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JBL 708P Review (Professional Monitor)

amirm

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This is a review and detailed measurements of the JBL 708P studio monitor (active speaker). It is on kind loan from a member and costs US $1,799 each.

Unlike the lower-end in the series, the 708P exudes seriousness both in look, feel and controls:

JBL 708P review Studio Monitor Powered Speaker.jpg


I appreciated the handles on each side as this is a heavy bookshelf speaker. The white LED stands out a bit much. Hopefully there is a way to turn it off your can put some tape on it.

As expected in this price, you have both analog and digital inputs with a bevy of features:
JBL 708P review Studio Monitor Powered DSP Active Speaker.jpg


Signal processing is at 24-bit/192 kHz and there are provisions for multi-band room EQ and such. Alas, the same primitive LCD interface is provided that is slow to respond and quite grainy. It does the job though. For my measurements I set the input to +4 dBu. For listening tests, I only had unbalanced so selected -10 dBu for that.

I left all the controls off/as you see them both for measurements and listening tests.

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 1000 measurement which resulted in error rate of around 1%.

Temperature was 59 degrees F at sea level. I kept the speaker indoor at 70 degrees prior to starting the measurements.

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 708P 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 708P Measurements frequency response spinorama cea-2034.png


Other than a slight issue around 600 to 900 Hz, this is extremely good frequency response, not only on-axis and off-axis. The cause of the disturbance is easy to identify when we measure each radiating surface up close:

JBL 708P Measurements driver resonse near-field.png


If you follow the orange curve which is the port response, we see that instead of continuing to decline, it starts to rise up (resonate) and that winds up disturbing the otherwise good response of the woofer. The woofer itself also gets a bit wiggly above 2 kHz but levels are pretty low there so impact is small (you can see a few notches in the spin graph before).

Early window reflections are good sans a dip which is caused by vertical bounce:
JBL 708P Measurements early window frequency response spinorama cea-2034.png


Putting the two together, our far-field response is such:

JBL 708P Measurements Predicted In-room frequency response spinorama cea-2034.png


As noted, there is less tilt here than we like to see for hi-fi speakers but for professional use, you want flatter response and that is what the 708P delivers. You can always tailor the response either inside the speaker or outside with EQ.

As noted, directivity is good but check out how good it is when we look at the beam width at constant SPL drop:
JBL 708P Measurements horizontal beam width.png


Wow, that is nice! It is also confirmed when we look at contour map:
JBL 708P Measurements horizontal directivity.png


Vertical response is not as good so stay a few degrees above or below the tweeter axis:
JBL 708P Measurements Vertical directivity.png


Waterfall display shows the port and woofer resonances:

JBL 708P Measurements waterfall csd.png


Distortion is quite low at 86 dBSPL but then rises at 96:
JBL 708P Measurements relative distortion.png


I was surprised to see the tweeter complaining at the higher level:
JBL 708P Measurements THD distortion.png


JBL 708P Speaker Listening Test and Equalization
The 708P is too large for my desktop so I used my far field listening setup. I was incredibly impressed by the fidelity from 10 foot distance. It produced the sound and tonality that I expect from a perfect speaker! OK, it got a bit better when I took out the port resonance:
JBL 708P equalization eq Studio Monitor Powered Speaker.png


The tonality didn't change much but there was a perception of more clarity and more open sound (could be placebo but I feel good saying otherwise).

The 708P could play loud with excellent dynamics. I was NOT able to find its limit even when playing music with sub-bass frequencies. Mind you, it did not play those tones loudly but neither did it get distorted. My listening space is open and massive and despite using just one speaker, I had no trouble filling the entire space. Pure pleasure is all I can say about the sound of the 708P.

Conclusions
Technically and objectively, the JBL 708P is near perfect. There is a bit of port resonance which while there, is far better than what we see especially in front-ported speakers. Distortion is excellent at low levels but becomes objectively an issue at elevated level but it was not something I noticed when listening. Speaking of listening, if you have $3,600, you can buy a pair of these and be done with it as far as superbly sounding system. This applies whether you are listening for enjoyment or work. Pervious JBL series I have tested had power limitations which are completely removed here. As such, subjectively I had nothing to complain about.

