Cornscala mid horn

[mopardave]

I'm reading that the M audio 2380 horn( JBL 2380A) produces a quacking sound at certain pressure levels and frequencies.   Would  a more open less restrictive horn like a selenium HM4750SLF or ZXPC horn 17.5x11x12 be a better choice for a 3 way Cornscala?  There is also a PRV WG45-50 horn with same 90*x40* dimensions that has an open throat.     I'm thinking the open throat horn might be the better choice?  Am I correct with this thinking?

[Tarheel TJ]

    The only mid-horns I have experience with are the stock K-400 from a La Scala, and the ZXPC 17.5x11 that you mention.  To me, the more open-throat horn was a big upgrade over a K400.  I do not have enough expertise in horn design to be able to tell you what role the openness of the throat plays, but the improvement in sound is not subtle. 

   I have no experience with the other horns you mention, though I have always read that diffraction horns (like the JBL2380) do not have the most pleasant sound.  They sacrifice sound quality for coverage. 

  Certainly the ZXPC horns are cheap enough to experiment with.  Of course, I ended up buying 2" drivers and a digital crossover and going fully active in the end.  I guess you could say the cheap $40 horns ended up being a gateway drug for me.  Buyer beware!

 

 

 

 

   

[PrestonTom]

The JBL 2380 (or its clone) is a good horn. First, do both cabinets show this symptom and how do know it is the midrange that is doing it?

 

In my limited experience, the symptom you describe can happen from a marginal diaphragm / driver, a mechanical problem (something rattling around or loose), or the crossover point set too low. I would track these down first and not abandon a perfectly good horn.

Good luck

-Tom

[Md5150]

I had the JBL 2380 ( clones ) in both pairs of my Cornscala's and never heard any kind of quacking, something else must be the cause.

 

Mike.

[mopardave]

4 hours ago, mopardave said:

I'm reading that the M audio 2380 horn( JBL 2380A) produces a quacking sound at certain pressure levels and frequencies.   Would  a more open less restrictive horn like a selenium HM4750SLF or ZXPC horn 17.5x11x12 be a better choice for a 3 way Cornscala?  There is also a PRV WG45-50 horn with same 90*x40* dimensions that has an open throat.     I'm thinking the open throat horn might be the better choice?  Am I correct with this thinking?

https://community.klipsch.com/index.php?/topic/95845-anyone-using-jbl-2370-2380-or-2385-midraneg-horns/&do=findComment&comment=1047232

[mopardave]

1 minute ago, mopardave said:

https://community.klipsch.com/index.php?/topic/95845-anyone-using-jbl-2370-2380-or-2385-midraneg-horns/&do=findComment&comment=1047232

Not sure how to copy and paste here, but I found a couple more threads on this subject.  Quack like a duck at higher spl and would not use in a home audio loud speaker.

[mopardave]

I wish I could copy paste these links for you to read,but I don't know how.  The klipsch member says he uses the 2380 horn at work in a variety of ways and would not use this horn in a home environment  .   He goes onto say the horn has a sketch sound and the horns distort at 10% with 1w and 10w and has graphs to show .

[avguytx]

Like this?

 

Link

 

What I did above is write the word "Link", copied the actual link from the article, then click the "chain link" symbol that's in the row of stuff like Bold, Italics, smileys, etc., next to the quotation marks.  That word or words you use then becomes a clickable link.

 

[mopardave]

I wish I could copy paste these links for you to read,but I don't know how.  The klipsch member says he uses the 2380 horn at work in a variety of ways and would not use this horn in a home environment  .   He goes onto say the horn has a sketch sound and the horns distort at 10% with 1w and 10w and

According to JBL, the 2370 has full loading to about 630Hz and is usable to 500Hz.

There really aren't any drivers with which one can achieve that performance. JBL's 2426 compression driver is recommended to cross @ 800 Hz minimum, and it's about the best for that horn. Sounds terrible, by the way.

Opinions are always welcome. I know the top end of the 2426 drops off rather suddenly.

