In this review, we will be comparing S20 and RTi A1, two Passive Bookshelf speakers by Polk Audio
Let's have a brief look at the main features
of Polk S20 and Polk RTi A1 first before getting into our more
detailed comparison.
Polk S20 Key Specs
- 2-way Design
- 1" Soft-Dome Tweeter
- 6.5" Mica-reinforced polypropylene Woofer
- 39-40k Hz Frequency Response
- 88 dB Sensitivity
- Impedance: 8ohms
- Power Range:20-125watts
- Weight:7.73kg
- Dimensions (H x W x D): 376.0" x 8.5" x 13.7"( 376.0 x 216.0 x 350.0mm )
Polk RTi A1 Key Specs
- 2-way Design
- 1" Dome Tweeter
- 5.25" Polymer composite Woofer
- 60-26k Hz Frequency Response
- 89 dB Sensitivity
- Impedance: 8ohms
- Power Range:20-125watts
- Weight:5.44kg
- Dimensions (H x W x D): 304.8" x 7.3" x 11.5"( 304.8 x 187.5 x 292.1mm )
What size room are the Polk S20 and Polk RTi A1 speakers good for?
The size of the room in which you are planning to use these loudspeakers is an important decision
factor. Here we have compared their suitability to various sizes of environments considering their size
and max power parameters:
| Listening Environment* |
Polk S20 |
Polk RTi A1 |
| Near-field |
Poor |
Poor |
| Small Room |
Average |
Average |
| Mid-size Room |
Good |
Good |
| Large Room |
Average |
Average |
| Very Large Room |
Poor |
Poor |
(* Approximate Room sizes: Small < 100sq. ft / 9 m2,
Mid-size: 100-220 sq. ft / 9-20 m2, Large 220-400 sq. ft / 20-36 m2, Very Large: >
400 sq. ft / 36 m2.
Average Floor Height: 9" / 2.7m. Typical room sizes differ from country to country, and the actual
listening experience changes depending on floor height, room shape, surface materials, listening
position, speaker locations, etc.)
In the following sections, we will get into more detail in order to better understand how the Polk S20 and Polk RTi A1 compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
**This post contains affiliate links, and I will be compensated if you make a purchase after clicking
through my links. As an Amazon Associate I earn from qualifying purchases.
Drivers
Both S20 and RTi A1 are 2-way speakers.
| Driver |
Polk S20 |
Polk RTi A1 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 6.5-inch
|
1 x 5.25-inch
|
S20 features a 1" Terylene Soft-Dome Tweeter and 1 x 6.5" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz. On the other hand, the RTi A1 features a 1" silk polymer composite Dome Tweeter and 1 x 5.25" Polymer composite Woofer with a Crossover frequency at 1900Hz.
Frequency Response
S20 has a frequency range of 39-40k Hz whereas RTi A1 has a frequency range of 60-26k Hz. With a minimum frequency of 39Hz, the S20 can go significantly deeper on the low side and provide stronger bass compared to the RTi A1's min frequency of 60Hz.
Below graphs depict how these two speakers compare with the max, min and average values of the Min and Max Frequencies of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
High Frequency
Bookshelf Speakers
None of these speakers achieves full range experience which is commonly agreed as 20Hz-20kHz. In order to achieve lower lows / deeper bass, we recommend you pair these with a subwoofer. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
S20 and RTi A1 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. S20 sensitivity is rated at 88 dB and the RTi A1's is at 89 dB. This 1 dB difference makes the Polk RTi A1 a more sensitive speaker compared to Polk S20, hence will play louder with the same amount of watts.
Sensitivity
Bookshelf Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. While using
an amplifier within this range ensures the nominal performance , inputting a power that is higher than the
max wattage can result in a damaged speaker.
S20 and RTi A1 has the same power range of 20-125 watts.
Keep in mind that a higher max power handling value doesn't necessarily make that a louder speaker
compared to a lower max handling speaker. Loudness or the sound level is also impacted by parameters
such as Impedance, sensitivity and system efficiencies.
Input Type and Bi-Amping / Bi-Wiring
RTi A1 features Pair of Dual 5-way Binding Posts - Gold-Plated posts which make bi-amping or bi-wiring possible. S20 has a 5-way post which doesn't feature bi-amping/bi-wiring.
