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Author Topic: Meyer JM-1  (Read 3688 times)

Frederik Rosenkjśr

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Re: Meyer JM-1
« Reply #10 on: February 14, 2014, 01:33:00 am »


Maybe there's more to the design than you're aware of, Ivan.

There are methods - some well-known, others we've patented

"We"!?
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Jon Arneson

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Re: Meyer JM-1
« Reply #11 on: February 14, 2014, 02:29:59 am »

"We"!?

"I - the royal we, you know, the editorial."

"Me... and (four) other guys..."

http://www.imdb.com/title/tt0118715/quotes




Jon

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Frederik Rosenkjśr

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Re: Meyer JM-1
« Reply #12 on: February 14, 2014, 03:37:40 am »

"I - the royal we, you know, the editorial."

"Me... and (four) other guys..."

http://www.imdb.com/title/tt0118715/quotes



Jon

What I mean is: Are you affiliated with Meyer? In that case it would be considered good netiquette to have your signature reflect this.
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Andrew Hastings

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Re: Meyer JM-1
« Reply #13 on: February 14, 2014, 07:42:19 am »

What I mean is: Are you affiliated with Meyer? In that case it would be considered good netiquette to have your signature reflect this.

Hi frederik

I recognised his name
You may have over looked this from one of Jon's earlier posts below his signature he typedMSLI
ie Meyer Sound Laboratories ?
He may also know something about high frequency transducers
http://www.linkedin.com/pub/jon-arneson/4/75b/227

Hope this helps

Glenn

]
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Jim McKeveny

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Re: Meyer JM-1
« Reply #14 on: February 14, 2014, 08:40:48 am »

The deep horn, a well-matched amp, and some clever signal processing tricks keep the compression driver happy by controlling excursion and distortio



Breakup modes of the HF diaphragm are related to several factors, but I don't think crossover frequency is one of them. If and when they occur in certain designs it's well above 520Hz, 900Hz, 3.24kHz, or whatever..



As the OP I was curious about IM distortions across such an unusually broad swath of audio frequency spectrum in the JM1.

Prior art suggests that HF diaphragms do not remain anywhere near pistonic when so tasked at high power.

If there are unique, Meyer-patented solutions, they are publicly available and protected, so please share! The prosound community is all-ears...(all puns intended).
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Jon Arneson

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Re: Meyer JM-1
« Reply #15 on: February 14, 2014, 02:20:20 pm »


As the OP I was curious about IM distortions across such an unusually broad swath of audio frequency spectrum in the JM1.

Prior art suggests that HF diaphragms do not remain anywhere near pistonic when so tasked at high power.

If there are unique, Meyer-patented solutions, they are publicly available and protected, so please share! The prosound community is all-ears...(all puns intended).



Hi Jim,

IMD, THD, and diaphragm breakup are all separate issues but all can be either reduced or prevented electronically (upstream of drivers), electro-acoustically (in the driver/horn design), and/or acoustically (downstream of the drivers), depending on the issue. IMD and breakup effects cannot be "canceled out" once they start, as far as I'm aware. THD can however.

Our patents are easily searchable but some of our methods are kept as trade secrets and John Meyer often prefers to do this over patenting some ideas and techniques.

I can't say if the JM-1P horn's wide bandwidth (5 octaves) is directly related to a greater amount of IMD than if it were a three- or four-way design since I haven't tested that exact relationship. We've found the pros of two-way self-powered systems tend to stack up pretty heavily against the cons, and IMD hasn't been an issue for JM-1P users as far as I'm aware.


I hope this info is useful.








Jon

MSLI

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Art Welter

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Re: Meyer JM-1
« Reply #16 on: February 14, 2014, 04:09:31 pm »

IMD and breakup effects cannot be "canceled out" once they start, as far as I'm aware. THD can however.

I can't say if the JM-1P horn's wide bandwidth (5 octaves) is directly related to a greater amount of IMD than if it were a three- or four-way design since I haven't tested that exact relationship.

I hope this info is useful.

Jon

MSLI
Jon,

In reply to the question of what signal processing is capable of eliminating breakup mode and excursion related distortion, in Post #8 you replied:
"None that I am aware of since these are non-linear effects."

Now you seem to suggest that though IMD and breakup effects can not be "canceled out", THD can be, though I see no reference to any "distortion cancelling" processing utilized in the JM-1P, or any other MSL product, with the possible exception of the Pressure Sensing Active Control used on the LF portion of the X-10 control room monitor.