I think we were talking more about changing out the K400/401 horn for the JBL, and the K55 crosses at 400, so there are drivers that will cross low enough. The horn wouldn't quite work, though. Maybe in an LS if you raised the crossover point. The LS can get to 500Hz.

These JBL horns are the wrong devices to use in a loudspeaker system as a bandwidth-limited midrange horn. They are designed to be used as the HF in a three-way sound reinforcement system. They are of a bi-radial design and are constant directivity as a result. Any compression driver mounted to them will require top octave compensation, and bottom octave compensation if you try to run these horns too low. The top octave comp allows the reproduction of higher frequencies with even horizontal polars over a greater than 10:1 frequency range, and works out to about 12 dB boost @ 15kHz depending on the driver used. According to JBL info, frequency response @ 500 Hz is -20 dB relative to 1500 Hz. So if you are running 1 watt in the midband of these horns you will need to put 100 watts into the low end of it's range to get flat frequency response. To my knowlege there are no 1" drivers with that capability, and adapting a 2" unit to a 1" throat won't get hi-fi results.

I've been through all of this before. I am currently using a Peavey 1" CH-941 CD horn as the HF in my system. It is about the size of the 2" JBL 2380 and is advertised to go down to 500, or 800 Hz, depending on which set of Peavey specs you are looking at. I am using an analog crossover so it is easy to change crossover points and to change from 3 way to 2 way operation. When used as a 2 way, there is next to nothing coming from the Peavey horn at the crossover point. Bottom octave comping the horn causes the limiters that I have set for driver protection to engage, which sounds terrible. You would get similar results from the JBLs.

If you want a HF horn for a 2 way system, get a K402 setup. It ain't cheap, it's big, but it will work and sounds good. Using a CD horn for HF in a home system works well in a 3 way setup due to the smooth horizontal polar dispersion but plan on using a midrange to go from the bass crossover frequency up to at least 1 kHz. I'm using the K400-K55 combo for that, crossing to the HF @1200 Hz, and it sounds great.

has graphs to show .

[mopardave]

2 minutes ago, mopardave said:

I wish I could copy paste these links for you to read,but I don't know how.  The klipsch member says he uses the 2380 horn at work in a variety of ways and would not use this horn in a home environment  .   He goes onto say the horn has a sketch sound and the horns distort at 10% with 1w and 10w and

According to JBL, the 2370 has full loading to about 630Hz and is usable to 500Hz.

There really aren't any drivers with which one can achieve that performance. JBL's 2426 compression driver is recommended to cross @ 800 Hz minimum, and it's about the best for that horn. Sounds terrible, by the way.

Opinions are always welcome. I know the top end of the 2426 drops off rather suddenly.

I think we were talking more about changing out the K400/401 horn for the JBL, and the K55 crosses at 400, so there are drivers that will cross low enough. The horn wouldn't quite work, though. Maybe in an LS if you raised the crossover point. The LS can get to 500Hz.

These JBL horns are the wrong devices to use in a loudspeaker system as a bandwidth-limited midrange horn. They are designed to be used as the HF in a three-way sound reinforcement system. They are of a bi-radial design and are constant directivity as a result. Any compression driver mounted to them will require top octave compensation, and bottom octave compensation if you try to run these horns too low. The top octave comp allows the reproduction of higher frequencies with even horizontal polars over a greater than 10:1 frequency range, and works out to about 12 dB boost @ 15kHz depending on the driver used. According to JBL info, frequency response @ 500 Hz is -20 dB relative to 1500 Hz. So if you are running 1 watt in the midband of these horns you will need to put 100 watts into the low end of it's range to get flat frequency response. To my knowlege there are no 1" drivers with that capability, and adapting a 2" unit to a 1" throat won't get hi-fi results.

I've been through all of this before. I am currently using a Peavey 1" CH-941 CD horn as the HF in my system. It is about the size of the 2" JBL 2380 and is advertised to go down to 500, or 800 Hz, depending on which set of Peavey specs you are looking at. I am using an analog crossover so it is easy to change crossover points and to change from 3 way to 2 way operation. When used as a 2 way, there is next to nothing coming from the Peavey horn at the crossover point. Bottom octave comping the horn causes the limiters that I have set for driver protection to engage, which sounds terrible. You would get similar results from the JBLs.

