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Author Topic: BMS 4590  (Read 3568 times)

Mike Caldwell

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Re: BMS 4590
« Reply #30 on: January 06, 2018, 03:44:39 pm »

Take a look at DDS horns, their website is still up but I'm not sure if they are still producing horns.
http://www.ddshorns.com/index.php

They built a lot of OEM horns for major speaker manufactures at one time. Used DDS horns are available with a little searching. 

Art Welter

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Re: BMS 4590
« Reply #31 on: January 06, 2018, 07:18:13 pm »

Thanks Art.

How would the JBL perform with a 700 to 800hz highpass? Choosing the right LF drivers should let me move a bit higher in terms of crossover point.

BTW: Does anybody know what the horn in a MSL3A was? Meyers own design or something rebadged?
Helge,

The MSL3A used a proprietary Meyers design horn, narrower pattern than what you have mentioned wanting.

The JBL 2380 would work well with the BMS 4590 (or any 3" or 4" diaphragm driver) from 630 Hz on up.
The 23XX series were one of the most popular JBL horns ever made for touring boxes, never had anyone complain about them back in the '80s and early '90s. The bi-radial design has been imitated by many other manufacturers, and imitation is the highest form of flattery (and easiest way to avoid trying to re-invent the wheel) ;^).

Art

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Helge A Bentsen

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Re: BMS 4590
« Reply #32 on: January 06, 2018, 07:37:11 pm »

Helge,

The MSL3A used a proprietary Meyers design horn, narrower pattern than what you have mentioned wanting.

The JBL 2380 would work well with the BMS 4590 (or any 3" or 4" diaphragm driver) from 630 Hz on up.
The 23XX series were one of the most popular JBL horns ever made for touring boxes, never had anyone complain about them back in the '80s and early '90s. The bi-radial design has been imitated by many other manufacturers, and imitation is the highest form of flattery (and easiest way to avoid trying to re-invent the wheel) ;^).


When I started in this business JBL 4771 with 2380 horns was available «everywhere» because the  biggest rental house here had offloaded their inventory and bought Flash/Flood.

Never really a fan of the 4771, I suspect a lot of this is down to the analog crossovers used at that time. I toured with a band that owned their own rig and replaced it with a Driverack PA. Sounded better. Maybe throwing a modern DSP amp on that horn could solve some issues?
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Art Welter

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Re: BMS 4590
« Reply #33 on: January 06, 2018, 08:47:19 pm »


Never really a fan of the 4771, I suspect a lot of this is down to the analog crossovers used at that time. I toured with a band that owned their own rig and replaced it with a Driverack PA. Sounded better. Maybe throwing a modern DSP amp on that horn could solve some issues?
The 4771 had design issues that can't be corrected using DSP, but the 2380 horn was not the source of those issues.

The 2380 has good polar response, the use of the dual diaphragm BMS 4590 will solve the polar problems that were caused by the side by side location of the tweeters and horn in the 4771.

At 630 Hz, using a 12" below the 2380 gets it close enough to 1/4 wavelength spacing to be "good enough" to avoid most of the spacing problems that kept the dual 15" 4771 from having a decent polar response.

Of course, if you want to avoid the polar problems, the way to do it best would be to incorporate the 12" (or 15") and the 4590 on the same (big) horn. Post #4 is an example of the Klipsch K-402 used in such a fashion.
http://www.diyaudio.com/forums/multi-way/285108-horn.html
Post #14 has a picture of the 15" mounting.

Took Chris about 2 years to take my suggestion, (and another year to forget about that nice K-horn  :-[ ) but he seems very happy with the results- and your 4590 should be an improvement over the HF driver he used.

Cheers,
Art
« Last Edit: January 06, 2018, 08:58:48 pm by Art Welter »
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Jack Arnott

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Re: BMS 4590
« Reply #34 on: January 08, 2018, 01:05:08 pm »

Helge,
I have not tried it, but the ME75 looks like a copy of the 2380 design with sharper "break" points, which would increase diffraction problems. Diffraction effects creating "high order modes" may be the biggest sonic problem with any 2" entrance horn that also has 90 degree dispersion above 12kHz, and may be what Jack is referring to as "harmonic distortion".

