In this review, we will be comparing ESL 9 and Forte IV, two Passive Floor-standing speakers from MartinLogan and Klipsch.
Let's have a brief look at the main features
of MartinLogan ESL 9 and Klipsch Forte IV first before getting into our more
detailed comparison.
| Key Specs | MartinLogan ESL 9 | Klipsch Forte IV |
|---|
| Design | 2-way | 3-way |
|---|
| Tweeter | 9.2 x 44" curved electrostatic transducer | 1" horn-loaded |
|---|
| Midrange | — | 1.75" |
|---|
| Woofer | 2 x 8" high-excursion paper cone | 12" Fibercomposite |
|---|
| Frequency response | 34-23k Hz | 38-20k Hz |
|---|
| Sensitivity | 90 dB | 99 dB |
|---|
| Impedance | 4 ohms | 8 ohms |
|---|
| Power range | 20-400 watts | up to 100 watts |
|---|
| Weight | 35.45kg / 78lbs | 32.73kg / 72lbs |
|---|
| Dimensions (H x W x D) | 59-13/16" x 10-7/16" x 25-7/16"
1520.0 x 266.0 x 647.0mm | 35-3/4" x 16-5/8" x 13"
909.0 x 423.0 x 331.0mm |
|---|
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
One of the fundamental differences between these two speakers is that ESL 9 is a 2-way design whereas the Forte IV is a 3-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.
MartinLogan ESL 9Klipsch Forte IV
TweeterMidrangeWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
MartinLogan ESL 9 |
Klipsch Forte IV |
|
Driver Setup
|
2-way
|
3-way
|
|
Tweeter
|
9.2 x 44-inch
|
1-inch
|
|
Midrange
|
- |
1 x 1.75-inch |
|
Woofer
|
2 x 8-inch
|
1 x 12-inch
|
ESL 9 features a 9.2 x 44" curved electrostatic transducer Tweeter and 2 x 8" high-excursion paper cone Woofer. On the other hand, the Forte IV features a 1" titanium-diaphragm compression horn-loaded Tweeter, a 1.75" Midrange and 1 x 12" Fibercomposite Woofer.
Frequency Response
ESL 9 has a frequency range of 34-23k Hz whereas Forte IV has a frequency range of 38-20k Hz. With a minimum frequency of 34Hz, the ESL 9 can go slightly deeper then the Forte IV's min frequency of 38Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Floor-standing class in our database.
Low Frequency
Floor-standing 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
ESL 9 is a 4 ohms speaker compared to the Forte IV 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 ESL 9 can provide this impedance level.
These two speakers also have different sensitivity levels. ESL 9 sensitivity is rated at 90 dB and the Forte IV's is rated at 99 dB. This 9 dB difference makes the Klipsch Forte IV a more sensitive speaker compared to MartinLogan ESL 9, hence will play louder with the same amount of watts.
Sensitivity
Floor-standing 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.
ESL 9 can handle a max power of 400 watts RMS, whereas Forte IV has a max power handling value of 100 watts RMS, 300 watts less than the ESL 9.
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
Both ESL 9 and Forte IV features dual binding post speaker terminals for bi-amping or bi-wiring.
MartinLogan ESL 9's Binding post terminals allows Bi-amping or 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 ESL 9's and Klipsch Forte IV's external dimensions. MartinLogan ESL 9 has external dimensions of 1520.0 x 266.0 x 647.0mm (59-13/16 x 10-7/16 x 25-7/16inch) whereas Klipsch Forte IV has external dimensions of 909.0 x 423.0 x 331.0mm (35-3/4 x 16-5/8 x 13inch).
Klipsch Forte IV is 611mm shorter and 316mm less deeper than MartinLogan ESL 9 but it is also 157mm wider.
Below you can see the front view size comparison of MartinLogan ESL 9 and Klipsch Forte IV in scale.
Comparison image of MartinLogan ESL 9 and Klipsch Forte IV 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 ESL 9 is approximately 1721.0cm2 / 266.8inch2 and base area of the Klipsch Forte IV is approximately 1400.1cm2 / 217.0inch2. The ESL 9 requires 23% more surface area than the Forte IV 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 MartinLogan ESL 9 weighs 35.45kg / 78lbs and the Klipsch Forte IV weighs 32.73kg / 72lbs. This makes the ESL 9 8% heavier than the Forte IV.
Here is a comparison of how ESL 9 and Forte IV's weights compare with the average, max and min weights in Passive Floor-standing class.
