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JBL M2 Reference Master Monitor Review

Absolute

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How does the 18Sound compare to the D2430K, for measurements and for sound?
My apology for the late reply, I forgot it after sending it to the "reply later" queue.

Here's how they both measure on-axis with no EQ on the M2 waveguide - 4015BE and D2430k;

4015 vs 2430k no EQ.jpg


As we can see, the 18Sound isn't optimized for the waveguide with more wiggly behavior in the upper range, but has considerably more output lower in the range. (Below 1kHz isn't really fair here because the 2430k is used with a passive filter with a highpass function involved).
Perhaps some of this uneven response with the 4015 could be solved by experimenting a little with different washers when mounting, but I can't be bothered.
I can't find distortion measurements, but if I remember correctly there was about 15-18 dB less distortion in the 4015BE around 1500 hz.

How does the sound compare? It's just more impact combined with a more relaxed mid the 4015BE driver. Smoother and more snap/punch at the same time, if that makes sense? Anyways, for a DIY'er I would probably recommend a JBL 2451 with or without Aquaplas as a sensible middle way between the pair.

Or cutting off the flat edges of the M2 waveguide and combining it with a good smaller woofer to cross over in the 1200-1800 hz range with the D2 driver.
 

Pearljam5000

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I don't if it's a psychological thing but all horn speakers sound weird to me, like boxy sounding or something
Despite that that's one of the best sounding horn speakers I've ever heard( as much as I can tell from YouTube videos)
 

dasdoing

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boxy sounding or something

without correction the FR has resonances all over the place.
horns are like electric cars imo....you had electric cars over a 100 years ago, but something was missing: modern bateries. horns were missing modern DSP, and now that we have the processing power they will have a comeback and beat all 0-100 times
 

puppet

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without correction the FR has resonances all over the place.
horns are like electric cars imo....you had electric cars over a 100 years ago, but something was missing: modern bateries. horns were missing modern DSP, and now that we have the processing power they will have a comeback and beat all 0-100 times
Altec, JBL, Pioneer, .. all had excellent horn based loudspeakers going back 50years. No DSP involved. I think better compression drivers and enhanced horn profiles are driving the resurgence today.
 

dasdoing

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Altec, JBL, Pioneer, .. all had excellent horn based loudspeakers going back 50years

did they meassure as good as dome based speakers? I don't think so. there is a reason they have that horn-sound fame. and there is a reason domes dominate in the last 50(?) years. a dsp corrected horn doesn't sound "horny"
 

puppet

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They all had models that where very well regarded by the public/professional customers. Question should be "Did they sound as good as dome based speakers?" To many, they did sound better than domes.
 

Frgirard

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I don't if it's a psychological thing but all horn speakers sound weird to me, like boxy sounding or something
Despite that that's one of the best sounding horn speakers I've ever heard( as much as I can tell from YouTube videos)
the genelec s360 is a compression/horn speaker, have you heard them ?

Look, your next setup.
 

Absolute

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Generalizations rarely hit their mark. There's a lot of good horn/waveguides around - both for dsp and non-dsp based speakers.
But I wonder if some of the explanation for the level of "horn/waveguide" sound can be attributed to the sudden shift of directivity where the dispersion goes from controlled to comparably uncontrolled?
I would assume that it's better to have a steadily increasing directivity or constant directivity than limited-range controlled dispersion. But as we know, assuming too much will make an ASS of U and ME.

Compression drivers have this visceral physicality and impact added to the sound when the volume goes up that domes can't match and a big woofer in a big box have the same effect in the lower range compared to smaller speakers. Other than in the case of pushing the drivers or huge differences in dispersion I don't feel there's any inherent sound quality differences between types of drivers. It's the quality of the drivers combined with their implementation that decides that, with frequency response both on and off-axis as the prime factor.
 

dasdoing

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To many, they did sound better than domes.

not to majority though.
even the M2 "lost" to the Revel Salon2 for these guys https://www.avsforum.com/threads/sp...akers-ever-made.2907816/page-18#post-54628832
though there could be 2 reasons for this. 1) the Revel has not a normal dome tweeter 2) "audiophile music" is probably not horns forte. it shows it's superiority with "transienty" music, while losing to domes above 10Khz.

the sudden shift of directivity where the dispersion goes from controlled to comparably uncontrolled?

what do you mean? narrowing in the top end? that can be "solved" with a difraction slot
 

Absolute

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what do you mean? narrowing in the top end? that can be "solved" with a difraction slot
If you look at the directivity curve on the M2 you'll see that it's controlled to around 1 khz and then shifts its directivity from constant to gradually changing.

