In this review, we will be comparing Ultra Bookshelf and S20, two Passive Bookshelf speakers from SVS and Polk Audio.
Let's have a brief look at the main features
of SVS Ultra Bookshelf and Polk S20 first before getting into our more
detailed comparison.
| Key Specs | SVS Ultra Bookshelf | Polk S20 |
|---|
| Brand | SVS
United States · founded 1998 | Polk Audio
United States · founded 1972 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Hard-Dome | 1" Soft-Dome |
|---|
| Woofer | 6.5" Composite glass-fiber | 6.5" Mica-reinforced polypropylene |
|---|
| Frequency response | 45-32k Hz | 39-40k Hz |
|---|
| Sensitivity | 87 dB | 88 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | 20-150 watts | 20-125 watts |
|---|
| Weight | 8.64kg / 19lbs | 7.73kg / 17lbs |
|---|
| Dimensions (H x W x D) | 14-15/16" x 8-9/16" x 11-1/16"
380.0 x 218.0 x 281.0mm | 14.8" x 8.5" x 13.7"
376.0 x 216.0 x 350.0mm |
|---|
What size room are the SVS Ultra Bookshelf and Polk S20 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* |
SVS Ultra Bookshelf |
Polk S20 |
| 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.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
Both Ultra Bookshelf and S20 are 2-way speakers.
SVS Ultra BookshelfPolk S20
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
SVS Ultra Bookshelf |
Polk S20 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 6.5-inch
|
1 x 6.5-inch
|
Ultra Bookshelf features a 1" aluminum Hard-Dome Tweeter and 1 x 6.5" Composite glass-fiber Woofer with a Crossover frequency at 2000Hz. On the other hand, the S20 features a 1" Terylene Soft-Dome Tweeter and 1 x 6.5" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz.
Frequency Response
Ultra Bookshelf has a frequency range of 45-32k Hz whereas S20 has a frequency range of 39-40k Hz. With a minimum frequency of 39Hz, the S20 can go significantly deeper on the low side and provide stronger bass compared to the Ultra Bookshelf's min frequency of 45Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf 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
Ultra Bookshelf and S20 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. Ultra Bookshelf sensitivity is rated at 87 dB and the S20's is at 88 dB. This 1 dB difference makes the Polk S20 a more sensitive speaker compared to SVS Ultra Bookshelf, 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. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
Ultra Bookshelf can handle a max power of 150 watts RMS, whereas S20 has a max power handling value of 125 watts RMS, 25 watts less than the Ultra Bookshelf.
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
Ultra Bookshelf features 5-way post posts which make bi-amping or bi-wiring possible. S20 has a 5-way post which doesn't feature bi-amping/bi-wiring.
SVS Ultra Bookshelf's 5-way post terminals allows Bi-amping or bi-wiring
Cabinet Type and Port Position
Both Ultra Bookshelf and S20 have rear firing ports. Rear ported speakers generally need more room between the backside of the speaker and the wall compared to sealed and front/bottom ported speakers. Placing the speakers too close to the walls may cause the bass to sound boomy.
If you are limited in space and can't get the speakers away from the backwall, check our Speakers with Front Firing Ports page.
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 SVS Ultra Bookshelf's and Polk S20's external dimensions. SVS Ultra Bookshelf has external dimensions of 380.0 x 218.0 x 281.0mm (14-15/16 x 8-9/16 x 11-1/16inch) whereas Polk S20 has external dimensions of 376.0 x 216.0 x 350.0mm (14.8 x 8.5 x 13.7inch).
Polk S20 is 2mm narrower and 4mm shorter than SVS Ultra Bookshelf but it is also 69mm deeper.
Below you can see the front view size comparison of SVS Ultra Bookshelf and Polk S20 in scale.
Comparison image of SVS Ultra Bookshelf and Polk S20 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 SVS Ultra Bookshelf is approximately 612.6cm2 / 95.0inch2 and base area of the Polk S20 is approximately 756.0cm2 / 117.2inch2. The Ultra Bookshelf requires 19% less surface area than the S20 which gives it a small advantage on placement in tight spaces.
Here is 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 SVS Ultra Bookshelf and Polk S20 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 SVS Ultra Bookshelf weighs 8.64kg / 19lbs and the Polk S20 weighs 7.73kg / 17lbs. This makes the Ultra Bookshelf 12% heavier than the S20.
Here is a comparison of how Ultra Bookshelf and S20's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of SVS Ultra Bookshelf?
Here are the items that are included inside the box of Ultra Bookshelf:
- 2 Bookshelf loudspeakers
- 2 Grilles
- 8 Rubber feet
- 2 Terminal jumpers (pre-installed)
- Owners Manual
- SVS brochure
- Online Product Registration Card
What's in the Box of Polk S20?
Here are the items that come with the S20:
- 2 Bookshelf loudspeakers
- 2 Grilles (attached)
- 8 Self-adhesive rubber feet
- Owners Manual
- Online Product Registration
 Max Input Power |
150 watts
vs
125 watts
|
Handle more power from your amplifier |
 Bi-Amping and Bi-Wiring |
Yes
vs
No
|
Allows bi-amping and bi-wiring connections |
 Base Surface Area |
612cm2
vs
756cm2
|
Takes less floor space |
 Sensitivity |
88 dB
vs
87 dB
|
Play louder with same amount of amplification power |
 Low Frequency Response |
39 Hz
vs
45 Hz
|
Generates deeper bass |
 High Frequency Response |
40k Hz
vs
32k Hz
|
Generates higher frequency |
 Height |
376mm
vs
380mm
|
Easier to fit in smaller spaces |
 Price per pair* |
299USD
vs
1200USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
SVS Ultra Bookshelf |
Polk Audio Signature S20 |
| Brand |
SVS |
Polk Audio |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
20-150 watts |
20-125 watts |
| Sensitivity |
87 dB |
88 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
45-32k Hz |
39-40k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6.5" |
6.5" |
| Woofer Composition |
Composite glass-fiber |
Mica-reinforced polypropylene |
| Woofer Surround Material |
Rubber |
Butyl rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Hard-Dome |
Soft-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
2000Hz |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
380.0mm (15") |
376.0mm (14.8") |
| Width |
218.0mm (8.6") |
216.0mm (8.5") |
| Depth |
281.0mm (11.1") |
350.0mm (13.8") |
| Weight |
8.64kg (19lbs) |
7.73kg (17lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Oak veneer |
Meddite MDF |
| Available Colors |
Black Oak,Piano Gloss Black,Piano Gloss White |
Black, Walnut, Brown Walnut |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
22-28" |
24-28" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
Yes |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
These sit in different price classes - SVS Ultra Bookshelf costs roughly 4x what Polk S20 does. Expect it to lead on paper; the question is whether the gap is audible enough in your room to be worth it.
| Area | Better | Why |
|---|
| Bass | B | Polk S20 digs deeper - 39Hz against 45Hz. A subwoofer would even that out. |
| Amplifier needs | evenly matched | Similar sensitivity (87dB vs 88dB) - both want much the same power. |
| Headroom | evenly matched | Similar power handling (150W vs 125W). |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Expandability | A | SVS Ultra Bookshelf: bi-amping. |
| Price | B | Polk S20 is cheaper - $299 against $1,200, about 75% less; arguably a different class. |
A SVS Ultra Bookshelf B Polk S20
depends neither is better in the abstract - it turns on your room, your system 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?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 45Hz anyway, so judge these on the other rows instead. Think about the whole system, not just the speakers: the roughly $901 saved by taking the cheaper pair would buy a subwoofer or a better amplifier, and either usually does more for the sound than the difference between these two.
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.