In this review, we will be comparing 4305P and LSX II, two Powered Bookshelf speakers from JBL and KEF. Being Powered speakers, they both have built-in amplifiers so you don't need an external power amp or an integrated amp to power them.
Let's have a brief look at the main features
of JBL 4305P and KEF LSX II first before getting into our more
detailed comparison.
| Key Specs | JBL 4305P | KEF LSX II |
|---|
| Brand | JBL
United States · founded 1946 | KEF
United Kingdom · founded 1961 |
|---|
| Design | 2-way | 2-way |
|---|
| Built-in amplifier | 300-watt RMS | 200-watt RMS |
|---|
| Uni-Q driver | — | 11th Generation Uni-Q |
|---|
| Tweeter | 1" Horn-Loaded | 0.75" Hard-Dome |
|---|
| Woofer | 5.25" Pulp | 4.5" Magnesium/Aluminium alloy |
|---|
| Frequency response | 45-25k Hz | 54-28k Hz |
|---|
| Max depth / sample rate | 24-bit / 192kHz | 24-bit / 384 kHz |
|---|
| Bluetooth | Built-in 5.1 | Built-in 4.2 |
|---|
| App control | Yes | Yes |
|---|
| Weight | 6.60kg / 14.5lbs | 3.60kg / 7.9lbs |
|---|
| Dimensions (H x W x D) | 13.3125" x 8.3125" x 8-3/4"
336 x 210 x 223 mm | 9.5" x 6.1" x 7.1"
240 × 155 × 180 mm |
|---|
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
Both 4305P and LSX II are 2-way speakers.
JBL 4305PKEF LSX II
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
JBL 4305P |
KEF LSX II |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
0.75-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 4.5-inch
|
4305P features a 1" Teonex Horn-Loaded Tweeter and 1 x 5.25" Pulp Woofer with a Crossover frequency at 1750 Hz. On the other hand, the LSX II features a 0.75" Aluminum Hard-Dome Tweeter and 1 x 4.5" Magnesium/Aluminium alloy Woofer.
Frequency Response
4305P has a frequency range of 45-25k Hz whereas LSX II has a frequency range of 54-28k Hz. With a minimum frequency of 45Hz, the 4305P can go significantly deeper on the low side and provide stronger bass compared to the LSX II's min frequency of 54Hz.
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.
Cabinet Type and Port Position
4305P has a front firing port whereas LSX II has a rear firing ports. JBL 4305P's front-firing port gives more flexibility in placement in regards to proximity to walls compared to KEF LSX II with its rear-firing port.
KEF LSX II Port
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 JBL 4305P's and KEF LSX II's external dimensions. JBL 4305P has external dimensions of 336 x 210 x 223 mm (13.3125 x 8.3125 x 8-3/4 inch) whereas KEF LSX II has external dimensions of 240 × 155 × 180 mm (9.5 × 6.1 × 7.1 inch).
JBL 4305P is clearly the larger of the two speakers. Its body is 55mm wider, 96mm taller and 43mm deeper than KEF LSX II.
Below you can see the front view size comparison of JBL 4305P and KEF LSX II in scale.
Comparison image of JBL 4305P and KEF LSX II 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 JBL 4305P is approximately 468.3cm2 / 72.6inch2 and base area of the KEF LSX II is approximately 279.0cm2 / 43.2inch2. The 4305P requires 68% more surface area than the LSX II which gives it a small disadvantage on placement in tight spaces.
Here is another comparison that shows both speakers on a BDI Octave Media Cabinet, next to a standard size amplifier and turntable in scale:
Size Comparison image of JBL 4305P and KEF LSX II on a Media Console
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 JBL 4305P weighs 6.60kg / 14.5lbs and the KEF LSX II weighs 3.60kg / 7.9lbs. This makes the 4305P 83% heavier than the LSX II.
Here is a comparison of how 4305P and LSX II's weights compare with the average, max and min weights in Powered Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of JBL 4305P?
