The official Theta Owners Thread - Page 392 - AVS Forum | Home Theater Discussions And Reviews
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post #11731 of 11757 Old 07-23-2017, 11:33 PM
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Originally Posted by k_lewis View Post
Jeff- Thanks for your input. My source of info is one and the same, interesting that we received completely polar opposite answers. I was told the internally generated noise is not as accurate as using the provided test tones on the AIX disc for the task of channel balancing. Of course if anyone has question certainly contact Theta directly. For me, John's suggestion and guidance worked great / spot on. AFAIK there would be no difference in test tone quality between the CB4 and the 4a.
I will check with John tomorrow, but when we were preparing the CBIVa preliminary manual, we had extensive discussions about test tones. Per John they are different between the IV and IVa (not surprising as they have different DSP's) and are accurate in the IVa.

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post #11732 of 11757 Old 07-24-2017, 12:39 AM
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Originally Posted by Stereojeff View Post
Per John, the test tones are accurate in the CBIVa. But, as Cannga has already noted and as stated in the preliminary manual, you must have a source playing before engaging the test tones.
How about just selecting an analog input (even if nothing connected to it). Then the A/D drives the system.

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post #11733 of 11757 Old 07-24-2017, 12:57 AM
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I had a phone call with JB about setting up the channel balances manually - He said to not use the internal pink noise generator, it is not accurate and is a normal issue with onboard noise generators.
Well, most internal noise generators are accurate, if the product was certified by Dolby. There may be products that activate the noise with the EQ bypassed, and that then is inaccurate because it does not reflect actual playback conditions.

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The proper method for channel balancing is to use the AIX setup disc with reference level tones, and a DB meter set to A weighting / slow response, you want to adjust all to 75dba.
The AIX test signals are not suitable for a 75 dB calibration like most other test discs. In my calibrated system they measure almost 10 dB higher -- 83 dB. Of course it will do no harm to set them to 75 dB, but "ref level" on the volume control will not be anywhere close to ref SPL.

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I don;t like the AIX test disc tones though with how they are set up.
I would prefer it if each channel tone were it's own track number. you could then set track repeat and have it loop that track until you are done, then you can manually skip to next track and channel, etc. - there are other test tone discs out there set up in this separate track manner, and I don't see why you could not use one of them as long as the tones are consistent. All we are doing here is ensuring each channel's volume at the speaker is consistent to the FL channel.
For all these reasons, plus the uncertainty as to what levels are actually printed on the AIX disc, I highly recommend the Spears&Munsil 2nd Edition BD. The noise signals are properly bandlimited, and spot on for a 75 dB SPL calibration (including subwoofer). And it's easy to park the signal on any channel you like.

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Originally Posted by Steve Bruzonsky View Post
C weighting, not A weighting, for the decibelt meter. A is fast, C is slow!!!@@@
No, A and C are frequency weighting curves. Slow/Fast is a separate selection that can be applied to either curve.

It's a good idea to use A/Slow for comparing relative channel levels if one must use the AIX disc, as this will reduce SPL errors caused by bass variations. But it's still not certain what is the correct target SPL for AIX, and using that for a subwoofer cal is another can of worms. Much better to use a known quantity as mentioned above. And **if** the product is designed right, there's no reason you cannot use the internal cal tones and get proper results. One way to see if that's true -- compare the results with the S&M test disc.
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post #11734 of 11757 Old 07-24-2017, 02:26 AM
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Originally Posted by cannga View Post
but essentially Theta's speaker setup is four speakers overhead - on top of MLP's head whereas the DTS:X channel call-out is height - on top of the front speaker. Object audio's remapping at work and all is good.
I would expect the Theta to allow declaring your four ceiling speakers (positioned at the typical Atmos top speaker locations) as height speakers, being the preferred way for DTS:X playback. The confusing part in all this is that the intended locations of the DTS:X height speakers are very close to the Atmos top speakers, and NOT to the Atmos height speakers.

A good idea and understanding lies at the basis of every successful project.

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post #11735 of 11757 Old 07-24-2017, 07:07 AM
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I went to their web site. Same cable and connector (star quad and Neutrik) XLR at all lengths seem to be around 2/3 the price of Blue Jeans from what I could see. Impressively cheap - thank you.
. Glad to help- Call them directly for custom order items they are very easy to deal with, and can advise on the best cables for a particular setup.

