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JBL 708i Monitor Review (DSP: Part 2)

Rate this speaker:

  • 1. Poor (headless panther)

    Votes: 28 22.8%
  • 2. Not terrible (postman panther)

    Votes: 69 56.1%
  • 3. Fine (happy panther)

    Votes: 23 18.7%
  • 4. Great (golfing panther)

    Votes: 3 2.4%

  • Total voters
    123
Not a compression driver aficionado but I’m going to hazard and guess that it’s due to the high sound pressure levels developed at the diaphragm and the throat of the waveguide (Edit: Or probably just within the driver itself) resulting in adiabatic compression since it does seem to be something they all share and they all have the same general design. Also the harmonic distortion components will be at 2x the fundamental so at some point they are at a high enough frequency not to be heard as easily.
Also guess so (neither a compression driver aficionado) and due to the displacement asymmetry of such non-linearity the 2nd harmonic is increased and not the 3rd:

1672909143603.png

Source of above chart: https://www.klippel.de/fileadmin/_migrated/content_uploads/Klippel_Nonlinearity_Poster.pdf
 
At the end, it´s not that simple sometimes and i fond out with this this - why DSP, EQ isen´t ? DSP, EQ on a different Brand

that is unfortunately true. I tried creating filters for my Motu DAC in REW, but the Qs are not compatible in any way.

On the manufacturer side, the trend is towards closed system solutions where the processing comes from in-house or a few third-party manufacturers are specified.
 
I'm not sure I understand all the negativity around this speaker relative to the original praise for the 708p. Just ditch the idea of the JBL dsp / amplification and roll your own using @pierre 's EQ, to get practically the same results as the 708p:


I'm doing exactly this with camillaDSP and ncore monoblocks. Loads more dsp flexibility plus much higher quality amplification.

-Jim
 
It is badly, or perhaps more accurately self-servingly, worded. Anyone with any intelligence knows an amp is a damn amp. The BSS processor or Intonato do not ask what amp you have upstream, and they are not locked to some magic key that only exists in Harman amps!
I disagree with you that it is badly worded. The speaker is designed to be used with an EQ and as that EQ is only supplied for the DSP of specific models of HARMAN amplifiers the notice is correct. Also, the active crossover is not done by those amplifiers hence the wording and a signal processor is also correct. Don't you agree?

I agree with everything else on your post though :)
 
I neither do know what a Twitter resonance is—does this got something to do with Elon’s latest endeavors?—nor what a Linkwitz Transport (??). But I can tell that you are making things up and do not care to memorize even most recent lessons.
By not even understanding the Linkwitz Transform (not Transport!) you are making a fool of yourself on the subject.

Please learn before you argue.
 
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Interesting to note that the unwanted HF “boost” and the distortion are correlated. The two track each other. Wonder if it’s a production issue? Port resonances are also interesting in that not all of them are scaling directly with the woofer output and being seen directly in the FR. Probably not great as it points to them being of a higher Q, perhaps. Still, if I had this speaker, the tweeter part is what would be somewhat concerning since it looks like an issue with QC, or perhaps something else.
It feels like it's a production unit to unit variation issue, because you'd expect the EQ to be optimising the speaker better than that, seems like the most likely explanation.
 
I'm not sure I understand all the negativity around this speaker relative to the original praise for the 708p. Just ditch the idea of the JBL dsp / amplification and roll your own using @pierre 's EQ, to get practically the same results as the 708p:


I'm doing exactly this with camillaDSP and ncore monoblocks. Loads more dsp flexibility plus much higher quality amplification.

-Jim
Apart from the obvious issues that people have already pointed out as being problems/issues with the 708i, the 708p was reviewed way back in Feb '21, quite a few speakers have been measured since then, I think it makes you more critical of speakers you see in the future because you've had more exposure to good speakers that have been reviewed with perfect or near perfect spinoramas (at various price points). I looked back at my comments in the 708p ASR thread and it looks like I quite liked the speaker, but my opinion has changed since then, probably for the reasons I mentioned.
 
