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Thought: I wonder how actual Cinema surround decoders measure?

Blumlein 88

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The cinema experience isn't high fidelity if you measure THD and such, but the big advantage a cinema has is that its such a big room.
This is a real big one. The Schroeder frequency can be really low. So while in our homes we struggle to get flat response below 300 hz, in a big theater that problem is pushed down so low as to effectively disappear.
 

tecnogadget

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I’ve attended soo many comercial Cinemas that sounded like if they were properly set up/calibrated for their opening, but then somehow times passes by and maybe some underpaid employee messes up something or config get lost.
Last movie I saw on February was “1917”...I had to lesve the theater and tell the employees at front desk the movie was playing WITHOUT SOUNDTRACK !!
 

Koeitje

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Completely irrelevant, but I just want to share this. Such great memories :D. I think "The audience is listening" was so true when this came on. Everybody would shut up because the real movie was going to start.

 

GXAlan

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I don't care much for descriptors like "musicality" or "pace rhythm and timing". I discuss subwoofers in terms of harmonic distortion, group delay, cabinet resonances, etc. Those measurements characterize most of how a subwoofer sounds, much like spinorama measurements for speakers.

I agree.

Here is JL Audio E112 ($2100) compared to Rythmik F18 ($1600). More detailed measurements are available at data-bass.com

There's the problem. You are looking at the budget E-line not the Fathom line.

25Hz
Rythmik F18HP: 114 dB peak - 9.4% THD @ 111dB
Rythmik FV15H: 113 dB peak - 17.94% THD
F113: 121 dB, peak - 8.2% THD @ 100 dB
https://hometheaterhifi.com/reviews/speaker/subwoofers/a-secrets-subwoofer-review56/

You have higher peaks with the F113 compared to larger 15 and 18" subs. There isn't a direct comparison of THD at equal SPLs but it's competitive.

Rythmik F18HP vs. JL Audio F110 (18" vs 10")
50Hz
Rythmik F18: 119.1 dB at 10.1% THD
Rythmik F15: 119.1 db @ 12.84% THD
F110: 114.79 dB at 10.0% THD
https://www.audioholics.com/subwoofer-reviews/jl-audio-f110/measurements-analysis

The 15" and 18" are better -- but it's 15 and 18" vs a 10".
-----
You pay a lot for
a) size. If you have room for a big sub, JTR's are good. But in the "smaller" sizes of the JL Audio, it's good.
http://data-bass.ipbhost.com/topic/531-jl-audio-fathom-f113-v2/page/2/?tab=comments#comment-19906

b) fit/finish

c) USA manufacturing
- pay more money without getting any additional "performance"
- important to some, not important to others

Unlike Harman, JL Audio actually gets to brag about bringing back
https://www.sun-sentinel.com/business/jobs/fl-audio-manufacturer-expansion-20150820-story.html
 

GXAlan

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This looks okay, but SINAD (inverse of THD+Noise) here is only 90.45 db. About like the better pre/pros and far below good DACs. Nothing in these specs is anything to write home about.

Excellent idea for a thread topic btw.

The AD1853 in the Lexicon has a rating of "–104 dB THD+N (Stereo)"

Given the chip they were working with, that's actually not horrible.
 

GXAlan

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This one? https://www.crownaudio.com/en/products/i-tech-5000hd
THD < 0.1%
Intermodulation Distortion < 0.2%

Yes. I forget where I saw the article -- may have been a Facebook from the movie theater post too. There was a whole rack of them for a single theater room. Quick google does confirm in a press release that Cinemark uses iTechHD amps, but the specific model I saw from a picture/caption.

The i-Tech uses the same fundamental DriveCore technology used in the XLS that was reviewed here.

Difference is that the XLS1502 retails for $0.5K and the i-Tech 5000HD is $6K.
12x as expensive -- presumably there is some improvement in sound too.

This is what the JBL M2 is built around.
https://www.sweetwater.com/store/detail/M2System--jbl-m2-reference-monitor-system
 

Senior NEET Engineer

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25Hz
Rythmik F18HP: 114 dB peak - 9.4% THD @ 111dB
Rythmik FV15H: 113 dB peak - 17.94% THD
F113: 121 dB, peak - 8.2% THD @ 100 dB
https://hometheaterhifi.com/reviews/speaker/subwoofers/a-secrets-subwoofer-review56/

You have higher peaks with the F113 compared to larger 15 and 18" subs. There isn't a direct comparison of THD at equal SPLs but it's competitive.

