In this review, we will be comparing S20 and Motion 35XTi, two Passive Bookshelf speakers from Polk Audio and MartinLogan.
Let's have a brief look at the main features
of Polk S20 and MartinLogan 35XTi first before getting into our more
detailed comparison.
| Key Specs | Polk S20 | MartinLogan 35XTi |
|---|
| Brand | Polk Audio
United States · founded 1972 | MartinLogan
United States · founded 1982 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Soft-Dome | 1.25 x 2.4" Folded Motion XT |
|---|
| Woofer | 6.5" Mica-reinforced polypropylene | 6.5" Aluminum |
|---|
| Frequency response | 39-40k Hz | 50-25k Hz |
|---|
| Sensitivity | 88 dB | 92 dB |
|---|
| Impedance | 8 ohms | 4 ohms |
|---|
| Power range | 20-125 watts | 20-250 watts |
|---|
| Weight | 7.73kg / 17lbs | 8.40kg / 18.5lbs |
|---|
| Dimensions (H x W x D) | 14.8" x 8.5" x 13.7"
376.0 x 216.0 x 350.0mm | 13.5" x 7.5" x 11.8"
343.0 x 192.0 x 300.0mm |
|---|
What size room are the Polk S20 and MartinLogan 35XTi 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 |
MartinLogan 35XTi |
| Near-field |
Poor |
Poor |
| Small Room |
Average |
Poor |
| Mid-size Room |
Good |
Good |
| Large Room |
Average |
Good |
| Very Large Room |
Poor |
Average |
(* 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 S20 and Motion 35XTi are 2-way speakers.
Polk S20MartinLogan 35XTi
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Polk S20 |
MartinLogan 35XTi |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1.25 x 2.4-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 6.5-inch
|
1 x 6.5-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 Motion 35XTi features a 1.25 x 2.4" Folded Motion XT Tweeter and 1 x 6.5" Aluminum Woofer with a Crossover frequency at 2200Hz.
Frequency Response
S20 has a frequency range of 39-40k Hz whereas Motion 35XTi has a frequency range of 50-25k Hz. With a minimum frequency of 39Hz, the S20 can go significantly deeper on the low side and provide stronger bass compared to the Motion 35XTi's min frequency of 50Hz.
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
S20 is a 8 ohms speaker compared to the Motion 35XTi which has a nominal impedance of 4 ohms. Lower impedance speakers, especially the ones that are rated at 4 ohms may put more pressure on the amplifier unit especially when played at high volume levels, so make sure the amp you pair with the Motion 35XTi can provide this impedance level.
These two speakers also have different sensitivity levels. S20 sensitivity is rated at 88 dB and the Motion 35XTi's is rated at 92 dB. This 4 dB difference makes the MartinLogan 35XTi 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. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
Motion 35XTi can handle a max power of 250 watts RMS, whereas S20 has a max power handling value of 125 watts RMS, 125 watts less than the Motion 35XTi.
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
Motion 35XTi features Custom 5-way bi-wire tool-less binding posts posts which make bi-amping or bi-wiring possible. S20 has a 5-way post which doesn't feature bi-amping/bi-wiring.
MartinLogan 35XTi's Custom 5-way bi-wire tool-less binding posts terminals allows Bi-amping or bi-wiring
Cabinet Type and Port Position
Both S20 and Motion 35XTi 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 Polk S20's and MartinLogan 35XTi'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 MartinLogan 35XTi has external dimensions of 343.0 x 192.0 x 300.0mm (13.5 x 7.5 x 11.8inch).
Polk S20 is clearly the larger of the two speakers. Its body is 24mm wider, 33mm taller and 50mm deeper than MartinLogan 35XTi.
Below you can see the front view size comparison of Polk S20 and MartinLogan 35XTi in scale.
