Response is excellent other than the dip around 1.6 kHz. I really like to see manufacturers do better in this region as it is so important to perception of fidelity in my opinion. Fortunately the dip is narrow. Here is the near-field measurements:

JBL 306P MKII Powered Two Way Active Studio Reference Monitor JBL 306P MKII Powered Two Way Active Studio Reference Monitor

This is most troubling when listening to bass guitars that have notes that span the 100-300Hz region where the data also correlates to showing a downward slope in response >200Hz. Really hard for me to ignore these issues as I hear them. If you tend to listen to music with synth or isolated guitar notes then you’ll likely notice this right away; especially in the nearfield as it is less likely to get swamped out by the room effects.

Customer Added Media

The JBL 306P MK II once again shows what happens when you follow the science of proper sound reproduction even with strict budget. You simply get great sound. Even in hostile situation of just being thrown on my desk. Point them at your ear, plug them in and you are in business. OK, you should apply that little EQ correction but that is it.

JBL 306P MkII - Sound On Sound

The 305 and 306 somewhat ended my hi-fi buying hobby. I'll be the first to admit the woofer and tweeter are nothing special. Cheap, even. But as Amir alluded to, thanks to their excellent controlled dispersion they have a wonderful ability to sound "right" in the less-than-ideal listening rooms many (most?) of us are working with. In practical usage, this trumps a number of other flaws one might see on the graphs. I have heard objectively better speakers, and more subjectively enjoyable ones, but they have more quirks and cost multiples of the JBLs. Based on my results above, it is obvious the output is limited significantly somewhere above the 96dB @ 1m output level. I haven’t confirmed with JBL if this is a built-in limiter, though, I assume it is.The MkI versions of JBL’s 3 series monitors were highly regarded for offering excellent sound quality at affordable prices. Now upgraded to feature refined drivers and a new Boundary EQ adjustment setting, the MkII versions improve upon the original design. As we'd expect, it's a whole other story when you high pass them so they're not trying to play deep bass. The JBL 306P MkII are an exceptional pair of studio monitors, absolutely worth buying for content creators who want a more serious window into their audio at an affordable price. Is there a better alternative? Soundstage width is also quite nice and extends past the sides of the speakers which I believe may come from the wide horizontal radiation pattern of ±70° out to ~13kHz.

JBL 305P MkII Review (Erin) | Audio Science Review (ASR) Forum JBL 305P MkII Review (Erin) | Audio Science Review (ASR) Forum

Integrated custom Class D amplifiers deliver 112 watts (LF: 56 watts; HF: 56 watts) of power for high output and dynamic range Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel. I understand these are really the “darlings” of the budget monitor scene. For the price, you do get a lot of good performance. However, I think it is important to highlight these concerns as they will ultimately affect a person’s final mix. For example, they may try to EQ out the midbass resonances I noted or the 1-2kHz issues or the HF shelf. If these attempts toward correcting the sound were made then the end user - who may have a much better system without these issues - would get bass that doesn’t sound right, or a 1-2kHz region that doesn’t right. I am providing this information so those who are shopping and/or use this speaker are aware of some of the things that were readily apparent to me with a variety of music genres. Bass response is excellent, delivering deep yet smooth low frequencies without sounding overblown or slow. Upper bass and low mids are firm and punchy with no hint of tubbiness, integrating seamlessly with the broader treble region. In our fairly large control room, best results were achieved with the Boundary EQ Control set flat. I experimented with this control and could clearly hear how it would reduce excessive bass when used in less-than-ideal situations, if they have to be placed close to a rear wall, for example.The speakers were placed on stands in a typical near-field listening setup — an equilateral triangle about four feet apart and four feet each from the listening position — with the tweeters positioned at ear level. Because of their placement and the room treatment, we didn’t need to employ EQ or high frequency trim adjustments. We set the volume to the halfway position on each speaker for the majority of listening, though we did raise it and lower it evenly on either side at various points during testing. Performance This particular model includes a magnetically shielded, 6.5-inch mid/low-frequency transducer with a 1.5-inch voice coil, and a self-repairing dust dome that smooths out any accidental dents all by itself. (I gave it a gentle prod to test that claim and all seems well!) By reducing thermal-related effects such as power compression, the monitors are able to perform consistently over the full range of listening levels. A continuous rated SPL of 98dB is quoted along with peak SPL handling of 110dB at one metre (pink noise, C–weighted). John Mayer’s “Free Fallin” - When he says, “she’s a good girl”, the word “good” tends to jump out of the mix at you in the 1-2kHz region. I used my RTA app to watch for where this peak occurs (in the nearfield, of course). The RTA shows the peakiness between 1.6kHz to 1.8kHz which is exactly where there is a +3dB jump in the on-axis response (apparently caused from port resonance). Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

JBL 306P MKII Powered Two Way Active Studio Reference Monitor

We see more of distortion between 1 and 2 kHz in the larger 308P than in 306P. The larger woofer seems unhappier in the higher range than the smaller one in 306P. Or there are sample variations. The below graphics indicate how much SPL is lost or gained in the long-term as a speaker plays at the same output level for 2 minutes, in intervals. Each graphic represents a different SPL: 86dB and 96dB both at 1 meter. As stated in the Foreword, this written review is purposely a cliff’s notes version. For more details about the performance (objectively and subjectively) please watch the YouTube video.In the nearfield (~1 foot to mitigate room), the first note sounds very thin and not at all in line with the other notes. Audacity indicates all 4 notes should be at roughly the same audible level. This note - at ~ 225Hz - is right where a dip in the response indicates a possible resonance (cabinet; driver?). At close range, they project a massive center image, anchoring the gorgeous bass of The Chain at the center of the expansive stereo-panned guitars and vocals. Riley Young/Digital Trends