Sort of like, if you are purely looking for unbridled 0-60 in 2.3 seconds automotive performance, why pay Bugatti Chiron money when you can get the exact same performance for Tesla Model S / Dodge Demon money? Of course, if you just want to look like a platinum level baller and impress the Joneses (or your Saudi Prince neighbor)... then it's the Chiron no question (in bright blue or yellow, or, the ultimate: gold chrome wrap, no less! lol).

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post #11736 of 11757 Old 07-24-2017, 07:11 AM
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Originally Posted by Stereojeff View Post
I will check with John tomorrow, but when we were preparing the CBIVa preliminary manual, we had extensive discussions about test tones. Per John they are different between the IV and IVa (not surprising as they have different DSP's) and are accurate in the IVa.

Jeff
Thanks Jeff- Would be good to know for those who have the 4 vs the 4a, indeed! I can say that with my 4, John's help and guidance were spot on.

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post #11737 of 11757 Old 07-24-2017, 07:26 AM
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Originally Posted by Steve Bruzonsky View Post
C weighting, not A weighting, for the decibelt meter. A is fast, C is slow!!!@@@
Steve- Weighting affects meter frequency response. A is more correct in this specific case. I've used both C and A in given situations. It depends on the meter and what you are doing, and typically the equipment mfr will advise on what methods work best for their product and application. Most dba meters have a separate "fast" or "slow" response switch independent of the selected weighting. "Slow" response is typically preferred for speaker setup regardless of weighting.

Here is a good basic overview (ref: http://www.hearforever.org/tools-to-...e-measurements )
---------------------
......The A weighting scale in a sound level meter replicates this filtering process of the human ear.
  • A-WEIGHTING
    • Follows the frequency sensitivity of the human ear at low levels. This is the most commonly used weighting scale, as it also predicts quite well the damage risk of the ear. Sound level meters set to the A-weighting scale will filter out much of the low-frequency noise they measure, similar to the response of the human ear. Noise measurements made with the A-weighting scale are designated dBA.
  • B-WEIGHTING
    • Follows the frequency sensitivity of the human ear at moderate levels, used in the past for predicting performance of loudspeakers and stereos, but not industrial noise.
  • C-WEIGHTING
    • Follows the frequency sensitivity of the human ear at very high noise levels. The C-weighting scale is quite flat, and therefore includes much more of the low-frequency range of sounds than the A and B scales.
----------------------------

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post #11738 of 11757 Old 07-24-2017, 08:04 AM
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Originally Posted by Roger Dressler View Post
Well, most internal noise generators are accurate, if the product was certified by Dolby. There may be products that activate the noise with the EQ bypassed, and that then is inaccurate because it does not reflect actual playback conditions.

The AIX test signals are not suitable for a 75 dB calibration like most other test discs. In my calibrated system they measure almost 10 dB higher -- 83 dB. Of course it will do no harm to set them to 75 dB, but "ref level" on the volume control will not be anywhere close to ref SPL.

For all these reasons, plus the uncertainty as to what levels are actually printed on the AIX disc, I highly recommend the Spears&Munsil 2nd Edition BD. The noise signals are properly bandlimited, and spot on for a 75 dB SPL calibration (including subwoofer). And it's easy to park the signal on any channel you like.
Roger thanks for adding to the conversation and spot on with the meter weighting. Just for clarity, there are two sets of speaker setup tone tracks on the AIX setup disc. One set is 10dba higher than the other (IIRC it is the Dolby encoded set that is higher). Just FYI on that. Also I would think the AIX tones to be accurate for CB setup otherwise there is no way Theta would have made it part of the setup package. The only thing I found frustrating on the AIX was the way they formatted all of the channel tones into one single track. That would seriously vex me if trying to tone in a 12 channel setup!!

Fortunately with the wonderful CB, we are not using the DB meter and tones to set global master volume reference level, which can be the case on lesser preamps / processors. We are only balancing the channel outputs relative to one another and in reference to Left Front, so the overall volumes are produced evenly at each speaker. This not only compensates for any internal processor differences (unlikely), but also compensates for differences in volume at the speaker due to things like: Speaker sensitivity variation, longer cable runs at some speakers vs others, amplifier internal channel differences, etc etc. - For example, my LF speaker is exactly 1/2 dba less sensitive than my RF (BG Radia LA-800's). It has been like this forever- a physical trait of the speaker itslf, and is highly repeatable regardless of amps, processors, cables. (unfortunately we still can't adjust the CB speaker level trims in 1/2 dba increments, but, no big deal really).

