• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Polk Reserve R350 Review (Center Speaker)

Rate this speaker:

  • Poor (headless panther)

    Votes: 120 53.6%
  • Not terrible (postman panther)

    Votes: 93 41.5%
  • Fine (happy panther)

    Votes: 10 4.5%
  • Great (golfing panther)

    Votes: 1 0.4%

  • Total voters
    224

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
37,895
Likes
161,507
Location
Seattle Area
This is a review and detailed measurements of the Polk Reserve R350 center home theater speaker. It is on kind loan from a member and costs US $599 from Amazon including Prime shipping.

The R350 is very slim, designed to sit under a TV or flank it on each side:
Polk Reserve R350 Review Center Home Theater Speaker.jpg


The back panel has brackets for wall mounting:
Polk Reserve R350 Review Center back panel bracket Home Theater Speaker.jpg


I like the idea of multiple drivers to increase power capability. But is it wise in a 2-way center speaker? We will find out!

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.

I performed over 1000 measurement which resulted in error rate of less than 1% but rising to 2% between 5 and 9 kHz.

Reference axis for measurements was the center of the tweeter. Grill was taken off.

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.

Polk Reserve R350 Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

Polk Reserve R350 Measurements Frequency Response Center back panel bracket Home Theater Speaker.png


While the are some wiggles on-axis, our ears are not very sensitive to them so overall tonality should be very good. Directivity Index though gets messy around 1 kHz.

But all is now how it seems. Let's look at our early window reflections:

Polk Reserve R350 Measurements Early Window Frequency Response Center back panel bracket Home ...png


We are losing energy in a wide band from 200 Hz to 2 kHz. The reason is horizontal response:

Polk Reserve R350 Measurements Horizontal and Vertical Frequency Response Center back panel br...png


This is backward of typical 2-way speaker and is caused by the extended "MTM" configuration of this speaker. You can cancellation between those mod-woofers depending on the angle. We can see this dramatically in our horizontal beam width and directivity:

Polk Reserve R350 Measurements Horizontal Beam width Center back panel bracket Home Theater Sp...png


Polk Reserve R350 Measurements Horizontal Directivity Center back panel bracket Home Theater S...png


As noted, vertically the situation is pretty good actually:

Polk Reserve R350 MeasurementsVertical Directivity Center back panel bracket Home Theater Spea...png


Back to our spin data, here is the predicted in-room response:

Polk Reserve R350 Measurements Predicted in-room Frequency Response Center back panel bracket ...png


Note that this is for on-axis listening. Of-axis is going to be far worse as shown in the directivity graphs above -- something you don't want in a center speaker.

There is no port which eliminates the typical interference we see from that in near-field measurements:

Polk Reserve R350 Measurements near-field Frequency Response Center back panel bracket Home Th...png


I am not sure what the rise in woofer response is post 2 kHz. I had the microphone side-ways to the mid-woofers so it may be picking up the tweeter response.

Lack of port also means low frequency response doesn't fall apart was we crank up the volume:

Polk Reserve R350 Measurements THD Distortion Center back panel bracket Home Theater Speaker.png


Polk Reserve R350 Measurements Distortion Center back panel bracket Home Theater Speaker.png


Polk R350 Listening Tests
My listening situation is as you see in the above picture. I had pointed the speaker toward me so listening on-axis initially. Response there was good. I felt no need to mess with EQ, nor was it going to be easy to develop EQ for those minor variations.

Knowledge of speaker design, i.e. MTM configuration, and measurements prompted me to test off-axis response. Wow, was this a dramatic change. Despite sitting some 8 to 9 feet away (3 meters), just moving one seating position would cause a massive suck out in response. You would hear bass and treble but the middle would fall out causing a somewhat hollow sound. Close approximation of it is if you listened to your speakers from behind them. Here, it is not as bad as you hear the tweeter for upper treble but not lower.

At closer distance, the effect was even more dramatic. It is a great listen in acoustics and physics to move around left and right as you listen to this speaker.

Power handling was very good and I could not get the speaker to become distorted at listening levels I could tolerate combined with worry of not overdriving the little drivers.

Conclusions
The R350 gets a number of things right from slim size to multiple drivers to handle power better which you need in a center speaker. Alas, it violates a key aspect of speaker design which is using multiple woofers flanking a tweeter. This always causes cancellations in the horizontal axis and we see it as a very extreme case of that. This completely rules out this speaker for its intended purpose: center speaker. Unless you are single and listen in one spot, the R350 simply is not good for this use. Using vertically on each side of the speaker is fine.

A proper center speaker needs to be 3-way. Maybe someone should make a coaxial mid-range+tweeter for this use and problem would be solved.

As it is, I can't recommend the Polk Reserve R350. A shame as I personally need a thin center speaker for our living room.

NOTE: there is a poll on top where you can rate this speaker as well. You don't have to be an owner to do so.

------------
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 Reserve R350 Center Frequency Response.zip
    60.1 KB · Views: 50

ROOSKIE

Major Contributor
Joined
Feb 27, 2020
Messages
1,235
Likes
2,169
Location
Minneapolis
Interestingly as bad as this is for a center, it has me excited for the reserve monitors tests. The R100 or R200. I bet they are excellent. Great review!
 

sarumbear

Major Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
3,777
Likes
3,429
Location
Southampton, UK
@amirm I wonder if all four low frequency drivers are fed the same signal or the outer ones are fed via a low pass filter (like a baffle step response filter) to avoid accentuating the side lopes? Is it possible to measure the inner and outer drivers separately?
 

maverickronin

Major Contributor
Forum Donor
Joined
Jul 19, 2018
Messages
2,275
Likes
2,874
Location
Midwest, USA
I simply don't understand how a speaker company can make such basic mistakes in engineering like this.

