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Polk Legend L800 Tower Measurements

MakeMineVinyl

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I do not doubt that if you sit close enough to the speaker and position them the appropriate distance apart from each other and angle them toward you, you will get the same effect that the design is meant to produce. But there just isn't any way that there can be any control of the effect experienced by a listener in a randomly chosen location more than a few feet from the speakers, because it is apparent that the effect will be different for different listeners in different locations. This is what it comes down to. The effect will be different for different listeners in different locations.

You are absolutely correct here. Given the vast range of room acoustics in most people's listening rooms (and the fact that said acoustics are usually bad), the probability of an average purchaser of these speakers getting the optimum intent is pretty small. And as shown by the picture of RMAF above, getting precise listener location for maximum effect is pretty laughably difficult.

Anyone with a set of relatively small speakers of any type can experiment with the "SDA effect" by setting these speakers up about 2' from your ears while keeping the speakers very far from reflecting (or diffusing) boundaries, including a computer monitor. The intent is to essentially have 'loudspeaker headphones' where each ear gets only its intended channel, with minimal crosstalk. You'll hear some pretty wild imaging effects on some recordings. The point is that these imaging effects are what was intended in the original recording, not added by the room.

One such recording is by Patricia Barber "Ode To Billy Joe" from "Cafe Blue", where her voice's reverb comes only from around and behind the listener (like surround), while her voice itself is towards the front wall behind the speakers. Another recording with the same vocal effect is Frank Sinatra's "When You're Smiling" from "Sinatra's Swingin' Session".
 
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Alice of Old Vincennes

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Interesting thought. Surely the answer is "no", and doing that would make it much easier to position the speakers where the effect actually works the way it is supposed to. Also, the woofers won't have that reflector thingamaboob sticking out and causing that messy stuff in the upper bass and lower midrange. I'd much rather have it that way. In fact, another way it could have been done is as a tall stand-mount speaker, tall enough to run the angled baffle further down so that two smallish woofers could fit one beside the other just like the midrange and tweeter. This would permit better subwoofer integration and would still permit the speakers to be placed right where they need to be placed. But even with that, I still think that you probably need to be sitting at the center of the sweet spot in order for the effect to work as intended.
I have played the sweet spot game. Retired several years ago. This speaker is an overpriced showroom gimmick.
 

napilopez

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I have played the sweet spot game. Retired several years ago. This speaker is an overpriced showroom gimmick.

To be fair, $6,000 a pair isn't all that expensive for a pair of massive towers, and I do think a sizeable portion of audio enthusiasts commit to sitting in the sweet spot. The on axis looks good and directivity looks decent, and the SDA effect is optional
 

Juhazi

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I just read through the excellent review by Matthew Poes at Audioholics. Strange that I couldn't find it from their web page, only with the link provided in post #1 here.

Double mids and tweeters don't give anything good for normal stereo, but the SDA effect obviously makes some interesting effects depending on the recording. Descriptions reminded a lot of how good dipole speakers sound in a room - expanding the stage wider than the room. and making classical orchestra sound like being at a hall. Spot in the midline gives best sound and off-line will change the spatial effect in haphazard way for good or bad.

Most of this SDA effect can be achieved simply by halving your listening distance at home! It also has some resemblance with orthoperspecta by Tapio Köykkä https://www.quadraphonicquad.com/forums/threads/orthoperspecta-anyone.15904/
NsYSgjV71mqlTkRJSF3ah-eyv0K0CvEmJ7QT3lB8eWHwwXt7cgMagruInBW9OKj9wIbzBd5y0ek0qI0ir5iLov99K_HZJgR2X2TQNmmFJj8_hdNf7oPmUz0EL0oe-lqIBQk7WmZyY9WNHpBBh8m9rk_I


I don't expect there will be commercial followers for SDA (obviously patented) , and it will remain a rare curiosity in diy-scene as well.
 
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thewas

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The posted measurements imho don't tell much as they were done with the SDA drivers disconnected which is a barely how someone would use loudspeaker which he bought for that special feature. With the SDA even with a mono signal the shown plots would get quite messy due to too high distances of the driver pairs compared to the wavelenghts radiated, similar to pseudo D'Appolitos but actually even worse due to the inversion of one side.
 

Sancus

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The posted measurements imho don't tell much as they were done with the SDA drivers disconnected which is a barely how someone would use loudspeaker which he bought for that special feature. With the SDA even with a mono signal the shown plots would get quite messy due to too high distances of the driver pairs compared to the wavelenghts radiated, similar to pseudo D'Appolitos but actually even worse due to the inversion of one side.