All that is critical here (IMO) is to ensure that for whatever level you set Front Left using 0 level trim and the master volume keys, and as long as your meter reads that accurately (75dba A or C weighted, slow response), then just repeat that same response with your meter on the remaining channels by adjusting channel trims. Should get you spot on enough and then let Dirac handle the remainder.

Side note, if you want to get completely OCD with determining what in your audio chain might be causing minor dba differences in one speaker vs another, or you just want an outboard source analog noise generator, you can get something like the Minirator or QBOX: https://www.markertek.com/category/a...one-generators

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post #11739 of 11757 Old 07-24-2017, 09:21 AM
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Originally Posted by Roger Dressler View Post
..
The AIX test signals are not suitable for a 75 dB calibration like most other test discs. In my calibrated system they measure almost 10 dB higher -- 83 dB. Of course it will do no harm to set them to 75 dB, but "ref level" on the volume control will not be anywhere close to ref SPL.

For all these reasons, plus the uncertainty as to what levels are actually printed on the AIX disc, I highly recommend the Spears&Munsil 2nd Edition BD. The noise signals are properly bandlimited, and spot on for a 75 dB SPL calibration (including subwoofer). And it's easy to park the signal on any channel you like.
Roger you have a propensity to post things that make me go "hmmmmmm" . I am mindful about these other issues (a vs c vs z weighting, slow vs fast, etc.) but has not thought about the reference loudness level itself being off.

For those of us with AIX disc and not Spears & Munsil, is it correct to assume that the calibration is still fine, I just have to keep in mind that for example my Theta volume at numerical 35 that I thought was reference 75 dB using AIX, would actually not be reference until some higher volume level say 40?

I will calibrate Casablanca's internal noise generator vs. AIX disc later. You use C weighting slow right?

Regards, Can
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post #11740 of 11757 Old 07-24-2017, 09:33 AM
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Originally Posted by cannga View Post
Roger you have a propensity to post things that make me go "hmmmmmm" . I am mindful about these otherissues (a vs c vs z weighting, slow vs fast, etc.) but has not thought about the reference loudness level itself being off.

For those of us with AIX disc and not Spears & Munsil, is it correct to assume that the calibration is still fine, I just have to keep in mind that for example my Theta volume at numerical 35 that I thought was reference 75 dB using AIX, would actually not be reference until some higher volume level say 40?

I will calibrate Casablanca's internal noise generator vs. AIX disc later. You use C weighting slow right?

Cannga- I was told A weighing, slow response, AIX setup disc, for the CB4. Maybe it is different for the 4a. I'd strongly suggest calling Theta for 100% legit answer and not go off what is written here. JMHO. I don't see the point of using C weighting but you can always try both side by side. if there is a disparity I'd go with A. Always use slow response though. Good luck I'm sure you are still feeling like a kid in a candy store right? :P

BTW the term "reference" here is relevant only to what is optimal reference for the CB output on all channels. We are not adjusting the global master volume output of the CB to a "reference" level such as Dolby etc. We are only ensuring audio output on all channels from the CB plays back at a relative even dba level from each speaker. To do this we are using the FL speaker as the starting reference point and 75dba is our starting reference loudness level to measure all other channels to as we adjust their trims.

This is proven by the first step. While playing the AIX test tones, whether you use the higher gain track or the lower gain track, you will raise CB master volume of FL until your db meter reads 75dba. You will leave LF channel trim at zero. The master volume reference is not changed. it does not matter whether you are hitting 75dba at number 30 on the CB or number 35. It is irrelevant here. All that is relevant is that you have a steady tone and metered dba measurement at the seating position (75dba in this case).

If we were setting optimal reference master volume gain we would be instructed to set the master volume to (example) 45, and then use the FL channel trim to adjust the FL gain to output dolby reference levels as read from avg. seating position on the db meter. Which can be upwards of 105dba in a theater application, but for most home use cases, most of the time it is set to 85dba. We are not doing this here with the CB - no need - because the CB's global master volume output gain vs volume level indicator is optimal.

