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JBL 4309 Review (Speaker)

voodooless

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The eye immediately goes to that bunched up response around 700 to 1000 Hz. What is the cause? We can see it in near-field measurement of each driver:

View attachment 158486
We have a boost in that region from the woofer which I suspect is due to baffle step. If so, interesting that they chose to not compensate for it. We also have a port/cabinet resonance there so the combination becomes erratic.
At first, I could not believe it, but I did a quick sim of the baffle step:

1634024735438.png

That seems to be pretty much spot on. It's a bit shifted to the low side, but that's just a guestimate of the woofer placement:
index.php
 
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voodooless

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There's also the step (ledge) between horn mouth and midbass driver which probably causes some of the funkiness (esp vertical) as well.
Yeah, thought of that first, but the distance to that ridge does not really make sense, given the frequency of the bump.
 

ROOSKIE

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708i has 91 dB sensitivity.
It's just it can boost its bass for baffle step via dsp instead of wasting that energy on heating passive elements like coils and resistors in the passive network. You can't boost in passive speakers, only reduce and sensitivity will always be of the sensitivity of the least sensitive part of FR (assuming it's linear).

Was this speaker tested with some (heavier) metal tracks?
FR looks pretty bad, but it's rather expected for a jbl speaker, jbl seems to prioritise other things than perfectly flat FR (after many speakers measured).
While I realize active speakers have some sensitivity advantages, how does boosting the bass change ultimate sensitivity?
To boost the bass with DSP requires more power to drive the boost.
In the 3 actives I have designed as a hobbyist there is about 5ish DB of BSC built-in. That did not come free.
Yes the tweeter amp is running very little juice because it's not seeing added resitances, but the woofer amp still has to power the woofer with plenty of juice.
 

ROOSKIE

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My biggest problem is that giant bass bump. I would definitely be running Room EQ and flattening that puppy out along with the room.
It can also cause bloated bass and a clouded lower midrange.
Maybe.
The Harman preference curves all have boosted bass. So if this is about preference then boosted bass appears essential.
I like a little boost starting from 150ish down to 40.
Have to measure in room and evaluate.
Also 100-130ish herz is often badly affected by nulls (depending on position) due to various common boundary interference so boosting it here may really be helping to slightly fill a deep dip.
 

Vict0r

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Ha, cute. They look like tiny PA speakers. Ugly as sin but luckily we don't listen with our eyes. €2200 a pair here in The Netherlands.
 

SS55

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@amirm Do you have the CSD data of this speaker? Would be interesting to see the resonances.
 

thewas

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At first, I could not believe it, but I did a quick sim of the baffle step:

View attachment 158556
That seems to be spot on.
Would be interesting to know if the reasons they decided not to correct it. Possibly both budget, crossover size and audibility related, not so audible for extra complexity, size and cost of the crossover. The crossover has already quite some size and components:

JBL-4309-Picture4.jpg


Source and more interesting info about the 4309 https://www.harmanluxuryaudionews.com/2021/04/27/jbl-4309-features/
 

MZKM

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Damn, that's lower than I was expecting. I was expecting low 5s, mainly due to the excellent directivity(which is SOTA). Also, while there are a lot of resonances, the overall shape of the FR looks decent. I think good directivity is maybe more important than the Olive score gives it credit for. Very similar situation to the DIYSG horn that Erin measured awhile back.

Is this the lowest Olive score we've seen for a 5/5(Golf panther) rating?
The preference formula doesn’t take into account directivity in terms of similarity between curves. So this is another instance where the formula could be improved (along with fixing the bias Smoothness gives bias to narrow dispersion).
 

headshake

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Another JBL head shadow XO. It seems 1500hz or so is where you put the mess.

From a paper on hearing aids, but the idea is the same.
"The findings reported here show that a fixed polar pattern can act very differently from expected when it is worn on a head, due to head-shadow effect and microphone placement. This finding suggests that a polar pattern will respond differently on differently shaped heads and with different instrument styles, and further investigation is warranted to examine these issues."

