In this review, we will be comparing Alpha T20 and S55, two Passive Floor-standing speakers from PSB and Polk Audio.
Let's have a brief look at the main features
of PSB Alpha T20 and Polk S55 first before getting into our more
detailed comparison.
| Key Specs | PSB Alpha T20 | Polk S55 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 0.75" Dome | 1" Dome |
|---|
| Woofer | 2 x 5.25" Polypropylene | 2 x 6.5" Mica-reinforced polypropylene |
|---|
| Frequency response | 36-21k Hz | 32-40k Hz |
|---|
| Sensitivity | 90 dB | 90 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | 15-120 watts | 20-200 watts |
|---|
| Weight | 11.89kg / 26.2lbs | 20.00kg / 44lbs |
|---|
| Dimensions (H x W x D) | 34-3/16" x 8-5/16" x 9-13/16"
869.0 x 212.0 x 250.0mm | 41-9/16" x 11-3/4" x 12-3/8"
1056.0 x 299.0 x 315.0mm |
|---|
What size room are the PSB Alpha T20 and Polk S55 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* |
PSB Alpha T20 |
Polk S55 |
| Near-field |
Bad |
Bad |
| Small Room |
Poor |
Poor |
| Mid-size Room |
Good |
Good |
| Large Room |
Good |
Good |
| 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.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
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through our links. As an Amazon Associate I earn from qualifying purchases.
Drivers
Both Alpha T20 and S55 are 2-way speakers.
PSB Alpha T20Polk S55
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
PSB Alpha T20 |
Polk S55 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
0.75-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
2 x 5.25-inch
|
2 x 6.5-inch
|
Alpha T20 features a 0.75" anodized aluminum with front waveguide Dome Tweeter and 2 x 5.25" Polypropylene Woofer with a Crossover frequency at 2500Hz. On the other hand, the S55 features a 1" Terylene Dome Tweeter and 2 x 6.5" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz.
Frequency Response
Alpha T20 has a frequency range of 36-21k Hz whereas S55 has a frequency range of 32-40k Hz. With a minimum frequency of 32Hz, the S55 can go slightly deeper then the Alpha T20's min frequency of 36Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Floor-standing class in our database.
Low Frequency
Floor-standing Speakers
Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
Alpha T20 and S55 have the same Impedance of 8 ohms and their sensitivity is also same at 90 dB.
Sensitivity
Floor-standing Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
S55 can handle a max power of 200 watts RMS, whereas Alpha T20 has a max power handling value of 120 watts RMS, 80 watts less than the S55.
Note that higher power handling does not make a speaker louder: that depends mainly on
sensitivity and impedance. The calculator below shows how loud each of these actually plays
on a real amplifier.
Which plays louder on your amplifier?
Starting with a popular amplifier — change it to the one you own, or any you are
considering, and watch both numbers move.
Input Type and Bi-Amping / Bi-Wiring
Both Alpha T20 and S55 features dual binding post speaker terminals for bi-amping or bi-wiring.
PSB Alpha T20's 5-Way post terminals allows Bi-amping or bi-wiring
Polk S55's 5-way post terminals allows Bi-amping or bi-wiring
Cabinet Type and Port Position
Alpha T20 has a rear firing port whereas S55 has a bottom firing ports. Polk S55's bottom-firing port gives more flexibility in placement in regards to proximity to walls compared to PSB Alpha T20 with its rear-firing port.
Polk S55 Port
Physical Specs
The size of a speaker can sometimes be an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare PSB Alpha T20's and Polk S55's external dimensions. PSB Alpha T20 has external dimensions of 869.0 x 212.0 x 250.0mm (34-3/16 x 8-5/16 x 9-13/16inch) whereas Polk S55 has external dimensions of 1056.0 x 299.0 x 315.0mm (41-9/16 x 11-3/4 x 12-3/8inch).
Polk S55 is clearly the larger of the two speakers. Its body is 87mm wider, 187mm taller and 65mm deeper than PSB Alpha T20.
Below you can see the front view size comparison of PSB Alpha T20 and Polk S55 in scale.