Weight
All Floor-standing Speakers
What's in the Box of MartinLogan ESL 9?
Here are the items that are included inside the box of ESL 9:
- Floorstanding hybrid electrostatic loudspeaker
- AC power adapter (w/ attached 10-feet DC cord)
- Grille
- 4 Spike Feet
- Users Manual
- Product Registration Card
What's in the Box of Klipsch Forte IV?
Here are the items that come with the Forte IV:
- 2 Floorstanding loudspeakers
- 2 Grilles
- 8 Self-adhesive rubber feet
- Owners Manual
- Congratulations letter
- Klipsch brochure
 Max Input Power |
400 watts
vs
100 watts
|
Handle more power from your amplifier |
 Number of Woofers |
2
vs
1
|
More woofers |
|
Low Frequency Response |
34 Hz
vs
38 Hz
|
Generates deeper bass |
 High Frequency Response |
23k Hz
vs
20k Hz
|
Generates higher frequency |
 Driver Setup |
3-way
vs
2-way
|
Have a dedicated mid-range driver |
 Sensitivity |
99 dB
vs
90 dB
|
Play louder with same amount of amplification power |
 Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
|
Woofer Size |
12 inches
vs
8 inches
|
Larger woofer |
 Passive Radiator |
rear-firing 15-inch
vs
None
|
Increases the bass performance |
 Height |
909mm
vs
1520mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1400cm2
vs
1721cm2
|
Takes less floor space |
 Price per pair* |
4998USD
vs
7000USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
MartinLogan Masterpiece Classic ESL 9 |
Klipsch Heritage Forte IV |
| Brand |
MartinLogan |
Klipsch |
| Speaker Type |
Floor-standing speaker |
Floor-standing speaker |
| Power Range |
20-400 watts |
up to 100 watts |
| Sensitivity |
90 dB |
99 dB |
| Impedance |
4 ohms |
8 ohms |
| Frequency Response |
34-23k Hz |
38-20k Hz |
Drivers |
|
|
| Woofer Quantity |
2 |
1 |
| Woofer Size |
8" |
12" |
| Woofer Composition |
high-excursion paper cone |
Fibercomposite |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
9.2 x 44" |
1" |
| Tweeter Type |
curved electrostatic transducer |
horn-loaded |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
1.75" |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
1520.0mm (59.8") |
909.0mm (35.8") |
| Width |
266.0mm (10.5") |
423.0mm (16.7") |
| Depth |
647.0mm (25.5") |
331.0mm (13") |
| Weight |
35.45kg (78lbs) |
32.73kg (72lbs) |
| Enclosure |
Bass Reflex |
Passive Radiator |
| Finish |
Composite |
MDF/Wood veneer |
| Available Colors |
Gloss Black |
Black |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
Yes |
Yes |
Other |
|
|
| Parts Warranty |
5 Years w/ Registration |
10 Years |
| Labor Warranty |
5 Years w/ Registration |
10 Years |
A generation apart: Klipsch Forte IV is the newer design, against a 2017 model. Newer is not automatically better, but the older one is more likely to be discounted or near run-out.
| Area | Better | Why |
|---|
| Bass |
A |
MartinLogan ESL 9 digs deeper - 34Hz against 38Hz. A subwoofer would even that out. |
| Amplifier needs |
B |
Klipsch Forte IV is more sensitive (99dB vs 90dB), so it goes louder on the same amplifier. |
| Amplifier match |
B |
Klipsch Forte IV is the easier load at 8 ohms; the other is 4 ohms and wants an amplifier rated for it. |
| Headroom |
A |
MartinLogan ESL 9 takes more power (400W vs 100W) - more in hand in a big room. |
| Size |
depends |
Klipsch Forte IV is easier to place; MartinLogan ESL 9 is bigger, which usually goes with fuller bass. Your room decides. |
| Cabinet |
depends |
Ported vs Passive Radiator. |
| Expandability |
depends |
MartinLogan ESL 9: bi-amping; Klipsch Forte IV: bi-amping. Klipsch Forte IV sits in a wider range (12 models), so a matched surround system is easier later. |
| Price |
B |
Klipsch Forte IV is cheaper - $4,998 against $7,000, about 29% less. |
A MartinLogan ESL 9
B Klipsch Forte IV
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?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. In a large or open-plan room, MartinLogan ESL 9 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Klipsch Forte IV is the easier speaker to get right. If your amplifier is modest, vintage or valve-based, Klipsch Forte IV is the safer partner - the other will want more current or more watts to sound its best.
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.