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JBL 306P MK II Review (Studio Monitor)

amirm

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This is a review and detailed measurements of the JBL Professional 306P MKII powered speaker. It is on kind loan from a member and costs US $149 including Prime shipping from Amazon (each).

Naturally the 306p has identical look and feel of the rest of the LSR series:

JBL 306P MK II Review.jpg


Same as the back panel:

JBL 306P MK II Revie Back Panel XLR.jpg


You can see the switches and gain control as tested.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

I performed over 800 measurement which resulted in error rate of less than 1% throughout the range.

Temperature was 59 degrees F. Measurement location is at sea level so you compute the pressure.

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.

Reference axis was the tweeter center.

JBL 306P MKII Measurements
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 MK II Measurements CEA-2034 spinorama frequency response.png


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 MK II Measurements Driver Response.png


Early window reflections are very similar to the on-axis courtesy of good directivity:
JBL 306P MK II Measurements CEA-2034 spinorama Early Window Reflections frequency response.png


Simulated far-field in-room response therefore is what we already know:
JBL 306P MK II Measurements CEA-2034 spinorama Predicted In-room frequency response.png


There is a blip around 700 Hz visible in the above graphs and we can see it as resonance in waterfall display:
JBL 306P MK II Measurements CSD Waterfall.png


It is very low in amplitude though so not a sonic issue.

Distortion has been classically high in this series and the 306P carries the family signature:

JBL 306P MK II Measurements Relative distortion versus frequency.png


Here is the JBL 308P MKII in comparison:

index.php


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.

Back to 306P, here is our absolute distortion measurement at 96 dBSPL:

JBL 306P MK II Measurements distortion versus frequency.png


Directivity as mentioned is very good:

JBL 306P MK II Measurements horizontal beamwidth.png


JBL 306P MK II Measurements horizontal directivity.png


JBL 306P MK II Measurements Vertical directivity.png


JBL 306P Mark II Speaker Listening Tests
It took playback of a couple of tracks to know that the sound of this speaker is "right" and fits with the family. My reference tracks sounded very nice. To see the effect of that dip though, I dialed in a quick EQ:

JBL 306P MK II Measurements Equalization.png


The correction was definitely needed. On female tracks it brought out their voices and detail therein resulting in more enjoyable experience. Once there, track after track in my reference list sounded beautiful.

I threw my "speaker killer" tracks the the 306P. It did not bother it although it did not try to play the deeper notes -- not much anyway. I cranked the volume way high and I could tell it was being limited as after certain point, it didn't get much louder. And became a bit unpleasant. But highly composed compared to passive speakers or powered ones with no limiter.

The usual hiss was there by the way and did not go away until about 2 feet when nothing was playing.

Conclusions
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.

Needless to say, I can recommend the JBL 306P MK II.

------------
As always, questions, comments, recommendations, etc. are welcome.

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Attachments

  • JBL 306P Mark II Spinorama.zip
    88.4 KB · Views: 206

sweetchaos

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Helicopter

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Thanks Amir. These look outstanding for the price. Maube I will get some monitors for my WAH setup someday, but a little guitar amp from Goodwill is still doing the job for now, but only when I am done with headphones.
 

JohnBooty

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These are my everyday speakers in my main setup. I'm no golden ears, but having listened to a lot of passive commercial and DIY speakers in this price range they are definitely my favorite, except for maybe the DIY Amiga towers (though that is a bit of an apples-to-oranges comparison)

I was really surprised when I measured mine and noticed that 1.6khz dip. Seems weird for their intended use as studio monitors.

But for recreational listening, as Amir noted, those kinds of narrow anomalies really aren't as much of a problem as you might think from looking at a graph. (I was relieved that his subjective impressions matched up with mine. I've seen people freak out over that 1.6khz dip when looking at graphs alone)

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.

The hiss does not bother me because I use these in a small den. Desktop use might be another story for some.

Actually with the distortion in 86db seems it should be quite prominent, did you notice that compared to other great speakers?

If you don't mind a subjective reply from somebody other than our leader....

Subjectively, yeah, they do not love to play that loud on their own. They play louder and deeper than the 305's, but they still run out of steam.

As we'd expect, it's a whole other story when you high pass them so they're not trying to play deep bass.

I've got mine crossed over to subs at around 55hz. In this configuration things go "plenty loud" for me. I'm generally not pushing avg SPL past 80dB or so (usually, much lower) and they do that with a respectable amount of headroom remaining. I'm sure one could eke even more headroom from them with a higher xover though obviously the tweeter output will be a limiting factor at some point.
 
Last edited:

Blumlein 88

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Thanks for the review. It does appear in order of performance the order is LSR305, then 306 and then 308 as the best.
 

dfuller

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Those distortion figures are crazy high. Really something. I suppose it's pretty obvious these speakers don't like being pushed hard much at all.
 