Oh.. that explains a lot tbh.
 

MrPeabody

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...Given the vast range of room acoustics in most people's listening rooms (and the fact that said acoustics are usually bad), the probability of an average purchaser of these speakers getting the optimum intent is pretty small. ...

Anyone with a set of relatively small speakers of any type can experiment with the "SDA effect" by setting these speakers up about 2' from your ears while keeping the speakers very far from reflecting (or diffusing) boundaries, including a computer monitor. The intent is to essentially have 'loudspeaker headphones' where each ear gets only its intended channel, with minimal crosstalk..

That is the goal. I expect that most people who will buy these speakers will not realize that this is what it really is, and that it probably doesn't work any better than a good pair of bookshelf speakers placed close to your comfy chair, on stands and with one on the right side of the comfy chair and the other on the left side of the comfy chair, both aimed at your head. And since your going to have to sit in one spot anyway ...
 

MakeMineVinyl

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That is the goal. I expect that most people who will buy these speakers will not realize that this is what it really is, and that it probably doesn't work any better than a good pair of bookshelf speakers placed close to your comfy chair, on stands and with one on the right side of the comfy chair and the other on the left side of the comfy chair, both aimed at your head. And since your going to have to sit in one spot anyway ...
These Polk speakers are in a strange no-win marketing position; Polk is not known as a brand 'audiophiles' (who know what great imaging is) would typically seek out, and the less critical 'typical Best Buy' listener who is most likely to be a Polk customer probably doesn't know or can appreciate great imaging anyway.
 

napilopez

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Revel F208 is cheaper and in the major leagues.

The F208 has dual 8-inch woofers compared to dual 10-inch woofers on the L800 though, and if Audioholics' bass measurements are at all comparable to amirs -- and I don't see why not, as Audioholics uses ground plane -- the L800 appears to far outclass the F208.


L800 vs F208.png


SDA aside, given seemingly similar on-axis performance (and here too, the L800 appears to have an edge), I'd wager the L800 would likely win a blind test on bass alone. Personally, the L800 could reasonably be called a full-range speaker, while the F208 does not cross that threshold.
 
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Laserjock

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The F208 has dual 8-inch woofers compared to dual 10-inch woofers on the L800 though, and if Audioholics' bass measurements are at all comparable to amirs -- and I don't see why not, as Audioholics uses ground plane -- the L800 appears to far outclass the F208.


View attachment 122644

SDA aside, given seemingly similar on-axis performance (and here too, the L800 appears to have an edge), I'd wager the L800 would likely win a blind test on bass alone. Personally, the L800 could reasonably be called a full-range speaker, while the F208 does not cross that threshold.
Interesting. Wonder how that blind would workout.
 

Alice of Old Vincennes

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The F208 has dual 8-inch woofers compared to dual 10-inch woofers on the L800 though, and if Audioholics' bass measurements are at all comparable to amirs -- and I don't see why not, as Audioholics uses ground plane -- the L800 appears to far outclass the F208.


View attachment 122644

SDA aside, given seemingly similar on-axis performance (and here too, the L800 appears to have an edge), I'd wager the L800 would likely win a blind test on bass alone. Personally, the L800 could reasonably be called a full-range speaker, while the F208 does not cross that threshold.
Wowww
 

Laserjock

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The F208 has dual 8-inch woofers compared to dual 10-inch woofers on the L800 though, and if Audioholics' bass measurements are at all comparable to amirs -- and I don't see why not, as Audioholics uses ground plane -- the L800 appears to far outclass the F208.


View attachment 122644

SDA aside, given seemingly similar on-axis performance (and here too, the L800 appears to have an edge), I'd wager the L800 would likely win a blind test on bass alone. Personally, the L800 could reasonably be called a full-range speaker, while the F208 does not cross that threshold.
Have you heard either or own either?
 

napilopez

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Have you heard either or own either?

No, just the Polk L200 which I enjoyed.

Just saying from the available measurements there's no reason to dismiss the L800 just because SDA is a little gimmicky. Don't use SDA? still looks better than most $6,000 towers imo.
 

Laserjock

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No, just the Polk L200 which I enjoyed.

Just saying from the available measurements there's no reason to dismiss the L800 just because SDA is a little gimmicky. Don't use SDA? still looks better than most $6,000 towers imo.
Understand. I heard the L800 at RMAF and I like Polk but own the Revel F208. (C208, F208, F206 and M106)

Not sure how they’d compare even if they might be bass superior.
 

