JBL 708i Monitor Review (DSP: Part 2)

[Robbo99999]

Just as a quick note, I appreciate @amirm 's candid review of this speaker given that it's a JBL (given affiliations with his past and/or present professional business beyond ASR), just another example of good impartial review!

 

[Tangband]

That's interesting, but that would shift the crossover closer to the woofer resonance which is at around 2.6kHz.....but like you say a steeper crossover to help mitigate that influence. I guess you're thinking the tweeter is playing too low and causing distortion at high levels, although the higher crossover wouldn't solve the 5-10kHz distortion and it wouldn't do anything to affect the messed up 600-1000Hz region that is being affected by bass port resonances. To be honest there's multiple fronts where this speaker looks like it needs to be improved on a design level, not to even mention the poor user integration related to the analog trim-pot ridiculousness.

Agree.
A two-way speaker with big differences in size of the used drivers are always a compromise, active or passive.

 

[Robbo99999]

Agree.
A two-way speaker with big differences in size of the used drivers are always a compromise, active or passive.

But they could design out those issues right, even if it is 2-way. Tune the bass port differently perhaps so it doesn't have those destructive resonances that mess up the 600-1000Hz. Do something about the tweeter, install a more capable tweeter. I'm pretty sure they could fix it totally with some changes.....whether or not cabinet size & cost would stay the same I don't know.

 

[Rahan]

There is no point to keep the passive crossover for the tweeter to me.
We all know that fully digital crossover is better now.
We'd rather to baypass the filter (not a big deal to do) and use a propoer DSP like nin disp Flex with a nice pair of amp to get the best of this box.
You'll have all the flexibility you want. But it comes at a price....
The P version seems hard to defeate.

 

[sebackman]

I have no idea if it is relevant here but sometimes the more basic DSP amps does not have the fire power to implement the full DSP settings, hence the correction is truncated. This was very evident in the JBL M2 studio monitor DSP settings as the settings for the stand alone DSP from BSS and the expensive Crown HD amps had more EQ points that the settings for the more wallet friendly Crown amps. The DSP macros "looked the same" but the contents is different.

 

[danbei]

A little off subject, but why do frequency response graphs have dB as linear? Is a 2dB difference at 70dB sound level the same as a 2dB difference at 60dB?

Yes, that is why the graph scale is linear. The logarithmic part is already "embedded" in the dB relative unit.

 

[ctrl]

@amirm just a little thing on the side, with bi-amping the polarity has probably reversed (see blue step response). This makes it a bit harder to compare the step response of the versions without and with DSP.



It is funny that the effects of the BR port resonances can be read directly from the step response (with a little courage to inaccuracy). About 5-6ms after the excitation, the decay is shaped by it.


Of course, this can be more easily read in the cumulative decay spectrum. The CSD also shows that around 600Hz there is a clearly delayed decay. Until a -30dB attenuation to the reference level is reached, many oscillation periods pass.

 

[sarumbear]

I cannot for the life of me understand why would JBL designed this speaker for bi-amp use but not use an active crossover? What did JBL gain from that omission?

There will be no extra cost involved. Why not leave the passive crossover for the single wire operation then rewire the existing link so that bi-amp terminals will bypass the passive crossover. There is a DSP on each amplifier channel. Adding LP and HP filters to the EQ is free!

 

[Waxx]

It's a bad design if you ask me. JBL should do better. The drivers are known to be good, so it must be in the design of the box and the crossover that the issues are. But I would pass for this one, especially as there are others (the ussual suspects) in that market who do much better for this price.

I'm busy with a similar design for a friend, but a bit bigger, and dsp is the only way to go for this i think to start with, and JBL should also use better amplifiers in their designs (in general) than the crowns they promote. The 2 JBL M2 setups i know and listened too were not using the Crown amps or dsp, nor the BSS but minidsp and hifi class D amps (Purifi based custom amp and NAD M22's) without ventilators and better sound. But here there are a lot more issues than that M2 in standard config, to much to think about fixing them...

 

[GWolfman]

Next year’s model will be a DIY kit where user selects the crossover components!

Shame on them for leaving too much to be decided by the end user.