Comparison image of PSB Alpha T20 and Polk S55 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 PSB Alpha T20 is approximately 530.0cm2 / 82.2inch2 and base area of the Polk S55 is approximately 941.9cm2 / 146.0inch2. The Alpha T20 requires 44% less surface area than the S55 which gives it a small advantage on placement in tight spaces.
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 PSB Alpha T20 weighs 11.89kg / 26.2lbs and the Polk S55 weighs 20.00kg / 44lbs. This makes the S55 68% heavier than the Alpha T20.
Here is a comparison of how Alpha T20 and S55's weights compare with the average, max and min weights in Passive Floor-standing class.
Weight
All Floor-standing Speakers
What's in the Box of PSB Alpha T20?
Here are the items that are included inside the box of Alpha T20:
- 2 Floorstanding loudspeakers
- 2 Grilles
- 8 Rubber feet
- 8 Spike feet
- 8 Hex-nuts
- Quick Start Guide
- Warranty Card
What's in the Box of Polk S55?
Here are the items that come with the S55:
- Floorstanding loudspeaker
- Grille (attached)
- 4 Feet (pre-installed)
- Owners Manual
- Online Product Registration
 Height |
869mm
vs
1056mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
530cm2
vs
941cm2
|
Takes less floor space |
 Max Input Power |
200 watts
vs
120 watts
|
Handle more power from your amplifier |
 Woofer Size |
6.5 inches
vs
5.25 inches
|
Larger woofer |
|
Low Frequency Response |
32 Hz
vs
36 Hz
|
Generates deeper bass |
 High Frequency Response |
40k Hz
vs
21k Hz
|
Generates higher frequency |
 Price per pair* |
658USD
vs
799USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
PSB Alpha T20 |
Polk Audio Signature S55 |
| Brand |
PSB |
Polk Audio |
| Speaker Type |
Floor-standing speaker |
Floor-standing speaker |
| Power Range |
15-120 watts |
20-200 watts |
| Sensitivity |
90 dB |
90 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
36-21k Hz |
32-40k Hz |
Drivers |
|
|
| Woofer Quantity |
2 |
2 |
| Woofer Size |
5.25" |
6.5" |
| Woofer Composition |
Polypropylene |
Mica-reinforced polypropylene |
| Woofer Surround Material |
Rubber |
Butyl rubber |
| Tweeter Size |
0.75" |
1" |
| Tweeter Type |
Dome |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
2500Hz |
2500Hz |
| Firing Direction |
rear |
bottom |
Physical Specs |
|
|
| Height |
869.0mm (34.2") |
1056.0mm (41.6") |
| Width |
212.0mm (8.3") |
299.0mm (11.8") |
| Depth |
250.0mm (9.8") |
315.0mm (12.4") |
| Weight |
11.89kg (26.2lbs) |
20.00kg (44lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF, Wood-grain vinyl |
Meddite MDF |
| Available Colors |
Black |
Black |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
Yes |
Yes |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
No single best speaker here - they are built to different priorities, and the right one depends on your room, your amplifier and what you listen to.
| Area | Better | Why |
|---|
| Bass |
B |
Polk S55 digs deeper - 32Hz against 36Hz. A subwoofer would even that out. |
| Amplifier needs |
evenly matched |
Similar sensitivity (90dB vs 90dB) - both want much the same power. |
| Headroom |
B |
Polk S55 takes more power (200W vs 120W) - more in hand in a big room. |
| Size |
depends |
PSB Alpha T20 is easier to place; Polk S55 is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability |
depends |
PSB Alpha T20: bi-amping; Polk S55: bi-amping. PSB Alpha T20 sits in a wider range (9 models), so a matched surround system is easier later. |
| Price |
B |
Polk S55 is cheaper - $658 against $799, about 18% less. |
A PSB Alpha T20
B Polk S55
depends neither is better in the abstract - it turns on your room, placement or how you will use them.
Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Polk S55 is the easier recommendation: it leads on most of the measured areas and costs less. Take PSB Alpha T20 if its size, looks or fit in your room suit you better. In a large or open-plan room, Polk S55 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, PSB Alpha T20 is the easier speaker to get right.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.