Apart from the obvious issues that people have already pointed out as being problems/issues with the 708i, the 708p was reviewed way back in Feb '21, quite a few speakers have been measured since then, I think it makes you more critical of speakers you see in the future because you've had more exposure to good speakers that have been reviewed with perfect or near perfect spinoramas (at various price points). I looked back at my comments in the 708p ASR thread and it looks like I quite liked the speaker, but my opinion has changed since then, probably for the reasons I mentioned.
I like(ed) the speaker too. I helped my friend install them in his home theater, the end result sounded tremendous, it performs well in his home theater and and are really well suited to HT. That being said, we spent three frustrating weekends getting all of the bits and pieces to work. JBL was helpful, but we worked with two support people who were not on the same page. I remember joking that the theater construction took us less effort that the filter install. His install is single-wire. I know he was considering abandoning the approved ecosystem and going third-party DSP, I need to visit him again and ask how that went. And refresh my memory now that I have this review to color my judgement, perhaps back to clear.;)
 
This is a very interesting review. My experience is in agreement, with a caveat.

I have a pair of these speakers with BSS BLU-50 acting as the crossover or dsp or whatever. I am running them with a single-wire configuration (so the BLU-50 is not operating as a crossover, more a dsp fine-tuner).

I bought this pair before the active version was available. In the beginning I though that there was something broken in my pair. Nothing was broken, as the service told me. But after a couple of software upgrade things looked (or sounded) much better. It took a couple of the software upgrades to get things up and shiny.

I am still running a bit older version of the software for BLU-50. In one time I tried the speakers with my friend's CROWN amplifier with the latest version of the dsp file. I did not like the result at all.

In addition, I have tweaked the BLU-50 tuning a bit after several measurements. Therefore it is likely that my relative happiness with 708i cannot be replicated to other rooms.
 
I like(ed) the speaker too. I helped my friend install them in his home theater, the end result sounded tremendous, it performs well in his home theater and and are really well suited to HT. That being said, we spent three frustrating weekends getting all of the bits and pieces to work. JBL was helpful, but we worked with two support people who were not on the same page. I remember joking that the theater construction took us less effort that the filter install. His install is single-wire. I know he was considering abandoning the approved ecosystem and going third-party DSP, I need to visit him again and ask how that went. And refresh my memory now that I have this review to color my judgement, perhaps back to clear.;)
(I'll just add that my opinions are based on the measurements, not actually having experienced the 708i/708p, but I think you already understood that was the case.)
 
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I think the I stands for Installation, and this one is likely trying to cater to the bigger studios and such. When the setup is big or complicated, it's probably easier to drive all the loudspeaker units from a rack of amplifiers than to bother trying to get to the power of every unit, servicing is also arguably easier with passive speakers that use external crossover+ampllification since it's usually the electronics that go first, and one can just pull the faulty electronics off of the rack in the case of passive speakers, while active will need to physically remove the speakers from their mounted position. That said, the 708P seems to be so much flatter than the 708I, even with the DSP profile applied, and I just don't see the attraction of these for the average enthusiast. Perhaps there is some per-unit calibration on the 708P?
Even for some residential applications, this is the primary advantage of the passive version. In my room, I use a total of 15 705i surround speakers augmenting my Salon2/Voice2 LCR using a JBL SDP-75 (re-badged Trinnov Altitude) controller - which provides the necessary DSP filters. The 705i were chosen over similar Revel models due to physically smaller dimensions, an important factor in a 20' by 14' by 9' room. And per the post above, the passive versions were chosen so I could just run 12 gauge Belden instead of AC plus balanced audio to every location - to say nothing of the reliability concerns associated with 30 separate amp modules of presumably cost-constrained design.
 
It feels like it's a production unit to unit variation issue, because you'd expect the EQ to be optimising the speaker better than that, seems like the most likely explanation.
This is a comment also to @jjaaha post:

This is a very interesting review. My experience is in agreement, with a caveat.

I have a pair of these speakers with BSS BLU-50 acting as the crossover or dsp or whatever. I am running them with a single-wire configuration (so the BLU-50 is not operating as a crossover, more a dsp fine-tuner).

I bought this pair before the active version was available. In the beginning I though that there was something broken in my pair. Nothing was broken, as the service told me. But after a couple of software upgrade things looked (or sounded) much better. It took a couple of the software upgrades to get things up and shiny.

