have read. The official Polk recommendation says, "Distance "S" should be at least 3 feet."

F1nut

TennMann, I have more than 5 feet to my side walls and I don't have a crazy wide sound stage, nor do I have sounds coming from behind me. My room is well damped, zero echo when clapping hands. In fact, I've never had those wild effects in any house I've lived in with any of my SDA's. I can't say I've ever heard that from SDA's in others homes either. When I read people describe those effects I think to myself that their room must be really bad because that is not how SDA is supposed to sound.

honestaquarian

F1nut wrote: »

honestaquarian wrote: »

Just because some people have never read this information does not mean it doesn't exist. This is something I came across in a review about the larger SRS series over two decades ago.

A review that only you seem to have read. The official Polk recommendation says, "Distance "S" should be at least 3 feet."

Just because the entire world has not chimed in on this thread to say whether or not they have read that (*or any other*) review does not mean it doesn't exist. Speak for yourself.
I already said that three feet is good and I myself have my speakers three feet from the sidewalls.
What's your point????

tugboat

F1nut wrote: »

honestaquarian wrote: »

Just because some people have never read this information does not mean it doesn't exist. This is something I came across in a review about the larger SRS series over two decades ago.

A review that only you seem to have read. The official Polk recommendation says, "Distance "S" should be at least 3 feet."

I think he's referencing the review done by Stereo Review in '85. They note that sound travels 5 1/2' in 5 milliseconds, so the speakers should be at least 5 1/2' from the side walls to eliminate a possible source of trouble.

honestaquarian

Thank you @tugboat
Sorry if I could not remember what review since it was over three decades ago.

tugboat

I would love to be able to set mine up the way intended, but I'm lucky enough to get 2 1/2' on the sides and 6' center to center. I have two walls long enough for that, but there are those pesky doorways in the way. Still, I get an incredible soundstage and have never been disappointed by them.

F1nut

My point is the official suggestion from the people that made the speakers says at least 3 feet, which has been the standard suggestion here forever.

Gunther16

Although by the photograph the listening area does not seem optimal to me and I can see several reasons the soundstage seems to be lacking there are compromise solutions which may or may not be feasible. The single largest issue I see here is that the speakers are located immediately next to wide open areas which I believe impact the soundstage. In this case I do not believe increasing/decreasing the space from side walls will do very much to help the situation. Just my humble opinion. In my own situation I had a wide open space approximately 12' on only one side and needed to experiment in order to obtain a relatively equal soundstage from both sides. My compromise solution was found by relocating the audio cabinet to the outside of the speaker which closed some of the space and provided a reflecting surface. I also installed a removable accordion style door so I can attain an additional reflecting surface and depending on the position of these doors there is a noticeable difference in soundstage and quality.

Gunther16

Another thing, I suppose it depends what someone considers "crazy" soundstage. In that realm of discussion you could say that the soundstage I consider normal is that in my experience my entire wall (15' X8') is the soundstage, speakers are at 32" from wall (best I could do in my environment) 13" from back wall and 9' apart. And yes I have noticed some effect relative to the 90 deg from listening position but this seems to be limited to one particular music score by Pink Floyd and not noticed on anything else. Call me crazy but that's my story and I'm sticking to it. This could be attributed to reflections. There are no other speakers that I have ever had or tried that give me this 15'X8' stage presence period.

tugboat

Gunther16 wrote: »

Another thing, I suppose it depends what someone considers "crazy" soundstage. In that realm of discussion you could say that the soundstage I consider normal is that in my experience my entire wall (15' X8') is the soundstage, speakers are at 32" from wall (best I could do in my environment) 13" from back wall and 9' apart. And yes I have noticed some effect relative to the 90 deg from listening position but this seems to be limited to one particular music score by Pink Floyd and not noticed on anything else. Call me crazy but that's my story and I'm sticking to it. This could be attributed to reflections. There are no other speakers that I have ever had or tried that give me this 15'X8' stage presence period.

Try either Suzie Q from Creedence or Purple Haze from Hendrix. Those two always give me a crazy effect. Most other material I play stays within the soundstage.

boston1450

Ive had 4 different sda's & never had issues

Gunther16

Will do!