We are only ensuring all speaker channels playback evenly at the speaker and are measured evenly at the avg seating position- this mainly provides adequate compensation for typical external-to-processor variables that can affect sound output (speaker locations, cable length, speaker sensitivity variance, amp channel output variance, etc). Make sense? Sorry if this sounds confusing.

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post #11741 of 11757 Old 07-24-2017, 10:14 AM
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Originally Posted by cannga View Post
Fellow Casablanca owners, we have lift-off. One giant step for Theta, 2 year wait LOL, one medium step for immersive audio for the hard-core audiophiles. :-) Using DTS and Dolby demo discs, things are checking out ok.
Finally I was able to go full monty 7.1.4 :-), at 3 am today. Basic functions are checking out nicely using sub, sub, sub reference-level pink noise (it was really 3 am) - channel call-outs for both DTS:X and Dolby Atmos are as expected, using DTS:X and Atmos demo discs. No explosion or sparks flying or anything like that.

I will dwell into the details over the next few weeks (nothing like an OCD beta tester, dear Theta) such as Dirac and the always "exciting" MODE setting (I'm starting to have a headache already :-)). Fingers crossed and hope all will be fine.

The high end audio business is not easy either financially or technologically as we all know, so congrats to the Theta team for a job well done. I am aware it has not been easy and took a lot of time and effort from everyone. Also thanks to my dealer VGI whose "street pricing" ;-) made this update so much less painful.

It seems to me paradigm shifts in movie codec (pro-logic to ac3, lossy to lossless, lossless to 3D, etc.) occur every ten years, just like real estate cycles :-), so this change means I am safe for 10 years, and by then I likely won't care anymore lol.

Regards, Can
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post #11742 of 11757 Old 07-24-2017, 11:52 AM
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Just for clarity, there are two sets of speaker setup tone tracks on the AIX setup disc. One set is 10dba higher than the other (IIRC it is the Dolby encoded set that is higher). Just FYI on that.
If we look only at the Speaker Balance Test menu, there is a choice of LPCM or DD. Both measure the same. (83 dBC in my room, FWIW.)

The Channel Identification menu has more codec options, and all measure the same 83 dBC except TrueHD, with is 4 dB lower (maybe it has Dialnorm set?). I'm not seeing a 10 dB offset.

Anyway, none of these tones works for a "75 dB" calibration.

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post #11743 of 11757 Old 07-24-2017, 12:00 PM
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Originally Posted by cannga View Post
Roger you have a propensity to post things that make me go "hmmmmmm" .


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I am mindful about these other issues (a vs c vs z weighting, slow vs fast, etc.) but has not thought about the reference loudness level itself being off.

For those of us with AIX disc and not Spears & Munsil, is it correct to assume that the calibration is still fine, I just have to keep in mind that for example my Theta volume at numerical 35 that I thought was reference 75 dB using AIX, would actually not be reference until some higher volume level say 40?
If you want to know what volume number represents reference level, you can use any of these:
-- Spears & Munsil 2nd Edition
-- Any THX certified movie disc -- they have the 75 dB test tones included. Example, Monsters Inc, Blu-ray, "THX Optimizer."

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I will calibrate Casablanca's internal noise generator vs. AIX disc later. You use C weighting slow right?
I only use bandlimited pink (as on the recommended discs), so I use C-wtg as otherwise the subwoofer calibrations would be incorrect.

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post #11744 of 11757 Old 07-24-2017, 12:34 PM
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Originally Posted by Roger Dressler View Post
If we look only at the Speaker Balance Test menu, there is a choice of LPCM or DD. Both measure the same. (83 dBC in my room, FWIW.)

The Channel Identification menu has more codec options, and all measure the same 83 dBC except TrueHD, with is 4 dB lower (maybe it has Dialnorm set?). I'm not seeing a 10 dB offset.

Anyway, none of these tones works for a "75 dB" calibration.
This is getting out of hand and diluted. I was only talking about speaker balance tracks not anything else. To anyone reading this or previous posts, please be advised none of this should be interpreted as accurate advice for your unit. Always contact your dealer or Theta directly if you have tech questions for the most informative answer. I say this because there is a wide degree of information on this topic, some good, some conjecture, and there are even different references in the CB owners manual vs what Theta support may tell you to do.

