In this review, we will be comparing Foundation B1 and ES20, two Passive Bookshelf speakers from MartinLogan and Polk Audio.
Let's have a brief look at the main features
of MartinLogan Foundation B1 and Polk ES20 first before getting into our more
detailed comparison.
| Key Specs | MartinLogan Foundation B1 | Polk ES20 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Folded Motion Ribbon | 1" Soft-Dome |
|---|
| Woofer | 5-1/2" Aluminum | 6.5" Mica-reinforced polypropylene |
|---|
| Frequency response | 48-23k Hz | 41-40k Hz |
|---|
| Sensitivity | 89 dB | 86 dB |
|---|
| Impedance | 5 ohms | 8 ohms |
|---|
| Power range | up to 100 watts | 20-125 watts |
|---|
| Weight | 5.23kg / 11.5lbs | 7.73kg / 17lbs |
|---|
| Dimensions (H x W x D) | 13-5/8" x 7-1/4" x 9-1/2"
347.0 x 185.0 x 242.0mm | 14-3/4" x 8-9/16" x 13-13/16"
375.0 x 218.0 x 351.0mm |
|---|
What size room are the MartinLogan Foundation B1 and Polk ES20 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* |
MartinLogan Foundation B1 |
Polk ES20 |
| Near-field |
Average |
Poor |
| Small Room |
Good |
Average |
| Mid-size Room |
Average |
Good |
| Large Room |
Poor |
Average |
| Very Large Room |
Bad |
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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Drivers
Both Foundation B1 and ES20 are 2-way speakers.
MartinLogan Foundation B1Polk ES20
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
MartinLogan Foundation B1 |
Polk ES20 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5-1/2-inch
|
1 x 6.5-inch
|
Foundation B1 features a 1" Gen2 Obsidian Folded Motion Ribbon Tweeter and 1 x 5-1/2" Aluminum Woofer with a Crossover frequency at 3400Hz. On the other hand, the ES20 features a 1" Terylene Soft-Dome Tweeter and 1 x 6.5" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz.
Frequency Response
Foundation B1 has a frequency range of 48-23k Hz whereas ES20 has a frequency range of 41-40k Hz. With a minimum frequency of 41Hz, the ES20 can go significantly deeper on the low side and provide stronger bass compared to the Foundation B1's min frequency of 48Hz.
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
Foundation B1 is a 5 ohms speaker compared to the ES20 which has a nominal impedance of 8 ohms.
These two speakers also have different sensitivity levels. Foundation B1 sensitivity is rated at 89 dB and the ES20's is rated at 86 dB. This 3 dB difference makes the MartinLogan Foundation B1 a more sensitive speaker compared to Polk ES20, 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.
ES20 can handle a max power of 125 watts RMS, whereas Foundation B1 has a max power handling value of 100 watts RMS, 25 watts less than the ES20.
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.
MartinLogan Foundation B1
Input Type and Bi-Amping / Bi-Wiring
Foundation B1 features 5-Way post type posts and ES20 has a 5-Way post type posts. None of these speakers feature bi-amping/bi-wiring.
MartinLogan Foundation B1's Binding post terminals
Cabinet Type and Port Position
Both Foundation B1 and ES20 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 MartinLogan Foundation B1's and Polk ES20's external dimensions. MartinLogan Foundation B1 has external dimensions of 347.0 x 185.0 x 242.0mm (13-5/8inch x 7-1/4inch x 9-1/2inch) whereas Polk ES20 has external dimensions of 375.0 x 218.0 x 351.0mm (14-3/4 x 8-9/16 x 13-13/16inch).
Polk ES20 is clearly the larger of the two speakers. Its body is 33mm wider, 28mm taller and 109mm deeper than MartinLogan Foundation B1.
Below you can see the front view size comparison of MartinLogan Foundation B1 and Polk ES20 in scale.