Muelli

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Thanks for the review.

It could have been my next speakers. Unfortunately, the self hiss bothers me a lot. I send the LSR 305 back because of it and I don't even think about ordering another JBL LSR or Kali speaker before they reduce it significantly.
 
Last edited:

JRAudio

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This is a review and detailed measurements of the JBL Professional 306P MKII powered speaker. It is on kind loan from a member and costs US $149 including Prime shipping from Amazon (each).

Naturally the 306p has identical look and feel of the rest of the LSR series:

View attachment 99900

Same as the back panel:

View attachment 99901

You can see the switches and gain control as tested.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

I performed over 800 measurement which resulted in error rate of less than 1% throughout the range.

Temperature was 59 degrees F. Measurement location is at sea level so you compute the pressure.

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.

Reference axis was the tweeter center.

JBL 306P MKII Measurements
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:

View attachment 99902

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:

View attachment 99903

Early window reflections are very similar to the on-axis courtesy of good directivity:
View attachment 99904

Simulated far-field in-room response therefore is what we already know:
View attachment 99905

There is a blip around 700 Hz visible in the above graphs and we can see it as resonance in waterfall display:
View attachment 99906

It is very low in amplitude though so not a sonic issue.

Distortion has been classically high in this series and the 306P carries the family signature:

View attachment 99907

Here is the JBL 308P MKII in comparison:

index.php


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.

Back to 306P, here is our absolute distortion measurement at 96 dBSPL:

View attachment 99908

Directivity as mentioned is very good:

View attachment 99909

View attachment 99910

View attachment 99911

JBL 306P Mark II Speaker Listening Tests
It took playback of a couple of tracks to know that the sound of this speaker is "right" and fits with the family. My reference tracks sounded very nice. To see the effect of that dip though, I dialed in a quick EQ:

View attachment 99914

The correction was definitely needed. On female tracks it brought out their voices and detail therein resulting in more enjoyable experience. Once there, track after track in my reference list sounded beautiful.

I threw my "speaker killer" tracks the the 306P. It did not bother it although it did not try to play the deeper notes -- not much anyway. I cranked the volume way high and I could tell it was being limited as after certain point, it didn't get much louder. And became a bit unpleasant. But highly composed compared to passive speakers or powered ones with no limiter.

The usual hiss was there by the way and did not go away until about 2 feet when nothing was playing.

Conclusions
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.

Needless to say, I can recommend the JBL 306P MK II.

------------
As always, questions, comments, recommendations, etc. are welcome.

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Above 30 kHz measurement? Hi Amir. I appreciate all your work and measurements. Have you dropped your new introduced above 30 kHz measurement? Would be great to see it. Thanks.
 

Maiky76

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Hi,

Here is my take on the EQ.

The raw data with corrected ER and PIR:
Score no EQ: 5.17
With Sub: 6.98

Spinorama with no EQ:
  • Not bad except for the 1500Hz trough
JBL 306p mkII No EQ Spinorama.png

Directivity:
I am wondering if the axis was set too high?
At -10deg Vertically the response looks smoother.
Excellent Horizontal directivity
JBL 306p mkII LW better data.png

JBL 306p mkII Normalized Directivity data.png

JBL 306p mkII 2D surface Directivity Contour Only Data.png


EQ design:

I have one EQs. The APO config files are attached.
  • I usually do a LW and a Score EQ but in this particular case they are practically the same
  • One would need to carefully listen to the results as the peak at 1500Hz may be an issue.

Score EQ: 6.52
with sub: 8.33

Code:
JBL 306p mkII APO EQ 96000Hz
December182020-140246

Preamp: -3.8 dB

Filter 1: ON PK Fc 135 Hz Gain -1 dB Q 2.5
Filter 2: ON PK Fc 916 Hz Gain -1.42 dB Q 3.33
Filter 3: ON PK Fc 1545 Hz Gain 3.84 dB Q 6.45
Filter 4: ON PK Fc 2415 Hz Gain 2 dB Q 3.28
Filter 5: ON PK Fc 2459 Hz Gain -1 dB Q 8.95
Filter 6: ON PK Fc 4693 Hz Gain -0.83 dB Q 2.63
Filter 7: ON PK Fc 8119 Hz Gain -0.81 dB Q 4.74
JBL 306p mkII EQ Design.png

Spinorama EQ
JBL 306p mkII EQ Spinorama.png

Zoom PIR-LW-ON
JBL 306p mkII Zoom PIR-LW-ON.png


Regression - Tonal
JBL 306p mkII Regression - Tonal.png


Radar no EQ vs EQ score
Nice improvements
JBL 306p mkII Radar.png


The rest of the plots is attached.

