best horn for 2425?

[alec]

hello,

i have a pair of the 2425j drivers an the 2370 horns. i don´t like the sound of the horns...is there an better sounding alternative?
the crossover frequenzy must not be so low.
does it work with the nice and small rcf H100 ?
the driver has to work with a 10" midbass.

thanks, alec

[Robh3606]

What don't you like about them??? There several combinations you could use but it's hard to say without some idea of what you are looking for. IMHO the 2344 is a tuff horn to beat. Can go to 1K. The standard 4 way crossed to a 10" mid @ 1.2k add a 2307 and 2308 Lense but you will probably want a 2405 on top.

Rob:)

[alec]

@rob

i want a small, 2way mid high top with a 10" midbass. it mustn run standalone, i will use it with a sub. the 1" has to run from ~1,2k to the end. the 2370 ist to big for my small satellite, thats the reason why i m looking for an 60/90 alternative.

regards, alec

[Guido]

Try the new waveguides

http://www.jblpro.com/ae/pdf/PT_WaveGuide.pdf

I'll try the 100x100 Version instead of the 2344 in near future.

[rpstephen]

Are these new waveguides available to purchase as separate components? I am looking for horns to build a system for a friend on the order of a 4430 type system. I already have some old LE-85s a 2440 driver, a pair of 2334s, 4 LX-5 xovers, etc.
Thanks

[sebackman]

Hi Alec

Are you using a 2425 or 2426?

I just got a couple of the new JBL OASR 1" horns to run with my 2426 drivers in the rear speakers of my HT. Fronts and Centre will be 2451 with 2332.

The OASR is a 4th (I think) generation conical horn with 85x85 pattern. I do not have much info about it, except that it is used in the SRX and Marquis series currently.

From what I can figure out it seems to have been introduced during 2002 or 2003 so it should be based upon then new equations, being used for among others the waveguides mentioned above.

It is a CD horn, which makes it a little different to the, by now, rather old 2370s. The 2370 is a Bi-Radial design.

I have no idea of how they sound for home use yet. I have heard the SRX, and they do sound decent to me. Anybody else with input on this horn paired with the 2426 driver?? Giskard, Mr. Widget or somebody else?

It is very compact and rather shallow which suits me perfectly for a small 2-way rear HT speaker. I'm going to flank it with two 8" drivers, one on each side.

My conclusion was the same as yours; the 2370s are too big for what it delivers for home use. The newer designs seem to be better suited for home use although the 2370 still do deliver the goods in professional applications. If I were designing a stage monitor for live performance I would seriously consider the 2370. But then gain, I’m not. J

Please se; http://www.jblpro.com/pub/mi/srx_chrt.pdf

The only difference between 2425 and 2426 seems to be the mounting options. The 26 have a threaded throat under the adapter ring where the 25 only offer flange mounting. The OASR is a thread-mounted horn

If you do have 2426's or know of how to make an adapter to threads I can post some measurements of the OASR/2426 during the weekend if you are interested.. Please advise.

Best regards

//Robert

[Guido]

Hi Stephen,

you can by them and they are not so expensive also.

See:

[alec]

hi,

i have the 2425 drivers-does that mean i have to use an adaptor for the OASR 1? the price is ok, but i don´t know if i can buy them for this price here in germany...

@sebackman
could you please send me a photo and datasheet of the OASR?
mailadress: axxe_at_gmx.net

thanks for your replies!
regards alec

[sebackman]

Hi Alec

I will try to take some pictures tonight and post them for you.

And yes, the OASR is does not have the flage but a screw-on neck with threads. I don't know if there are adapters that go from flange to thread. The other way arround is easy.

You could possibly find somebody in you area that repairs JBL and ask if they would be willing to swap the houses if they have 2426s mounted on a flange type horn, where they do not need the treaded neck. 2426 uses an adapter ring to mount to horns with flange mounting. You just unscrew the adapter and there you have the treads.

You will see from the pictures later how it works.

Best regards
//Robert

[alec]

thanks sebackman!

[sebackman]

Hi Alec

Here are some pictures of the horn and the 2426 drivers. The other driver on the pictures is an 8" driver just for comparison in size.

http://www.bostream.nu/sebackman/OASR/Cargonet1A%20001.jpg

http://www.bostream.nu/sebackman/OASR/Cargonet1A%20002.jpg

http://www.bostream.nu/sebackman/OASR/Cargonet1A%20004.jpg

http://www.bostream.nu/sebackman/OASR/Cargonet1A%20005.jpg

http://www.bostream.nu/sebackman/OASR/Cargonet1A%20006.jpg

http://www.bostream.nu/sebackman/OASR/Cargonet1A%20007.jpg

http://www.bostream.nu/sebackman/OASR/Cargonet1A%20008.jpg

Best regards

//Robert

[Robh3606]

Hey Rob how do those OASR's sound?? Do you have to compensate them?? If so how?? Any frequency response curves on the horn??