For example, on page 24 of v4.03b of the CB4 owner manual, it states to use the AIX speaker setup tones, use C weighting on your db meter, and measure to 70dba. Then for subs, measure to 76dba. That is different than what I was instructed to do. Just FYI. IMHO, you should be ok measuring to 70, 75, 80, etc dba, C or A, as long as you follow the rest of the process as outlined and each channel measures equally. This is a much less critical process than setting master volume gain which fortunately we do not need to do with the CB.

From my end, all I can do is relay what I as instructed to do for speaker balance setup by Theta for my CB4, and it worked as expected. Things however may be different for the 4a. Roger if you get the same exact dba reading from DD vs LPCM on the speaker balance tracks then there is something amiss - those tracks are recorded at different reference levels. It may not necessarily be a full 10db but the two will be significantly different. I'd say double check?

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post #11745 of 11757 Old 07-24-2017, 12:42 PM
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Originally Posted by k_lewis View Post
For example, on page 24 of v4.03b of the CB4 owner manual, it states to use the AIX speaker setup tones, use C weighting on your db meter, and measure to 70dba. Then for subs, measure to 76dba.
>>use C weighting on your db meter, and measure to 70dba<< This is incorrect. When you measure with C-wtg, you write dBC, not dBa. That's contradictory.

The 6 dB increase is correct for wideband pink recorded equally in every channel (as on tnis AIX disc and also for the Atmos test discs). It's just not very precise because it relies on the subwoofers being flat to 20 Hz.


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Roger if you get the same exact dba reading from DD vs LPCM on the speaker balance tracks then there is something amiss - those tracks are recorded at different reference levels. It may not necessarily be a full 10db but the two will be significantly different. I'd say double check?
How do you know how they were recorded?

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post #11746 of 11757 Old 07-24-2017, 12:58 PM
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>>use C weighting on your db meter, and measure to 70dba<< This is incorrect. When you measure with C-wtg, you write dBC, not dBa. That's contradictory.
Technically in geek-speak that is correct (dBc va dbA), but the common layman norm is to cite measurements in db or dba. Even though it may technically be incorrect to the letter. reference: http://www.hearforever.org/tools-to-...e-measurements

If you feel the CB4 owners manual is incorrect with the 70db setup / C weighting reference, talk to Theta and ask them to correct it. All I can do is provide information from a verified legitimate source such as the published owner manual.

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How do you know how they were recorded?
Do your homework !

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post #11747 of 11757 Old 07-24-2017, 02:24 PM
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Technically in geek-speak that is correct (dBc va dbA), but the common layman norm is to cite measurements in db or dba.
I think there is enough confusion without adding more by propagating "layman" misuse of terminology.

Quote:
If you feel the CB4 owners manual is incorrect with the 70db setup / C weighting reference, talk to Theta and ask them to correct it. All I can do is provide information from a verified legitimate source such as the published owner manual.
I take no issue whatsoever with what is in the Theta manuals. I already acknowledged that the AIX disc could be used for relative channel balance, just not for calibrating the absolute SPL reference.

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Do your homework !
I did. Twice. Are we looking at the same set of test signals?
>AIX Disc
>System Calibration
>Speaker Balance Test

>>Start 96 kHz/24-bit x.y LPCM test (pick any of 3 channel configs)
vs.
>>Start 48 kHz/16-bit/5.1 ch Dolby Digital Test

They all measure the same SPL. What do you measure?

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post #11748 of 11757 Old 07-24-2017, 03:32 PM
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Quote:
Originally Posted by k_lewis View Post
...
For example, on page 24 of v4.03b of the CB4 owner manual, it states to use the AIX speaker setup tones, use C weighting on your db meter, and measure to 70dba. Then for subs, measure to 76dba.
Quote:
Originally Posted by Roger Dressler View Post
The 6 dB increase is correct for wideband pink recorded equally in every channel (as on tnis AIX disc and also for the Atmos test discs). It's just not very precise because it relies on the subwoofers being flat to 20 Hz.


Hmmmm.
Kidding aside very interesting discussion.