If you want a HF horn for a 2 way system, get a K402 setup. It ain't cheap, it's big, but it will work and sounds good. Using a CD horn for HF in a home system works well in a 3 way setup due to the smooth horizontal polar dispersion but plan on using a midrange to go from the bass crossover frequency up to at least 1 kHz. I'm using the K400-K55 combo for that, crossing to the HF @1200 Hz, and it sounds great.

has graphs to show .

We use the 2380 at work in a variety of configurations and there is no way I would ever consider using them in a home environment. In fact, if it were my choice, we wouldn't be using them at work either.

The 2380 certainly has a very decent coverage pattern and can get real loud with the right drivers, but they are shrill as all get out...or more of a congested shrill sound - it's hard to describe. You know there's something wrong when you can walk into other venues and identify the 2380 after hearing just a few seconds of music. Ideally, you just wanna be hearing the music - not the speakers.

I actually ran some curves at work to see ifthere wasn't anything blaringly wrong in the frequency response, but overall they looked well behaved. When I get back home or find an internet connection for my laptop I can post those curves. I recall them being extremely similar to the curves that JBL posts. The only downside is that it's a system response with some JBL2226H drivers in the mix (so I can't verify the LF extension)...I think we're crossing to them at around 800Hz.

Actually, here's the PDF for the 2380:
http://www.jblpro.com/pages/pub/components/2380a.pdf
I was just noticing they're rated for 10% distortion at 1W and 10W of input power. []

 

[mopardave]

15 minutes ago, mopardave said:

I wish I could copy paste these links for you to read,but I don't know how.  The klipsch member says he uses the 2380 horn at work in a variety of ways and would not use this horn in a home environment  .   He goes onto say the horn has a sketch sound and the horns distort at 10% with 1w and 10w and

According to JBL, the 2370 has full loading to about 630Hz and is usable to 500Hz.

There really aren't any drivers with which one can achieve that performance. JBL's 2426 compression driver is recommended to cross @ 800 Hz minimum, and it's about the best for that horn. Sounds terrible, by the way.

Opinions are always welcome. I know the top end of the 2426 drops off rather suddenly.

I think we were talking more about changing out the K400/401 horn for the JBL, and the K55 crosses at 400, so there are drivers that will cross low enough. The horn wouldn't quite work, though. Maybe in an LS if you raised the crossover point. The LS can get to 500Hz.

These JBL horns are the wrong devices to use in a loudspeaker system as a bandwidth-limited midrange horn. They are designed to be used as the HF in a three-way sound reinforcement system. They are of a bi-radial design and are constant directivity as a result. Any compression driver mounted to them will require top octave compensation, and bottom octave compensation if you try to run these horns too low. The top octave comp allows the reproduction of higher frequencies with even horizontal polars over a greater than 10:1 frequency range, and works out to about 12 dB boost @ 15kHz depending on the driver used. According to JBL info, frequency response @ 500 Hz is -20 dB relative to 1500 Hz. So if you are running 1 watt in the midband of these horns you will need to put 100 watts into the low end of it's range to get flat frequency response. To my knowlege there are no 1" drivers with that capability, and adapting a 2" unit to a 1" throat won't get hi-fi results.

I've been through all of this before. I am currently using a Peavey 1" CH-941 CD horn as the HF in my system. It is about the size of the 2" JBL 2380 and is advertised to go down to 500, or 800 Hz, depending on which set of Peavey specs you are looking at. I am using an analog crossover so it is easy to change crossover points and to change from 3 way to 2 way operation. When used as a 2 way, there is next to nothing coming from the Peavey horn at the crossover point. Bottom octave comping the horn causes the limiters that I have set for driver protection to engage, which sounds terrible. You would get similar results from the JBLs.