Is audio preference like phrenology (but real)?
 

aac

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While I realize active speakers have some sensitivity advantages, how does boosting the bass change ultimate sensitivity?
To boost the bass with DSP requires more power to drive the boost.
In the 3 actives I have designed as a hobbyist there is about 5ish DB of BSC built-in. That did not come free.
Yes the tweeter amp is running very little juice because it's not seeing added resitances, but the woofer amp still has to power the woofer with plenty of juice.
Ultimately you don't need to heat up some passive elements in the crossover and it might be simpler to drive.
 
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uwotm8

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I'd post some obviously better measurements from reviews here with a lot more "issues" marked but I'm too lazy for that.
1 kHz mess can't be unhearble but is nicely ignored through the review (textbook perfect directivity).
Estimated response is a tragicomedy. It must sound heavily colored in upper midrange.
Binding posts are dirt cheap, a shame for $2k speakers.
Also didn't find the bass (except "cheap hi-fi trick" - a 100+ Hz bump).

Definitely a top tier:)
 

abdo123

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I’m really scratching my head now. What’s going on here?
Most of the FR graphs look horrible. Psychoacoustic outlier?

I have just checked the KH310 estimated in-room response graph which was marked by amir as a bit “uneven”.
Then how should this here be labeled?

Why bother measuring all that stuff if it seems that there are single/few/unknown (?) parameters which can outweigh every other sin? This result does support all the high end nonsense (?) that there is more to a speaker as you can measure and that designing speakers is not understood at all.

And please explain what is “nice tonality”. Colored speaker which happens to sound good?

Don’t take this post too seriously, I’m shocked.
Must meditate…

my 50 cents:

the speaker is flat to ~100Hz with a slow LF roll-off so it's F10 is ~37Hz. This is really the best response for 'quick' reviews because the speaker doesn't stimulate the axial room modes so intensely and the bump at 100Hz gives the illusion of punchier faster bass.

Now since the speaker has naturally high maximum output this meant that Amir had basically flawless reproduction of dynamics (he has 1000W on tap afaik) and none of the resonances were severe enough to muddy the 'punchy fast bass' illusion of the 100Hz bump.

The directivity was also good so nothing stood out in the sound stage.
 

aac

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Why it is omnidirectional at around 1 khz? Cabinet vibrates the same as the driver does at that frequency?
 

xaviescacs

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Personally, I use the score as a summary of speaker's performance, don't even look at the panther. If anything could be improved is the way the score is calculated, to take into account some more factors as @MZKM explains. However, then some speakers that have already a good score and also perfect directivity may increase their score, leaving others behind again. This will also have the benefit of being able to recalculate everything, unlike subjective opinions. Some people may trust amir's judgment, some may not. What is nice is that we have all: measurements, opinions and score.
 

Dmitri

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I hear you but not sure of your logic. Here, you are seeing objective measurements of this speaker with a $100,000 measurement system. Where would you go to get such data???

Getting more specific, the measurements are not the same. Outside of a few near perfect speakers, the rest have different levels of aberrations. We could sit there and guess what they mean as far as audibility or listen. I do the latter and provide that data point. In this case, you have not only me, but another reviewer, @napilopez having measured and listened with the same conclusions.

I think with many speakers, our objective clues are very revealing. Ultimately though, this is not a 100% precise science given the screwed up way audio systems are designed (we never know the tonality of music that is produced). I could paper over this and damn or praise speakers strictly on measurements. But I have chosen a balanced approach, damn the criticism I get from both camps.

I think we should be happy with 80% correlation between measurements and listening tests. The other 20% is there for us to think about. Could be that I am totally wrong in my assessment. Or that some factors in the measurements we are not appreciating (e.g. textbook perfect directivity of this speaker -- try to find that in headless panther measurements).

We could make forward progress if you could get a pair to listen to with return privileges. Do that and let us know what you think. I am quite confident this speaker will perform and perform very well.
That was one of the best man pants responses I’ve heard from anyone in a long time. Well done.
 
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