JBL 308 MKIII

An 8-inch reference from the JBL 3 MkII series

The JBL 308P MkII is part of the 3 MkII series, a range of nearfield monitors designed to provide reliable mixing tools for home studios, production control rooms and modern creative spaces. This MkII version incorporates the acoustic principles developed for the brand’s high-end professional monitors, including the Image Control waveguide derived from the JBL 7 and M2 series.

Compared with previous generations, this evolution refines the transducers’ response, improves linearity and introduces the Boundary EQ control. This helps compensate for excess bass caused by placing the monitor too close to a wall, corner or work surface. It is a practical improvement for maintaining consistent mixing decisions in an untreated or small studio.

A nearfield monitor for mixing, producing and critical listening

With its 203 mm woofer, the JBL 308P MkII is particularly well suited to producers looking for extended low-frequency response without systematically relying on a subwoofer. Kick drums, electric bass, sub-bass, synthesizers and cinematic effects become more clearly defined while remaining integrated into the overall balance of the mix.

It will naturally fit into a serious home studio, a post-production control room, a composition setup or a DJing space requiring analytical monitoring. Its 112 dB SPL peak level also makes it possible to work at a comfortable volume in a medium-sized room, provided it is positioned in an equilateral triangle with the listening position.

Sold individually, this active loudspeaker is intended to be paired with a second 308P MkII to create a stereo system. It can also be integrated into an immersive or multichannel setup thanks to its consistent reproduction and controlled directivity.

Wide, adjustable and precise monitoring

Image Control waveguide: a more generous sweet spot

The Image Control waveguide optimizes the dispersion of the 25 mm soft-dome tweeter. The soundstage remains precise, with clearer placement of vocals, reverbs and panned instruments. Its 120-degree horizontal and 90-degree vertical cover widens the useful listening area, which is a valuable advantage during long sessions, mix comparisons or two-person work in front of the console.

Dedicated Class D bi-amplification for each frequency range

The 308P MkII features two 56 W Class D amplifiers, delivering 112 W in total. The woofer and tweeter therefore each have their own dedicated amplification, providing better control of transients and more responsive reproduction. The fourth-order 1,800 Hz Linkwitz-Riley acoustic crossover ensures a coherent transition between the two loudspeakers.

The frequency response extends down to 45 Hz within the +/- 3 dB range, with an advertised extension down to 37 Hz at -10 dB. This low-end foundation makes it easier to control bass energy and identify resonances that could compromise the mix’s translation on other monitoring systems.

Practical studio adjustment options

The Boundary EQ selector operates on the low frequencies around 50 Hz and offers three positions: 0 dB, -1.5 dB and -3 dB. It helps limit bass build-up when the monitor is placed close to a wall. The HF Trim control, available at -2 dB, 0 dB and +2 dB, adjusts the high-frequency brightness according to the room’s acoustics or listening preferences.

The balanced connectivity combines an XLR input and a 6.35 mm TRS jack input. The +4 dBu or -10 dBV sensitivity selector makes it easy to integrate the JBL 308P MkII with professional studio equipment as well as more consumer-oriented audio gear. A rear-panel volume control completes the setup, allowing precise gain adjustment for each loudspeaker.

Technical specifications

Bluetooth	No	EQ	No
Connection	XLR, Jack	Color	Black
Speaker diameter	8"	Quantity	1
Number of speakers	2

Type	active 2-way studio monitor, sold individually	Signal-to-noise ratio	75 dBA A-weighted, 70 dBr unweighted
Configuration	bi-amplified	Electrical distortion	0.2 percent THD at 1 kHz and 2.83 VRMS; less than 1 percent THD at full rated power
Woofer	203 mm, 8 inches	Balanced analog inputs	1 female XLR and 1 female 6.35 mm TRS jack
Tweeter	25 mm, 1 inch, soft dome	Input sensitivity at -10 dBV	92 dB at 1 m
Waveguide	JBL Image Control	Maximum input level	+6 dBV or +20.3 dBu
Bass-reflex port	Slip Stream	Sensitivity selector	+4 dBu or -10 dBV
Crossover frequency	1,800 Hz, fourth-order Linkwitz-Riley acoustic filter	HF Trim	-2 dB, 0 dB, +2 dB
Cover angle	120 degrees horizontal x 90 degrees vertical	Boundary EQ	0 dB, -1.5 dB or -3 dB at 50 Hz
Woofer amplification	56 W Class D	Volume control	adjustable on the rear panel
Tweeter amplification	56 W Class D	Enclosure type	bass-reflex
Total power	112 W	Enclosure construction	15 mm MDF
Frequency response at +/- 3 dB	45 Hz to 20 kHz	Front panel	injection-molded structural ABS
Frequency range at -10 dB	37 Hz to 24 kHz	Finishing	matte Black PVC
Low-frequency extension at -10 dB	37 Hz	Power supply	100 to 240 V AC, 50/60 Hz
Maximum continuous SPL level	102 dB	Dimensions	419 x 254 x 308 mm
Maximum peak SPL level	112 dB	Weight	8.1 kg