JBL 708P Review (Professional Monitor)

[echopraxia]

#378: Clearly, a Neumann KH 310 is better in many aspects compared with a JBL 308, my doubt is how much of this superiority will reach the buyer's ears in the average listening room. But this is not possible to compare objectively - you can send your speaker to Amir, but not your room Objective testing as ASR does it is necessary and important, but it will not be able to tell you everything about how a speaker will perform in your room, unless you have a studio-like treated room (most don't).
With all desire for objectivity, we should not expect things that are physically not possible IMHO.

It still should be possible to reach a theoretical understanding some day where we can make broad but accurate claims about how various speakers will interacts with one’s room, depending on a few key variables (e.g. size, reflective surfaces, speaker positioning constraints, etc.) Speaker-room interaction isn’t magic, though maybe sometimes it seems like it

 

[jhaider]

I don't think there's any doubt about it. CEA 2034 is simply one test metric that can be used, but there have been numerous data points now that highlight relative evaluation issues.

I don’t believe the “preference score” is part of the standard. The actual standard, ie capture and display methodology for “Spin” data, is a useful advance. There are parts of it that I think are massively overemphasized here (notably PIR) but it’s at its core a chart that gives a lot of - but not all of the! - useful information at a glance. I think a spin chart coupled with horizontal polar map and some sort of standardized SPL/compression metric would get us even closer. But the latter is hard to do outside of dedicated measurement spaces that few can practically have.

I also don't believe the Klippel NFS is anywhere near a 100% effective testing scheme that can correctly evaluate the objective (or even subjective) performance of speaker systems. It seems an excellent tool, but there have been numerous data points and misinterpretations of its results.

Can you elaborate?

In this particular case it's highlighted well because the 308P and 708P are in different leagues, performance wise. I've listened to both of them quite a bit.

I haven’t, because 3-series is uninteresting to me (no grilles, noisy amps). It’s worth repeating (again) that 705 beats 308 in bass output capability, per Sound und Recording’s measurements. LSR708 is several steps more capable than its teeny tiny line-mate. It would be interesting to know if, with levels consciously limited and self-noise mitigated, if sighted observations hold up in blind listening. In one sense it doesn’t matter - those are contrived circumstances. But it would demonstrate internal consistency of preference metrics.

 

[respice finem]

#381: Theoretically, we can, this is all known to the science of acoustics, but translating this into precisely and completely modeling the acoustics of a real room, and its interaction with the speaker(s) can be quite a challenge. Roughly it's feasible, there is software that can do it, but most people (including me) have too little technical prowess to do it accurately, and last but not least the results might leave them depressive. So, as a "surrogate gratification" it's easier to say "hey now I have better speakers/amp/DAC...", that's what the industry has been living off for decades.
Sidenote: my personal "tactics" for now, I've treated my room best I could, then EQed my humble 5.1.2 system and as long as it sounds good enough for me, I leave it as it is. Audio frugalism FTW. Nothing is ever perfect.
"to search for perfection is all very well, but to look for heaven is to live here in hell" (Sting)

 

[Sancus]

Likewise, with active speakers amplification appears to be a limiting factor. What's enough on the desktop isn't enough at 10 feet.

IMO, what typically handicaps active speakers in the loudness department is just that the bass is EQed up for greater extension, assuming you aren't going to push them beyond their design limits, and that if you do want to do that, you will at least get a sub. Some manufacturers are more ambitious about this than others.

A useful comparison is the 708p vs 8050B... the 8050B actually has better distortion numbers across the board than the 708p except for the lowest bass. Yet the 8050B failed the subjective "loudness test", but high passing mostly-fixed it("I dialed in a 35 Hz steep high-pass filter and this got rid of most of the problem at a slight loss in low frequency response.") They're both 8" woofers. But the 8050B's -6dB point is ~30hz relative to ~38hz for the 708p. The 8050B has a very steep slope of output capability loss below 100hz. So it's obvious that if you are stressing those frequencies, the 8050B will give up quickly.

These are really just slightly different optimization choices for two speakers that are equally limited by physics.

