MartinLogan Installer Series IW5-LCR vs Definitive UIW RLS III Comparison

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MartinLogan Installer Series IW5-LCR

Passive In-wall | 60-20kHz

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Definitive UIW RLS III

Passive In-wall | 24-30kHz

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Definitive UIW RLS I...

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MartinLogan Installer Series IW5-LCR vs Definitive UIW RLS III Speaker Comparison

In this review, we will be comparing Installer Series IW5-LCR and UIW RLS III, two Passive In-wall speakers from MartinLogan and Definitive Technology.

Let's have a brief look at the main features of MartinLogan Installer Series IW5-LCR and Definitive UIW RLS III first before getting into our more detailed comparison.

Key Specs	MartinLogan Installer Series IW5-LCR	Definitive UIW RLS III
Brand	MartinLogan United States · founded 1982	Definitive Technology United States · founded 1990
Design	2-way	2-way
Tweeter	0.75" Hard-Dome	1" Hard-Dome
Woofer	2 x 5.5" Mineral-filled poly	2 x 5.25" Polypropylene
Frequency response	60-20kHz	24-30kHz
Sensitivity	89 dB	92 dB
Impedance	8 ohms	8 ohms
Power range	15-70 watts	10-325 watts
Weight	2.68kg / 5.9lbs	—
Dimensions (H x W x D)	8.2500" x 11.6250" x 3.0000" 210.0 x 296.0 x 77.0mm	23.7500" x 5.8750" x 3.8750" 604.0 x 150.0 x 99.0mm

What size room are the MartinLogan Installer Series IW5-LCR and Definitive UIW RLS III 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 Installer Series IW5-LCR	Definitive UIW RLS III
Near-field	Good	Are you nuts?
Small Room	Good	Bad
Mid-size Room	Average	Poor
Large Room	Poor	Good
Very Large Room	No way	Good

(* 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 Installer Series IW5-LCR and UIW RLS III are 2-way speakers.

MartinLogan Installer Series IW5-LCR

Definitive UIW RLS III

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 Installer Series IW5-LCR	Definitive UIW RLS III
Driver Setup	2-way	2-way
Tweeter	0.75-inch	1-inch
Midrange	-	-
Woofer	2 x 5.5-inch	2 x 5.25-inch

Installer Series IW5-LCR features a 0.75" Hard-Dome Tweeter and 2 x 5.5" Mineral-filled poly Woofer. On the other hand, the UIW RLS III features a 1" Hard-Dome Tweeter and 2 x 5.25" Polypropylene Woofer.

Frequency Response

Installer Series IW5-LCR has a frequency range of 60-20kHz whereas UIW RLS III has a frequency range of 24-30kHz. With a minimum frequency of 24Hz, the UIW RLS III can go significantly deeper on the low side and provide stronger bass compared to the Installer Series IW5-LCR's min frequency of 60Hz.

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

Installer Series IW5-LCR

UIW RLS III

Min

Average

Median

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

Installer Series IW5-LCR and UIW RLS III have the same Impedance of 8 ohms but where they differ is the sensitivity levels. Installer Series IW5-LCR sensitivity is rated at 89 dB and the UIW RLS III's is at 92 dB. This 3 dB difference makes the Definitive UIW RLS III a more sensitive speaker compared to MartinLogan Installer Series IW5-LCR, hence will play louder with the same amount of watts.

Sensitivity

In-wall Speakers

Installer Series IW5-LCR

UIW RLS III

Min

Average

Median

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 RLS III can handle a max power of 325 watts RMS, whereas Installer Series IW5-LCR has a max power handling value of 70 watts RMS, 255 watts less than the UIW RLS III.

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.

Amplifier - change this

Distance

Playing as

MartinLogan Installer Series IW5-LCR

Definitive UIW RLS III

Input Type and Bi-Amping / Bi-Wiring

Installer Series IW5-LCR features Spring post type posts and UIW RLS III 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 MartinLogan Installer Series IW5-LCR's and Definitive UIW RLS III's external dimensions. MartinLogan Installer Series IW5-LCR has external dimensions of 210.0 x 296.0 x 77.0mm (8.2500-inch x 11.6250-inch x 3.0000-inch) whereas Definitive UIW RLS III has external dimensions of 604.0 x 150.0 x 99.0mm (23.7500-inch x 5.8750-inch x 3.8750-inch).

