Question about SDA SRA in 5.1 setup...
jcmccorm
Posts: 103
First post so be gentle...
I've got a pair of SDA SRS's as the mains in a 5.1 setup. Until I get my new theater built, I'm stuck with a non-optimal room. With the volume at moderate levels and above, I get some problems that sound like distortion, but I believe is really an effect from having the speakers too close to the side walls (a few feet, but the walls have features, like a fireplace, that probably don't help). Either that or it's an artifact of the SDA effect.
Anyway, I wanted to toe in the speakers to see if it would help. If I do that, I realize that I destroy the SDA effect. So, first, I disconnected the SDA cable. Sure enough, that nice enveloping effect flattens out to the front wall.
Then I toe'd them in towards the (my) sweet spot. The resulting sound is very very different and I must say, not bad. Yes, the soundstage is still flattened to the front, but isn't that what the rears are for?? Does SDA even make sense in a 5.1 setup?? I can level up the volume as much as I want now with no "shrill" effect.
So, I can either put them back the way they are supposed to be by eliminating the toe-in and reconnecting the cable (which I'll try at least once more for comparison's sake). Or, keep it the way it is and wire up the 4 SDA drivers to the 4 stereo drivers (unless there's a problem doing this) thereby saying goodby to the SDA. Or keep the SDA's for 2 channel listening only (or sell them) and get something else for 5.1.
Any comments? Anyone else using SDA's for 5.1? Thanks.
Cary
PS. Looks like this is my second post. Must have been awhile ago...
I've got a pair of SDA SRS's as the mains in a 5.1 setup. Until I get my new theater built, I'm stuck with a non-optimal room. With the volume at moderate levels and above, I get some problems that sound like distortion, but I believe is really an effect from having the speakers too close to the side walls (a few feet, but the walls have features, like a fireplace, that probably don't help). Either that or it's an artifact of the SDA effect.
Anyway, I wanted to toe in the speakers to see if it would help. If I do that, I realize that I destroy the SDA effect. So, first, I disconnected the SDA cable. Sure enough, that nice enveloping effect flattens out to the front wall.
Then I toe'd them in towards the (my) sweet spot. The resulting sound is very very different and I must say, not bad. Yes, the soundstage is still flattened to the front, but isn't that what the rears are for?? Does SDA even make sense in a 5.1 setup?? I can level up the volume as much as I want now with no "shrill" effect.
So, I can either put them back the way they are supposed to be by eliminating the toe-in and reconnecting the cable (which I'll try at least once more for comparison's sake). Or, keep it the way it is and wire up the 4 SDA drivers to the 4 stereo drivers (unless there's a problem doing this) thereby saying goodby to the SDA. Or keep the SDA's for 2 channel listening only (or sell them) and get something else for 5.1.
Any comments? Anyone else using SDA's for 5.1? Thanks.
Cary
PS. Looks like this is my second post. Must have been awhile ago...
Post edited by jcmccorm on
Comments
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Cary,
You shouldn't be having any problems with distortion even if the speakers are next to the walls. What kind of power are you feeding them?Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Thanks for responding!
I'm feeding each speaker with an Adcom 555 2 channel amp so they get 400W each so that *shouldn't* be the problem.
It's right around the midrange frequencies, and it's most noticable when there are horns in the instrument mix, I get kind of a shrill effect that's uncomfortable. Not all of the time though. It could certainly be an effect of the room, but I haven't been bothered by it since I toe'd the speakers in (which still means that it could be a room effect I believe).
Cary -
Hmmm......I suppose it could be a room anomaly and if it is I would try to correct that first with room treatments before killing the SDA effect. Those SL2000 tweeters have a 5dB spike between 12kHz and 13kHz, are you sure it's not from that? Have you had the speakers long? If so, did you have this problem in a different set up?Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Thanks again F1. I just did a search and discovered DK's excellent post on modifying the SDA SRS's and he mentioned the 5db spike (resonance as he called it) and although that's a little high, that certainly could be it. I'm thinking of asking Polk about the SL2000T's (anyone know if they still sell them and for how much?)
However, with the speakers toe'd in, I don't seem to have this problem. I plan to spend some more time AB'ing some material since it's so easy to go back and forth.
This is the only place these speakers have been installed so unfortunately I don't have a good comparison of rooms.
I take it then that you recommend maintaining the SDA effect, even with a 5.1 setup, and cure whatever ailments I have with the room (or tweeters).
Cary -
Yep, no problem....glad to help.
Polk sells a replacement tweeter which is out of stock until 11/12/04, give them a call then.I take it then that you recommend maintaining the SDA effect, even with a 5.1 setup, and cure whatever ailments I have with the room (or tweeters).
Absolutely.
I'm going to add a comment about the amps you're using and hope you don't take it wrong. Adcom amps are known to be rather harsh/grainy sounding. Just another area you might want to look at.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
No offense taken at all. I don't take information like that personally. I'm really glad when someone shares with me (and everyone else - gotta love forums) what they know. It helps us all out.
I do reserve the right to disagree with you though
but in this case, I don't have enough data or experience to do that. I bought the SDA SRS's and Adcom amps from a friend that moved away a few years ago. Since then, I've replaced the Adcom 740 preamp with an Outlaw 950, added another Adcom 555 amp, and replaced the Boston Acoustic dipoles (just don't like dipoles) with Rocket 750's (which sound great on their own, but don't match the Polk's well. Another story...) Before that, I was using the lo-fi stuff I had in college.
Hmmm, well, it certainly could be the amps as well. Harsh and grainy would definitely be words to describe what I'm hearing. At the risk of opening a can of worms, do you have any recomendations for some good amps to drive the SDA's? I've also read of a few mods for the Adcom amps but unless they change the transistors and general architecture of the circuit, it's not going to fix them. I guess I at least need to find a way to audition other amps.
Cary -
Cool, no offense was meant. I didn't mean to imply it was the amps alone as these things can easily be a combination of factors.
If you were to provide a price range that would help point you in the right direction and perhaps some of the other nuts here would be able to chime in with their suggestions.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Cary,
Welcome (back) to the Forum. There are quite a few of us here who use SDA's in HT applications. I use SRS's for my front speakers which are driven by an Adcom GFA-5500.
The original Adcom GFA-555 can be somewhat grainy, forward, and aggresive sounding. The sound was smoothed out considerably with the Mark II version of the GFA-555. Even better still are Adcom's 5000 series MOSFET amplifiers.
The inherent brightness of the GFA-555 coupled with the tweeter resonance of the SRS is probably aggravating some problem with the room.
There are a lot of posts concerning SDA and home theater. Doing a search using the keywords "SDA home theater" will provide some interesting insights.Proud and loyal citizen of the Digital Domain and Solid State Country!
