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View Full Version : JBL 2446 crossing to JBL 2405 what frequency?



David Ketley
10-17-2014, 11:08 AM
I use the JBL 2446 on a 18 Sound XT1464 horn, this crosses from the JBL 2123 at 1600hz and I like the sound it makes.

Im in a quandary of what crossover frequency to use between the 2446 and the 2405?

The 2446 seems to drop off at about 7000 hz whilst a lot of recommendations seem to state the 2405 should be crossed a lot higher?

Im having to run the 2405 passive as my Marchand active crossover is only 3 way any suggestions on the best way to solve this problem?

Dave

yggdrasil
10-18-2014, 02:44 AM
Easiest approach: set crossover point to -6dB point and add high-pass to only the 2405's.

Kalle
10-18-2014, 10:44 PM
Easiest approach: set crossover point to -6dB point and add high-pass to only the 2405's.

I think that can be achieved with a 1f cap on the positive lead to the 2405. I`we been told it is an old trick for adding 2405/2404 for more UHF in boxes with large format drivers. One possible problem is angliment/delay/phase due to placement.

/Karl

ivica
10-19-2014, 12:30 PM
I use the JBL 2446 on a 18 Sound XT1464 horn, this crosses from the JBL 2123 at 1600hz and I like the sound it makes.

Im in a quandary of what crossover frequency to use between the 2446 and the 2405?

The 2446 seems to drop off at about 7000 hz whilst a lot of recommendations seem to state the 2405 should be crossed a lot higher?

Im having to run the 2405 passive as my Marchand active crossover is only 3 way any suggestions on the best way to solve this problem?

Dave




Hi Dave,
May be I am wrong, but mentioned 1464 horn is 1.4-inch throat horn, while 2446 is 2-inch driver, so a kind of interface plug would be well-come. I think that such way of using 2446 driver is not the best solution at all.
One more thing is that if you plan to use a kind of CD type horns a kind of CD-horn correction has to be applied.
Using 2446 up to 10kHz (even 12kHz) would be usual, with the proper horn type.
so using 2405 over 10kHz would be optimal (from my point of view). A proper filter for 2405 can be seen as 3155 network as an example.

regards
ivica

David Ketley
10-19-2014, 01:23 PM
Hi Dave,
May be I am wrong, but mentioned 1464 horn is 1.4-inch throat horn, while 2446 is 2-inch driver, so a kind of interface plug would be well-come. I think that such way of using 2446 driver is not the best solution at all.
One more thing is that if you plan to use a kind of CD type horns a kind of CD-horn correction has to be applied.
Using 2446 up to 10kHz (even 12kHz) would be usual, with the proper horn type.
so using 2405 over 10kHz would be optimal (from my point of view). A proper filter for 2405 can be seen as 3155 network as an example.

regards
ivica

My aim is to try and use speakers in there best range without EQ hence ending up with a 4 way system. All because a speaker gives a straight line on a graph it doesn't mean it sounds good.

I know I run my systems with more top end than my son likes thats how I like it.

Im trying to get the speakers to perform in there most linear response region without putting anything else into the path.

We put testing equipment onto speakers to get a linear response but without due accord to our own hearing foibles and room deficiencies.

I was messing around with a number of horns and then put a 1.4 to 2" reducer on the 18 sound horn it sounds good to me crossed at 1600 kHz. Im also considering trying the Jabo KH=55 Horns budget allowing they have a 2" throat.

I don't believe there is any need to drive the response down to its limits on a 4 way system.

The 2446 curves seem to show a drop off at 7000k-8000 kHz on most horns so I guess thats my target for the crossover to the 2405.

The JBL graphs seem to be smoothed from reality to give the impression of a linear response hence my questioning crossover frequencies.

Looking at a lot of builds the 2405 seems to be used naked or just with a small back plate, but any suggestions would be welcome.

If in the end I cannot get a sound Im happy with I will try and start measuring.

frank23
10-24-2014, 02:28 PM
I crossover from 2123>2420 at 1600Hz, there is no need to use a 2446 when crossing over that high. I use my 2420 on a 2344A horn. I'd love to hear your opinion on the Marchand crossover. I use a modded active M553 crossover that has built in CD correction needed for the 2344A horn (and then some...). That is missing from the Marchand, which is the reason I have never bought one.

David Ketley
10-24-2014, 04:20 PM
I just like the sound that the 2446 makes with the 18 sound horn and it gives me the opportunity to use other horns, I'm looking at Jabo from Germany.

The Marchand active crossovers do have a facility for horn correction inserts I believe, but I'm trying to run my system quite bare in the best possible range of each driver without correction.