MartinLogan Installer Series IW5-LCR is 394mm shorter and 22mm less deeper than Definitive UIW RLS III but it is also 146mm wider.

What's in the Box of MartinLogan Installer Series IW5-LCR?

Here are the items that are included inside the box of Installer Series IW5-LCR:

In-wall loudspeaker
Grille
User-feets Manual
Cutout Template

What's in the Box of Definitive UIW RLS III?

Here are the items that come with the UIW RLS III:

In-wall loudspeaker
Grille
Self-adhesive foam gasket
Paint mask
Wall-Mount Template
Owners Manual
Online Product Registration Card

Reasons to choose MartinLogan Installer Series IW5-LCR over Definitive Technology UIW RLS III

Woofer Size	5.5 inches vs 5.25 inches	Larger woofer
Height	210mm vs 604mm	Easier to fit in smaller spaces
Price per pair*	760USD vs 1398USD	costs less (*prices may change depending on the seller, location and time)

Reasons to choose Definitive Technology UIW RLS III over MartinLogan Installer Series IW5-LCR

Max Input Power	325 watts vs 70 watts	Handle more power from your amplifier
Sensitivity	92 dB vs 89 dB	Play louder with same amount of amplification power
Low Frequency Response	24 Hz vs 60 Hz	Generates deeper bass
High Frequency Response	30k Hz vs 20k Hz	Generates higher frequency
Passive Radiator	2 x 5.25-inch vs None	Increases the bass performance
Base Surface Area	148cm² vs 227cm²	Takes less floor space

MartinLogan Installer Series IW5-LCR vs Definitive UIW RLS III Specs Table

Detailed comparison of specifications

General	MartinLogan Installer Series IW5-LCR	Definitive Technology UIW RLS III
Brand	MartinLogan	Definitive Technology
Speaker Type	Passive In-wall Speaker	Passive In-wall Speaker
Power Range	15-70 watts	10-325 watts
Sensitivity	89 dB	92 dB
Impedance	8 ohms	8 ohms
Frequency Response	60-20kHz	24-30kHz
Drivers
Woofer Quantity	2	2
Woofer Size	5.5"	5.25"
Woofer Composition	Mineral-filled poly	Polypropylene
Woofer Surround Material	Rubber	Butyl Rubber
Tweeter Size	0.75"	1"
Tweeter Type	Hard-Dome	Hard-Dome
Aimable Tweeter	No	No
Midrange Driver	No	No
Physical Specs
Height	210.0mm (8.3")	604.0mm (23.8")
Width	296.0mm (11.7")	150.0mm (5.9")
Depth	77.0mm (3")	99.0mm (3.9")
Weight	2.68kg (5.9lbs)	n/a
Enclosure	In-wall	In-wall
Moisture Resistancy	No	Yes
Connections
Biamp Inputs	No	No
Other
Parts Warranty	5 Yrs w/ Registration	5 Years
Labor Warranty	5 Yrs w/ Registration	5 Years

Verdict

These sit in different price classes - Definitive UIW RLS III costs roughly 1.8x what MartinLogan Installer Series IW5-LCR 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	Definitive UIW RLS III digs deeper - 24Hz against 60Hz.
Amplifier needs	B	Definitive UIW RLS III is more sensitive (92dB vs 89dB), so it goes louder on the same amplifier.
Headroom	B	Definitive UIW RLS III takes more power (325W vs 70W) - more in hand in a big room.
Size	depends	MartinLogan Installer Series IW5-LCR is easier to place; Definitive UIW RLS III is bigger, which usually goes with fuller bass. Your room decides.
Price	A	MartinLogan Installer Series IW5-LCR is cheaper - $760 against $1,398, about 46% less; arguably a different class.

A MartinLogan Installer Series IW5-LCR B Definitive UIW RLS III
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?

The usual trade-off: Definitive UIW RLS III measures better, MartinLogan Installer Series IW5-LCR costs about about 84% more% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 60Hz anyway, which makes the cheaper MartinLogan Installer Series IW5-LCR much easier to justify. Match it to your room: we rate MartinLogan Installer Series IW5-LCR the better fit for a small room and a mid-size room, and Definitive UIW RLS III for 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.