If you want a HF horn for a 2 way system, get a K402 setup. It ain't cheap, it's big, but it will work and sounds good. Using a CD horn for HF in a home system works well in a 3 way setup due to the smooth horizontal polar dispersion but plan on using a midrange to go from the bass crossover frequency up to at least 1 kHz. I'm using the K400-K55 combo for that, crossing to the HF @1200 Hz, and it sounds great.

has graphs to show .

We use the 2380 at work in a variety of configurations and there is no way I would ever consider using them in a home environment. In fact, if it were my choice, we wouldn't be using them at work either.

The 2380 certainly has a very decent coverage pattern and can get real loud with the right drivers, but they are shrill as all get out...or more of a congested shrill sound - it's hard to describe. You know there's something wrong when you can walk into other venues and identify the 2380 after hearing just a few seconds of music. Ideally, you just wanna be hearing the music - not the speakers.

I actually ran some curves at work to see ifthere wasn't anything blaringly wrong in the frequency response, but overall they looked well behaved. When I get back home or find an internet connection for my laptop I can post those curves. I recall them being extremely similar to the curves that JBL posts. The only downside is that it's a system response with some JBL2226H drivers in the mix (so I can't verify the LF extension)...I think we're crossing to them at around 800Hz.

Actually, here's the PDF for the 2380:
http://www.jblpro.com/pages/pub/components/2380a.pdf
I was just noticing they're rated for 10% distortion at 1W and 10W of input power. []

Distortion is also the function of the cut-off frequency of the horn, the lower the horn goes, the higher the distortion will be at high frequencies.

The 2360 horn has 30% THD with 5W input at 10Khz (for instance)

http://www.jblpro.com/pub/technote/tn_v1n08.pdf

The newer OA series 1.5" throat horns and drivers have about 10dB less distortion in the 8Khz region.

http://www.jblpro.com/pub/technote/tn_v1n21.pdf

This is due to a higher cut-off frequency, and opening up the slot in the throat.

The narrow slot, long tail throat gives rise to a 'quacking' or 'frying bacon' sound at high volumes.

If you think about it, the air has to create a vacum on its rear-wave to go above 162dB (at the diaphragm). This creates a 'clap' similar to a lightning bolt when the air rushes back in, this is the audible 'quack' that can be heard. Keep in mind that most of these large drivers are about 117dB/mW on a terminated tube, or 162dB for 32W input.

(the Carver PM1.5 was often seen driving the 2445, it can put out in excess of 350W/16R on program material)

The air in the throat simply overloads.

PS, I've had the Atlas drivers 'quack' with less than 100W on the wrong type horn.

If you want something that doesn't 'quack', andhas much lower distortion than any other midrange driver I've heard, look into the Community M200 on the SH494 horn

[PrestonTom]

There is a great deal of misinformation in the thread that you linked. The application listed in this thread was for a three way system (with an unknown driver) and a 2380 mid horn (not a 2360 etc, etc, etc). The 2380 is a good mid horn. At SPLs found in the home, there should not be any problem. It is NOT a 2360 with a severe diffraction slot etc, etc.

Again, first look at the driver, whether there is something loose or rattling and whether the cross over point is set too low.

Has this horn been provided with any CD compensation or was that unaccounted for?

 

 

EDIT: Wait, I may be wrong on whether this needs equalization (CD compensation) or not .... need to double check

Edited March 27, 2019 by PrestonTom
double check

[mopardave]

1 hour ago, avguytx said:

Like this?

 

Link

 

What I did above is write the word "Link", copied the actual link from the article, then click the "chain link" symbol that's in the row of stuff like Bold, Italics, smileys, etc., next to the quotation marks.  That word or words you use then becomes a clickable link.

 

Ok. Here you go. A little hack up but readable.  A lot of info here.

[mopardave]

8 hours ago, PrestonTom said:

The JBL 2380 (or its clone) is a good horn. First, do both cabinets show this symptom and how do know it is the midrange that is doing it?

