JBL 708P Review (Professional Monitor)

[Robbo99999]

That loud listening was done only for testing, to see how much I can crank them up. It was unpleasantly loud for me as well. According to Amir's measurements they fell apart at 96 dB, assuming this is rms level and again assuming my measured value of 88dB is (close to) correct, this is 8dB more, i.e. more than twice as loud, really nothing anyone should listen to for an extended time period, it's more like a PA sound level. I am a happy camper and totally fine with accepting that they are not playing at this loud level without massive distortion. I will get 1-2 subs anyway, supporting the low range (where the distortion is most pronunced).

I'm sure you're fine with your 308p's, just like me. If I wanted to play them louder then I would buy a different speaker to the 308p, but there is still some headroom beyond by normal listening level, so no need for anything else. I have no doubt the 708p would sound more pleasant & cleaner than the 308p at louder volumes. At my normal levels I'm quite sure the 708p wouldn't offer anything better. (If I wanted louder levels than the 308p I wouldn't buy the 708p anyway, I'd probably go whole hog & buy a good Genelec, albeit massive price increase, but that's the way I see it).

 

[jhaider]

I'm sure you're fine with your 308p's, just like me. If I wanted to play them louder than I would buy a different speaker to the 308p, but there is still some headroom beyond by normal listening level, so no need for anything else. I have no doubt the 708p would sound more pleasant & cleaner than the 308p at louder volumes. At my normal levels I'm quite sure the 708p wouldn't offer anything better. (If I wanted louder levels than the 308p I wouldn't buy the 708p anyway, I'd probably go whole hog & buy a good Genelec, albeit massive price increase, but that's the way I see it).

One thing to consider is, “sounding” loud isn’t the same thing as SPL. I don’t know the precise mechanisms are in play - likely some combination of compression, changes in motor force/compliance/inductance over stroke, and diffraction - but speakers “sound loud” at different SPL. Others just sound bigger. LSR708 is one that just does not “sound loud” in reasonable use. Erin’s compression data IMO shows a big reason why. It’s also worth noting that, per the distortion thresholds published by Sound und Recording, Neumann’s new “high output” KH 150 is neck and neck in bass capability with JBL’s teeny tiny 705. I would expect 708 to be closer to KH 410 than KH 310 in bass output.

As for 308 vs 708, I’ve no meaningful experience with the former. 708 is good enough to be my effective “end game.” In particular, for a multi-seat room their constant HF dispersion to the edge of human audibility makes them great for all seats. If only they looked like the Revel Gem2’s down the hall instead of like dumpy boxes with indifferent paint quality…

 

[MacClintock]

I'm sure you're fine with your 308p's, just like me.

Don't forget that Amir mentions that he was wearing hearing protection when doint the 96 dB measurements ( "During the sweep even with my ear protection on, I could hear anomalies at 96 dB"), so it is really already almost unbearable loud at this point.

If I wanted to play them louder then I would buy a different speaker to the 308p, but there is still some headroom beyond by normal listening level, so no need for anything else.

I feel no need as well.

I have no doubt the 708p would sound more pleasant & cleaner than the 308p at louder volumes.

Neither do I.

At my normal levels I'm quite sure the 708p wouldn't offer anything better. (If I wanted louder levels than the 308p I wouldn't buy the 708p anyway, I'd probably go whole hog & buy a good Genelec, albeit massive price increase, but that's the way I see it).

As I already mentioned, I would go for the Neumann KH 310, they are similary priced, play louder, have less distortion and even better on- and off-axis response.

 

[Robbo99999]

One thing to consider is, “sounding” loud isn’t the same thing as SPL. I don’t know the precise mechanisms are in play - likely some combination of compression, changes in motor force/compliance/inductance over stroke, and diffraction - but speakers “sound loud” at different SPL. Others just sound bigger. LSR708 is one that just does not “sound loud” in reasonable use. Erin’s compression data IMO shows a big reason why.

