In this review, we will be comparing Model Three and R-51M, two Passive Bookshelf speakers from KLH and Klipsch.
Let's have a brief look at the main features
of KLH Model Three and Klipsch R-51M first before getting into our more
detailed comparison.
| Key Specs | KLH Model Three | Klipsch R-51M |
|---|
| Brand | KLH
United States · founded 1957 | Klipsch
United States · founded 1946 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" | 1" Tractrix Horn |
|---|
| Woofer | 8" Pulp-Paper Cone | 5.25" Copper-spun IMG |
|---|
| Frequency response | 46-20k Hz | 62-21k Hz |
|---|
| Sensitivity | 88 dB | 93 dB |
|---|
| Impedance | 6 ohms | 8 ohms |
|---|
| Power range | 30-150 watts | Up to 85 watts |
|---|
| Weight | 13.20kg / 29lbs | 5.00kg / 11lbs |
|---|
| Dimensions (H x W x D) | 19.0" x 12.25" x 10.5"
482.0 x 311.0 x 267.0mm | 13.3" x 7.0" x 8.4"
338.0 x 178.0 x 215.0mm |
|---|
What size room are the KLH Model Three and Klipsch R-51M 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* |
KLH Model Three |
Klipsch R-51M |
| Near-field |
Poor |
Average |
| Small Room |
Average |
Good |
| Mid-size Room |
Good |
Average |
| Large Room |
Average |
Poor |
| Very Large Room |
Poor |
Bad |
(* 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 Model Three and R-51M are 2-way speakers.
KLH Model ThreeKlipsch R-51M
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
KLH Model Three |
Klipsch R-51M |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 8-inch
|
1 x 5.25-inch
|
Model Three features a 1" Aluminum Tweeter and 1 x 8" Pulp-Paper Cone Woofer with a Crossover frequency at 1600Hz. On the other hand, the R-51M features a 1" Tractrix Horn Tweeter and 1 x 5.25" Copper-spun IMG Woofer with a Crossover frequency at 1660Hz.
Frequency Response
Model Three has a frequency range of 46-20k Hz whereas R-51M has a frequency range of 62-21k Hz. With a minimum frequency of 46Hz, the Model Three can go significantly deeper on the low side and provide stronger bass compared to the R-51M's min frequency of 62Hz.
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
Model Three is a 6 ohms speaker compared to the R-51M which has a nominal impedance of 8 ohms.
These two speakers also have different sensitivity levels. Model Three sensitivity is rated at 88 dB and the R-51M's is rated at 93 dB. This 5 dB difference makes the Klipsch R-51M a more sensitive speaker compared to KLH Model Three, 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.
Model Three can handle a max power of 150 watts RMS, whereas R-51M has a max power handling value of 85 watts RMS, 65 watts less than the Model Three.
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
Model Three features Single Gold Plated Binding Posts - 5-way type posts and R-51M has a Single Gold Plated Binding Posts - 5-way type posts. None of these speakers feature bi-amping/bi-wiring.
KLH Model Three's Binding post terminals
Klipsch R-51M's Single Gold Plated Binding Posts - 5-way terminals
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 KLH Model Three's and Klipsch R-51M's external dimensions. KLH Model Three has external dimensions of 482.0 x 311.0 x 267.0mm (19.0 x 12.25 x 10.5inch) whereas Klipsch R-51M has external dimensions of 338.0 x 178.0 x 215.0mm (13.3 x 7.0 x 8.4inch).
KLH Model Three is clearly the larger of the two speakers. Its body is 133mm wider, 144mm taller and 52mm deeper than Klipsch R-51M.
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 KLH Model Three is approximately 830.4cm2 / 128.7inch2 and base area of the Klipsch R-51M is approximately 382.7cm2 / 59.3inch2. The Model Three requires 117% more surface area than the R-51M 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 KLH Model Three weighs 13.20kg / 29lbs and the Klipsch R-51M weighs 5.00kg / 11lbs. This makes the Model Three 164% heavier than the R-51M.
Here is a comparison of how Model Three and R-51M's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of KLH Model Three?
Here are the items that are included inside the box of Model Three:
- Floorstanding loudspeaker
- Riser base
- Grille
- Owners Manual
What's in the Box of Klipsch R-51M?
Here are the items that come with the R-51M:
- 2 Bookshelf loudspeakers
- 2 Grilles (installed)
- 8 Self-adhesive rubber feet
- Quick Setup Guide
- Important Safety Instructions
- Warranty Information
 Max Input Power |
150 watts
vs
85 watts
|
Handle more power from your amplifier |
 Woofer Size |
8 inches
vs
5.25 inches
|
Larger woofer |
|
Low Frequency Response |
46 Hz
vs
62 Hz
|
Generates deeper bass |
 Sensitivity |
93 dB
vs
88 dB
|
Play louder with same amount of amplification power |
 Nominal Impedance |
8 ohms
vs
6 ohms
|
Less selective with amplifiers |
 High Frequency Response |
21k Hz
vs
20k Hz
|
Generates higher frequency |
 Height |
338mm
vs
482mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
382cm2
vs
830cm2
|
Takes less floor space |
 Price per pair* |
359USD
vs
2000USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
KLH Model Three |
Klipsch Reference R-51M |
| Brand |
KLH |
Klipsch |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
30-150 watts |
Up to 85 watts |
| Sensitivity |
88 dB |
93 dB |
| Impedance |
6 ohms |
8 ohms |
| Impedance |
3.7 ohms |
n/a |
| Frequency Response |
46-20k Hz |
62-21k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
8" |
5.25" |
| Woofer Composition |
Pulp-Paper Cone |
Copper-spun IMG |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
n/a |
Tractrix Horn |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1600Hz |
1660Hz |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
482.0mm (19") |
338.0mm (13.3") |
| Width |
311.0mm (12.2") |
178.0mm (7") |
| Depth |
267.0mm (10.5") |
215.0mm (8.5") |
| Weight |
13.20kg (29lbs) |
5.00kg (11lbs) |
| Enclosure |
Acoustic Suspension |
Bass Reflex |
| Finish |
MDF/Wood Veneer |
MDF/Wood-grain vinyl |
| Available Colors |
English Walnut, West African Mahogany |
Black |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
n/a |
24-28" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
No |
Other |
|
|
| Parts Warranty |
10 Years |
5 Years |
| Labor Warranty |
10 Years |
5 Years |
These sit in different price classes - KLH Model Three costs roughly 5.6x what Klipsch R-51M 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 | KLH Model Three digs deeper - 46Hz against 62Hz. |
| Amplifier needs | B | Klipsch R-51M is more sensitive (93dB vs 88dB), so it goes louder on the same amplifier. |
| Amplifier match | B | Klipsch R-51M is the easier load at 8 ohms. |
| Headroom | A | KLH Model Three takes more power (150W vs 85W) - more in hand in a big room. |
| Size | depends | Klipsch R-51M is easier to place; KLH Model Three 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. |
| Price | B | Klipsch R-51M is cheaper - $359 against $2,000, about 82% less; arguably a different class. |
A KLH Model Three B Klipsch R-51M
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?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 62Hz anyway, which makes the cheaper Klipsch R-51M much easier to justify. Match it to your room: we rate KLH Model Three the better fit for a mid-size room and a large room, and Klipsch R-51M for near-field listening and a small 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.