JBL Master Reference Monitor

[pos]

Hi Ivica,

M2 waveguide is said to be 120° horizontally, which corresponds to a 15" around 800Hz according to the Altec chart you linked above.
There will always be "problems" on the vertical axis with non coincident drivers, and looking at the power curves the Linkwitz-Riley characteristics are quite obvious around 800Hz :


- the "listening window" measurement tracks the on-axis one, which implies a well behaved forward lob
- the early reflexions curve shows a dimple, which is the result of the off axis null
- the sound power curve shows a ~3dB dimple, which is also expected with a LR crossover

All in all I'd say it looks like a pretty well behaved system

Regarding lens directivity behavior, here is an excerpt of the Smith/Keele/Eargle 1981 AES article on the 4430/4435, with directivity measurement comparisons between expo+lens and 2344 horns:

expo+lens :


2344 :

[ivica]

Hi Ivica,

M2 waveguide is said to be 120° horizontally, which corresponds to a 15" around 800Hz according to the Altec chart you linked above.
There will always be "problems" on the vertical axis with non coincident drivers, and looking at the power curves the Linkwitz-Riley characteristics are quite obvious around 800Hz :


- the "listening window" measurement tracks the on-axis one, which implies a well behaved forward lob
- the early reflexions curve shows a dimple, which is the result of the off axis null
- the sound power curve shows a ~3dB dimple, which is also expected with a LR crossover

All in all I'd say it looks like a pretty well behaved system

Regarding lens directivity behavior, here is an excerpt of the Smith/Keele/Eargle 1981 AES article on the 4430/4435, with directivity measurement comparisons between expo+lens and 2344 horns:

Hi POS,

Interestingly for me, from the figures You have attached (2344), is that the DI index for "old 4430/35" is almost like the new M2.
In either cases 2-driver box solution is applied.
Looking at the M2 DI index vs frequency, it seems to me that M2 "starts beaming" over 10kHz, something like 2344, but in either horizontal and vertical planes [as M2 horn is almost (120 x110 deg) axis symmetrical ].


Regards
ivica

[4313B]

Keep in mind that there is a single protection capacitor of undetermined value and a passive resistor network of undetermined attenuation between the D2430K and the amp. So 6 dB electronic filter coupled with 6 dB passive filter on the D2430K in the M2, just like a properly bi-amped 4430 or 4435.

38 uF series capacitor followed by 13 ohm series resistor followed by 11 ohm parallel resistor.

[pos]

Thanks!!

Driver, High Freq.
D2430K
(5032754X)
No Diaphragm Kit
Driver Only

[ivica]

38 uF series capacitor followed by 13 ohm series resistor followed by 11 ohm parallel resistor.

It seems to me that such RC network just protect the driver from ultra low frequency as its Hi-pass frequency (-3dB) is about
250Hz = 1/(2*pi*R*C) = 1/(2*3.14*18*38e-6), but sensitivity is reduced about -12dB ( driver connected as 8 ohm).

regards
ivica

[Jonas_h]

A question to the ones who own/has heard the M2: Everytime I have heard the S9900 and the Everest, I have been blown away with the characteristics of a 4" compression driver. I can't explain it, but the effortless sound and that "body" of the sound is really something I want. (I am using 3" CD's now).

How are the M2's in that regard? Do they miss something that the S9900/Everest have with respect to the 4" compression driver?

[4313B]

A question to the ones who own/has heard the M2: Everytime I have heard the S9900 and the Everest, I have been blown away with the characteristics of a 4" compression driver. I can't explain it, but the effortless sound and that "body" of the sound is really something I want. (I am using 3" CD's now).

How are the M2's in that regard? Do they miss something that the S9900/Everest have with respect to the 4" compression driver?

Maybe someone at Harman will put an M2 up against an E2 or K2 in their double blind sound room and let us know. Well, maybe not the "let us know" part...

I've heard them all in various venues, but never together, and all I can say is that the M2 is ridiculously good.

[ratitifb]

Maybe someone at Harman will put an M2 up against an E2 or K2 in their double blind sound room and let us know. Well, maybe not the "let us know" part...

I've heard them all in various venues, but never together, and all I can say is that the M2 is ridiculously good.

nice to hear you again

[Valentin]

The M2 are effortless

[audiomagnate]

It seems to me that such RC network just protect the driver from ultra low frequency as its Hi-pass frequency (-3dB) is about
250Hz = 1/(2*pi*R*C) = 1/(2*3.14*18*38e-6), but sensitivity is reduced about -12dB ( driver connected as 8 ohm).

regards
ivica

Just to be clear, all M2s come with this blocking network in place?

[Robh3606]

Hello 4313B

Thanks for posting that techsheet. Couldn't have been more timely. Just about ready to cut wood.

Rob

[MikeM]

What does the new top of the line go for retail

[JeffW]

Hello 4313B

Thanks for posting that techsheet. Couldn't have been more timely. Just about ready to cut wood.

Rob

Kudos on sourcing the M2 horns!

[Robh3606]

Kudos on sourcing the M2 horns!

I didn't source the horns. I wish! I have 2216's the PTH 1010's with 476Mg's. I was happy to get the box dimensions for the 2216's

Rob

[4313B]

You might want to make the waveguide baffle separately removable and replaceable just in case.