As for 308 vs 708, I’ve no meaningful experience with the former. 708 is good enough to be my effective “end game.” In particular, for a multi-seat room their constant HF dispersion to the edge of human audibility makes them great for all seats. If only they looked like the Revel Gem2’s down the hall instead of like dumpy boxes with indifferent paint quality…

I agree that if a speaker is misbehaving then it can sound unpleasantly loud at a given SPL vs another speaker at the same SPL that is not misbehaving. I'm lucky enough to have one or two good measuring headphones that I also know I don't need to listen loud (but can because they're clean, but don't like doing so really), so I'm quite confident I also don't want to listen louder to speakers than I currenly already am with my 308p - as it stands I already have 7dB of headroom over my normal listening level with the 308p (from 78dB to 85dB at 2.8m), so I just don't want to listen louder, but I do know from turning up my 308p (& sub) beyond that that something wrong is happening above 85dB at 2.8m). If I wanted a clean experience above that I think I'd need to buy a different speaker to the 308p, and for me that would be a Genelec (a big price bump - no way I would compromise if upgrading my current speakers - I'd go the whole hog, anything short I don't think would be worth it as I think the 308p really do perform exceptionally at low/medium volumes (as supported by measurements)).

EDIT: I'm also sure the 708p would sound better than the 308p at louder levels, but it's not the one I'd buy if I wanted to go louder.

 

[jhaider]

I agree that if a speaker is misbehaving then it can sound unpleasantly loud at a given SPL vs another speaker at the same SPL that is not misbehaving.

The broader point I was trying to make is, often speakers with drivers that pull out all the stops to manage heat and keep the drivers linear under dynamic conditions sound subjectively “cleaner” than speakers with basic drivers. Our current standard measurement battery doesn’t capture dynamic behavior. Erin’s compression testing is a meaningful start. It would be very interesting to see if dynamic behavior correlates to differences in subjective impressions of 308 and 708, or e.g. @amirm’s subjective comments on Infinity Reference vs. Revel with similar steady state performance.

 

[Robbo99999]

The broader point I was trying to make is, often speakers with drivers that pull out all the stops to manage heat and keep the drivers linear under dynamic conditions sound subjectively “cleaner” than speakers with basic drivers. Our current standard measurement battery doesn’t capture dynamic behavior. Erin’s compression testing is a meaningful start. It would be very interesting to see if dynamic behavior correlates to differences in subjective impressions of 308 and 708, or e.g. @amirm’s subjective comments on Infinity Reference vs. Revel with similar steady state performance.

So you think that is above & beyond distortion measurements?

 

[jhaider]

So you think that is above & beyond distortion measurements?

How could it not be? Distortion is a static measurement.

Generally I think distortion measurements are near worthless. Rate of change of distortion with increasing level may be more interesting, but nobody does that.

 

[MacClintock]

The broader point I was trying to make is, often speakers with drivers that pull out all the stops to manage heat and keep the drivers linear under dynamic conditions sound subjectively “cleaner” than speakers with basic drivers. Our current standard measurement battery doesn’t capture dynamic behavior. Erin’s compression testing is a meaningful start. It would be very interesting to see if dynamic behavior correlates to differences in subjective impressions of 308 and 708, or e.g. @amirm’s subjective comments on Infinity Reference vs. Revel with similar steady state performance.

Yes, these compression measurements really do seem interesting, they seem to describe well the dynamic behaviour. Do you know why Amir is not providing them?

 

[jhaider]

Yes, these compression measurements really do seem interesting, they seem to describe well the dynamic behaviour. Do you know why Amir is not providing them?

Probably because they’re a huge, loud pain to do.

 

[Robbo99999]

How could it not be? Distortion is a static measurement.

Generally I think distortion measurements are near worthless. Rate of change of distortion with increasing level may be more interesting, but nobody does that.

I'm not convinced, but ok.

(I think intermodulation distortion could be something that's not currently captured that could be important, but don't think that's related to what you're talking about.)

 

[MacClintock]

I'm not convinced, but ok.

(I think intermodulation distortion could be something that's not currently captured that could be important, but don't think that's related to what you're talking about.)

Have a look here, this shows very nicely the "falling apart" of loudspeakers driven too loud for their construction:

 

[MacClintock]

The broader point I was trying to make is, often speakers with drivers that pull out all the stops to manage heat and keep the drivers linear under dynamic conditions sound subjectively “cleaner” than speakers with basic drivers. Our current standard measurement battery doesn’t capture dynamic behavior. Erin’s compression testing is a meaningful start. It would be very interesting to see if dynamic behavior correlates to differences in subjective impressions of 308 and 708, or e.g. @amirm’s subjective comments on Infinity Reference vs. Revel with similar steady state performance.

@amirm, what do you think about these compression measurements, are they easy to perform and do they bring valuable additional information in addition to distortion measurements?

 

[Newman]

@amirm, what do you think about these compression measurements, are they easy to perform and do they bring valuable additional information in addition to distortion measurements?