 

[FrantzM]

Hi

I understand and share the disappointment from the performances of this speaker. We , however must understand, that this speaker could well be for some specific, non-domestic purposes.
JBL tend to be very opaque and some time even clue-less about their own products but they are not/cannot be stupid. Let us look at the prices (from Sweetwater.com) for the 708i and 708p, Respectively $1921.oo and $2095.oo, a difference of $174.oo.. Basically the same price, yeah I know $174 difference but, the 708p comes with 2 amps and DSP and DAC and connections.. a complete active speaker... If one needs to build a system based on the 708i you need at least a stereo amp and a DSP .. JBL recommends bi-amping thus you need 4 amps ... plus DSP... I am sure that such would not cost a total of $350,oo. This suggest other, different applications than what you would with the 708p... and they relegate control to ancillary components. There is for example the JBL Intonato 24 which can control up to 24 (!!) JBL 7 series and can be networked with JBL BLU processor. It allows automatic room correction and speaker calibration, and can control/linearize up to 4 subwoofers, and is able to use more subwoofers for LFE, situations.. Those are applications very much out of the domestic/audiophile realm. The tediousness encountered by @amirm in configuring the 708i, perhaps could be alleviated/eliminated with the Intonato 24, since it does automatic monitor calibration... It cost about $4,000.oo, plus another $1000 for its desktop controller. In the case of the 708i you would still need powerful, DSP amplifiers with the appropriate filters, they would not cost $350.oo.
All that to say the 708p is is not a solution for the casual or even, invested audiophile. It is a pure Professional product, IMHO.

The 708 p OTOH, can be (is) used with great success in audiophile systems. I think I may go this route or, to impersonate @Pearljam5000 , Genelec The One or Neuman KH-xxx or ...

Peace.

 

[GXAlan]

This “system” with the Crown amps is “not terrible” but a big disappointment.

It does suggest that using your own EQ setup would work better?

Still, I would love to see this measured with an AVR and room correction EQ. Do you have any extra AVRs you can use? @amirm

 

[jhaider]

Conclusions
At high level, the 708i provides more flexibility compared to integrated 708p. In practice, at least in the setup I tested, it proved fussy and rather difficult to optimize. Worst part is that it seems that the EQ profiles as provided by Harman are not accurate/representative of actual speaker samples.

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.

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.

But with 708p standing by, ready to go, I am not sure it is worth our while to keep testing and testing another configurations.

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.

 

[sarumbear]

Hi

I understand and share the disappointment from the performances of this speaker. We , however must understand, that this speaker could well be for some specific, non-domestic purposes.
JBL tend to be very opaque and some time even clue-less about their own products but they are not/cannot stupid. Let us look at the prices (from Sweetwater.com) for the 708i and 708p, Respectively $1921.oo and $2095.oo, a difference of $174.oo.. Basically the same price, yeah I know $174 difference but, the 708p comes with 2 amps and DSP and DAC and connections.. a complete active speaker... If one needs to build a system based on the 708i you need at least a stereo amp and a DSP .. JBL recommends bi-amping thus you need 4 amps ... plus DSP... I am sure that such would not cost a total of $350,oo. This suggest other, different applications than what you would with the 708p... and they relegate control to ancilliary components. There is for example the JBL Intonato 24 which can control up to 24 (!!) JBL 7 series and can be networked with JBL BLU processor. It allows automatic room correction and speaker calibration, and can control/linearize up to 4 subwoofers, and is able to use more subwoofers for LFE, situations.. Those are applications very much out of the domestic/audiophile realm. The tediousness encountered by @amirm in configuring the 708 i could be alleviated/eliminated with the Intonato 24, since it does automatic monitor calibration... It cost about $4,000.oo, plus another $1000 for its desktop controller. In the case of the 708i you would still need powerful, DSP amplifiers with the appropriate filters, they would not cost $350.oo.
All that to say the 708p is is not a solution for the casual or even, invested audiophile. It is a pure Professional product, IMHO.

The 708 p OTOH, can be (is) used with great success in audiophile systems. I think I may go this route or, to impersonate @Pearljam5000 , Genelec The One or Neuman KH-xxx or ...

Peace.

I can’t follow your logic. JBL says these speakers must be used with their own amplifiers. They are never intended to be be used by other amplifiers. In short they are part of a system.

The problem is in engineering. When used as bi-amp they still use the passive crossover when the DSP in their recommended amplifiers can do the active crossover with no extra cost. Everyone knows that an active crossover is always better than a passive one.

It looks like someone ferked in the Harman empire.

 

[jhaider]

If one needs to build a system based on the 708i you need at least a stereo amp and a DSP .. JBL recommends bi-amping thus you need 4 amps ...

They don't - or didn't, at least. As I've previously written the engineers behind it (many of whom are no longer there) generally preferred a single more powerful channel over biamping.

There is for example the JBL Intonato 24 which can control up to 24 (!!) JBL 7 series and can be networked with JBL BLU processor. It allows automatic room correction and speaker calibration, and can control/linearize up to 4 subwoofers, and is able to use more subwoofers for LFE, situations.. Those are applications very much out of the domestic/audiophile realm. The tediousness encountered by @amirm in configuring the 708 i could be alleviated/eliminated with the Intonato 24, since it does automatic monitor calibration... It cost about $4,000.oo, plus another $1000 for its desktop controller. In the case of the 708i you would still need powerful, DSP amplifiers with the appropriate filters, they would not cost $350.oo.

