JBL3 SeriesMkIII

Woofer size, bass and level. The 305P has a 5-inch woofer, reaches 45 Hz at −10 dB and 109 dB peak; the 306P has a 6.5-inch woofer, 43 Hz and 112 dB; the 308P an 8-inch woofer, 41 Hz and 113 dB. All three share the 1-inch soft dome tweeter, the 120° × 90° Image Control Waveguide, the front-firing port and the four room controls. They stand 320, 370 and 444 mm tall.

From JBL’s owner’s manual: new woofers and tweeters, the Slipstream port moved from the back to the front, four DSP room controls with 81 combinations instead of the Boundary EQ and HF trim switches, one Neutrik combo input instead of separate XLR and jack, eight M4 mounting points in a 75 × 75 mm pattern, and a front LED and auto-standby you can switch off. The treble now reaches 27 kHz within ±3 dB instead of 20 kHz. The coverage stays 120° × 90°.

Yes, that is what the front port and two of the four controls are for. Set MONITOR SETUP to DESKTOP and WALL DISTANCE to the gap behind the speaker: more than 0.5 m, 0.1 to 0.5 m, or under 0.1 m. For the best bass, JBL still recommends stands, and on a desk the four rubber pads in the box.

Four buttons on the back with three positions each: MONITOR SETUP (desktop, stand or bracket), WALL DISTANCE (three distances), LF ADJUST (±2 dB below 300 Hz) and HF ADJUST (±2 dB above 3 kHz). 3 × 3 × 3 × 3 = 81. The monitors remember them after you switch off. JBL’s advice: set the first two to match where the speakers stand and start with LF and HF at NEUTRAL.

For voice, podcasts and most acoustic music, no. The 308P reaches 41 Hz at −10 dB, about the low E of a bass guitar; the 310S goes down to 26 Hz and 116 dB peak. For hip-hop, EDM and film, where much of the energy sits below 40 Hz, the sub lets you hear what you are mixing. JBL recommends its 80 Hz crossover with all three monitors.

Our rule of thumb in the size picker above: the 305P for a desk up to about 1 m from you, the 306P up to about 1.6 m, the 308P beyond that. In a small untreated room a bigger woofer mostly excites more boom, so bigger is not automatically better.

Yes, with a cable ending in a 6.35 mm (¼-inch) jack and the INPUT SENSITIVITY switch on −10 dBV. Each monitor has one Neutrik combo input for XLR or jack, so one source per speaker. There is no Bluetooth and no RCA input.

Yes. Each monitor has eight M4 threaded points, four on top and four underneath, in a 75 × 75 mm VESA pattern, so standard brackets fit. Set MONITOR SETUP to BRACKET. JBL asks for a qualified installer and a safety tether for anything overhead.

Thomann has all four in stock today. JBL’s own pages list US and Canada availability from January 7, 2027.

The 305P MkII costs $156 against $219 for the MkIII, the 306P MkII $167 against $275, the 308P MkII $201 against $324. On paper the MkII reaches 2 to 6 Hz lower. The MkIII moves the port to the front and gives you 81 room settings instead of 9, mounting points and treble to 27 kHz. On stands well away from the wall, the MkII still makes sense for the money; on a desk against a wall, the front port and the WALL DISTANCE control are the reason to pay more.

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