I’m surprised there isn’t more discussion about the fact that literally everyone who hears the 708P say they’re leagues better than the 308P Mk II, despite the CEA2034 spin measurements indicating that they should sound similar at best, and the Olive Score indicating that the (10x cheaper) 308P Mk II should actually sound better, with or without subs.

FWIW, I agree with you in general that CEA2034 doesn't tell the whole story. I think blind testing of these two speakers would be very useful in establishing what's going on there. But I will say that, as lauded as the 305/308p are, they show exceptionally poor distortion numbers in mids and high frequencies(and weird noises) for their size. A subwoofer can't even hope to fix that.

And I do think it's entirely possible that that difference alone is more significant, after all the pref score diff is damn near 50/50(~54% for 5.0 vs 5.64) even if you fully buy the validity of all aspects of that formula. It's very important to remember that below 0.8 +/- you are getting into the error margin.

 

[echopraxia]

A useful comparison is the 708p vs 8050B... the 8050B actually has better distortion numbers across the board than the 708p except for the lowest bass. Yet the 8050B failed the subjective "loudness test", but high passing mostly-fixed it("I dialed in a 35 Hz steep high-pass filter and this got rid of most of the problem at a slight loss in low frequency response.") They're both 8" woofers. But the 8050B's -6dB point is ~30hz relative to ~38hz for the 708p. The 8050B has a very steep slope of output capability loss below 100hz. So it's obvious that if you are stressing those frequencies, the 8050B will give up quickly.

Yes, it seems obvious that Genelecs are tuned to be better standalone desktop speakers when used without a subwoofer and extreme SPL is not demanded of them, while also being fully capable of near-concert-level SPL when paired with a subwoofer that unloads the extreme end of bass demands from them. Like @richard12511, I can attest that my Genelec 8351B effortlessly reach nearly 'concert level' loudness with impressive dynamics as long as they're paired with a subwoofer so their otherwise deep-bass-extension-in-small-package doesn't become the SPL bottleneck.

For example, notice that the Genelec 8050B is about -5db at 30hz, while the JBL 708P is -16db at 30hz! It should be no surprise then that Amir found the Genelec's limiter engaging more often on loud bass content and the JBL 708P to have "no limits"; the 708P is nowhere near the same category of deep bass extension as the 8050B, and this is probably intentionally so.

Also, I find that Genelec's electronic limiter is very aggressive and ensures no significant distortion ever occurs, while other brands tend to allow far more distortion before the limited kicks in. I don't know about JBL, but when I tested my Neumann KH310, it would allow almost 100% THD in the bass frequencies before self-limiting. In contrast, the 8351B limiter would kick in before any significant distortion is seen in the measurements.

I think it'd be interesting to understand how something like the Genelec 8050B compares to the JBL 708P in terms of 'dynamics' and loudness capabilities if the Genelec 8050B's low end is EQ'ed down to match the JBL 708P's much shallower bass extension. I know Amir commented briefly that this solved his 8050B limiter issues, but it would be good to have a more detailed comparison vs the 708P when they’re EQ’ed similarly.

 

[dfuller]

#378: Clearly, a Neumann KH 310 is better in many aspects compared with a JBL 308, my doubt is how much of this superiority will reach the buyer's ears in the average listening room. But this is not possible to compare objectively - you can send your speaker to Amir, but not your room Objective testing as ASR does it is necessary and important, but it will not be able to tell you everything about how a speaker will perform in your room, unless you have a studio-like treated room (most don't) - then you can take the results 1:1. With all desire for objectivity, we should not expect things that are physically not possible IMHO.

More than you'd think. The distortion performance of the KH310 is lightyears better than the 308, and it's easily audible - especially the IMD component, which is considerably lessened by virtue of a 3 way design rather than the two way.

bass extension in a small size for people who run them to do desktop mastering work).

I feel like I need to correct something here - no mastering engineer is using these little desktop monitors. Mixers maybe, but mastering guys use at the very least big standmounts.

 

[echopraxia]

I feel like I need to correct something here - no mastering engineer is using these little desktop monitors. Mixers maybe, but mastering guys use at the very least big standmounts.

