Thanks for sharing this pos, its really interesting stuff. Similar measurements with the 476Be/Mg would be a real treat but I know they are hard to come by.
/Mostly
Thanks for sharing this pos, its really interesting stuff. Similar measurements with the 476Be/Mg would be a real treat but I know they are hard to come by.
/Mostly
Thanks for the measurements. Did you pick these up from Ebay in USA? I had my eye on a pair!
The 32 ohms may actually be a problem if the amp is specifically optimised for low noise.
Have you made any measurements with the VCs in parallel rather than series?
Best wishes
David
Yes these come from ebay.
I did not try the 8ohms setup, but I'd expect the measurements too look the same, once the noise floor of the amp has be taken off the equation (by the use of an lpad or an autoformer)
What amp are you thinking of?
Lucky I did not bid and raise your cost. Must check here next time I want a pair.
I think there is a coupled mode that can exist when the VCs are in parallel, that does not exist for series connection.I did not try the 8ohms setup, but I'd expect the measurements too look the same
Ideally the two sides are perfectly equal and there will be no excitation of that mode, the measurements will be the same.
I wondered about the difference in reality. Would be an informative test, if the results are the same then the driver is close to theory.
I plan a dedicated compression driver amp of ultra low noise.What amp...?
Much better than a standard amp that has to be wastefully padded down
I have mentioned it a few times in DIYaudio, where I see some of your posts too.
Lower VC resistance alters some of the trade-offs in resistor noise, power loss in the feedback network etc.
Best wishes
David.
4313b posted the M2 technical manual in another thread.
The manual clearly states there is no replacement diaphragm for the D2430K:
This is quite choking for such an (apparently) fragile driver aimed at professional use.Driver, High Freq.
D2430K
(5032754X)
No Diaphragm Kit
Driver Only
One advantage of this technology over big Be (or Mg) diaphragms is obviously the cost of the diaphragms themselves, so if one cannot buy replacements this is getting a bit silly.
Then I checked the VTX25 tech manual, and it states the opposite:
Compression Driver (3)
D2430K
(446213-001X)
Diaph Repl
D32RD2430
The 32 ohms marking seems to indicate that the replacement kit is the pair of diaphragms, maybe already assembled as opposing rings?...
That would be logical as matching between the two diaphragms is critical (for distortion canceling), and sealing is also probably a big issue here.
Also interesting to note: the part list for the driver itself is different... (?!)
That said, I have had a pair of D2430K in my hands and to be honest I do not even see how one is supposed to open the damn thing to install new diaphragms...
Maybe under the foilcal, like the old ring radiators?
Would anyone have information (price?) on these replacement diaphragms?
I wouldn't sweat it... I doubt you would ever be able to buy replacement diaphragms.
The current direction JBL is going is free driver replacement while under warranty and buying a replacement driver after that until NLA... my real fear is that NLA may be sooner than would have been considered reasonable before everyone started sharpening their pencils scalpel sharp.
Widget
JBL Pro took down their Transducer Parts List a while back, no more checking by the public to see if a replacement part is even produced anymore.
Well, I think I'll stick with the good ol' 1.5"/4" compression drivers: they are easy to service, can perform admirably (especially with Be), and beside JBL there will always good diaphragms for these on the market for a reasonable price (Radian, Truextent, etc.).
It seems JBL expects the M2 owners not to blow them, and if they do then to have the money to buy a complete replacement.
But PA/tour operators are expected to blow out drivers so can buy replacement parts,
That would almost make sense if the M2 driver is perhaps a selected/matched unit, perhaps why the different part number?
Or is it just an assumption that M2 owners can be squeezed harder?
A >$1000 driver that is a throw-away item would make me very reluctant to buy.
Best wishes
Dave
That is exactly what I was told today by KW55 (he also told me the M2 exceeded by far everything he had listen to in his showroom )
That makes sense indeed, as matching between rings and proper installation is probably paramount with this push/push distortion cancellation strategy.
The D2 is considered a replacement part rather than a finished good like other JBL compression drivers so it runs around $1.5k a pop instead of $2k a pop.
Harman has gone to a whole driver replacement strategy.
There were D2 replacement diaphragm kits, I would assume they are still available to JBL Pro Service Centers.
The performance of the M2 isn't trivial. JBL was not blowing smoke when they called it a game changer.
The only problem I have with the entire scenario is people having spent serious money on K2's and E2's... my very first reaction to the M2 was within the context of the K2 and E2. "Uh oh..."
What about the "selected D2" scenario for the M2?
Have you heard anything along those lines?
That would explain the difference in part number between the VTX25 and M2 spec sheets.
No, I have not discussed that with anyone.
Having seen conflicting info, I'd like to check my understanding...
The 2430K uses 3" VCs, the 2415k 1.5" VCs. Correct?
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