EDIT
iI I roughly offset the axis by 10deg and recalculate the ER/PIR/LW:
Score no EQ: 5.17 -> 5.45
With Sub: 6.98 -> 7.26
It not 100% correct though as the Horizontal data would not be the same...
I am pretty sure the score would be higher still as the trough would likely be shallower on all ER/PIR/LW curves.

JBL 306p mkII No EQ  Offset Spinorama.png


BTW on distortion:
http://gedlee.azurewebsites.net/Papers/The Perception of Distortion.pdf
 

Attachments

  • JBL 306p mkII APO EQ 96000Hz.txt
    391 bytes · Views: 70
  • JBL 306p mkII Vertical 3D Directivity data.png
    JBL 306p mkII Vertical 3D Directivity data.png
    585.4 KB · Views: 47
  • JBL 306p mkII Horizontal 3D Directivity data.png
    JBL 306p mkII Horizontal 3D Directivity data.png
    571.7 KB · Views: 64
  • JBL 306p mkII Raw Directivity data.png
    JBL 306p mkII Raw Directivity data.png
    824 KB · Views: 47
  • JBL 306p mkII Reflexion data.png
    JBL 306p mkII Reflexion data.png
    244.1 KB · Views: 46
  • JBL 306p mkII LW data.png
    JBL 306p mkII LW data.png
    247.4 KB · Views: 48
  • JBL 306p mkII 2D surface Directivity Contour Data.png
    JBL 306p mkII 2D surface Directivity Contour Data.png
    259.2 KB · Views: 44
  • JBL 306p mkII 3D surface Vertical Directivity Data.png
    JBL 306p mkII 3D surface Vertical Directivity Data.png
    483 KB · Views: 54
  • JBL 306p mkII 3D surface Horizontal Directivity Data.png
    JBL 306p mkII 3D surface Horizontal Directivity Data.png
    494.6 KB · Views: 44
Last edited:

YSC

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These are my everyday speakers in my main setup. I'm no golden ears, but having listened to a lot of passive commercial and DIY speakers in this price range they are definitely my favorite, except for maybe the DIY Amiga towers (though that is a bit of an apples-to-oranges comparison)

I was really surprised when I measured mine and noticed that 1.6khz dip. Seems weird for their intended use as studio monitors.

But for recreational listening, as Amir noted, those kinds of narrow anomalies really aren't as much of a problem as you might think from looking at a graph. (I was relieved that his subjective impressions matched up with mine. I've seen people freak out over that 1.6khz dip when looking at graphs alone)

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.



If you don't mind a subjective reply from somebody other than our leader....

Subjectively, yeah, they do not love to play that loud on their own. They play louder and deeper than the 305's, but they still run out of steam.

As we'd expect, it's a whole other story when you high pass them so they're not trying to play deep bass.

I've got mine crossed over to subs at around 55hz. In this configuration things go "plenty loud" for me. I'm generally not pushing avg SPL past 80dB or so (usually, much lower) and they do that with a respectable amount of headroom remaining. I'm sure one could eke even more headroom from them with a higher xover though obviously the tweeter output will be a limiting factor at some point.
nice feedback, did you get the annoying 200hz distortion spike? this looks more of the problem than the low bass where a subwoofer can fix, and that the 200hz 5% distortion looks annoying to me personally
 

Cahudson42

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Hmmm. I look at the measurements and see a distortion factory. Yet they 'sound great' and are recommended. If both observations are correct, what else can I conclude but 'distortion doesn't matter'..

A corollary conclusion is, obviously, ' distortion sounds great'...

Confused..:)
 
Last edited:

JohnBooty

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nice feedback, did you get the annoying 200hz distortion spike? this looks more of the problem than the low bass where a subwoofer can fix, and that the 200hz 5% distortion looks annoying to me personally
I don't notice it. To put it into subjective but perhaps useful terms, the JBLs + subs can play cleanly (to my ears) loudly enough to the point where I don't realize they're loud... until my wife and I realize we have to shout to be heard over the music. This is in a somewhat small room though, like 200 square feet.

I would mention three things about that 200hz distortion "spike" --

1. It's rather narrow. If you're distorting at 5% across the entire frequency range that's one thing, this is another - perceptibility of narrowband stuff like that tends to be much lower than we'd think when we see those sharp peaks on a graph.
2. Keep in mind that Amir measured this distortion at 86dB which is fairly loud - into danger territory, even. Hopefully nobody is listening at an average near 86dB. Though we would indeed like to have plenty of headroom to push higher than 86dB for those brief dynamic peaks.
3. 200hz is right in the middle of the female vocal range so it is not like the deep bass region where we want enough power to shake the foundations of the house.

I would not use the phrase "high-output monsters" nor "oodles of effortless headroom" for these speakers, but crossed over to a sub or two I don't think too many folks would find them lacking for horsepower in a small or medium room.

If you are shooting for massive SPL or have a focus on classical music with a truly ginormous dynamic range then these JBLs would not be the weapons of choice.
 
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