 

In my limited experience, the symptom you describe can happen from a marginal diaphragm / driver, a mechanical problem (something rattling around or loose), or the crossover point set too low. I would track these down first and not abandon a perfectly good horn.

Good luck

-Tom

I don't know, but you can read what I posted and see what you get out of it.  The guy sounds knowledgable to me.

[mopardave]

3 hours ago, PrestonTom said:

There is a great deal of misinformation in the thread that you linked. The application listed in this thread was for a three way system (with an unknown driver) and a 2380 mid horn (not a 2360 etc, etc, etc). The 2380 is a good mid horn. At SPLs found in the home, there should not be any problem. It is NOT a 2360 with a severe diffraction slot etc, etc.

Again, first look at the driver, whether there is something loose or rattling and whether the cross over point is set too low.

Has this horn been provided with any CD compensation or was that unaccounted for?

 

 

EDIT: Wait, I may be wrong on whether this needs equalization (CD compensation) or not .... need to double check

Does the 2380 have a diffraction slot?   Drwho posted the 2380 should not be used in a home environment.  I'm shopping for a horn for my cornscala project and want to stick with an open horn design.  Too many dislike the 2380. Thanks

[mopardave]

8 hours ago, PrestonTom said:

There is a great deal of misinformation in the thread that you linked. The application listed in this thread was for a three way system (with an unknown driver) and a 2380 mid horn (not a 2360 etc, etc, etc). The 2380 is a good mid horn. At SPLs found in the home, there should not be any problem. It is NOT a 2360 with a severe diffraction slot etc, etc.

Again, first look at the driver, whether there is something loose or rattling and whether the cross over point is set too low.

Has this horn been provided with any CD compensation or was that unaccounted for?

 

 

EDIT: Wait, I may be wrong on whether this needs equalization (CD compensation) or not .... need to double check

The poster says he checked the driver and found nothing wrong.  Another poster says he doesn't like any of the JBL horns listed 2370,2380 and 2385.   The 2380 is said to be a screechy horn.   I have also read either you love or hate the 2380 horn.    Looks like more hate than love just from what I have read so far.    Had my mind set on the 2380, but now I think i'll look harder at the 4750 open throat horn or something similar.   Thanks guys

[mopardave]

21 hours ago, Md5150 said:

I had the JBL 2380 ( clones ) in both pairs of my Cornscala's and never heard any kind of quacking, something else must be the cause.

 

Mike.

Have you tried them at high volume, like 100+db?   Just curious how they sound up there.  

[mopardave]

16 hours ago, PrestonTom said:

There is a great deal of misinformation in the thread that you linked. The application listed in this thread was for a three way system (with an unknown driver) and a 2380 mid horn (not a 2360 etc, etc, etc). The 2380 is a good mid horn. At SPLs found in the home, there should not be any problem. It is NOT a 2360 with a severe diffraction slot etc, etc.

Again, first look at the driver, whether there is something loose or rattling and whether the cross over point is set too low.

Has this horn been provided with any CD compensation or was that unaccounted for?

 

 

EDIT: Wait, I may be wrong on whether this needs equalization (CD compensation) or not .... need to double check

I'm curious which part of the posts were misinformation?   Just trying to learn here.

[avguytx]

So do you already have most of the parts to make them a 3-way?  I'm thinking about building a set one day but will be going 2-way with the Faital Pro driver/horn.  I'd also initially thought about using the same drivers to make my Belle clones a 2-way versus 3.  Might try that one day.

[mopardave]

54 minutes ago, avguytx said:

So do you already have most of the parts to make them a 3-way?  I'm thinking about building a set one day but will be going 2-way with the Faital Pro driver/horn.  I'd also initially thought about using the same drivers to make my Belle clones a 2-way versus 3.  Might try that one day.

I have the vertical cornwalls, no parts yet. Horns and tweets will be first purchase.  I'm trying to use my original motor board. I need to cover the current k600 horn hole in the board with the 17x11 big horn and I would like to mount everything to the rear of the board. Just makes things easier. I will leave the tweet vertical and where at.