Comparison image of MartinLogan Foundation B1 and Polk ES20 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 MartinLogan Foundation B1 is approximately 447.7cm2 / 69.4inch2 and base area of the Polk ES20 is approximately 765.2cm2 / 118.6inch2. The Foundation B1 requires 41% less surface area than the ES20 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 MartinLogan Foundation B1 and Polk ES20 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 MartinLogan Foundation B1 weighs 5.23kg / 11.5lbs and the Polk ES20 weighs 7.73kg / 17lbs. This makes the ES20 48% heavier than the Foundation B1.
Here is a comparison of how Foundation B1 and ES20's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
MartinLogan Foundation B1
What's in the Box of Polk ES20?
Here are the items that come with the ES20:
- 2 Bookshelf loudspeakers
- 2 Grille (attached)
- 8 Self-adhesive rubber feet
- Owners Manual
- Online Product Registration
 Sensitivity |
89 dB
vs
86 dB
|
Play louder with same amount of amplification power |
 Height |
347mm
vs
375mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
447cm2
vs
765cm2
|
Takes less floor space |
 Max Input Power |
125 watts
vs
100 watts
|
Handle more power from your amplifier |
 Nominal Impedance |
8 ohms
vs
5 ohms
|
Less selective with amplifiers |
 Woofer Size |
6.5 inches
vs
5-1/2 inches
|
Larger woofer |
|
Low Frequency Response |
41 Hz
vs
48 Hz
|
Generates deeper bass |
 High Frequency Response |
40k Hz
vs
23k Hz
|
Generates higher frequency |
 Price per pair* |
399USD
vs
599USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
MartinLogan Foundation B1 |
Polk Audio Signature Elite ES20 |
| Brand |
MartinLogan |
Polk Audio |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
up to 100 watts |
20-125 watts |
| Sensitivity |
89 dB |
86 dB |
| Impedance |
5 ohms |
8 ohms |
| Frequency Response |
48-23k Hz |
41-40k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5-1/2" |
6.5" |
| Woofer Composition |
Aluminum |
Mica-reinforced polypropylene |
| Woofer Surround Material |
n/a |
Butyl rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Folded Motion Ribbon |
Soft-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
3400Hz |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
347.0mm (13.7") |
375.0mm (14.8") |
| Width |
185.0mm (7.3") |
218.0mm (8.6") |
| Depth |
242.0mm (9.5") |
351.0mm (13.8") |
| Weight |
5.23kg (11.5lbs) |
7.73kg (17lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
n/a |
MDF, Wood-grain vinyl |
| Available Colors |
Walnut,Black,Satin White |
Black,White,Walnut |
| Mounting Bracket |
|
No |
| Recommended Stand Height |
n/a |
22-26" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
No |
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 ES20 digs deeper - 41Hz against 48Hz. A subwoofer would even that out. |
| Amplifier needs |
A |
MartinLogan Foundation B1 is more sensitive (89dB vs 86dB), so it goes louder on the same amplifier. |
| Amplifier match |
B |
Polk ES20 is the easier load at 8 ohms. |
| Headroom |
B |
Polk ES20 takes more power (125W vs 100W) - more in hand in a big room. |
| Size |
depends |
MartinLogan Foundation B1 is easier to place; Polk ES20 is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability |
depends |
Neither adds bi-amping, a sub output or height drivers. Polk ES20 sits in a wider range (12 models), so a matched surround system is easier later. |
| Price |
B |
Polk ES20 is cheaper - $399 against $599, about 33% less. |
A MartinLogan Foundation B1
B Polk ES20
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 ES20 is the easier recommendation: it leads on most of the measured areas and costs less. Take MartinLogan Foundation B1 if its size, looks or fit in your room suit you better. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 48Hz anyway, so judge these on the other rows instead. Match it to your room: we rate MartinLogan Foundation B1 the better fit for near-field listening and a small room, and Polk ES20 for a mid-size room and a 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.