Yes, I mixed those two up (mastering vs mixing) Fixed.

 

[respice finem]

...The distortion performance of the KH310 is lightyears better than the 308, and it's easily audible - especially the IMD component, which is considerably lessened by virtue of a 3 way design rather than the two way...

Plausible - but then again, why are there rather few IMD measurements to be seen if it's so important, and why do many manufacturers like JBL rely on 2-way designs even in their more expensive product lines? JBL makes its own drivers so cost wouldn't be that much higher, probaby. This suggests that they at least think their 2-way designs are not "automatically inferior" to a similarly priced 3-way design.

 

[Senior NEET Engineer]

I’m surprised there isn’t more discussion about the fact that literally everyone who hears the 708P say they’re leagues better than the 308P Mk II, despite the CEA2034 spin measurements indicating that they should sound similar at best, and the Olive Score indicating that the (10x cheaper) 308P Mk II should actually sound better, with or without subs.

IMO this should be the final nail in the coffin of CEA2034 (or the derived Olive score) as a metric that supposedly can give a complete enough picture of a speaker to find the best speaker. Notice that whenever we are comparing two speakers whose measurements are both beyond some minimum bar of CEA2034 performance, the predictive power of CEA2034 in determining the winner seems to vanish rapidly. Therefore CEA2034 is clearly missing something hugely important.

Maybe it’s missing THD, maybe IMD, maybe it’s dynamic compression, maybe just total SPL capability, maybe it’s beam width, maybe it’s some combination of all those — who knows, but it’s exceedingly clear that something very important is missing from CEA2034, and the science here is not complete (and not just for a rare few outliers).

Either that, or everyone (including Amir) who has heard the 708P and found it to be much superior to the sound quality of the 308P either has bad hearing or is lying. I just don't believe that.

Spinorama prediction model is for blind tests in controlled environment not sighted

 

[echopraxia]

Spinorama prediction model is for blind tests in controlled environment not sighted

Yeah, and the sky is blue, and your low-effort response lacks punctuation -- all obvious facts. So what's your point?

I assume you are implying that you think the JBL 308P Mk II would achieve a similar or better subjective preference score than the JBL 708P in a blind test in a controlled environment (within the error margin limits)?

I doubt it. I trust the sighted judgement of Amir (and literally everyone else who has heard these two speakers) more than that. I don't think you can chalk this one up to sighted bias.

 

[Senior NEET Engineer]

Yeah, and the sky is blue, and your low-effort response lacks punctuation -- all obvious facts. So what's your point?

I assume you are implying that you think the JBL 308P Mk II would achieve a similar or better subjective preference score than the JBL 708P in a blind test in a controlled environment (within the error margin limits)?

I doubt it. I trust the sighted judgement of Amir (and literally everyone else who has heard these two speakers) more than that. I don't think you can chalk this one up to sighted bias.

It's apples and oranges. In a sighted preference model, sound quality would matter a lot less. Instead characteristics like speaker size, cost, aesthetics, and reputation would have major influence even on so-called "experienced listeners".

If you want to expose spinorama model, then blind testing will be needed. Anything else is just speculation and doesn't hold much weight from audio science point of view. But it is a lot of fun to speculate.

 

[Robbo99999]

Yeah, and the sky is blue, and your low-effort response lacks punctuation -- all obvious facts. So what's your point?

I assume you are implying that you think the JBL 308P Mk II would achieve a similar or better subjective preference score than the JBL 708P in a blind test in a controlled environment (within the error margin limits)?

I doubt it. I trust the sighted judgement of Amir (and literally everyone else who has heard these two speakers) more than that. I don't think you can chalk this one up to sighted bias.

Considering the 708p costs over 10 times as much as the 308p then that would be quite a psychological influencer on buyers of the 708p. It's super hard to properly compare speakers without any bias or inaccuracies entering, although if there are massive deficiencies in one of the speakers then that's probably quite obvious to pinpoint & differentiate, but comparing two speakers where more subtle differences exist then I think that's extremely hard to do accurately without bias.

