2425J vs 2426J vs 275ND for 4344 clon

[manley]

Hallo

i am startet to find all the drivers for a 4344 clon (i already got JBL 2226H and some empty 2226H chassis that i will recone to 2235H

atm i am looking for the high driver 2425J

After what i can read on this forum 2425J and 2426J is the same? the 2425J is just the old production, but they should be similar in terms and speck, is that right?

and now i have strompled on the JBL 276ND (the 275ND is used in the 4344 MKII)

and it looks for me that the 276ND has the same spec as the 2425J and the 2426J


Is there someone who can confirm that i can replase the 2425J with the 275ND and use the same crossover? (see data below)

2425 Specifications:
http://www.jblpro.com/pub/obsolete/2425hj.pdf


2426 Specifications:Throat Diameter: 25 mm (1 in)Nominal Impedance: 2426H - 8 ohms2426J - 16 ohmsMinimum Impedance: 5 ohms (H), 9 ohms (J) @ 5 kHzD.C. Resistance: 3.3 ohms (H), 6.5 ohms (J) ± 10% @ 25°CPower Capacity1: 70 W continuous program above 800 Hz100 W continuous Program above 1.2 kHzSensitivity: 107 dB SPL, 1 W @ 1 m, JBL 2344A horn2110 dB SPL, 1 W @ 1 m, JBL 2370A horn2117 dB SPL, 1 mW on plane wave tubesNominal Efficiency: 25% (800 Hz to 2.5 kHz)Frequency Range: 500 Hz to 20 kHzRecommended Crossover4: 800 Hz or higher, 12 dB/octave slope minimunDiaphragm: 0.05 mm (0.002 in) pure titaniumVoice Coil Diameter: 44 mm (1% in)Voice Coil Material: Edgewound aluminum ribbonFlux Density: 1.8 T (18,000 gauss)Bl Factor: 6.3 N/A(H)9.3 N/A (J)Positive voltage to black terminal gives diaphragm motion toward phasing plugMOUNTING INFORMATION:Mounting: Three ¼-20 threaded holes, 120° apart on 57.2 mm(2¼ in) diameterFront snout may be removed (unscrewed) to exposestandard 1 3/8 in -18 screw threadsDimensions: 149 mm (5 7/8 in) diameter104 mm (4 1/8 in) depthNet Weight: 4.3 kg (9½ lb)

https://www.parts-express.com/pedocs...ifications.pdf

276ND Specifocations:
Throat Diameter: 25 mm (1 in)
Nominal Impedance:
2426H - 8 ohms
2426J - 16 ohms
276ND - 8 ohms
Minimum Impedance: 5 ohms (H), @ 5 kHz
D.C. Resistance: 3.3 ohms (H), ± 10% @ 25°C


Power Capacity1:
70 W continuous Program above 800 Hz
100 W continuous Program above 1.2 kHz


Sensitivity: 107 dB SPL, 1 W @ 1 m, JBL 2344A horn
110 dB SPL, 1 W @ 1 m, JBL 2370A horn
117 dB SPL, 1 mW on plane wave tubes
Nominal Efficiency: 25% (800 Hz to 2.5 kHz)
Frequency Range: 500 Hz to 20 kHz
Recommended Crossover4: 800 Hz or higher, 12 dB/octave slope minimum
Diaphragm: 0.05 mm (0.002 in) pure titanium
Voice Coil Diameter: 44 mm (1% in)
Voice Coil Material: Edgewound aluminum ribbon
Flux Density: 1.8 T (18,000 gauss)
Bl Factor: 6.3 N/A(H)


Positive voltage to black terminal gives diaphragm motion toward phasing plug


MOUNTING INFORMATION:
standard 1 3/8 in -18 screw threads
Dimensions: 149 mm (5 7/8 in) diameter
104 mm (4 1/8 in) depth
Net Weight: 4.3 kg (9½ lb)

https://picclick.com/JBL-276-compres...465906172.html




BR
Manley

[Earl K]

Functionally, I think the 276nd is much more like using a neodymium 2426H ( & therefore can't be used as a 2425/6-J substitute ).

One; it has the wrong impedance ( and two; the diaphragm lacks the aquaplas coating found on the 275nd ) .

See this ;







PS; BTW, the 2226H can't be reconed as a bona-fide 2235H. You can recone a 2225H as a 2235H ( if one uses OEM > JBL recone kits ).

[sebackman]

Hi maley,

A 2425 and 2426 have the same motor so with the same diaphragm they should sound identical, if within spec. The 2425 has flange mounting and the 2426 has threaded mouth and a screw-on adapter to bring it to flange mount. The diaphragms are interchangeable.

275Nd is a different animal with a Neodym core and a bigger back-cap as with most K2-series drivers. The diaphragm is also different being a coated diaphragm. I don’t now if the phasing plus is identical, maybe someone here knows.