Comparison image of Polk S20 and MartinLogan 35XTi 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 MartinLogan 35XTi is approximately 576.0cm2 / 89.3inch2. The S20 requires 31% more surface area than the Motion 35XTi which gives it a small disadvantage 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 Polk S20 and MartinLogan 35XTi 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 MartinLogan 35XTi weighs 8.40kg / 18.5lbs. This makes the Motion 35XTi 9% heavier than the S20.
Here is a comparison of how S20 and Motion 35XTi'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 loudspeakers
- 2 Grilles (attached)
- 8 Self-adhesive rubber feet
- Owners Manual
- Online Product Registration
What's in the Box of MartinLogan 35XTi?
Here are the items that come with the Motion 35XTi:
- Bookshelf loudspeaker
- Grille
- 4 Rubber feet
- 2 Jumper-straps (pre-installed)
- Users Manual
- Warranty/Registration Information
 Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
 Low Frequency Response |
39 Hz
vs
50 Hz
|
Generates deeper bass |
 High Frequency Response |
40k Hz
vs
25k Hz
|
Generates higher frequency |
 Price per pair* |
299USD
vs
1500USD
|
costs less (*prices may change depending on the seller, location and time) |
 Max Input Power |
250 watts
vs
125 watts
|
Handle more power from your amplifier |
 Sensitivity |
92 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 |
 Height |
343mm
vs
376mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
576cm2
vs
756cm2
|
Takes less floor space |
| General |
Polk Audio Signature S20 |
MartinLogan Motion 35XTi |
| Brand |
Polk Audio |
MartinLogan |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
20-125 watts |
20-250 watts |
| Sensitivity |
88 dB |
92 dB |
| Impedance |
8 ohms |
4 ohms |
| Frequency Response |
39-40k Hz |
50-25k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6.5" |
6.5" |
| Woofer Composition |
Mica-reinforced polypropylene |
Aluminum |
| Woofer Surround Material |
Butyl rubber |
Rubber |
| Tweeter Size |
1" |
1.25 x 2.4" |
| Tweeter Type |
Soft-Dome |
Folded Motion XT |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
2500Hz |
2200Hz |
| Firing Direction |
rear |
rear |
| Suggested Break-in Period |
n/a |
Allow 72 hours of break-in at 90 dB |
Physical Specs |
|
|
| Height |
376.0mm (14.8") |
343.0mm (13.5") |
| Width |
216.0mm (8.5") |
192.0mm (7.6") |
| Depth |
350.0mm (13.8") |
300.0mm (11.8") |
| Weight |
7.73kg (17lbs) |
8.40kg (18.5lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
Meddite MDF |
MDF/Lacquer |
| Available Colors |
Black, Walnut, Brown Walnut |
Gloss Black, Matt White, Red Walnut |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
24-28" |
24-26" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
Yes |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
These sit in different price classes - MartinLogan 35XTi costs roughly 5x 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 | A | Polk S20 digs deeper - 39Hz against 50Hz. |
| Amplifier needs | B | MartinLogan 35XTi is more sensitive (92dB vs 88dB), so it goes louder on the same amplifier. |
| Amplifier match | A | Polk S20 is the easier load at 8 ohms; the other is 4 ohms and wants an amplifier rated for it. |
| Headroom | B | MartinLogan 35XTi takes more power (250W vs 125W) - more in hand in a big room. |
| Size | depends | MartinLogan 35XTi is easier to place; Polk S20 is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | B | MartinLogan 35XTi: bi-amping. MartinLogan 35XTi sits in a wider range (18 models), so a matched surround system is easier later. |
| Price | A | Polk S20 is cheaper - $299 against $1,500, about 80% less; arguably a different class. |
A Polk S20 B MartinLogan 35XTi
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?
MartinLogan 35XTi is ahead, but only on 1 of the measured areas, and it costs about 5x the price. That is a lot of money for a narrow margin on paper - Polk S20 looks like the sensible buy unless something else about the MartinLogan 35XTi appeals to you. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 50Hz anyway, so judge these on the other rows instead. Match it to your room: we rate Polk S20 the better fit for a small room, and MartinLogan 35XTi for a large room and a very large room.
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.