We have been over this before. Here are a couple of comments by Amir.

Measuring compression/limiting?

Some active speakers use processing to limit signals sent to drivers, and presumably such processing is engineered taking things like driver and amp characteristics into account (perhaps also subjective and/or psycho-acoustic knowledge). If a design uses something like multi-band limiting (e.g...

www.audiosciencereview.com

Master Thread: Are measurements Everything or Nothing?

I really have no objection at all to your reasoning. As I understand it, it is your perception that your tube-amp is coloring the sound, and that this in your opinion sounds better. Fair enough. I myself have a tube-power amp that I listen to sometimes, and it can sound nice. But I usually...

www.audiosciencereview.com

cheers

 

[MacClintock]

We have been over this before. Here are a couple of comments by Amir.

Measuring compression/limiting?

Some active speakers use processing to limit signals sent to drivers, and presumably such processing is engineered taking things like driver and amp characteristics into account (perhaps also subjective and/or psycho-acoustic knowledge). If a design uses something like multi-band limiting (e.g...

www.audiosciencereview.com

Master Thread: Are measurements Everything or Nothing?

I really have no objection at all to your reasoning. As I understand it, it is your perception that your tube-amp is coloring the sound, and that this in your opinion sounds better. Fair enough. I myself have a tube-power amp that I listen to sometimes, and it can sound nice. But I usually...

www.audiosciencereview.com

cheers

Thanks for pointing out these discussions. So it seems it could quite easily be measured (maybe with an additional module for the Klippel), but Amir doesn't like the concept, saying that compression is visible as a drop in frequency response. But I have the impression that the measurements done by Erin do reveal a bit more than this.

 

[Flaesh]

Show me a music recording that has more than 25 dB RMS Peak/RMS Average

And show me! Do we have a thread on the forum about music recordings that have significant dynamic range?
We sometimes listen to Danley's https://www.danleysoundlabs.com/tom-danleys-mic-recordings/ and Katz's https://www.digido.com/portfolio-item/we-have-lift-off-now-in-surround/ with great pleasure, but that's not music

 

[Robbo99999]

And show me! Do we have a thread on the forum about music recordings that have significant dynamic range?
We sometimes listen to Danley's https://www.danleysoundlabs.com/tom-danleys-mic-recordings/ and Katz's https://www.digido.com/portfolio-item/we-have-lift-off-now-in-surround/ with great pleasure, but that's not music

That Danley Sounds recordings were good, listened to them with my headphones, I'll see how they fair on my speakers & sub. That Youtube Katz's shuttle launch, that wasn't too impressive, felt like there wasn't that much low frequency in that Youtube recording, and it sounded distorted - I think the mics distorted when trying to capture the sound, if I was to guess?

EDIT: tried those Danley Sound recordings on my speakers & sub - to get a good impact I had to crank the system to it's limits to the point where I previously measured compression of the sub in the 20-30Hz region. So I had to crank it up to the equivalent of 105dB (for a 0dBFS sine tone) at 40Hz (at 3.8m listening distance). At those settings it was the first time I've looked to see the cone of the sub moving in & out significantly. Quite a lot of feeling in the body from the bass through the floor & sofa & through the air. Orban Loudness Meter shows after analysing those sound samples that the highest peaks are at -0.0dB, so at some points (very very brief points) it's using the full digital range which would at those points equate to the 105dB at 40Hz I mentioned earlier re Sine Tone.

 

[Flaesh]

That Youtube Katz's

Stereo *.wav file is (was?) free available somewhere on digido; registration may be required.
My system is limited at low frequencies (link in signature)

 

[Robbo99999]

Stereo *.wav file is (was?) free available somewhere on digido; registration may be required.
My system is limited at low frequencies (link in signature)

Ah, you have to register & there is a link there in the Youtube video to that original file. The Youtube version doesn't sound right though, did you try the Youtube? To me it sounds distorted. I also think it's not recorded with enough dynamic range within that Youtube vid. Yes, but no doubt about the low frequency content then from the graph that you took from the website, the Youtube recording doesn't seem to be doing it justice.

 

[dasdoing]

To me it sounds distorted.

I think what you are hearing is those CRAZY transients of that "crackling" that when I first heard it on my PA speakers made me think they will break lol

 

[Robbo99999]

I think what you are hearing is those CRAZY transients of that "crackling" that when I first heard it on my PA speakers made me think they will break lol

Yes, that is what I heard, I figured that could be an artifact generated from the microphone capture process.