Typical 4" diaphragm horn/driver combinations exceed 10% distortion above 9 kHz at around 108 dB one meter, similar to the level the JM-1P HF should do (midband) at one watt, working back from a rated output of 138 dB at a presumed 550 watt peak. At an output level nearly four orders of magnitude higher, HF distortion must exceed 100%.

To insure having "enough rig for the gig", what SPL should users expect from the JM-1P above 8000 Hz without exceeding 10% THD?

Art
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Jon Arneson

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Re: Meyer JM-1
« Reply #17 on: February 14, 2014, 04:38:42 pm »

Jon,

In reply to the question of what signal processing is capable of eliminating breakup mode and excursion related distortion, in Post #8 you replied:
"None that I am aware of since these are non-linear effects."

Now you seem to suggest that though IMD and breakup effects can not be "canceled out", THD can be, though I see no reference to any "distortion cancelling" processing utilized in the JM-1P, or any other MSL product, with the possible exception of the Pressure Sensing Active Control used on the LF portion of the X-10 control room monitor.



That's right! Thanks for reminding me about the X-10's PSAC. I need to check with the guys who designed that - they are way, way smarter than I am and will know if the technology cancels IMD as well as THD.

(I was only thinking of upstream, open-loop distortion cancellation in that quote.)


Quote
Typical 4" diaphragm horn/driver combinations exceed 10% distortion above 9 kHz at around 108 dB one meter, similar to the level the JM-1P HF should do (midband) at one watt, working back from a rated output of 138 dB at a presumed 550 watt peak. At an output level nearly four orders of magnitude higher, HF distortion must exceed 100%.


Assuming you're right, I can't hear the 2nd harmonic of 9kHz or anything above that so what's the problem?  :)


Quote
To insure having "enough rig for the gig", what SPL should users expect from the JM-1P above 8000 Hz without exceeding 10% THD?


Sorry Art, but I'm not going down this rabbit hole with you. Prospective and existing users can consult with our Design Services department for these kinds of questions. If they need more specific info (like THD percentages) then R&D will get involved.






Jon


Edit: poor choice of words
« Last Edit: February 14, 2014, 10:14:51 pm by Jon Arneson »
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Jim McKeveny

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Re: Meyer JM-1
« Reply #18 on: February 14, 2014, 05:58:49 pm »


 Actual users

Jon

Well, this prospective user has crossed MSLI from my PAC's short list!
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Art Welter

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Re: Meyer JM-1
« Reply #19 on: February 14, 2014, 06:29:05 pm »

Assuming you're right, I can't hear the 2nd harmonic of 9kHz or anything above that so what's the problem?  :)

Sorry Art, but I'm not going down this rabbit hole with you. Actual users can consult with our Design Services department for these kinds of questions. If they need more specific info (like THD percentages) then R&D will get involved.
Jon
Jon,

The second harmonic of 9kHz would not be a problem for me either, but the harmonic distortion stacking up from crossing at 520 Hz at 520 Hz intervals to 14560 are still a bother to me  ;).

But in the long list of harmonics, really the odd order ones are the bother, the rest are just "rock and roll".

Breakup modes- well, like the output of an air compressor hose, they can measure flat but just don't sound very good.
Ask John M. why he stopped using piezos decades ago  ;).

In humid San Francisco, HF distortion is not such a big deal as it is here in the high dry desert, where HF air attenuation can require 10-20 dB more VHF SPL than in the wetlands.

One can see the HF air attenuation problem here:
http://www.meyersound.com/sites/default/files/leo_application_profile_marysville.pdf

The Leo array at 12.5 kHz drops from about 82 dB at 30 meters to 60 dB at 120m, a 22 dB drop.
We see the HF basically dropping in to the noise floor at 120 meters, although the rest of the audio range has only dropped about 6 dB in the same distance.

Obviously, 22 dB boost ain't going to work when driver distortion is already fairly high, and the additional 12 or more dB HF gain needed in the desert, well, as you said, you aren't going down that rabbit hole  :).

Since no other manufacturers publish HF distortion figures above a few watts, I really did not expect you would reveal that Meyer also has not made much progress in that regard either.

I still find it a hoot that we scoff at amps with 1% THD, but regularly listen to systems at levels that produce 10 to 20 times that distortion.

Thanks for the "info"!

Art

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