In this review, we will be comparing UIW RSS II and CWM663, two Passive In-wall speakers from Definitive Technology and Bowers Wilkins.
Let's have a brief look at the main features
of Definitive UIW RSS II and B&W CWM663 first before getting into our more
detailed comparison.
| Key Specs | Definitive UIW RSS II | B&W CWM663 |
|---|
| Brand | Definitive Technology
United States · founded 1990 | Bowers Wilkins
United Kingdom · founded 1966 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Hard-Dome | 1" Soft-Dome |
|---|
| Woofer | 2 x 4.5" Polypropylene | 6" Kevlar |
|---|
| Frequency response | 26-30kHz | 45-50kHz |
|---|
| Sensitivity | 90 dB | 88 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | 10-250 watts | 25-150 watts |
|---|
| Weight | 5.67kg / 12.5lbs | — |
|---|
| Dimensions (H x W x D) | 11.6250" x 9.8750" x 3.8750"
296.0 x 251.0 x 99.0mm | 11.0000" x 7.2500" x 3.7500"
280.0 x 185.0 x 96.0mm |
|---|
What size room are the Definitive UIW RSS II and B&W CWM663 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* |
Definitive UIW RSS II |
B&W CWM663 |
| Near-field |
Poor |
Poor |
| Small Room |
Poor |
Average |
| Mid-size Room |
Good |
Good |
| Large Room |
Good |
Average |
| Very Large Room |
Average |
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 UIW RSS II and CWM663 are 2-way speakers.
Definitive UIW RSS IIB&W CWM663
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Definitive UIW RSS II |
B&W CWM663 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
2 x 4.5-inch
|
1 x 6-inch
|
UIW RSS II features a 1" Hard-Dome Tweeter and 2 x 4.5" Polypropylene Woofer. On the other hand, the CWM663 features a 1" Soft-Dome Tweeter and 1 x 6" Kevlar Woofer.
Frequency Response
UIW RSS II has a frequency range of 26-30kHz whereas CWM663 has a frequency range of 45-50kHz. With a minimum frequency of 26Hz, the UIW RSS II can go significantly deeper on the low side and provide stronger bass compared to the CWM663'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 In-wall class in our database.
Low Frequency
In-wall 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
UIW RSS II and CWM663 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. UIW RSS II sensitivity is rated at 90 dB and the CWM663's is at 88 dB. This 2 dB difference makes the Definitive UIW RSS II a more sensitive speaker compared to B&W CWM663, hence will play louder with the same amount of watts.
Sensitivity
In-wall 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.
UIW RSS II can handle a max power of 250 watts RMS, whereas CWM663 has a max power handling value of 150 watts RMS, 100 watts less than the UIW RSS II.
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
UIW RSS II features Spring post type posts and CWM663 has a Spring 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 Definitive UIW RSS II's and B&W CWM663's external dimensions. Definitive UIW RSS II has external dimensions of 296.0 x 251.0 x 99.0mm (11.6250-inch x 9.8750-inch x 3.8750-inch) whereas B&W CWM663 has external dimensions of 280.0 x 185.0 x 96.0mm (11.0000-inch x 7.2500-inch x 3.7500-inch).
Definitive UIW RSS II is clearly the larger of the two speakers. Its body is 66mm wider, 16mm taller and 3mm deeper than B&W CWM663.
What's in the Box of Definitive UIW RSS II?
Here are the items that are included inside the box of UIW RSS II:
- In-wall/In-cieling bipolar speaker
- Grille
- 7 Foam strips
- 2 Screws
- Paint mask
- Wall template
- Owners Manual
- Online Product Registration Card
What's in the Box of B&W CWM663?
Here are the items that come with the CWM663:
- 2 In-wall loudspeakers
- 2 Mounting frames
- 2 Grilles
- 2 Paint mask
- 2 Cut-out templates
- Quick Start Guide
- Template
- Warranty Information