I am still running a bit older version of the software for BLU-50. In one time I tried the speakers with my friend's CROWN amplifier with the latest version of the dsp file. I did not like the result at all.

In addition, I have tweaked the BLU-50 tuning a bit after several measurements. Therefore it is likely that my relative happiness with 708i cannot be replicated to other rooms.
First @amirm thank you for testing the passiv version of the 708. Agree that its interesting to see what design considerations Harman takes when aiming to make at statement mid-field monitor. FUN! Their choice of port/tuning with the resulting resonances looks plain wrong but it is a deliberate compromise based on a knowledge base few if any other companies possess. Harman have published whitepapers on port design, both for medium sized speakers and all out PA subwoofers.

I do have a pair of 708i that is waiting to be hooked up but my M2s are taking up the only place in the mediaroom with really good acoustic properties. I found the 708P to be excellent when I demoed them. Tonally accurate IMHO, huge soundstage, resolving of micro/macro dynamics and a physicality to the sound when playing loud that's usually the domain of 12-15" midwoofers.

It is fully possible that @amirm ended up testing a Crown network amplifier where the DSP does not perform the (rather intricate) EQing as it should. I am sorry to report that these units (= some firmware versions, not the hardware) are now not to be trusted. I still have 3 Crown network amps but I do not trust EQ and levels before measuring the result. And in this review the tweeter response and the blend with the woofer does not look as it should.

1) In an earlier post @jhaider stated that the software situation at Harman Pro was a mess. I agree. The last couple of years I have experienced some inconsistencies with the firm-/software in the DCi/CDi series from Crown. Levels between channels have mysteriously become unmatched, some crossovers and filters of my own design do not perform as designed. Early on I thought this was myself fumbling but its happened too often. A huge problem with the pre defined config files from Harman has been with the M2 config files which leaves the amplifier generating noise on some channels and distorted sound on the others. The issues came after upgrading the firmware in the amps at some point.

2) I do not see how it is meaningful to review a Crown DSP amp without mastering the Audio Architect software as it is a part of the system. And the JBL 708i is a part of the system Crown DSP amp/Audio Architect/JBL 708i. There are so many parameters that will inflict on the measurements. Did the guy that delivered the amp help with setting up Audio Architect?

3) Two of your complaints on the amplifier is not an issue when one use the whole amplifier system. First EQ, yes the loudspeaker/system EQ/limiting on the output is locked when one uses a Harman speaker preset but you do have 8 EQ points available pr band on each channels input. That gives you 16 EQ points for each loudspeaker for room related issues. Not bad! Then the trim pots on the backside where they belong on an INSTALL amp. If you use Audio Architect then you can easily adjust trim input levels by sending a signal to the amp and monitor the levels in the input level window to match them with high precision.

4) Why did you have to adjust the input trims? In the review one get the impression that level matching between the low and high channels are done with the trims. The level matching is done by the config file from Harman. Trim is for adjusting to the sources output level. As one can adjust the amplifiers gain modes 26/34/37dBu (in Audio Architect..) my gain structure is usually fine with the trim fully open.

Edit: some line shifts for better readability
 
2) I do not see how it is meaningful to review a Crown DSP amp without mastering the Audio Architect software as it is a part of the system. And the JBL 708i is a part of the system Crown DSP amp/Audio Architect/JBL 708i. There are so many parameters that will inflict on the measurements. Did the guy that delivered the amp help with setting up Audio Architect?
[...]
4) Why did you have to adjust the input trims? In the review one get the impression that level matching between the low and high channels are done with the trims. The level matching is done by the config file from Harman. Trim is for adjusting to the sources output level. As one can adjust the amplifiers gain modes 26/34/37dBu (in Audio Architect..) my gain structure is usually fine with the trim fully open.
I agree with this poster. I have been trying to make it clear that this speaker is part of a system but it was measured in both occasions as just a module of that system. Naturally it is judged by the members as the finished speaker as they are accustomed to judge a speaker, not a speaker system. This is not fair for the manufacturer and frankly not a good show for ASR's reputation.
 