BenB

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Is this some marketing spiel that you copied and pasted, or is it a strong assertion of your own? I tend to be skeptical of a great many things that are claimed in audio because over the years I've seen too much stuff that wasn't much more than a marketing gimmick. As I look at this...

Perhaps I read this wrong, but your discussion of blending wavefronts sounds at odds with the concept of superposition, which describes how waves add in a linear medium (which air is until very high sound pressure levels).

This speaker is rather cleverly designed. Because the mids and tweeters in each speaker are separated by about the width of a human head, anyone sitting on the center line and facing the speakers will be well positioned to experience the crosstalk cancellation. The left drivers in the left speaker, and the left drivers in the right speaker are equidistant from the left ear. The right drivers in the left speaker, and the right drivers in the right speaker are equidistant from the right ear. The left stereo signal is played by the right drivers in the left speaker. At the same time, an inverted version of the left stereo signal that has been filtered to roughly account for the shadowing effect of the human head is played from the right drivers in the right speaker. Similarly, the right stereo signal is played by the left drivers in the right speaker. Simultaneously, an inverted and filtered version of the right stereo signal is played from the left drivers in the left speaker.
Consider a signal that is panned completely left. The right drivers in the left speaker play the signal, while the right drivers in the right speaker play the cancellation. The sound from the right drivers in the left speaker arrive at the left ear first. Shortly after that, the sound from the right drivers in the left speaker arrive at the right ear. The cancellation arrives at the right ear simultaneously. Shortly after that, the cancellation signal from the right drivers in the right speaker arrive at the left ear. I don't believe they have any crosstalk cancellation cancellation, and I have often pondered how this might be perceived.
Consider a signal centered in the mix. The signal is played simultaneously from the right drivers in the left speaker, and the left drivers in the right speaker. The cancellation is played at the same time from the left drivers in the left speaker, and the right drivers in the right speaker. The signals from the right drivers in the left speaker arrive at your left ear at the same time as the signal from the left drivers in the right speaker arrive at your right ear. Soon afterward, the signals and cancellation signals arrive at the opposite ears, and the crosstalk is cancelled. Soon after that, the cancellation signals arrive at the opposite ears.
At any rate, the crosstalk cancellation is what gives the speakers their apparent soundstage, and it does not rely on sidewall reflections. In fact, assuming that the speakers are placed equidistant from the sidewalls, the mirroring effect of the reflection may make it so that for signals panned fully left, the cancellation signal reflection is the first to arrive (at the right ear), then both the signal and cancellation signal arrive at the left ear (but in this case, the cancellation signal has been shadowed by the head while the signal has not, so there's a spectral mismatch), followed by the signal arriving at the right ear. I have never been a fan of these types of contralateral reflections, and this is probably something not to be over emphasized. Of course, with an asymmetric placement, this would not occur. At any rate, the system probably works best with the sidewall reflections absorbed.
 
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napilopez

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Understand. I heard the L800 at RMAF and I like Polk but own the Revel F208. (C208, F208, F206 and M106)

Not sure how they’d compare even if they might be bass superior.

Totally fair. I don't particularly care about polk or revel one way or another, but unless many people have heard both speakers in the same setup, I just think we shouldn't just assume revel is better just because it's ~~revel~~, you know? Just looking at what the measurements tell us.

The aforementioned F208 is good but doesn't exactly have impeccable directivity.

Revel F208 ASR Directivity (hor).png


More apparent normalized:

Revel F208 ASR Directivity (hor).png


From the available data (we don't know what the verticals are like, nor beyond 60 degrees, of course), the polk looks in line with other good ~$6,000-ish towers. Slightly worse directivity than the F208, slightly better on-axis, significantly more bass.
 

McFly

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^woofer bunching up hard into midrange, mid to high transition looks a little better
 

Laserjock

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Totally fair. I don't particularly care about polk or revel one way or another, but unless many people have heard both speakers in the same setup, I just think we shouldn't just assume revel is better just because it's ~~revel~~, you know? Just looking at what the measurements tell us.

The aforementioned F208 is good but doesn't exactly have impeccable directivity.

View attachment 122693

More apparent normalized:

View attachment 122692

From the available data (we don't know what the verticals are like, nor beyond 60 degrees, of course), the polk looks in line with other good ~$6,000-ish towers. Slightly worse directivity than the F208, slightly better on-axis, significantly more bass.
https://www.polkaudio.com/en-us/product/floor-standing-towers/reserve-r700

@ ~ $2000 a pair, the Polk Reserve R700 might be the ticket? No SDA, dual 8” etc etc
 
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