My latest tomfoolery: SDA RT3000p... kinda
I've always wanted to experience the SDA effect... ever since I was a young little lad...
Right I won't start this off like a Skyrim monologue, however since I got into the audio hobby and became a Polkie, the SDA speakers have been on my wishlist.
Unfortunately... I have not, in the last 3 years, seen an SDA speaker pop up for sale in good old Nova Scotia.
After listening to some music in my basement after using my Sennheiser headphones, I realized that my stereo image, well, kinda SUCKED. My room isn't great, which is definitely the issue, but I wanted to find a way to fix it.
I immediately remembered Matt Polk had, at one point, LSi speakers in SDA configuration. I looked at my RTi70 and went "what if I disconnect the tweeter, and use the bi-amp function on my Onkyo, and wire them out of phase with the opposing channel"
BEHOLD. THIS.
AND IT ACTUALLY WORKS
Right I won't start this off like a Skyrim monologue, however since I got into the audio hobby and became a Polkie, the SDA speakers have been on my wishlist.
Unfortunately... I have not, in the last 3 years, seen an SDA speaker pop up for sale in good old Nova Scotia.
After listening to some music in my basement after using my Sennheiser headphones, I realized that my stereo image, well, kinda SUCKED. My room isn't great, which is definitely the issue, but I wanted to find a way to fix it.
I immediately remembered Matt Polk had, at one point, LSi speakers in SDA configuration. I looked at my RTi70 and went "what if I disconnect the tweeter, and use the bi-amp function on my Onkyo, and wire them out of phase with the opposing channel"
BEHOLD. THIS.
AND IT ACTUALLY WORKS
Comments
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Ken had a write up somewhere on how to do this doing something similar and essentially the correct way.- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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@VR3 You wouldn't happen to know where I could find that, would you? I'm doing this in a super ghetto way lol, definitely not 'correct'
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The best approach would be to set up an amplified SDA arrangement. You would connect a speaker wire to the left and right positive terminals on your main amplifier or receiver. This is the "difference signal" between the two channels. This would be connected to a simple 10:1 voltage divider (a 1k resistor in series with a 10k resistor). This would reduce the difference signal to a line level signal, this would be fed to an aux input on an integrated amp or receiver. A pair of smaller speakers would be connected to the amp/receiver in opposite polarity to the main speakers. The treble would be reduced on the amp/receiver and the two speakers would reproduce the difference information and the level could be adjusted and placed to the sides of the main speakers.
This would be an active SDA system, similar to what was done in the SRT system.- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
Ah that makes sense, I guess my approach would be considered passive?
I have my AVR outputting the L and R channels from 2 different sets of binding posts. The L and R are connected normally to the RT3000p. The second L and R is flipped and going 180° to the RTi70. I disconnected the tweeter as I realized it destroyed the stereo image and high frequencies over 3000Hz are pretty localizable anyways.
I actually have a really stupid idea. Taking 4 CS245i center channels, mounting 2 together vertically, and then essentially wiring them in SDA. -
*raises hand*
Well, I see that I am not going to be any help here, so I won't bother . . . . commenting.
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I believe what you are currently doing would just be considered fooling around... none of it is really anything :-P- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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Sounds about right. It's fun though so eh, why not?
One day I'll have an SRT or SDA that I can actually properly enjoy the way it was intended. -
*raises hand*
Well, I see that I am not going to be any help here, so I won't bother . . . . commenting.
Well! Never stopped you before Jim...
🤭🤭 -
After reading the OP I was going to say what Matt did was a lot more involved, but I don't recall all the details. I do recall the pairs were slightly angled back (due to the low cabinet they were on) and one of each pair was set back slightly from the other, perhaps one inch or slightly less.
Other than that VR3 seems to have it covered.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 -
@F1nut I recall reading about it SOMEWHERE on the forum here, and yeah, it was definitely a "Matt Polk, founder of Polk Audio" way of doing it, certainly more involved than what I did. My attempt is essentially just what the CRS and SRS did, but without being in one cabinet.