Art

The harmonic distortion was showing up on my measurement software. I was guessing it was more from the compression in the throat.
This leads me to believe that the BMS horn will be a better match for Helge. It has the same sharp break points, but less throat compression. The DDS that I have used have the same problems with measurable harmonic distortion, but they have less in the narrower dispersion horns, as the compression is much less.

Also, DDS is a dead end for horns. No one that I know can get a hold of them to buy any product. I stopped trying years ago, as when they were sold they stopped giving me a discount, so I started sending my customers directly to them.

This is not a great view, but you can kind of see that there is not the throat compression mechanism in this horn.
http://www.bmsspeakers.com/index.php?id=bms_2236

This plus the size makes me think that this would be the best recommendation so far for this driver.

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Art Welter

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Re: BMS 4590
« Reply #35 on: January 08, 2018, 03:00:48 pm »

The harmonic distortion was showing up on my measurement software. I was guessing it was more from the compression in the throat.
This leads me to believe that the BMS horn will be a better match for Helge. It has the same sharp break points, but less throat compression.
This is not a great view, but you can kind of see that there is not the throat compression mechanism in this horn.
http://www.bmsspeakers.com/index.php?id=bms_2236

Jack,

The BMS 2236 not only has "throat compression", AKA known as a "diffraction slot", but has hard chines in two places on the horizontal expansion for more diffraction fun. It is a 60 degree horizontal dispersion horn, Helge says he's looking for a 90.

The BMS 2236 does have a relatively short distance between the 2" exit and the diffraction slot, longer throat/horn expansions with the same cross-sectional area result in higher harmonic distortion levels.

Art
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Helge A Bentsen

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Re: BMS 4590
« Reply #36 on: January 08, 2018, 03:28:42 pm »

I see that 1.4->2’’ throat adaptors are available from various manufacturers.
It also looks like there’s a larger selection of 1.4’’ horns available.
Would such an adapter work with a 4590 and a 1.4’’ horn?

Or is it A Really Bad Idea?
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Craig Hauber

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Re: BMS 4590
« Reply #37 on: January 08, 2018, 08:29:37 pm »

but has hard chines
Never seen hull-design terminology used to describe horn features before.
-cool way to describe it!

(something new every day here)
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Craig Hauber
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Art Welter

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Re: BMS 4590
« Reply #38 on: January 09, 2018, 01:52:42 am »

I see that 1.4->2’’ throat adaptors are available from various manufacturers.
It also looks like there’s a larger selection of 1.4’’ horns available.
Would such an adapter work with a 4590 and a 1.4’’ horn?

Or is it A Really Bad Idea?
Helge,

Yes, it is A Really Bad Idea to reduce the cross-sectional area in a high frequency horn throat. To use a non-technical analogy, it is quite similar to "pissing into the wind", you can do it, but the results are not good by any metric.

I have several 1.4" to 2" adapters available for sale if you'd like to "hear for yourself" ;^).

2" entrance/exits are largely a hold-over from the days when nearly all horns were designed with an exponential expansion. The early popularity of JBL's 4" diaphragm/2" exit drivers in portable sound systems has led to the continuance of an exit size that really serves no purpose for wide dispersion constant directivity high frequency horns.

The ratio of 1.4" to 2" exits has progressively gone up this century, but like rock and roll, 2" will never die...

Art

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Art Welter

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Re: BMS 4590
« Reply #39 on: January 09, 2018, 02:10:04 am »

Never seen hull-design terminology used to describe horn features before.
-cool way to describe it!

(something new every day here)
Thanks, Craig!
Everything old is new again..
There can be advantages to hard chines in boat hulls, but in high frequency horns, they are simply used for cost saving in the design or manufacture (or both) at the expense of sonic quality.

Art
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