Thanks Rob:)

[Guido]

The network of the 4722x looks strange.

I do not understand that kind of compensation :confused:

http://www.jblproservice.com/pdf/SR-X%20Series/SR4722X.pdf

[4313B]

Here's what I get tossing it into spice real quick Guido:

[Guido]

Strange, isn't it?

[sebackman]

Hi all fellow JBL nuts

I will try to run some FFT analysis on the horn/dríver combo today or tomorrow and post it to the forum.

-And hopefully listen to it in my test rig. It is really a neat horn/driver combo and if it sounds decent if would be nice.

I just got my new Crown CTs8200 Power Amp that I just have to set up first. 8x200W with digital active XO’s for the low (above 40Hz) and mid's in my new HT system. Yeeeeehaaaa.

I will run a Crown CE4000 or K2, if I can find a used one at a decent price, for my JBL SUB1500 subs. :D Nice to keep the stuff in the family… Any hints on where to get one in the US or Europe?

Why does it always get out of hand once you start building. :D :D

The nice XO curve posted by Giskard seems very normal from my experience. XO is 1.2k and the difference between the curves is the difference in sensitivity between the 2206 and the 2417, about 20db at XO from the looks of it. Remember that the 2206 is a 12db XO and the 2417 is a 18db XO so the summation is not just to add them. I will have to throw in the in my simulator to se what the sum looks like but Giskards probably have that curve already. The 2206 will continue further up in frequency before dropping off, hence the damping on the 2427 will have to be higher that the actual sensitivity difference in the spec sheets because the sum is higher than either of the components.

Then you have the CD horn compensation from about 3k. A CD horn, Constant Directivity, falls about 6db per octave from about 3k as a consequence of keeping the energy pattern constant over the distribution angle. In order to keep the energy constant over the distribution angle you will lose sensitivity as frequency increases. In a regular horn with reasonable dispersion, the fall in sensitivity by increasing frequency is compensated by narrowing the dispersion pattern with increasing frequency. The horn gets narrower as frequency increases. This is normally not the case with a CD-horn, hence you will have to compensate for the lost sensitivity in the filters (active or passive). I know that there is a good White Paper about CD/Bi-Radial horn design at the JBLProService site, I just can’t find it. Anybody have a good link.

The filter topology seems to be JBL standard. It is the same as in many of the newer designs, even the new K2 with minor additions.

The dip between 1.5k and 3k’s is probably not there in the real world. I guess that Giskard may have run his graph with zero inductance for the driver and if you add that it may be rather flat. One also has to include baffle refraction into the equation to see the final result as measured by JBL. Giskard please correct me if I’m wrong.

I normally use measured curves when I model so I’m not so familiar with what happens if the parameters are simplified

Best regards

//Robert

[4313B]

"I will try to run some FFT analysis on the horn/dríver combo today or tomorrow and post it to the forum."

Excellent! :)

If you could provide an impedance curve of the combo that would be great too ;)
Maybe one of just the driver as well so we can see how the horn loads it :)

"The dip between 1.5k and 3k’s is probably not there in the real world."

Yes, probably so. I don't know what the DCR values of the actual inductors are and I simply ran a quick voltage drive on the filter from a "service" perspective ala "Standard Test Fixture (http://www.jblproservice.com/pdf/Network%20Schematics/Standard%20Test%20Fixture.pdf)" only I used the DCR values of the drivers instead of the "standard" 8 ohm or 16 ohm loads just for fun :p

"I normally use measured curves when I model so I’m not so familiar with what happens if the parameters are simplified."

Yep, that's best practice :yes:

[Guido]

Giskard!

Maybe I'm to stupid but I have such problems to handle the p-spice program.
You could do me a big big favour if you could mail me the network that you made for the x-over curves.
Starting from this and examining this I will learn how to do it.

Thanks!

[email protected]

[sebackman]

Hello all,

Here are some simple curves for the 2426/OASR combo.

I have run it in my testbed and it sounds quite good. The highs (>13k) are better than the 2451/2332 combo but for the rest the 2451/2332 sounds better and more relaxed. But there is a big defference in size and price.

2426/OASR does a good job and I find the OASR better suited for home use that the 2370. I will use the combo in a two-way construction.