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It is fully possible that @amirm ended up testing a Crown network amplifier where the DSP does not perform the (rather intricate) EQing as it should.
In my experience with installations, you should not trust a Crown to operate correctly without a very detailed analysis of the software versions and additional measures. I have learned to use BSS and third party amplifiers.

I was momentarily depressed after reading amirm's review. Am I already that deaf? :p But if I am deaf enough, then things will be much cheaper.

I do not have access to a Klippel system, but I have access (and unused reservation hours) to a semi-anechoid chamber (>40Hz) with the required measuring hardware and software. I will try to reserve time for personal purposes. I may not get the timeslice because the chamber is normally booked somewhere in 90-98% for commercial use. But it would be nice to have a look at the performance of a BSS with 708i.
 
This is not fair for the manufacturer and frankly not a good show for ASR's reputation.
Ah, actually I think that to be very fair to the manufacturer. If the manufacturer does not include sufficient quidance for setting the system up, then the fault goes for the manufacturer. I have found that JBL Pro is not a very consistent and documenting manufacturer. Even in a fairly straightforward situations the documentation is lagging. You have to use field measurements and personal experience. That is a bad habit for a professional manufacturer.

The products are, in my opinion, wonderful. But the documentation has some very annoying gaps.
 
Interesting, disappointing, and a somewhat bizarre parallel to the 705P you tested. One should be able to expect Neumann/Genelec-grade consistency from JBL but it seems clear that is not an expectation currently met in the real world. I inferred from my measurements of the output of a "raw" 705i and the output of a BSS BLU-50 loaded with the tuning file may have, as well as Sound und Recording's measurements, that your sample had the filters flashed incorrectly somehow: missing a filter in the 1kHz region.

Here my guess is sample variation with the tweeter, or running change that was not reflected in the tuning files. Yours has roughly equal lumps in the FR, centered at of roughly equal size centered at 2.5 and 6 kHz, give or take. The one I measured has basically the same two lumps one, but the higher one is much lower in level. I haven't used FuzzMeasure in so long I've forgotten how to add markers to a graph (or maybe the program is broken due to malign neglect by its current owners, Røde, coupled with advances in Apple hardware and macOS), but it's clear from an eyeball of the screenshot below.

View attachment 254799

I suspect the filter is designed with a tweeter measuring like mine. I highly doubt they tune 708P individually given the performance of your 705P sample, so my hunch is that a 708P with this specific tweeter would measure the same. Someone correct me if I'm wrong, but I believe you and Erin measured the same sample of 708P.

Admittedly I've not taken measurements of 708i run through a processor, and my measurements were performed using a Class AB amp (Parasound Zamp v3 is my usual measurement amp) rather than the DCIn - in theory the Class D amp could be interacting with the compression driver's impedance curve. However, based on the Dirac-generated sound power measurements (spatial average of measured area) of my L and R (driven by a DCI 8|600n in single-wire configuration) there's no misbehavior to note in the 5-7 kHz region either.

View attachment 254803


It's worth noting that, as I pointed out in Part I, the engineers behind 7-Series were not bullish on the biamp option. They said it added little, and explicitly expressed a preference to me and many others around that time for a stronger amp channel in single amp mode over two channels in biamp mode. I wonder if that even carried over to the marketing, given the use of the audiophool term "biwire" instead of "biamp." Single-amp mode also moots out the analog pot matching issue. All that to say it may be worthwhile to test it in single-amp mode, though OTOH if my hunch that the tweeter's raw FR is the issue then it should have the same issue.
I think your results showing single wire mode with the crown amps are important to show there doesn't appear to be the elevated treble using that configuration. When I get the units back I will flip the amp to single wire mode and take some measurements to confirm.
 
This is a comment also to @jjaaha post:


First @amirm thank you for testing the passiv version of the 708. Agree that its interesting to see what design considerations Harman takes when aiming to make at statement mid-field monitor. FUN! Their choice of port/tuning with the resulting resonances looks plain wrong but it is a deliberate compromise based on a knowledge base few if any other companies possess. Harman have published whitepapers on port design, both for medium sized speakers and all out PA subwoofers.