It is my pleasure to highly recommend the JBL 708P.

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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/
 

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MZKM

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Note: Rating is for far-field listening.

Preference Rating
SCORE: 5.0
SCORE w/ sub: 6.8

Frequency response: +/- 4.8dB 41Hz-20kHz

Spinorama 9.png
Horizontal Directivity 9.png
Horizontal Directivity Normalized 10.png
Vertical Directivity 10.png
Vertical Directivity Normalized 9.png
chart 14.png

_______
360° polars, to analyze positioning accuracy:

Horizontal:
chart 15.png

Vertical:
chart 16.png

So a the mic was off center by a bit to the right and a bit too low.
 
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dfuller

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That's pretty good! Comfortably flat response down to 40hz or a little lower, pretty low distortion at nearfield levels... And then there's that dispersion!
 
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amirm

amirm

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So a the mic was off center by a bit to the right and a bit too low.
Yeh, the horn makes it hard to position the mic correctly as does the curved sides on the enclosure.
 

cursive

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Thanks for the review Amir, always admired these speakers online over the years, as they seemed like the serious studio version of the 305/308p.

I'm a bit surprised to see the distortion levels at 96db, although that is admittedly loud for a mid/nearfield type speaker. Am I correct in assuming 2.5% distortion on the tweeter wouldn't be audible in listening?
 

infinitesymphony

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Thanks for the review Amir, always admired these speakers online over the years, as they seemed like the serious studio version of the 305/308p.

I'm a bit surprised to see the distortion levels at 96db, although that is admittedly loud for a mid/nearfield type speaker. Am I correct in assuming 2.5% distortion on the tweeter wouldn't be audible in listening?
Yeah, looking back at the JBL LSR308P MkII review, it's clear that JBL might be eating its own lunch with that model at an 85% discount versus the 708P. The 308P MkII has smoother in-room response and better directivity, and the only sacrifice appears to be a bit more distortion.
 

respice finem

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For a two-way speaker, this is impressive performance, on par (to my eyes) with similarly priced Neumann 3-way monitors, and the JBL have digital in- and throughput. No analog subwoofer out, but not really a problem for not too large listening rooms, probably. I'll put it on my list of "must hear" speakers. Then again, in my poor listening room it would probably be "pearls before swine"...
308p are interesting too, and would be easier to integrate into my listening (and living) room, but have only analog in (maybe not that important) and might have too much hiss, though, at their low price, they might be worth trying out. Compared to 20 years ago, we are quite spoiled for choice.
 
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Alice of Old Vincennes

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Yeah, looking back at the JBL LSR308P MkII review, it's clear that JBL might be eating its own lunch with that model at an 85% discount versus the 708P. The 308P MkII has smoother in-room response and better directivity, and the only sacrifice appears to be a bit more distortion.
Me thinks Amir was at an uninvited JBL lunch table.
 

m8o

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I'm pretty surprised at how the tweeter driver hardly has any attenuation in the lower mid and all bass but the lowest bass.
 

infinitesymphony

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I'm pretty surprised at how the tweeter driver hardly has any attenuation in the lower mid and upper bass.
I had the same thought, but I think these measurements are taken at close range with the other drivers still playing.
 
D

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I'm pretty surprised at how the tweeter driver hardly has any attenuation in the lower mid and all bass but the lowest bass.
If you could secure the woofer for that test you would see as expected response of the tweeter.
The woofer output bleeds all over the tweeter plot. Likewise, the tweeter response bleeds onto the woofer plot as well.
Everything below about 1.5khz on the tweeter plot is irrelevant.

Dave.
 

dfuller

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So is this using a traditional tweeter or a compression driver?
 
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amirm

amirm

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Nice to see the compression driver in this form factor. @amirm how do drums and cymbals sound at high levels? Pretty lifelike?
Some of the best I have heard!
 
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