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I also recall the 4th and 5th generation SDA speakers sounded better than Matt's LSi SDA experiment.
For a shear balls to the wall rock concert experience the full SRT rig can't be beat.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 -
@skrol did it.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Whatever you do, make sure you toe them.I disabled signatures.
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@msg Having them toed in actually caused sounds supposed to be isolated to one channel (Pink Floyd's Wish You Were Here intro for instance) to sound like they were coming from both sides in a really weird and interfere-y way.
@F1nut I can assure you that one day I'll be an owner of the SRT rig. I've half considered buying a bunch of RT series drivers and custom building an SRT clone, but it'd cost me thousands and be more of a long term project for after university. -
Haha, sorry Chris, that was just an old forum joke. I think it only works with the SDA-15TLs, anyway
I disabled signatures. -
@msg Ah, I should have known. I searched the forum for around a half hour about SDA toe-in and not a single person said to toe them in.
It does make me wonder how Polk did toe-in with the L800, and the dimensional tweeter, which was removed in later generation SDA speakers because it could ruin imaging in some tracks. -
Also made-up is the SDA15-TL. Doesn't exist.
Re:the L800 toe-in, presuming you mean the angled baffle? Funny, at order time, I completely forgot about that 2nd tweeter elimination in original SDAs as they progressed. I heard the same about that tweeter messing things up when I posed the question re:some SDA-2s for sale near me years ago, and it was recommended to pass for just that reason.
No idea how they managed it, design-wise. Could be due exactly to the angled baffle?
I've never had a proper vintage SDA experience, but it's pretty wicked on the L800 at times. I've described that experience from initial impression that the sound stage was wide and diffuse, and that the music seemed to present on an arc. In my space, it's about 3-4ft out and forward of the speakers at times. I enjoy it, but still want to get the vintage SDAs upgraded and compared at some point.I disabled signatures. -
Stu stated they wanted to do the 15 degree angled tweeters on the early SDA speakers, but design tech and the related cost prevented them from doing so.
Personally, I didn't believe him.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 -
My understanding is the tweeter in the L800 on the sda side does not play play a certain point- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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That is correctPolitical 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 -
My understanding is the tweeter in the L800 on the sda side does not play play a certain point
Was that play past?I disabled signatures. -
I forget the range but it doesn't play the highest frequencies...
I could throw out an arbitrary number.. I would say it doesn't play over 10khz- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
Stu stated they wanted to do the 15 degree angled tweeters on the early SDA speakers, but design tech and the related cost prevented them from doing so.
Personally, I didn't believe him.
Did you call him a liar and shove him into a plant in the corner?I disabled signatures. -
Ummm...noPolitical 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 -
Interesting Polk cuts the tweeter out at a certain point. Makes sense, as only really high frequencies are super localizable.
I wonder if this mod can be done to older SDA speakers with a dimensional tweeter? -
I think the recommendation was just to disconnect the dimensional tweeter in earlier models?I disabled signatures.
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I wonder if this mod can be done to older SDA speakers with a dimensional tweeter?
The biggest difference is the L800's front plane is angled verses the older are on the same front plane. The older dimensional tweeter created a phasiness to the outside of each ear. It always had me looking for something to the side. I've had them (dimensional tweeter) at first I liked them. When I took the fuse out to disable them it seemed to make the stage collapse some. In reality it was that phasiness that was so unnatural, once I gave them a good week of listening I then heard the true stage. I then put the fuse back in and once again it was very distracting and hard (for myself) to enjoy the music.
There's a reason Polk did away with them in future generations of the SDA
My understanding of the L800 is that neither tweeter in in the dimensional SDA zone.
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The sda tweeter in the L800 is definitely a sda driver but as mentioned above it doesn't play that high, or just goes higher then the typical midrange xover point. I know I said 10khz above but I want to say it is even closer to 6khz- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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Honestly for the L800, it probably could even go up to 4KHz. Chances are it's just for upper midrange or perhaps it is up to presence (up to 6KHz are VR3 said). Anything in the brilliance range is so easily localizable it makes no sense to create an SDA effect.
