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Polk Signature Elite ES20 Review (Bookshelf Speaker)

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amirm

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This is a review and detailed measurements of the Polk Signature Elite ES20 bookshelf speaker. I purchased it from Amazon for US $349 a pair including shipping.
Polk Signature Elite ES20 Review  Bookshelf Speaker.jpg


I really like the look and finish of this series from Polk. Despite budget pricing, it looks nice and purposeful as you can tell from the unique rear port plate:
Polk Signature Elite ES20 Review Back Panel Port Bookshelf Speaker.jpg


Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.


Reference axis was the tweeter center. No grill was used. Measurement temperature was about 62 degrees F (17 degrees C).

Polk ES20 Measurements
Let's start with our usual "spinorama" graph:
Polk Signature Elite ES20 Measurements Klippel NFS Bookshelf Speaker.png


On axis is reasonably good, marred by some resonances between 600 and 1000 Hz. And some unevenness in high treble area. There is a directivity dip around 4 kHz.

I forgot to note on the graph the deep bass extension. F10 is at nearly 35 Hz! This is partly due to a cabinet that is deeper than normal.

We see the cause of that roughness around 600 Hz in our near-field measurements:

Polk Signature Elite ES20 Measurements Near-field frequency response Klippel NFS Bookshelf Spe...png


We see more of a dip in directivity caused in vertical axis mostly:

Polk Signature Elite ES20 Measurements Early Window  frequency response Klippel NFS Bookshelf ...png


Fortunately my listening room has a thick carpet and high ceilings so I will be hearing a more optimal off-axis response than averaged above.

Predicted in-room response with my custom trend line is thus:
Polk Signature Elite ES20 Measurements Predicted in-room  frequency response Klippel NFS Books...png


I usually draw the trend line after my listening tests are completed and do in a manner that is consistent with that experience. See the next section.

I was impressed by the smooth and constant horizontal beam width and dispersion:

Polk Signature Elite ES20 Measurements Horizontal Beam width Klippel NFS Bookshelf Speaker.png

Polk Signature Elite ES20 Measurements Horizontal Directivity Klippel NFS Bookshelf Speaker.png


This also has wider than usual response which should create a more diffused field around the speaker (my preference).

Vertically we have the usual restrictions but again, the sweet spot is larger than I normally see in this class:
Polk Signature Elite ES20 Measurements Vertical Directivity Klippel NFS Bookshelf Speaker.png


I like the low distortion especially at 86 dBSPL:
Polk Signature Elite ES20 Measurements relative THD Distortion Klippel NFS Bookshelf Speaker.png


But notice how that resonance around 600 Hz is also showing up here in the form of distortion. This means that we will have impact beyond that frequency due to harmonics.
Polk Signature Elite ES20 Measurements THD Distortion Klippel NFS Bookshelf Speaker.png


We see the same resonance in impedance graph and waterfall:
Polk Signature Elite ES20 Measurements Impedance and phase Klippel NFS Bookshelf Speaker.png


Polk Signature Elite ES20 Measurements CSD waterfall Klippel NFS Bookshelf Speaker.png


Finally for fans of timing tests, here are the impulse and step response:
Polk Signature Elite ES20 Measurements Impulse Klippel NFS Bookshelf Speaker.png


Polk Signature Elite ES20 Measurements Step Klippel NFS Bookshelf Speaker.png


Polk ES20 Listening Tests
My female starting track which lacks bass sounding a bit muddy/tubby and somewhat bright. So I brought out the EQ tool:

Polk Signature Elite ES20 Equalization EQ roon Klippel NFS Bookshelf Speaker.png


First filter was around 600 Hz. It is a small filter but per past experience, it not only removed a bit of muddiness but also reduced distortion. The latter caused the sound to be more open and clear. Once there, on tracks with good bass, the sound was more or less balanced. But with female tracks without such, it sounded too bright to me. A quick and dirty shelving filter fixed that nicely.

Once there, I was extremely impressed with the fidelity. Track after track sounded beautiful. Not only was the tonality right but there was this clarity and lack of distortion that kept impressing me. ES20 could play pretty loud and distorted gracefully in that the woofer just lost deep bass and became a tubby. Pull back a bit and you were golden.

Conclusions
I can see Polk having to both want to create an accurate speaker while working within strict budget and retain channel that demands "showroom sound." To that end, they have done a very good job here, producing bass response that is way above what you expect. And do so with very little distortion. The only issue is the port/cabinet resonance which makes the sound muddy and screws up upper bass a bit. And elevated treble which can be a bit much if bass response is not there. Fortunately both of these factors are excess output meaning EQ not only fixes them, but also reduces distortion. Result is a speaker and sound that you can really be proud of.

I can recommend the Polk Signature Elite ES20 as is but hugely so with equalization. You are getting so much performance for so little money.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Attachments

  • Polk ES20 Frequency Response.zip
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Excellent value speaker. Would be hard to choose between these, the KEF Q150, and Emotiva B1+
 
Last edited:
Thanks again!
I had a good feeling about these. I am glad to see you had one for testing and that they work well.
I had a similar experience with the Polk S20, a very good speaker to work with as well.

This one does even better. When on sale in the USA these are really quite affordable. Good job Polk!
 
The specs online say 88 dB sensitivity (1 Watt, 1 meter). Is that realistic? Their "higher" line speakers are less sensitive. With sub(s) these might be quite nice.
 
Thanks for an excellent review amirm!
The ES20's anti-diffraction, magnetic grille minimizes sonic interference and can be easily removed to provide a striking look.
Are you able to test this claim easily?
 
Are you able to test this claim easily?
I could but hate to spend 3 hours on the machine to test this when I could be testing another speaker.
 
That’s an admirable horizontal polar map for an inexpensive speaker with tweeter on a basically flat waveguide. Not surprised they sounded good to you after EQ based on that. Probably plug that port if using subs though.
 
PS. Polk has Super great customer service. They will even sell you parts if they have them in stock. Blew a tweeter on my tower speakers. Phone call, and in about a week, I was back up and running with my towers.

One of the better company's to work with. And they have Humans to answer the telephone if you need any help.
Never ran into a Polk Product that I did not like. Hard to go wrong with Polk.
 
Good Morning Amir,

many thanks for another excellent review. It's nice to know we have great sounding choices in the budget segment. Good for recommendations for friends.
 
Does this work for a nearfield use scenario (computer speakers) in a very small room or better look for another alternatives?
 
So many speakers have nasty upper mid resonances apparently caused by the port (can't speak of the boxes themselves buzzing along), yet others seem to avoid it. Got to say I wonder how this can be dealt with inexpensively?
 
This vs Wharfedale 12.2 will be interesting to compare if/when the latter gets measured.
 
So many speakers have nasty upper mid resonances apparently caused by the port (can't speak of the boxes themselves buzzing along), yet others seem to avoid it. Got to say I wonder how this can be dealt with inexpensively?
Damped port slits will solve it.
 
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