RX-V1400 and "Dial Norm"

Charles_Y · 05-10-2004, 03:46 PM

I recently purchased the Yamaha RX-V1400 after I started having significant problems with my RX-V995. The "YPAO" calibration worked well for me, though it set my center and surround speakers as "small" rather than "large." It's certainly best to double check things afterward but it really is a help in my estimation!

My real question is something that never showed up on the RX-V995. Occasionally on the RX-V1400, I'll notice "Dial Norm = 40db" or some such value come up on my on-screen briefly when loading a DVD menu or movie start to play.

I emailed Yamaha about this twice and got no response. It isn't mentioned in the manual as a system parameter or anything.

Could anyone enlighten me as to what this is? Is it a glitch or some new DVD disc status info?

Michael Reuben · 05-10-2004, 04:11 PM

"Dialnorm" is a little-understood feature of Dolby Digital. I could go into a long technical explanation, but it's probably more information than you want. In general, you can ignore the reading (especially since there's no consistent standard among receiver and pre/pro makers for the format in which they report dialnorm values). If you're interested, there's material on Dolby's site. Or you can do a search in this part of HTF; I'm sure there are former threads.

M.

jeff peterson · 05-10-2004, 07:34 PM

Get the online version (PDF) on the manual from the Yamaha web site and do a search on dialnorm. It's in the manual, just hard to find.

Charles_Y · 05-11-2004, 02:07 AM

Thanks Michael. Though I must admit if the value can't be changed (if one would even want to), then this would appear to be information nobody needs - just an annoyance, unless one turns off the on-screen display altogether which I don't wish to do as I want to continue to monitor my volume levels. I wonder if this is like some "FCC must carry" rule.

I also think I saw somewhere recently that "dial norm" spells out as "dialog normalization" - probably some component involved in the mixing process on Dolby Digital tracks.

Jeff - As I said in my message I couldn't find a reference in the manual. A second search proved fruitless as well. Yamaha's lack of response to my emails probably confirms this. No problem in the long run I guess.

jeff peterson · 05-11-2004, 05:06 AM

Charles, it's on the lower right of page 30 of the user's manual:

Quote:

When this unit detects Dolby Digital signals, the following display appears for a few seconds. This shows how the signal level is being corrected to become -27 dB (THX recommendation)

Also, this article from hometheaterhifi.com may be of value.

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Michael Reuben · 05-11-2004, 08:58 AM

Ugh. That extract from the manual simply confirms that hardware makers don't understand what they're doing (or maybe it's just the manual writers).

First of all, it isn't "-27 dB". It's "-27 DBFS" ("decibels below full scale"). And "-27" isn't a THX recommendation; it's the default dialnorm setting on the Dolby Digital encoder. Most DVDs use the encoder default, but many do not. A setting of -27 DBFS tells the decoder to lower the overall volume by 4db (which, BTW, is why most DTS tracks sound louder than their DD counterparts; DTS doesn't have the dialnorm feature).

The theory behind dialnorm is to allow DD signals to be adjusted so that dialogue is always at a constant level when switching among soundtracks. The dialnorm setting achieves this by instructing the decoder to raise (or lower) the overall volume by a set amount. The feature would be useful in things like TV broadcasts, where it could be applied to maintain a constant volume across different channels -- if only it were used correctly. But it almost never is. For example, I receive one cable channel that has a dialnorm setting of 0 DBFS, because some idiot in the broadcast chain obviously thinks that's a "neutral" setting, when in fact it drops the DD volume by 31db (27 more than a typical DVD), which makes it almost inaudible.

Because the volume of dialogue is used as the reference point, many people mistakenly think that dialnorm adjusts the volume of dialogue relative to the entire signal. Nope. All that dialnorm does is tell the decoder to raise or lower the overall volume by a set amount. It doesn't change the mix or balance of the recording.

M.

John Garcia · 05-11-2004, 12:09 PM

Quote:

The "YPAO" calibration worked well for me, though it set my center and surround speakers as "small" rather than "large."

Unless you have full range speakers (capbable of nearly 20Hz) for center and surrounds, they SHOULD be set to small, so YPAO did what it should have done.

Steve Winkler · 05-11-2004, 02:19 PM

This was one of the reasons I returned my RX-V2400. The dialnorm function played havoc with my dth satellite audio, jumping from -27dbfs to +4 dbfs depending on which channel was on. Having said that, with my situaution I'm 99% sure the problem is with my dth satellite provider's audio encoding/software much like Michael's cable provider. Excellent explanantion Michael Reuben, thanks for that.

Perhaps this feature should be defeatable in Yamaha's newer receivers.

Cheers,

Steve

Michael Reuben · 05-11-2004, 02:38 PM

Quote:

Perhaps this feature should be defeatable in Yamaha's newer receivers.

AFAIK, there were a few Denon receivers that allowed defeatable dialnorm, but it's rare. As a technical matter, I believe that a decoder with defeatable dialnorm would be considered by Dolby not to conform to the DD specs.

M.

Charles_Y · 05-11-2004, 02:39 PM

Looks I may have opened up a can of worms on this one. Thanks Jeff. I must be blind for missing that one on pg. 30 of the manual.

I'm not that technically proficient but it appears that this feature in principle was well intentioned but in practice proves to be a problem. I think Steve W. has a good suggestion - make it defeatable in future models if possible.

I don't like having the decoder take control of my overall volume levels in DD playback. Leave it to the users.

Michael Reuben · 05-11-2004, 02:52 PM

Quote:

I don't like having the decoder take control of my overall volume levels in DD playback. Leave it to the users.

You still have control. Most dialnorm settings can be compensated for by simply raising or lowering the volume. It's only the out-and-out mistakes (like the looney setting on my one cable channel) that are a problem, because there isn't enough "play" in the volume knob to compensate. And that's a rare occurrence.

Again, the vast majority of DVDs use the encoder default. But if you have one that sounds too loud or too soft, it's always a good idea to check the dialnorm setting (assuming your decoder permits this -- not all do).

M.