Rythmik F18HP vs. JL Audio F110 (18" vs 10")
50Hz
Rythmik F18: 119.1 dB at 10.1% THD
Rythmik F15: 119.1 db @ 12.84% THD
F110: 114.79 dB at 10.0% THD
https://www.audioholics.com/subwoofer-reviews/jl-audio-f110/measurements-analysis

Those measurements aren't comparable. The hometheaterhifi one is in-room, 1 foot distance, max output. Data-bass is outdoor ground plane, 2 meters, CEA-2010.
 

GXAlan

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Those measurements aren't comparable. The hometheaterhifi one is in-room, 1 foot distance, max output. Data-bass is outdoor ground plane, 2 meters, CEA-2010.

Ah! That is a big mistake on my part. Interesting.
 

Timme

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Ah! That is a big mistake on my part. Interesting.

yes, F113 won't hold a candle against a F18HP
But its nothing weird about that. An 18inch driver in a big ported box will have a huge output advantage over a sealed box 13,5 inch driver
 

GXAlan

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yes, F113 won't hold a candle against a F18HP
But its nothing weird about that. An 18inch driver in a big ported box will have a huge output advantage over a sealed box 13,5 inch driver

I agree. I was comparing equal sizes to equal sizes.
 

Blumlein 88

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I looked on Harman's site for theater solutions.

For premium large format theaters (one they label the Ultimate Moviegoing experience) they use a Lexicon QLI32 to feed Crown amps and various JBL speakers. 32 channels worth or so.
Claimed specs for the QLI32 which has its own networked connection to all the amps. Now the analog inputs and mic inputs are mostly for calibration of the theater. The Blu Link digital to the amps is what carries the signal. It is receiving AES/EBU inputs from the Cinema server.

1589609173632.png


They have ample power in various models.
1589611358081.png

The Blu link digital signal goes into Crown DCI 4 2400 N Drive core based amplifiers. Sometimes they go thru 70v transformer systems to power speakers and sometimes not. The PDF doesn't show up well in a screen shot so here is the file on those.
https://www.crownaudio.com/en/produ...inal-pdf-817cf81c-7e3d-49f8-b42a-adedfb15cdc2

This PDF shows a sample system schematic. Lots and lots of speakers and lots of power.
https://e265b8fd1ff9a586c366-1acdfa...an_Standard_Template_-_Cinema_-_350__Seat.pdf

I will excerpt some of the pertinent specs here. FR is +/- .25 db. SNR A-wtd >108 db. THD at full power is .35% on these amps.
Amir has reviewed on DriveCore amp, and it has results you'd expect from such specs. Very powerful, but versus something like Purefi, Hypex, or Benchmark amps probably 3rd rate.
https://www.audiosciencereview.com/.../crown-xls2502-stereo-amplifier-review.10627/


1589609603163.png


Since the signal is digital until the DriveCore amps, the performance of those amps will be the electronic bottleneck on the quality of the output signal. As your basic Marantz or Denon pre/pro at its rated output level equals or outperforms (mostly outperforms) these amps, they will in no way give you a lesser result than the big movie theaters. If you partner pre/pro's with quality amplifiers, then the pre/pro is a limiting bottleneck to electronic performance, but it generally is a 10 db or greater improvement over the results you'd get at a large premium movie theater.

Now getting the sound level, even bass response, and number of channels equal to those theaters is a different problem. One that may give the theater an advantage. Basic purity and quality of the signals if you have highly capable home speakers is not going to give you lesser results however.

It still is unfortunate that expensive pre/pros give us 3rd rate DAC performance. They may be audibly transparent nonetheless in nearly all real use scenarios. So with good amps and speakers with good room EQ and setup we probably aren't missing anything.

Furthermore, the better AVR's are likely equaling the overall results on the electronic signal if feeding good speakers compared to a large movie theater. They generally fall short of the pre/pros, and some are just poorly engineered. The better ones from Denon or Marantz are getting results about like the big theaters. A Denon AVR X3600H is better than them. It equals and slightly exceeds most pre/pros even. With cleaner than Crown power amps of substantial power capability.

So use a pre/pro and good power amps and the big movieplex has nothing on you. Use the AV receivers that do well in Amir's testing and you'll generally equal the big movieplex system.

More than a few people have commented that other than getting really, really loud the movie theaters don't have better sound. This just corroborates that.
 
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