I will likely have a slightly different output and I typically find the coated dias sounding better, smoother.

I have found that the extended back-cap design has very limited impact on the sound (at least with my ears). Changing the foam to felt may give the same result. I think all the newer large format K2-series drivers use felt instead of foam. I typically always change to felt when possible.

Best

[engineerjoe]

i believe there are different versions of the 2426. Not all have threaded throat design. I believe I have some (most) that have regular bolt on mounting? I'd have to check.
I also believe that the 2426 was a newer version and replaced the older 2425. That's only going from memory though.
I thought the 2426 came with a diaphragm that reached higher frequencies (and enhanced phase plug)?
http://www.jblpro.com/pub/components/2426.pdf
Specifications: Throat Diameter: 25 mm (1 in) Nominal Impedance: 2426H - 8 ohms 2426J - 16 ohms Minimum Impedance: 5 ohms (H), 9 ohms (J) @ 5 kHz D.C. Resistance: 3.3 ohms (H), 6.5 ohms (J) ± 10% @ 25°C Power Capacity1: 70 W continuous program above 800 Hz 100 W continuous Program above 1.2 kHz Sensitivity: 107 dB SPL, 1 W @ 1 m, JBL 2344A horn2 110 dB SPL, 1 W @ 1 m, JBL 2370A horn2 117 dB SPL, 1 mW on plane wave tubes Nominal Efficiency: 25% (800 Hz to 2.5 kHz) Frequency Range: 500 Hz to 20 kHz Recommended Crossover4: 800 Hz or higher, 12 dB/octave slope minimun Diaphragm: 0.05 mm (0.002 in) pure titanium Voice Coil Diameter: 44 mm (1% in) Voice Coil Material: Edgewound aluminum ribbon Flux Density: 1.8 T (18,000 gauss) Bl Factor: 6.3 N/A(H) 9.3 N/A (J) Positive voltage to black terminal gives diaphragm motion toward phasing plug MOUNTING INFORMATION: Mounting: Three ¼-20 threaded holes, 120° apart on 57.2 mm (2¼ in) diameter Front snout may be removed (unscrewed) to expose standard 1 3/8 in -18 screw threads Dimensions: 149 mm (5 7/8 in) diameter 104 mm (4 1/8 in) depth Net Weight: 4.3 kg (9½ lb) lContinuous program is defined as 3 dB greater than continuous pink noise and is a conservative expression of
Key Features: 25 mm (1 in) horn throat diameter Alternate 1 3/8” - 18 screw mounting 70 watts continuous program at 800 Hz 100 watts continuous program above 1.2 kHz 44 mm (1¾ in) pure titanium diaphragm Patented diamond-pattern diaphragm suspension 44 mm (1¾ in) edgewound aluminum ribbon wire voice coil Copper-plated pole piece for reduced inductance and increased high-frequency output
The model 2426H is a professional quality high frequency compression driver which incorporates JBL’s titanium diamond diaphragm. This titanium diamond structure combines the ruggedness of phenolic and composite-type diaphragms with the outstanding frequency response of fragile aluminum and exotic metal diaphragms. JBL’s exclusive suspension1, consisting of a three-dimensional diamond pattern, reduces bending stresses in the diaphragm support structure. The depth of the diamond pattern is closely controlled to provide predictable frequencies for the 2nd and 3rd normal resonance modes and for the basic suspension resonance. The mathematically determined phasing plug consists of concentric exponential horns to minimize phase cancellations. Phasing plug, throat exit tube and diaphragm assemblies are identical to the previous model. All cast parts and tolerances are held to the same levels traditionally associated with JBL designs. Additionally the press-fit assembly and interlocking parts assure greater resistance to the mechanical shock. Diaphragm assemblies are rim centered rather than pin mounted, for instant interchangeability and ease of field service. Mounting is provided for standard 25 mm (1 in) three bolt pattern. The front snout may be removed (unscrewed) to allow standard 1 3/8” 18 screw mounting. Through holes for

[manley]

Hallo All

Thanks for all the replays to this thread.

Earl K# Functionally, I think the 276nd is much more like using a neodymium 2426H ( & therefore can't be used as a 2425/6-J substitute ).

sebackman# 75Nd is a different animal with a Neodym core and a bigger back-cap as with most K2-series drivers. The diaphragm is also different being a coated diaphragm.

Earl and Sebackman: will it not produce the same sound?, because it use another diaphragm type than the 2425J/2426J?


Regarding if they have flange or threaded mounting doesn't matter, i can just make a special adapter (i hope )


I have been looking more into the 275ND and on page is saying that the 275ND is using the same diaphragm as the 2426 (2425)

have several of these JBL 276ND compression driver *NEW*
(Compare this to the 2426H that sells new for $440 at Parts Express Part # 294-412)
Identical in performance and using the same diaphragm as the JBL 2426H.
The 276ND has the legacy model numbering reminiscent of classic JBL home versions; 175 275 375 376.

https://picclick.com/JBL-276-compression-driver-New-Neodymium-123465906172.html[/URL]


The thing is when you look at the data for the 3 units (2425, 2426 and the 275ND) they have the same specification.