Hope it helps.

SPL

http://www.bostream.nu/sebackman/OASR/2426OASRrev0.jpg

Without horn

http://www.bostream.nu/sebackman/OASR/Impedance2426OASR%20no%20horn.jpg

With OASR horn

http://www.bostream.nu/sebackman/OASR/Impedance2426OASR%20with%20horn.jpg


Best regards
RoB

[sebackman]

Hi again

Here is a curve over a active two-way system with two 8" drivers together with the 2426 and OASR horn. It is from my test bed, meaning that the signal is fed in digital form from the computer into the digital XO, corrected and converted to analog and then on to the power amps.

Cross-over is at 1k and I have a shelving filter on OASR with 12db slope +13db @ 14kHz.

Not bad. Look at the scale!! :D

Sounds relaxed and fine. When I add the O25Ti from 14k the sound opens up a bit.

The lack of SPL below 400Hz is a function of the short window and in reality the SPL is pretty even down to 50Hz in this set up.

***Should be an image here, but i don't know why it does not show up. I will edit this post later and see if I can get it in there***

http://www.bostream.nu/sebackman/OASR/Dual%208%20&%202426%20OASR.jpg

Robert

[johnaec]

...active two-way system with two 8" drivers together with the 2426 and OASR horn.Robert - is that an 8" low-mid in your avatar picture? 2118H/J?

Also - I saw your pic by clicking on the link before you edited it. Could you maybe explain it a little for those of us not quite up on Fast Fourier Transform, especially what the red dashed lines are in the pic/link you're editing?

Thanks - John

[sebackman]

Hi johnaec and others,

I don't know why the picture becomes a link instead of showing the picture. Well, the link works at least.

You can read about FFT/MLS at:
www.MLSSA.com
www.linearx.com

and others

MLS/FFT is basically a very noise robust measuring system that gives you the opportunity to make measurements in a normal environment without the draw-back of room interference destroying your info. It's simple to use but rather complex technically. There are many programs in the market offering this feature so please run a Google (or similar) search for FFT + MLS if you want to dig in to the technical stuff (be prepared for long nights… :D )

The red line is the phase shift. It looks kind of funny because the timing was not right. This was only a quick run and normally you would set up each driver on it’s own and then add the curves in the program. The strange phase curve here is probably due to the drivers being in different “time windows” due to physical placement (2426 just laying loose on the to of the speaker) and the window being rather short. I could run a real suite, but it would take time and this was just meant to give an idea of what it could do and it’s really not bad.

Simplified, please disregard the red line.

Oh, and yes it is a 2118J in the picture. You do have sharp eyes. The others are a 2234, a 2421 (with 2425 membrane) on a 2344 and a 2404.

Best regards

//Robert

[johnaec]

Thanks for the info on the FFT. I used to work for a sound company that used a B&K FFT analyzer at live gigs, but wasn't aware enough of it at the time to really get into what it was doing.

How do you like the 2118J? What crossover points are you using? Was it problematic incorporating the 16 ohm 2118J in the crossover? I've been thinking of picking up a pair of used 2118 to see what they'll do, but am thinking of the 8 ohm H version to simplify things.

Thanks - John

[GordonW]

Guido wrote:

Strange, isn't it?

No, that's not strange, for use with a constant-directivity (CD) horn.

Remember, CD horns have a natural falling frequency response with increasing frequency! To make them flat, a crossover with an "upward" tilt, such as the HF section of the graph above, is needed. They're VERY efficient at low frequencies, so the inherent extra output of the driver/horn down low, will "fill in" what looks to be a hole, and by the time we get to the highest frequencies, the horn will have "toned down" enough to be at the right level up there too...

Regards,
Gordon.

[herve M]

sebackman,
minimum recommended crossover frequency for oasr ?
Herve

[sebackman]

Hi Herve,

By the looks of the curves it seems like it will load the driver from about 750-800Hz. JBL uses above 1k XO's with 1.2k being the lowest I have seen. I think the horn can do lower than that and that it might be a power handling issue for the driver.

I have tried to move the XO lower in my digital filter and with a steep slope (>=18dB) it seems to be ok but sounds a bit harsh. From 1.2-1.4 k that harshness is completely gone.

I will have to XO at 1k due to the fall off in my drivers below the 2426/OASR combo. With a steep filter, 24 or 48 db slope, it sounds fine to me.

Using a 12db filter I would do1.5-2.5 k XO. Using 18db slope I think it is fine from about 1.2k.

Hope it helps

Best regards
//Robert

[alec]

@sebackman

1000 thanks, great job!

regards from snow-white germany