 

[echopraxia]

So, let’s be clear @Robbo99999 and @Senior NEET Engineer — are you asserting that in a blind test in a controlled environment, the JBL 308P Mk II and JBL 708P would yield very similar subjective preference scores (with the 308P perhaps scoring a bit better than the 708P, +- some margin of error) as the CEA2034 measurements imply?

 

[Robbo99999]

So, let’s be clear @Robbo99999 and @Senior NEET Engineer — are you asserting that in a blind test in a controlled environment, the JBL 308P Mk II and JBL 708P would yield very similar subjective preference scores (with the 308P perhaps scoring a bit better than the 708P, +- some margin of error) as the CEA2034 measurements imply?

I'm more saying that I don't think anybody has done controlled enough listening tests on both to be certain that one is better than the other for all the reasons that have already been mentioned - it's nigh on impossible to do it properly to eliminate all the variables to make sure speakers are in exactly the same position and that not too much time passes between switching, and doing it blind, level matched, etc....it's just darn hard for people to do such tests. But regardless, the two speakers have very similar characteristics according to the spins so I think it would be hard to tell between them. I do think if you did your listening test at very high & increasing volume that you'd notice the 308p doing some funky stuff before the 708p, but I kinda doubt distinguishing differences at most normal listening levels.

 

[echopraxia]

I'm more saying that I don't think anybody has done controlled enough listening tests on both to be certain that one is better than the other for all the reasons that have already been mentioned - it's nigh on impossible to do it properly to eliminate all the variables to make sure speakers are in exactly the same position and that not too much time passes between switching, and doing it blind, level matched, etc....it's just darn hard for people to do such tests. But regardless, the two speakers have very similar characteristics according to the spins so I think it would be hard to tell between them. I do think if you did your listening test at very high & increasing volume that you'd notice the 308p doing some funky stuff before the 708p, but I kinda doubt distinguishing differences at most normal listening levels.

Yes, we understand that you (and some percentage of others) do not trust the subjective impressions of @amirm, or any other trained listener. This inevitably gets brought up on every single thread ever on ASR, so I hope you can also see why many find it a tired old topic that is not a very meaningful contribution to rehash on every thread.

It would be a lot easier to reach consensus on these topics if we could actually agree on what blind test procedure and parameters you would respect as reliable and trustworthy. But as seen in this large thread here, even that seems impossible to achieve consensus on — no matter how strict the test procedure, it seems there will always be people who will pre-emptively critique any results from the methodology as meaningless.

So I think it is doubly counter-productive when people drop by a thread to post why they find the listening test results meaningless, without actually also being able to agree on what procedure they would find meaningful.

I think what many people are reluctant to admit is that the world is not black-and-white: sighted subjective evaluations are not 100% meaningless, and Harman’s blind tests are not 100% meaningful. You will never reach 100%. And conversely, almost all data is useful and interesting to some degree (unless your objective is not to learn but find ways to fit the world to your preconceived expectations of what it should be).

 

[Ron Texas]

Yes, we understand that you (and some percentage of others) do not trust the subjective impressions of @amirm, or any other trained listener. This inevitably gets brought up on every single thread ever on ASR, so I hope you can also see why many find it a tired old topic that is not a very meaningful contribution to rehash on every thread.

Our host has impressions that I am far more likely to trust than most people publishing reviews. However, he does have certain well known preferences such as the importance of dynamic range (loudness without distortion) and that stand mounts should have decent bass. Actually, I believe these are more mainstream preferences than some might think. Hence, he downgrades some active speakers with limited output and some small speakers with limited bass in the 50 to 200 hz range. I can't say the topic is tired or old.

It's not a good idea to jump on other members because eventually they will jump on you

 

[Robbo99999]

Yes, we understand that you (and some percentage of others) do not trust the subjective impressions of @amirm, or any other trained listener. This inevitably gets brought up on every single thread ever on ASR, so I hope you can also see why many find it a tired old topic that is not a very meaningful contribution to rehash on every thread.

