In this review, we will be comparing Black T55E MKII and Monitor XT90, two Passive Surround speakers from OSD and Polk Audio.
Let's have a brief look at the main features
of OSD Black T55E MKII and Polk Audio Monitor XT90 first before getting into our more
detailed comparison.
| Key Specs | OSD Black T55E MKII | Polk Audio Monitor XT90 |
|---|
| Brand | OSD
United States · founded 2003 | Polk Audio
United States · founded 1972 |
|---|
| Design | 2-way | 1-way |
|---|
| Tweeter | 1" Soft-Dome | — |
|---|
| Woofer | 5.25" | 4" |
|---|
| Frequency response | 100-20k Hz | 94-22k Hz |
|---|
| Sensitivity | 87 dB | 89 dB |
|---|
| Impedance | 4 ohms | 8 ohms |
|---|
| Weight | 3.05kg / 6.7lbs | 2.72kg / 6lbs |
|---|
| Dimensions (H x W x D) | 6.64" x 7.48" x 10.43"
168.7 x 190.0 x 264.9mm | 5-11/16" x 7-9/16" x 8-1/2"
144.5 x 192.1 x 215.9mm |
|---|
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
One of the fundamental differences between these two speakers is that Black T55E MKII is a 2-way design whereas the Monitor XT90 is a 1-way speaker. 3-way designs utilize a midrange driver in addition to the tweeter and woofer on 2-way designs. Designing a crossover for a 3-way speaker is a complicated process and generally increases the overall cost of the speaker.
OSD Black T55E MKIIPolk Audio Monitor XT90
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
OSD Black T55E MKII |
Polk Audio Monitor XT90 |
|
Driver Setup
|
2-way
|
1-way
|
|
Tweeter
|
1-inch
|
-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 4-inch
|
Black T55E MKII features a 1" Soft-Dome Tweeter and 1 x 5.25" Woofer. On the other hand, the Monitor XT90 features a " Tweeter and 1 x 4" Woofer.
Frequency Response
Black T55E MKII has a frequency range of 100-20k Hz whereas Monitor XT90 has a frequency range of 94-22k Hz. With a minimum frequency of 94Hz, the Monitor XT90 can go significantly deeper on the low side and provide stronger bass compared to the Black T55E MKII's min frequency of 100Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Surround class in our database.
Low Frequency
Surround 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
Black T55E MKII is a 4 ohms speaker compared to the Monitor XT90 which has a nominal impedance of 8 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 Black T55E MKII can provide this impedance level.
These two speakers also have different sensitivity levels. Black T55E MKII sensitivity is rated at 87 dB and the Monitor XT90's is rated at 89 dB. This 2 dB difference makes the Polk Audio Monitor XT90 a more sensitive speaker compared to OSD Black T55E MKII, hence will play louder with the same amount of watts.
Sensitivity
Surround Speakers
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
Black T55E MKII features 5-Way post type posts and Monitor XT90 has a 5-Way post type posts. None of these speakers feature bi-amping/bi-wiring.
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 OSD Black T55E MKII's and Polk Audio Monitor XT90's external dimensions. OSD Black T55E MKII has external dimensions of 168.7 x 190.0 x 264.9mm () whereas Polk Audio Monitor XT90 has external dimensions of 144.5 x 192.1 x 215.9mm ().
Polk Audio Monitor XT90 is 24.2mm shorter and 49mm less deeper than OSD Black T55E MKII but it is also 2.1mm wider.
Size, drawn to scale
Both speakers and both views share one scale, so everything here is directly comparable. Hover a box for its dimensions.
One scale for both, standing on the same surface and pushed back to the same wall, so the deeper one visibly sticks out further.
OSD Black T55E MKII needs about 21% more floor or shelf area. OSD Black T55E MKII is 49mm deeper, so it stands that much further out from the wall. OSD Black T55E MKII is 24mm taller.
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 OSD Black T55E MKII is approximately 503.3cm2 / 78.0inch2 and base area of the Polk Audio Monitor XT90 is approximately 414.7cm2 / 64.3inch2. The Black T55E MKII requires 21% more surface area than the Monitor XT90 which gives it a small disadvantage 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 OSD Black T55E MKII weighs 3.05kg / 6.7lbs and the Polk Audio Monitor XT90 weighs 2.72kg / 6lbs. This makes the Black T55E MKII 12% heavier than the Monitor XT90.
Here is a comparison of how Black T55E MKII and Monitor XT90's weights compare with the average, max and min weights in Passive Surround class.
Weight
All Surround Speakers
 Driver Setup |
2-way
vs
1-way
|
Have a dedicated mid-range driver |
 Woofer Size |
5.25 inches
vs
4 inches
|
Larger woofer |
 Sensitivity |
89 dB
vs
87 dB
|
Play louder with same amount of amplification power |
 Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
|
Low Frequency Response |
94 Hz
vs
100 Hz
|
Generates deeper bass |
 High Frequency Response |
22k Hz
vs
20k Hz
|
Generates higher frequency |
 Height |
144mm
vs
168mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
414cm2
vs
503cm2
|
Takes less floor space |
 Price per pair* |
119USD
vs
400USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
OSD Black T55E MKII |
Polk Audio Monitor XT90 |
| Brand |
OSD |
Polk Audio |
| Speaker Type |
Surround speaker |
Surround speaker |
| Sensitivity |
87 dB |
89 dB |
| Impedance |
4 ohms |
8 ohms |
| Frequency Response |
100-20k Hz |
94-22k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
4" |
| Woofer Composition |
|
|
| Tweeter Size |
1" |
- |
| Tweeter Type |
Soft-Dome |
n/a |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
Physical Specs |
|
|
| Height |
168.7mm (6.6") |
144.5mm (5.7") |
| Width |
190.0mm (7.5") |
192.1mm (7.6") |
| Depth |
264.9mm (10.4") |
215.9mm (8.5") |
| Weight |
3.05kg (6.7lbs) |
2.72kg (6lbs) |
| Enclosure |
|
|
| Finish |
MDF/Vinyl |
MDF, Vinyl |
| Available Colors |
Black |
Black |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
Limited Lifetime |
5 Years |
| Labor Warranty |
Limited Lifetime |
5 Years |
These sit in different price classes - OSD Black T55E MKII costs roughly 3.4x what Polk Audio Monitor XT90 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 Audio Monitor XT90 digs deeper - 94Hz against 100Hz. A subwoofer would even that out. |
| Amplifier needs | B | Polk Audio Monitor XT90 is more sensitive (89dB vs 87dB), so it goes louder on the same amplifier. |
| Amplifier match | B | Polk Audio Monitor XT90 is the easier load at 8 ohms; the other is 4 ohms and wants an amplifier rated for it. |
| Size | depends | Polk Audio Monitor XT90 is easier to place; OSD Black T55E MKII is bigger, which usually goes with fuller bass. Your room decides. |
| Cabinet | depends | Sealed vs Ported. Sealed is tighter and happier near a wall; ported digs lower but wants space behind it. |
| Expandability | depends | Neither adds bi-amping, a sub output or height drivers. Polk Audio Monitor XT90 sits in a wider range (9 models), so a matched surround system is easier later. |
| Price | B | Polk Audio Monitor XT90 is cheaper - $119 against $400, about 70% less; arguably a different class. |
A OSD Black T55E MKII B Polk Audio Monitor XT90
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?
Polk Audio Monitor XT90 is the easier recommendation: it leads on most of the measured areas and costs less. Take OSD Black T55E MKII 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 100Hz anyway, so judge these on the other rows instead. In a large or open-plan room, OSD Black T55E MKII has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Polk Audio Monitor XT90 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.