I do have a pair of 708i that is waiting to be hooked up but my M2s are taking up the only place in the mediaroom with really good acoustic properties. I found the 708P to be excellent when I demoed them. Tonally accurate IMHO, huge soundstage, resolving of micro/macro dynamics and a physicality to the sound when playing loud that's usually the domain of 12-15" midwoofers.

It is fully possible that @amirm ended up testing a Crown network amplifier where the DSP does not perform the (rather intricate) EQing as it should. I am sorry to report that these units (= some firmware versions, not the hardware) are now not to be trusted. I still have 3 Crown network amps but I do not trust EQ and levels before measuring the result. And in this review the tweeter response and the blend with the woofer does not look as it should.

1) In an earlier post @jhaider stated that the software situation at Harman Pro was a mess. I agree. The last couple of years I have experienced some inconsistencies with the firm-/software in the DCi/CDi series from Crown. Levels between channels have mysteriously become unmatched, some crossovers and filters of my own design do not perform as designed. Early on I thought this was myself fumbling but its happened too often. A huge problem with the pre defined config files from Harman has been with the M2 config files which leaves the amplifier generating noise on some channels and distorted sound on the others. The issues came after upgrading the firmware in the amps at some point.

2) I do not see how it is meaningful to review a Crown DSP amp without mastering the Audio Architect software as it is a part of the system. And the JBL 708i is a part of the system Crown DSP amp/Audio Architect/JBL 708i. There are so many parameters that will inflict on the measurements. Did the guy that delivered the amp help with setting up Audio Architect?

3) Two of your complaints on the amplifier is not an issue when one use the whole amplifier system. First EQ, yes the loudspeaker/system EQ/limiting on the output is locked when one uses a Harman speaker preset but you do have 8 EQ points available pr band on each channels input. That gives you 16 EQ points for each loudspeaker for room related issues. Not bad! Then the trim pots on the backside where they belong on an INSTALL amp. If you use Audio Architect then you can easily adjust trim input levels by sending a signal to the amp and monitor the levels in the input level window to match them with high precision.

4) Why did you have to adjust the input trims? In the review one get the impression that level matching between the low and high channels are done with the trims. The level matching is done by the config file from Harman. Trim is for adjusting to the sources output level. As one can adjust the amplifiers gain modes 26/34/37dBu (in Audio Architect..) my gain structure is usually fine with the trim fully open.

Edit: some line shifts for better readability
Well, from what you're saying & your experience that could certainly explain the less than optimum result of the EQ on the frequency response. (So it wouldn't have to be the unit to unit variation of the 708i that I mentioned).
 
Ah, actually I think that to be very fair to the manufacturer. If the manufacturer does not include sufficient quidance for setting the system up, then the fault goes for the manufacturer. I have found that JBL Pro is not a very consistent and documenting manufacturer. Even in a fairly straightforward situations the documentation is lagging. You have to use field measurements and personal experience. That is a bad habit for a professional manufacturer.

The products are, in my opinion, wonderful. But the documentation has some very annoying gaps.
I disagree. This is a pro speaker system for pros to set-up. If the “pro” doesn’t know how to set up a 2-way speaker using the DSP files he was given he should be sacked. Education is not a manufacturer’s job.

I will repeat again: these are not standalone speakers. They are elements of a sound system. Find someone to set them up or use the P versions. Simples!
 
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4) Why did you have to adjust the input trims?
Because the tweeter level was too hot based on my acoustic measurements -- something no tech will be able to do, not easily anyway. What you saw was post compensation of the levels using the trim controls by me.
 
I disagree. This is a pro speaker system for pros to set-up. If the “pro” doesn’t know how to set up a 2-way speaker using the DSP files he was given he should be sacked. Education is not a manufacturer’s job.
Education is manufacturer's job. They need to clearly document what needs to be done to configure this system. A link in the manual on where to get the software should not get a "page not found" on JBL website. That aside, the key here is mismatch of passive speaker response relative to EQ profile provided by Harman. No tech out there has a Klippel NFS to accurately assess this as I did. For all we know, every 708i out there is running suboptimally -- something that squarely falls in the domain of the manufacturer.
 
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