I have cards to cross at 260 hz with the 2245/2123 so im going to see how it sounds.

What I did find useful was using the old Ashley crossovers to get the crossover frequencies just right, as the frequencies were easily adjustable, then get cards to suit for the Marchand, a much better sounding product, but I have sold the Ashley.... so

Dave

frank23
10-25-2014, 05:10 AM
The Marchand active crossovers do have a facility for horn correction inserts I believe, but I'm trying to run my system quite bare in the best possible range of each driver without correction.

Ok, I'll look into the Marchand correction options. About running the drivers in their ranges, this is what you do, but some horns need CD correction as without it their on axis response droops. Not because of the driver, but because of the horn. So the CD correction is not meant to use a driver outside its range, its a design aspect of a certain type of horn.

David Ketley
10-25-2014, 09:53 AM
Frank I've tried many horns with different JBL drivers including the Bi-radial but have settled on the 18 sound/2446 combination because it sounds so good. I also think horns like the Jabo series are excellent but you have to be willing to add mass to stop resonance at lower crossover frequencies. I also think its a big mistake trying to drive these drivers, 2446 etc, to low thats where the problems start.
Having tried 3 different crossovers the Marchand is outstanding, also a big improvement was using a stepped attenuator as the master volume control.
Keep it simple

Dave

Lee in Montreal
11-06-2014, 06:08 PM
2405 is best crossed at 8KHz. If you cross at 7KHz, the lower range will be too "in yo face" ;-)

Lee

David Ketley
11-07-2014, 01:31 AM
2405 is best crossed at 8KHz. If you cross at 7KHz, the lower range will be too "in yo face" ;-)

Lee


Thanks Lee I'm crossing with a 8000 hz high pass filter but have the choice of 12db or 18 db which would you recommend?

I will also have to pad down the 2446 111 db to the 2405 105 db.

ivica
11-07-2014, 02:10 AM
I just like the sound that the 2446 makes with the 18 sound horn and it gives me the opportunity to use other horns, I'm looking at Jabo from Germany.

The Marchand active crossovers do have a facility for horn correction inserts I believe, but I'm trying to run my system quite bare in the best possible range of each driver without correction.

I have cards to cross at 260 hz with the 2245/2123 so im going to see how it sounds.

What I did find useful was using the old Ashley crossovers to get the crossover frequencies just right, as the frequencies were easily adjustable, then get cards to suit for the Marchand, a much better sounding product, but I have sold the Ashley.... so

Dave
Hi David,

May be 18-Sound horn XR2064 ( 2" throat) would be better to be used with 2446 driver, especially if used up to 10kHz.
I have tested 18-Sound 2060A (2" inch driver) with 18-Sound Xr2064 Horn. I believe that 2446 would behave very similarly, so almost no EQ needed if +/-30deg off-axis in the horizontal plane is acceptable.

regards
Ivica

David Ketley
11-07-2014, 07:28 AM
Im also messing around with HORN HL-1018 ABS very cheap I will see if I can adapt it to a 2".

Dave

Flaesh
11-09-2014, 04:44 AM
HORN HL-1018 ABS very cheap I will see if I can adapt it to a 2".
McGee HL 1018 is 1 3/8"TPI and is usable for 1" driver.
http://hailuo.en.gasgoo.com/auto-products/2079758.html - another HL 1018 horn :D..

Mike Caldwell
11-16-2014, 05:27 PM
In general when you use a throat adapter going from a larger driver exit to a smaller horn throat entrance
you will loss some high frequency output. The constriction of the throat causes high frequency cancellations from the reflections inside throat, to a degree that happens even in non reduced driver throats.

David Ketley
11-17-2014, 04:09 AM
In general when you use a throat adapter going from a larger driver exit to a smaller horn throat entrance
you will loss some high frequency output. The constriction of the throat causes high frequency cancellations from the reflections inside throat, to a degree that happens even in non reduced driver throats.

Thanks for the information Mike I will just have to try with my 2405 crossed at 8000 hz with a 18db high pass and see how it sounds. With Heil tweeters before it sounded fine but they were the P5s.

I am just waiting for my boxes to be built for my 2245s I just don't have the equipment to make a good job of them myself.

Mike Caldwell
11-17-2014, 04:57 AM
The reflections / standing waves happen in all driver throats, the small the driver throat the better the high frequency response due to the cancellations being moved to a higher frequency bandwidth. Some driver designs have almost no throat with the driver exit right at the end of the phase plug. On the other hand some horn designs take in account the throat length of the driver or lack for the horn to work as designed.
There's a always a trade off to be made!!!