Sensitivity: 107 dB SPL, 1 W @ 1 m, JBL 2344A horn
110 dB SPL, 1 W @ 1 m, JBL 2370A horn
117 dB SPL, 1 mW on plane wave tubes
Nominal Efficiency: 25% (800 Hz to 2.5 kHz)
Frequency Range: 500 Hz to 20 kHz
Recommended Crossover4: 800 Hz or higher, 12 dB/octave slope minimum
Diaphragm: 0.05 mm (0.002 in) pure titanium
Voice Coil Diameter: 44 mm (1% in)

Or have i missed something?


So where can i find more data on the 275ND that can show me what diaphragm it can use?



Earl K# BTW, the 2226H can't be reconed as a bona-fide 2235H. You can recone a 2225H as a 2235H ( if one uses OEM > JBL recone kits ).

Sorry was miss writing, it is the 2225H i have 2 working 2225H and 2 chassis ready for new 2235H recone kits.


BR
Manley

[sebackman]

Hi maley,

Here is what I think.

2425 and 2426 will sound very similar, if not identical, with the same diaphragm. They may differ ever so slightly due to the threaded nose on the 2426 but if so that is probably compensated in the design. To my ears they sound the same.

If you were to use 2426 and the adapter is gone, I have a pair in the shop.

The 275Nd is a 2425 with Neodym magnet and different back-cap. The 276Nd is a 2426 with Neodym magnet and different back-cap. Ie the horn mounting differs.

As far as I know, they both used coated diaphragms from factory. I have seen pictures of non coated dia's in them but I'm not sure that is original dia's.

The coated dia's will sound different and will have a lower sensitivity. They do have a different curve that falls off a little faster upwards but do sound "calmer/better over 5k. That can easily be compensated in a filter or in a DSP.

You can also mount a coated dia in any 2425/2426 core to acheive almost the same result as the Nd's. That is what I would do.

And indeed that is what I do in all large format driver now, I mount SL dia's in all of them if they are to be used for audiophile listening.

All the best

[manley]

Hallo sebackman

Thanks for the replay and the explaining.

That make sense to me that the 275Nd is a 2425 with Neodym magnet and different back-cap. The 276Nd is a 2426 with Neodym magnet and different back-cap. nad both the 275Nd and the 276Nd is new versions of the 2425 and the 2426

because the 275Nd is used in the 4344 MKII and is very hard to get as i it look like.

Do you know in what speaker the 276Nd is used in, i've have been searched online but can't find anything about it beside it is used in some of the Synthesis home speakers ?

And do you know if the diaphragm is the same on all the models? ( 275Nd, 2425, 2426 and the 276Nd) then i can just change the diaphragm to a J type to get the right impedance.

also have can i see if diaphragm is coated?

is it possible to see the diaphragm on a 2425/2426 to if they have been change with new ones, and what shall i look for?

sorry for all my question, but i am new to this world, i am just trying to learn as much as i can.

Btw. you was mention something about a store? do you have a link to it, you are welcome to send it to me in a private message if it is not allowed in the open forum, because i am looking for places to buy some of the parts for my 4344 clons.


BR
Manley

[sebackman]

Hi manley,

Not much help here. Sorry.

I have no idea where the 276Nd's were used.

275Nd’s comes up for sale now and then but I have not seen any in a while. And to be honest I’m not really looking 😊

The diaphragms are interchangeable between all of them, but I would expect that the Nd series used coated dia's where the 2425/2426 used Alu or Ti diaphragms.

The coated diaphragms would have a matt black layer on the outside of the dome. The rest would be Alu silver or Ti silver/grey.

There are so many aftermarket dia's out there so you will have to look at the dia's installed and check against pictures and potentially identify any markings/numbers on them. There are couple of threads here at LH dealing with that.

However, if they are used and you do not know where they have been the chance is that they are out of spec and when putting in that much effort and money to build a serous monitor I recommend getting a fresh pair. I have historically used some Radian diaphragms with good results but would be deviating from the JBL originality if that is important.

I do not have access to any of the rest of the parts you need but there are many here on LH that sits on loads of nice JBL parts. Just ask.

I do have a pair of adapters from 2426/276Nd threaded nose to flange mounted horn if you need them. I’m in Europe so the chance that a fellow LH member has a pair in the US is high and that would save on shipping cost.

Kind regards

[manley]

Hallo Bebackman

i have found a pair of 2425J here in denmark

he also had a pair of 2123H i very good condition

and a pair of 075

so i have all the drivers now

next step will be to get the parts for the crosower, and wait for better whether to start building the cabinets

thanks for all the help.

BR
Manley