I understood "what," but not "why." Could you please explain why wideband pink needs to be 6 dB higher for subwoofer, and why this relies on subwoofer being flat to 20 Hz? TIA

Surely will test CB IVa vs AIX disc tonight. Unfortunately I only have the original Spears & Munsel, not the Second edition. This mundane test now becomes somewhat *exciting*. :-)

Last edited by cannga; 07-24-2017 at 03:54 PM.
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post #11749 of 11757 Old 07-24-2017, 04:04 PM
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Originally Posted by cannga View Post
I understood "what," but now "why." Could you please explain why wideband pink needs to be 6 dB higher for subwoofer, and why this relies on subwoofer being flat to 20 Hz? TIA
At the risk of acting like I know what I'm talking about, the starting point is a wideband (10 Hz - 22.5 kHz) pink signal recorded "-20 dBFS". That signal is played through the main speakers and set for 85 dBC SPL. The LFE channel is calibrated 10 dB higher than the main channels. A full scale signal at, say, 80 Hz in the C speaker would be 105 dB SPL, and that same signal in the LFE channel will be 115 dB.

So why only a 6 dB difference with pink noise? Because a good portion of the signal is not reproduced by the subwoofer. The subwoofer only covers roughly 2 octaves, and that remaining portion reads roughly 4-5 dB lower than the whole.

I mentioned previously that this is not very precise, because if the frequency response of the subwoofer is not flat, or does not cover the entire 10 Hz to 120 Hz range, the reading will be affected. But it's fine for a ballpark calibration or a quick sanity check of the system. Then let your ears decide how to finalize the subwoofer gain.

Quote:
Surely will test CB IVa vs AIX disc tonight. Unfortunately I only have the original Spears & Munsel, not the Second edition. This mundane test now becomes somewhat *exciting*. :-)
Do you have Monsters Inc or any other THX certified BD or DVD? There were lots of them.

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post #11750 of 11757 Old Yesterday, 06:25 PM
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My Casablanca IVA has landed! YEA!

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post #11751 of 11757 Old Yesterday, 09:02 PM
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The official Theta Owners Thread

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Originally Posted by cannga View Post
IMHO 203. AFAIK 205's main advantage is the DAC section that improves SQ of Oppo's analog out. In these days and ages, unless you have a turntable or tape player etc., there is simply no better solution than HDMI for SSP connection (no need for Oppo analog out), so there is no need for the 205.



Second, I guess you might still hook up Oppo analog if the DAC section of Oppo 205 (the whole Blu-ray player is $1300) is *HUGELY* better than Theta DAC (just the Xtreme D3 card is MSRP $5000, very likely best SSP's ever produced). The answer is obviously no.



If there is any significant difference between the 2 players' video performance, I do not know. Anybody would like to comment on this?





The 205 has well thought out jitter reduction circuitry on the HDMI 1.4 audio output that is unique to that unit.


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post #11752 of 11757 Old Yesterday, 09:13 PM
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Do your homework !


Ha! You might want to google Roger.


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post #11753 of 11757 Old Yesterday, 09:57 PM
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Quote:
Originally Posted by Steve Goff View Post
The 205 has well thought out jitter reduction circuitry on the HDMI 1.4 audio output that is unique to that unit.
Thanks. Since Casablanca has Jitter Jail, perhaps this is also redundant for Casablanca owner?
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post #11754 of 11757 Old Yesterday, 10:19 PM
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Quote:
Originally Posted by Roger Dressler View Post
d
....I mentioned previously that this is not very precise, because if the frequency response of the subwoofer is not flat, or does not cover the entire 10 Hz to 120 Hz range, the reading will be affected. But it's fine for a ballpark calibration or a quick sanity check of the system. Then let your ears decide how to finalize the subwoofer gain.

Do you have Monsters Inc or any other THX certified BD or DVD? There were lots of them.
Thanks Roger for the nice explanation. I found 2 THX certified DVD's, but they only have "THX Optimizer" for speaker location, not level. I do plan to get Monster 2 Blu-ray to check.

Because the AIX disc does not have ceiling speaker level check (is there any disc that has this yet?), I am limited to using the Casablanca's internal generator to set all levels, but for academic interest I did do the check anyway.

I first adjusted Casablanca IVa with internal noise generator, so that all 7.1 channels are at 75 dB, then the AIX disc was played at exact same volume setting. As such the AIX renders L&R and subwoofer at around same volume level 74-75 dB, but Center + Left & Right Side Surround + Left & Right Rear Surround were very clearly louder at 77 dB. All measurements with C weighting.