Here are the items that are included inside the box of 4305P:
- 2 Powered speakers
- 2 Grilles
- Two 69-inch AC power cords
- 10-feet CAT5e cable
- Remote control
- 2 AAA batteries
- 8 Self-adhesive feet
- Owner-feets Manual
- Important Safety Instructions
What's in the Box of KEF LSX II?
Here are the items that come with the LSX II:
- 2 Wireless powered speakers
- Two 6.5-feet AC power cords
- 10-feet Cat-6 interconnect speaker cable
- Remote control
- 2 AAA batteries
- Quick Start Guide
- Important Safety Information
- Warranty Information
- Maintenance Guide
 Woofer Size |
5.25 inches
vs
4.5 inches
|
Larger woofer |
|
Low Frequency Response |
45 Hz
vs
54 Hz
|
Generates deeper bass |
 Port Position |
Front
vs
Rear
|
Gives more flexibility placing close to walls |
 High Frequency Response |
28k Hz
vs
25k Hz
|
Generates higher frequency |
 Height |
240mm
vs
336mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
279cm2
vs
468cm2
|
Takes less floor space |
 Price per pair* |
1299USD
vs
2200USD
|
costs less (*prices may change depending on the seller, location and time) |
 HDMI Input |
ARC
vs
No
|
Connect HDMI sources directly |
| General |
JBL 4305P |
KEF LSX II |
| Brand |
JBL |
KEF |
| Speaker Type |
Powered Stereo Speakers |
Powered Stereo Speakers |
| Frequency Response |
45-25k Hz |
54-28k Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
300-watt RMS |
200-watt RMS |
| Max Bit Depth |
24-bit |
24-bit |
| Max Sample Rate |
192kHz |
384 kHz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
4.5" |
| Woofer Composition |
Pulp |
Magnesium/Aluminium alloy |
| Woofer Surround Material |
n/a |
Rubber |
| Tweeter Size |
1" |
0.75" |
| Tweeter Type |
Horn-Loaded |
Hard-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1750 Hz |
n/a |
| Firing Direction |
front |
rear |
Physical Specs |
|
|
| Height |
336.0mm (13.2") |
240.0mm (9.4") |
| Width |
210.0mm (8.3") |
155.0mm (6.1") |
| Depth |
223.0mm (8.8") |
180.0mm (7.1") |
| Weight |
6.60kg (14.5lbs) |
3.60kg (7.9lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
3/4-inch MDF with real wood veneer |
n/a |
| Available Colors |
Satin Walnut, Black Walnut |
Carbon Black, Mineral White, Cobalt Blue, Lava Red, and Soundwave |
| Mounting Bracket |
No |
No |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Aux Inputs |
3.5mm |
3.5mm |
| USB Port |
USB-B |
USB-C (connects to your computer) |
| Phone Input |
No |
No |
| Subwoofer Output |
mono-RCA |
Wired |
| Digital Input |
Optical |
Optical |
| HDMI Input |
No |
ARC |
| Headphone Jack |
No |
No |
| Ethernet Port |
Yes |
Yes |
Other |
|
|
| Parts Warranty |
5yr drivers/2 yr amp |
1 Year |
| Labor Warranty |
5yr drivers/2 yr amp |
1 Year |
These sit in different price classes - JBL 4305P costs roughly 1.7x what KEF LSX II 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 | JBL 4305P digs deeper - 45Hz against 54Hz. A subwoofer would even that out. |
| Built-in power | A | JBL 4305P has the bigger amplifier (300W vs 200W RMS). |
| Connections | B | KEF LSX II adds HDMI. |
| Size | depends | KEF LSX II is easier to place; JBL 4305P is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | JBL 4305P: a sub output; KEF LSX II: a sub output. |
| Price | B | KEF LSX II is cheaper - $1,299 against $2,200, about 41% less; arguably a different class. |
A JBL 4305P B KEF LSX II
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?
JBL 4305P is ahead, but only on 1 of the measured areas, and it costs about 69% more. That is a lot of money for a narrow margin on paper - KEF LSX II looks like the sensible buy unless something else about the JBL 4305P appeals to you. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 54Hz anyway, which makes the cheaper KEF LSX II much easier to justify. In a large or open-plan room, JBL 4305P has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, KEF LSX II 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.