I believe the spinorama paints the M2 in a too good picture, actually. I suspect the far off-axis, between 40 to 60 degrees, matters more than we think and in that regard the Salon2 is a lot better behaved.
But I don't think that alone explains that the Salon won (by a relatively small margin).

I think the benefits with reduced SBIR of several woofers distributed in height with the Salon and the 7-10 khz peaking in the M2 is a more likely explanation. I don't believe the type of drivers or horn vs normal speaker is relevant.
 

Absolute

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Theoretically can a 708P+ sub sound like the M2?
Not likely in-room because the dispersion characteristics are different. There's also the issue of SBIR where the distance from drivers to floor/ceiling and also walls will create peaks and dips in different areas.
 

Frgirard

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Not likely in-room because the dispersion characteristics are different. There's also the issue of SBIR where the distance from drivers to floor/ceiling and also walls will create peaks and dips in different areas.
He wrote 708p+sub. The sub can deal with the sbir due to the floor.
For the celling m2 or 708 is the same fight.
 

jmpsmash

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My apology for the late reply, I forgot it after sending it to the "reply later" queue.

Here's how they both measure on-axis with no EQ on the M2 waveguide - 4015BE and D2430k;

View attachment 190134

As we can see, the 18Sound isn't optimized for the waveguide with more wiggly behavior in the upper range, but has considerably more output lower in the range. (Below 1kHz isn't really fair here because the 2430k is used with a passive filter with a highpass function involved).
Perhaps some of this uneven response with the 4015 could be solved by experimenting a little with different washers when mounting, but I can't be bothered.
I can't find distortion measurements, but if I remember correctly there was about 15-18 dB less distortion in the 4015BE around 1500 hz.

How does the sound compare? It's just more impact combined with a more relaxed mid the 4015BE driver. Smoother and more snap/punch at the same time, if that makes sense? Anyways, for a DIY'er I would probably recommend a JBL 2451 with or without Aquaplas as a sensible middle way between the pair.

Or cutting off the flat edges of the M2 waveguide and combining it with a good smaller woofer to cross over in the 1200-1800 hz range with the D2 driver.

Thanks for the reply.

The D2430k Achilles seems to be the rising 2nd harmonic after 1k.

Depends on the value/order of the high pass filter, it might recover a couple of dB in the 1-2k range so they are fairly close to each other. In either case, the limitation of final sound level is the level at 10kHz, assuming passive XO.
 

Bugal1998

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That's right, 4367 looks really attractive now. (until it might also measure not as good as what Harman shows.)

The 4367 klippel results mirror the Harman measurements closer than the M2 results. Speculation, but this makes me suspect the M2 wasn't just a smoothing difference vs. Harman, but was more likely aggressive DSP correction to make the prettiest spin for marketing.

Also surprising that the DSP'd M2 has a rougher response than the analog 4367... Really puzzled trying to understand what happened here.

A little disappointing--and not making excuses--but the pretty Harman spin-o-Rama nonetheless demonstrates the M2 system's potential when properly calibrated in-room.
 

Jonas_h

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@hardisj, some info/thoughts regarding the M2s sounding a little bright.

The M2 was once sold through Synthesis with a JBL SDEC DSP as a crossover instead of iTech amps (Similar to BSS Soundweb). Aka. the "consumer-package". It has all the M2 presets as we know them from the iTechs and it also has a high-shelf filter which is defaulted to the image below when you load the speakers.

I own the M2s and to my ears, the filter below makes them sound smoother and more "enjoyable".

1650189915047.png
 
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