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post #11755 of 11757 Old Yesterday, 11:03 PM
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Quote:
Originally Posted by cannga View Post
Thanks Roger for the nice explanation. I found 2 THX certified DVD's, but they only have "THX Optimizer" for speaker location, not level.
That's weird. I've never seen one that does not step the noise through the channels.

Quote:
I do plan to get Monster 2 Blu-ray to check.
I hope it is the dual pack with the DVD, as that is the disc with the THX Optimizer. The Blu-ray has some other test tones, but I cannot vouch for their level accuracy.

Quote:
Because the AIX disc does not have ceiling speaker level check (is there any disc that has this yet?), I am limited to using the Casablanca's internal generator to set all levels, but for academic interest I did do the check anyway.
The Atmos test discs have up to 9.1.6 test tones, but they are like the AIX in that they are wideband at -20 dBFS. Can also download these test signals at the Dolby website. Link.

Quote:
I first adjusted Casablanca IVa with internal noise generator, so that all 7.1 channels are at 75 dB, then the AIX disc was played at exact same volume setting. As such the AIX renders L&R and subwoofer at around same volume level 74-75 dB, but Center + Left & Right Side Surround + Left & Right Rear Surround were very clearly louder at 77 dB. All measurements with C weighting.
There may be more to the story, but just based on those results, it appears that the internal noise is indeed inaccurate as Theta said, and more specifically, the C and surround noises are ~2 dB low, and the subwoofer noise is 6 dB high. In other words, change your gain trims so all channels are same, with subwoofer being 6 dB higher.

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post #11756 of 11757 Old Yesterday, 11:15 PM
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Ha! You might want to google Roger.


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Why? Is this person so important they can't look things up for themselves or make a phone call like any of us normal folk?
It was not my intention to step on your idol here, I have read many of Roger's posts (as well as other long time members here), and of course he has contributed a lot of solid, good information and seems quite knowledgeable- Some things posted I disagreed with, based on what's in the Theta user manual, what I as told by JB @ Theta, and my own knowledge which is quite valid. So what. Big deal. I think Roger can speak up for himself if necessary.

If you'd prefer to contact this person instead of Theta for your Casablanca support and guidance, that is your choice of course- free country and all. The whole fan-boy thing, I just don't get that.

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post #11757 of 11757 Old Yesterday, 11:39 PM
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Quote:
Originally Posted by Roger Dressler View Post
I think there is enough confusion without adding more by propagating "layman" misuse of terminology.

I take no issue whatsoever with what is in the Theta manuals. I already acknowledged that the AIX disc could be used for relative channel balance, just not for calibrating the absolute SPL reference.
Heh, I don't disagree. However no matter what product user manual you read regarding speaker setup and setting speaker levels, it will always be referenced in Db or dBa. By being technically accurate with dBc, you're actually causing the confusion. Silly right? Product setup manuals are written more for laymen than technical folk.

On the AIX disc, I think you misunderstood- I never once mentioned setting absolute volume SPL reference. That is not necessary with the CB and I actually mentioned that. I was only discussing speaker channel balancing - so not sure how you turned this into something different but no big deal.

Quote:
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I did. Twice. Are we looking at the same set of test signals?
>AIX Disc
>System Calibration
>Speaker Balance Test

>>Start 96 kHz/24-bit x.y LPCM test (pick any of 3 channel configs)
vs.
>>Start 48 kHz/16-bit/5.1 ch Dolby Digital Test

They all measure the same SPL. What do you measure?
That's darn interesting Roger and I do believe you. I got about 10db difference DD vs LPCM. When I spoke with JB he too mentioned the DD track will play back at a higher level. I did some googling and read other posts citing similar, and mentioning the mastering of the AIX DD track was set at a higher more commercial reference level. No did not save any links, but that info stacked up pretty well with what I experienced.

Would be interesting to see if anyone else here has a gain difference on the DD track vs the LPCM track, for sure.

But over it does not really matter because as I will say again, we are not setting global master volume SPL, we are only balancing all of the channel outputs at the speakers to they are consistent, as measured at the listening location. Does not matter whether the initial measured tone on FL is 70b, 75db, 85db etc as long as it is set the same on all channels. E.G. if you start out with 85db on FL, 0 trim and master volume adjusted, then make sure all remaining channels test out to 85db as well using the trim setting.

Your other posted comments on why the sub needs to be approx 6db higher for the speaker balance setup is spot on. that was good info.

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