Cabinet Type and Port Position
S20 has a rear firing port whereas RTi A1 has a back and front firing ports.
Physical Specs
Size of a speaker can sometimes become an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare Polk S20's and Polk RTi A1's external dimensions. Polk S20 has external dimensions of 376.0 x 216.0 x 350.0mm ( 14.8 x 8.5 x 13.7inch) whereas Polk RTi A1 has external dimensions of 304.8 x 187.5 x 292.1mm ( 12.0 x 7.3 x 11.5inch) .
Polk S20 is clearly the larger of the two speakers. Its body is 28.5mm wider, 71.2mm taller and 57.9mm deeper than Polk RTi A1.
Below you can see the front view size comparison of Polk S20 and Polk RTi A1 in scale.
Comparison image of Polk S20 and Polk RTi A1 Size and External Dimensions
Base Surface Area Comparison
Base surface area of a loudspeaker may become a determining factor when the space in your room or desk is limited.
The base surface area of the Polk S20 is approximately 756.0cm2 / 117.2inch2 and base area of the Polk RTi A1 is approximately 547.7cm2 / 84.9inch2. The S20 requires 38% more surface area than the RTi A1 which gives it a small disadvantage on placement in tight spaces.
Here is an another comparison that shows both speakers on a BDI Octave Media Cabinet, next to a standard size amplifier and turntable in scale:
Size Comparison image of Polk S20 and Polk RTi A1 on a Media Console
Weight Comparison The weight of a loudspeaker can become an important factor if you need to move and reposition the unit often. Weight of a speaker can also "sometimes" be an indicator of the rigidity of the enclosure and the quality of the internal components used. The Polk S20 weighs 7.73kg / 17lbs and the Polk RTi A1 weighs 5.44kg / 12lbs. This makes the S20 42% heavier than the RTi A1.
Here is a comparison of how S20 and RTi A1's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of Polk S20?
Here are the items that are included inside the box of S20:
2 Bookshelf loudspeakers2 Grilles (attached)8 Self-adhesive rubber feetOwners ManualOnline Product Registration
What's in the Box of Polk RTi A1?
Here are the items that come with the RTi A1:
2 Cherry bookshelf speakers 2 Self-tapping screws 8 Self-adhesive rubber feet Owner's Manual Template Online registration sheet Polk Audio product brochure
 Woofer Size |
6.5 inches
vs
5.25 inches
|
Larger woofer |
|
Low Frequency Response |
39 Hz
vs
60 Hz
|
Generates deeper bass |
 High Frequency Response |
40k Hz
vs
26k Hz
|
Generates higher frequency |
 Sensitivity |
89 dB
vs
88 dB
|
Play louder with same amount of amplification power |
 Bi-Amping and Bi-Wiring |
Yes
vs
No
|
Allows bi-amping and bi-wiring connections |
 Mounting Bracket |
Yes
vs
No
|
Allows mounting on walls |
 Height |
304mm
vs
376mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
547cm2
vs
756cm2
|
Takes less floor space |
| General |
Polk Audio Signature S20 |
Polk Audio RTi A1 |
| Brand |
Polk Audio |
Polk Audio |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
20-125 watts |
20-125 watts |
| Sensitivity |
88 dB |
89 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
39-40k Hz |
60-26k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6.5" |
5.25" |
| Woofer Composition |
Mica-reinforced polypropylene |
Polymer composite |
| Woofer Surround Material |
Butyl rubber |
Butyl rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Soft-Dome |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
2500Hz |
1900Hz |
| Firing Direction |
rear |
back and front |
Physical Specs |
|
|
| Height |
376.0mm (14.8") |
304.8mm (12") |
| Width |
216.0mm (8.5") |
187.5mm (7.4") |
| Depth |
350.0mm (13.8") |
292.1mm (11.5") |
| Weight |
7.73kg (17lbs) |
5.44kg (12lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
Meddite MDF |
Real wood veneer |
| Available Colors |
Black, Walnut, Brown Walnut |
Black, Cherry |
| Mounting Bracket |
No |
Keyhole |
| Recommended Stand Height |
24-28" |
28-36" |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
Yes |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |