JBL M2 Reference Master Monitor Review

[MAB]

What is the frequency cut of the woofer?

790Hz. The crossover details are here. Erin has a graph of individual driver responses in the review:

 

[jtwrace]

Still the best speaker I've ever heard and owned; I just don't see them going anywhere.

 

[Pulkass]

790Hz. The crossover details are here. Erin has a graph of individual driver responses in the review:
View attachment 398402

 

[Pulkass]

Oh yes, a compression wide range mid tweeter, can't get lower 800 hz.

 

[JoshK]

Did anyone every measure the larger format drivers (e.g. JBL 2451SL) on the M2 waveguide? I am in need of replacing the CDs in my M2s due to damage and am really intrigued with giving the larger format driver a go.

 

[jtwrace]

Did anyone every measure the larger format drivers (e.g. JBL 2451SL) on the M2 waveguide? I am in need of replacing the CDs in my M2s due to damage and am really intrigued with giving the larger format driver a go.

Why mess around with a proven design? Replace them!

 

[MAB]

Did anyone every measure the larger format drivers (e.g. JBL 2451SL) on the M2 waveguide? I am in need of replacing the CDs in my M2s due to damage and am really intrigued with giving the larger format driver a go.

The 2451 has 1.5" exit, the D2 lens throat is 1", so it seems like a particularly bad fit.
It will also need an adapter, since the bolt pattern on the 2451 is much different. And the clearance is minimal.

 

[JoshK]

The 2451 has 1.5" exit, the D2 lens throat is 1", so it seems like a particularly bad fit.
It will also need an adapter, since the bolt pattern on the 2451 is much different. And the clearance is minimal.

the D2 is a 1.5" exit CD. The bolt pattern could be different, I'll give you that.

I am ordering a pair of replacement D2s, but that is a month out ETA right now. I've read some others experimenting and preferring larger format drivers, but I had wondered if anyone had data to back it up.

P.S. I have a 3rd M2 that took most of the damaging to the cabinet, but quite possibly to the CD as well. It is in storage, but I was planning on taking the waveguide out of that cabinet to experiment with and measure. Haven't done measurements in many many years, but I do have one traditional 1.5" exit CD coming, the SB Rosso something or other that was inexpensive, that I was planning to use to resurrect another project in storage for fun.

 

[kemmler3D]

am really intrigued with giving the larger format driver a go.

I think you should try it if you're game, but per other commenters, it's not necessarily a 1:1 swap, more like redesigning the speaker. It could be worthwhile but you'd need to redo the crossover, do lots of measurements, etc. etc.

 

[MAB]

the D2 is a 1.5" exit CD.

Oops! Yes, I forgot they are 1.5"!

The bolt pattern could be different, I'll give you that.

I am ordering a pair of replacement D2s, but that is a month out ETA right now. I've read some others experimenting and preferring larger format drivers, but I had wondered if anyone had data to back it up.

P.S. I have a 3rd M2 that took most of the damaging to the cabinet, but quite possibly to the CD as well. It is in storage, but I was planning on taking the waveguide out of that cabinet to experiment with and measure. Haven't done measurements in many many years, but I do have one traditional 1.5" exit CD coming, the SB Rosso something or other that was inexpensive, that I was planning to use to resurrect another project in storage for fun.

What the heck happened to damage them?

 

[JoshK]

Yeah, I understand it isn't a straight ahead swap. I am well aware of what goes into designing crossovers, as I used to play around with this a lot in the past. I am soon to get my dspNexus 2/8 which will yield measurement capability and ability to designing crossovers in the digital domain. First, I want to get the M2s running again per original design, but I have an itch to scratch, which I may just do with the 3rd damaged one.

 

[JoshK]

Oops! Yes, I forgot they are 1.5"!

What the heck happened to damage them?

smoke damage from an adjacent fire. At first I thought they were fine as the impedance measures fine and two cabinets don't have an noticeable damage, but when I setup the crown files again the tweeters sound really veiled, which was very much the opposite of how they used to sound. I am going to measure them to see if it isn't something else, but I think they were sensitive to the smoke.

The one cabinet got water damaged when putting out said fire and the cabinet warped and delaminated badly. The lense is perfectly fine cosmetically still so I can use that for playing around.

 

[Bugal1998]

First, I want to get the M2s running again per original design, but I have an itch to scratch, which I may just do with the 3rd damaged one.

I've had that same itch on many projects.

 

[beatelund]

My friend @sebackman have done measurements on many JBL CD on different JBL WG.

This what i had in my Phone.
Can do some other comparisions when i get home.

Attached is
No smoothing, 1m, no eq or comp.
-D2 on VTX, M2 & 4367 WG
-2451(475ND Old K2 diaphragm, flat Alu +coating) on VTX, M2 & 4367 WG
-D2 and 2451(475ND) on M2 WG

The 475ND is smoother than standard 2451-SL

In a M2 i had taken the D2. It is a proven system and very good sounding (have 5 of them)

In a Diy solution or if you just want to do something different and try to best JBL engineers try the 2451-SL.

We have built some very Nice sounding 4367 with the 2451-475ND combo.
Magical

 

[JoshK]

Thanks for the info and data. I'm curious where you got the 4367 horn. The 475 on the 4367 looks great.

I am not trying to better JBL engineers. I was more curious on the tradeoffs. Would it sound "more effortless" with a larger format driver but give up some top end? Don't know how you measure that.

 

[beatelund]

What i know JBL stopped the 4367 WG for DIYers a time ago

Did some more comaprison. Aligned at 2khz, no smoothing, 50cm or 1m, 6ms, if eq it says so


And some picture on my 4367 diy. They are active and with 2451+475ND and 2216ND-1
They turned out amazing

Sometime ago a couple of friends i did a comaprison with my M2s.
We had a rotating chair and so we could turnaround easy. Then we controled the music with Roon, so we could easily paus the other setup when turning around.
The systems where level matched and had the same bass curve, so as good as we could do it in this setup.

Both systems is crazy good, but we could all agree that the 4367 with 475ND was our choice for music

The conclusion was that much of it comes from the lower part of the CD, the 4367 have a crossover at 700hz and M2 is original at aprox 800hz.
But it also sounds a bit moore smother/warmer up top, even if the freq after eq is really close.
Also the 2216ND doesnt have to be stretched that high and problably something to do with the bigger WG as well.

Really fun experience.

 

[Speaker-Inquisitor]

IIRC the 4“ Voicecoil Drivers have a much lower distortion in the area between 700-1500hz.
I use 2450SL on the M2 Waveguide in my living Room Setup, sounds Great.
Imho JBL uses the D2 because its a cheaper driver to manufacture and its good enough for the purpose.

 

[MAB]

What i know JBL stopped the 4367 WG for DIYers a time ago

Did some more comaprison. Aligned at 2khz, no smoothing, 50cm or 1m, 6ms, if eq it says so


And some picture on my 4367 diy. They are active and with 2451+475ND and 2216ND-1
They turned out amazing

Sometime ago a couple of friends i did a comaprison with my M2s.
We had a rotating chair and so we could turnaround easy. Then we controled the music with Roon, so we could easily paus the other setup when turning around.
The systems where level matched and had the same bass curve, so as good as we could do it in this setup.

Both systems is crazy good, but we could all agree that the 4367 with 475ND was our choice for music

The conclusion was that much of it comes from the lower part of the CD, the 4367 have a crossover at 700hz and M2 is original at aprox 800hz.
But it also sounds a bit moore smother/warmer up top, even if the freq after eq is really close.
Also the 2216ND doesnt have to be stretched that high and problably something to do with the bigger WG as well.

Really fun experience.

They look really great too. Thanks for sharing, very inspirational.

 

[JoshK]

Yeah I was going to say, the 4367s look great! I love Mahogany. I built a pair of AE TD15X bass bins, I still have in storage and used dyed Mahogany as my ex liked the old bombay mahogany look.

I'd still love to mate some good horns with those "bass bins" to play around with; the 4367 horn or ones like it would probably work well. I plan to use D2s in the M2s as intended, but since I was fixing them anyway, thought it might be a good time to tinker.

 

[srm51555]

IIRC the 4“ Voicecoil Drivers have a much lower distortion in the area between 700-1500hz.
I use 2450SL on the M2 Waveguide in my living Room Setup, sounds Great.
Imho JBL uses the D2 because its a cheaper driver to manufacture and its good enough for the purpose.

Greg Timbers mentions the higher distortion in that range is due to the lack of mass of the annular diaphragm. This was mentioned on Lansing Heritage in the 4367 First Impressions thread along with some other information. The site is currently down, but I will post a link when it's back up. I have tried both D2, 2450SL, and 2451's. I settled on the 2451's in m M2 build per recommendations from sebackman who has put great effort in measuring many combination of waveguide and compression driver.

Thanks,
Scott