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:
The back panel has brackets for wall mounting:
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:
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:
We are losing energy in a wide band from 200 Hz to 2 kHz. The reason is horizontal response:
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:
As noted, vertically the situation is pretty good actually:
Back to our spin data, here is the predicted in-room response:
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:
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 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/
The R350 is very slim, designed to sit under a TV or flank it on each side:
The back panel has brackets for wall mounting:
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:
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:
We are losing energy in a wide band from 200 Hz to 2 kHz. The reason is horizontal response:
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:
As noted, vertically the situation is pretty good actually:
Back to our spin data, here is the predicted in-room response:
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:
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 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/