It would be a lot easier to reach consensus on these topics if we could actually agree on what blind test procedure and parameters you would respect as reliable and trustworthy. But as seen in this large thread here, even that seems impossible to achieve consensus on — no matter how strict the test procedure, it seems there will always be people who will pre-emptively critique any results from the methodology as meaningless.

So I think it is doubly counter-productive when people drop by a thread to post why they find the listening test results meaningless, without actually also being able to agree on what procedure they would find meaningful.

I think what many people are reluctant to admit is that the world is not black-and-white: sighted subjective evaluations are not 100% meaningless, and Harman’s blind tests are not 100% meaningful. You will never reach 100%. And conversely, almost all data is useful and interesting to some degree (unless your objective is not to learn but find ways to fit the world to your preconceived expectations of what it should be).

Yeah, that's right, I think it's super hard to compare speakers, especially when there are a lot of similarities between two that you might be comparing. You can see by your thread that it's a minefield. I do like to hear people's impressions of speakers and the discussions and comparisons they draw in terms of saying I like this one better for x or y reasons....but you can see that the measurements on this site are a more reliable focus. I personally don't think the differences in the spins of 708p & 308p are different enough to reliably judge which ones would come out better in proper blind listening preference tests (if that were possible), if the speakers were very different and/or one with significant flaws then I could understand that differences are more likely to be heard. With two very similar speakers other factors like brand/cost/bias are probably more influential in determining preference of people doing semi-controlled / uncontrolled listening tests at home.....that's my opinion. But I think I will admit that you could find differences in 708p & 308p when you were pushing the volume up & up, at which point 308p will reach it's limits earlier, and I would think the distortion factor comes into play there.....at most normal listening levels I wouldn't expect that to come into play. I just think it's super hard to compare speakers in listening tests, and especially if you're comparing two speakers that are very similar and only have subtle differences.

 

[Sancus]

But I think I will admit that you could find differences in 708p & 308p when you were pushing the volume up & up, at which point 308p will reach it's limits earlier, and I would think the distortion factor comes into play there.....at most normal listening levels I wouldn't expect that to come into play.

Really depends on listening distance and definition of "normal". Would the 308p distort at 83dBC reference in the nearfield? Yes, quite horribly on peaks too I suspect. At 75dB @ 3m? Again, yes. At 65dB in nearfield? No, probably not. If you are doing tests in mono, then it's even harder for the 308p.

I suspect people continuously underestimate the dynamic requirements of music. The other day I saw instantaneous peaks of 107dbZ in commercially recorded classical with an Leq of 72-75.

 

[echopraxia]

As @Sancus explains, even the factor of SPL capabilities (which is undeniably missing from CEA2034) is all we need recognize to prove my point that CEA2034 is insufficient.

But it doesn’t end there. There’s dynamic compression, THD, IMD, beam width (horizontal and vertical) ... all of which we know impacts speaker preference to some degree. We know these matter. The question we don’t yet have a definitive answer to is how much they matter vs other factors, but that just means that the science here is not “case closed” (and that CEA2034 is demonstrably insufficient).

Personally, I agree with Amir’s reasoning here: It would make no sense for many companies like Revel and JBL and others to spend so much engineering effort and expense towards reducing distortion, dynamic compression effects, etc., if they ultimately didn’t matter very much towards subjective blind speaker preference in reality.

It's not a good idea to jump on other members because eventually they will jump on you

I don’t disagree with this, though you may want to heed your own advise here. That said, I hope nobody feels “jumped on” here. I think we should all be able to energetically disagree while simultaneously respecting each other’s differing opinions and avoiding ad hominem.

 

[Robbo99999]

Really depends on listening distance and definition of "normal". Would the 308p distort at 83dBC reference in the nearfield? Yes, quite horribly on peaks too I suspect. At 75dB @ 3m? Again, yes. At 65dB in nearfield? No, probably not. If you are doing tests in mono, then it's even harder for the 308p.

I suspect people continuously underestimate the dynamic requirements of music. The other day I saw instantaneous peaks of 107dbZ in commercially recorded classical with an Leq of 72-75.

Yes, that's right, it would depend on listening distance, 708p would be more suitable for longer listening distances then.