Intonato is both more and less powerful than you describe. It includes equalization for 70Xi, so you can use any amplifiers with analog or BLU-link inputs downstream. Maybe AES/EBU as well, though if memory serves Intonato only has AES/EBU inputs. However, Intonato's subwoofer capabilities are puzzlingly useless - it linearizes each subwoofer's response rather than making any attempt to optimize multisubs as a system.

I can’t follow your logic. JBL says these speakers must be used with their own amplifiers. They are never intended to be be used by other amplifiers. In short they are part of ay system.

Sure they did. You can use 70Xi with any amplifier, provided a BSS processor or JBL Intonato is upstream to complete the crossover. That option was available from launch (not Intonato, which came later, but with BSS).

 

[GXAlan]

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 think this is reflective of what we are seeing with a brand that has undergone a lot of changes. There are certainly great people working at JBL, but if you look at older “statement” products from US manufacturing era (K2 S9900) or statement products from before Samsung acquisition (4367), you can see that they measure quite a bit better than the latest SCL line from JBL Synthesis which depend more on EQ.

Mark Levinson used to be a gold standard for luxury hifi and Harman Kardon a gold standard for accessible hifi. JBL/Infinity a gold standard for speakers. Today, Arcam puts out AVRs with the same 5W SINAD as a 1965 JBL SA600. The K2 and Everest have yet to be updated with the technologies and lessons learned (differential drive woofers and HDI/ICW wave guides).

The LSR line brought Dr Toole’s and Olive’s research to the market and it is Genelec and Neumann that have taken over.

The 708 and 705 are eternally out of stock, and you would think with Samsung as the parent company there wouldn’t be supply chain issues. It is very likely that the design specifications for the speakers are good (hence Harman’s internal measurements) but manufacturing consistency flawed.

All that said, I am pretty sure I got a good copy of the 708p since it sounds great and has been very reliable. This review makes me realize that it is a bit of luck to get a good unit. (I actually bought mine from @Dj7675 ).

 

[audio2920]

I think the HF/LF balance thing is a non-issue in their real world use; but the probability of variation in the tweeters, if that is the case, is a bit of a disappointment, at least on paper. I've largely retired my 7-series (p) setup now, but I can't say I was ever aware of audible differences between them. I guess the discrepancies might need to be larger to recognise them by ear or by in-room measurement. Or maybe mine were just off the production line close enough together that they came out similar.

It is a pure Professional product, IMHO.

I agree. I'd also put some money on a large number of the installers coming from a JBL Screen Array in larger spaces, who will be competent/familiar with BSS & Crown products. I say this because the facilities I've seen them in tend to use Screen Array (OK, sometimes Meyer equivalent) in their larger spaces, and when the 7-series was launched they started be swapped in to their supporting smaller rooms. If someone can install a 4-way Screen Array, a 2-way single box install shouldn't cause them too much trouble.

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.

This is a good point, I've often seen them run in single wire mode. Maybe that's what everyone's contacts at Harman were telling them to do back when these things were new. And yeah, aside from simplifying installation, it makes obvious sense that if maximum headroom is needed (and in pro audio, it always is...) then a single 1000w amp is clearly more powerful than 2x500w (if we ignore those weird & wonderful power sharing amp designs of course )

 

[sarumbear]

Sure they did. You can use 70Xi with any amplifier, provided a BSS processor or JBL Intonato is upstream to complete the crossover. That option was available from launch (not Intonato, which came later, but with BSS).

Edit: this is the label on the speaker. It clearly says only a specified Harman amp and a signal processor should be used. Not any amplifier.

In which case there is no reason for either of these tests whatsoever other than to satisfy a hobbyist curiosity.

The diagram I posted on the part 1 thread shows both a DSP equipped Crown amplifier and a BSS. Do you know what is the reason why the Crown amp's DSP is not used for LP/HP filtering to form an active crossover?

 

[ExUnoPlura]

@amirm Can you please update the following paragraph:

Another problem is the loud ran in the Crown amp. During setup, it seemed to shut off after being powered on. Alas, once testing was done, I realized it had was running (I could not hear due to my hearing protection). This may have impacted the measurements a bit.

I am not sure what "ran" is referring to, nor what "it had was running" is back-referencing? Thanks!

 

[MAB]

@amirm Can you please update the following paragraph:


I am not sure what "ran" is referring to, nor what "it had was running" is back-referencing? Thanks!

I believe it is a typo. Ran = Fan. The amp has a fan that makes noise when it runs.