Just constraints from the marketing department. It's not like there's much else you can do once they've told you it has to be a short 2.5 way and you have to use the same drivers from the rest of the model line.
 
Last edited:

sarumbear

Major Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
3,777
Likes
3,429
Location
Southampton, UK
I simply don't understand how a speaker company can make such basic mistakes in engineering like this.
I’m expect there were no engineers involved on the design. Marketing needed a narrow height speaker.
 
Last edited:

sarumbear

Major Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
3,777
Likes
3,429
Location
Southampton, UK
Just constraints from the marketing department. It's not like there's much else you can do once they've told you it has has to be a short two way and you have to use the same drivers from the rest of the model line.
They could say no, and get fired :D
 

3125b

Addicted to Fun and Learning
Joined
May 18, 2020
Messages
954
Likes
1,488
Location
Northern Germany
Apparently nobody at Polk listened to this thing before it went on sale, not to mention measure it ...
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
37,895
Likes
161,507
Location
Seattle Area
@amirm I wonder if all four low frequency drivers are fed the same signal or the outer ones are fed via a low pass filter (like a baffle step response filter) to avoid accentuating the side lopes? Is it possible to measure the inner and outer drivers separately?
It is a pain to measure it that way on Klippel as it rotates in the horizontal axis, not go left and right.

Looking at the spec now, it does seem like they are driven differently:

CROSSOVER​

Tweeter/Mid-range Crossover Frequency2700
Mid-range/Mid-bass Crossover Frequency1400
 

sarumbear

Major Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
3,777
Likes
3,429
Location
Southampton, UK
It is a pain to measure it that way on Klippel as it rotates in the horizontal axis, not go left and right.

Looking at the spec now, it does seem like they are driven differently:

CROSSOVER​

Tweeter/Mid-range Crossover Frequency2700
Mid-range/Mid-bass Crossover Frequency1400
That’s a relief. At least engineering tried their best to save a speaker designed by marketing.
 

LTig

Major Contributor
Forum Donor
Joined
Feb 27, 2019
Messages
4,248
Likes
6,849
Location
Europe
This could be a stereo speaker for a lively environment and would get a not terrible panther rating from me (because of no bass) but as a center speaker it fails utterly, so sorry, headless panther it is.
 

Billy Budapest

Major Contributor
Forum Donor
Joined
Oct 11, 2019
Messages
1,219
Likes
1,726
I simply don't understand how a speaker company can make such basic mistakes in engineering like this.
Under its former ownership, Polk was an engineering-driven company. So were (are?) the speaker companies descended from it, Definitive Technology (“DefTech”) and GoldenEar Technology. I believe Polk and Definitive Technology are now owned by the same parent corporation. Sandy Gross is still attached to GoldenEar which appears to still be engineering-driven.
 

Berwhale

Major Contributor
Forum Donor
Joined
Aug 29, 2019
Messages
2,427
Likes
2,881
Location
UK
@amirm do we need a poll? I rather you call it as you see it. Obviously, this is headless.

It's a test to make sure we've been paying attention.
 

Sancus

Major Contributor
Forum Donor
Joined
Nov 30, 2018
Messages
2,297
Likes
5,743
Location
Canada
Polk even made a 3-way center, the LSiM 704c, I guess it's discontinued now(maybe wrong about this, it's so hard to tell if things are just out of stock or gone...). It was like, 2 inches higher I suppose, but yikes. There are reasonably priced 3-way centers out there like the Emotiva C1+ and Monoprice 365C. And of course all the coaxials from Kef.

These bad 2-way centers bug me, because they ruin the whole speaker line for home theatre basically, even when the bookshelf/floorstanders are pretty good/great.
 
Last edited:

Matias

Major Contributor
Forum Donor
Joined
Jan 1, 2019
Messages
3,248
Likes
5,963
Location
São Paulo, Brazil
Interestingly as bad as this is for a center, it has me excited for the reserve monitors tests. The R100 or R200. I bet they are excellent. Great review!
Yes the R200 are excellent.

 

Beave

Addicted to Fun and Learning
Joined
May 10, 2020
Messages
641
Likes
1,200
Under its former ownership, Polk was an engineering-driven company. So were (are?) the speaker companies descended from it, Definitive Technology (“DefTech”) and GoldenEar Technology. I believe Polk and Definitive Technology are now owned by the same parent corporation. Sandy Gross is still attached to GoldenEar which appears to still be engineering-driven.

Sandy Gross sold Goldenear to the group that owns (Fr)Audioquest. He stayed on for a short while before leaving for good.

https://www.soundandvision.com/content/sandy-gross-departs-goldenear-technology
 

Beave

Addicted to Fun and Learning
Joined
May 10, 2020
Messages
641
Likes
1,200
Polk even made a 3-way center, the LSiM 704c, I guess it's discontinued now(maybe wrong about this, it's so hard to tell if things are just out of stock or gone...). It was like, 2 inches higher I suppose, but yikes. There are reasonably priced 3-way centers out there like the Emotiva C1+ and Monoprice 365C. And of course all the coaxials from Kef.

These bad 2-way centers bug me, because they ruin the whole speaker line for home theatre basically, even when the bookshelf/floorstanders are pretty good/great.

The 704c had the "correct" driver layout, but it wasn't that great of a center IMO.

The Reserve series offers three different center channel speakers, though none of them are three-way designs.
 
Top Bottom