Jack Gvozdjak Posted January 18, 2009 Share Posted January 18, 2009 Is 0dB on the reciever considered reference level? Normally I listen between -30 to -20 dB. Thank you! Jack Quote Link to comment Share on other sites More sharing options...
ben. Posted January 18, 2009 Share Posted January 18, 2009 By definition, 0 dB is a reference. Any measurement expressed in decibels is described by its relationship to this reference level. Whether it's a nominal level (0VU) in an analog mixer or 0dBFS in a digital device, it's the same idea. Of course, this does not mean that you should listen to your system at 0dB on that dial for any particular reason. Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 18, 2009 Share Posted January 18, 2009 Only if your system is calibrated properly. Shawn Quote Link to comment Share on other sites More sharing options...
tigerwoodKhorns Posted January 19, 2009 Share Posted January 19, 2009 I can't hear my system at 0 db. My preamp doesn't have a digital scale so I have to use my meter. Can't hear it at all. Quote Link to comment Share on other sites More sharing options...
laager Posted January 19, 2009 Share Posted January 19, 2009 Is 0dB on the reciever considered reference level? Absolutely not. Just think about it for a moment. At 0dB on the receiver a given amount of power is being produced by the amp. Push that amount of power though an inefficient speaker (say 84dB sensitivity) and it might be 90dB SPL produced. Swap out those 84dB sensitivity speakers for a set of 105dB sensitivity K-Horns and you might be blasting your eardrums into permanent paralysis. Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 19, 2009 Share Posted January 19, 2009 "Absolutely not." That is why it needs to becalibrated. The way you calibrate it is to set the volume to 0dB andthen play a -30db or -20dB channel balance test noise and use the speakerlevel controls. If you play a -30db tone you set all speakers to 75dBat the listening position. If it is a -20dB tone you set all speakersto 85dB at the listening position. That calibrates thesystem so that the max output level per speaker at the listeningposition is 105dB when the volume control is at 0dB on thereceiver/pre-pro. That is THX Reference Level. Shawn Quote Link to comment Share on other sites More sharing options...
laager Posted January 19, 2009 Share Posted January 19, 2009 That's nice. Who said anything about THX? Quote Link to comment Share on other sites More sharing options...
Zen Traveler Posted January 19, 2009 Share Posted January 19, 2009 Is 0dB on the reciever considered reference level? Normally I listen between -30 to -20 dB. Thank you! Jack On AVRs that use Audyssey, "0" is THX reference level after calibration. As mentioned, most people listen considerably lower than that....On my Denon I usually listen at -18 to -16 or so. Quote Link to comment Share on other sites More sharing options...
Kain Posted January 19, 2009 Share Posted January 19, 2009 Don't different receivers/amps produce different wattages of power? Therefore, at 0dB, different receivers/amps put out different amounts of power and that would mean they would produce different sound levels of loudness. As a result, I believe it would be hard to judge what 0dB really means considering the different receivers/amps out there. Am I right? Quote Link to comment Share on other sites More sharing options...
Zen Traveler Posted January 19, 2009 Share Posted January 19, 2009 Don't different receivers/amps produce different wattages of power? Therefore, at 0dB, different receivers/amps put out different amounts of power and that would mean they would produce different sound levels of loudness. As a result, I believe it would be hard to judge what 0dB really means considering the different receivers/amps out there. Am I right? I wondered the same thing and came to the conclusion that speakers that couldn't play efficiently at that level were more than likely going to clip even though they could play that loud. Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 19, 2009 Share Posted January 19, 2009 "Who said anything about THX?" The original poster, that is what Reference Level refers to. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 19, 2009 Share Posted January 19, 2009 "Don't different receivers/amps produce different wattages of power? Therefore, at 0dB, different receivers/amps put out different amounts of power and that would mean they would produce different sound levels of loudness. As a result, I believe it would be hard to judge what 0dB really means considering the different receivers/amps out there. Am I right?" No, not once the system is calibrated as I outlined above. When you calibrate the system it doesn't matter how much power you have, how efficient your speakers are, how big your room is or how far away from your speakers you sit. They will all play at the same level if calibrated properly, that is the whole point of calibrating your system. Take a speaker 'A' that is 95dB/w/m and speaker 'B' that is 115dB/w/m. To make the math simple say we loose 10dB at the listening position from whatever the speaker is producing. You set the volume to 0dB on the master volume control (or your receiver does this automatically when you go into the calibration section). Its built in test tones are typically -30dB. With a SPL meter you adjust each speakers output levels such that you read 75dB on the meter at the listening position. Now you play a movie and have the volume at 0dB again. At the maximum possible output level (0dBFS) each speaker will produce 105dB at the listening position (115 at the speaker minus 10dB for distance). Speaker A is using 100w to do this, speaker B needs 1 w. The speaker trims calibrated for the differences in efficiency. This is no different at all then having a surround system that has speakers of differing efficiencies, differing distances to the listeners and quite possibly differing amounts of power to the different speakers. Once you calibrate the speaker levels they all play at the same volume level no matter where you set the volume control. And if you calibrated your system properly you will always know what the maximum possible SPL is per speaker at the listening position. That is what your volume control is telling you. 0dB on the volume control means Reference Level (THX came up with this, that is why it is THX Reference Level). Reference Level is 105dB per main speaker at the listening position, LFE can be 115dB. If you set your volume control to -10dB that means the maximum possible level is 10dB below reference level. So each main speaker could hit a peak of 95dB and the LFE could be 105. -20dB on the volume control means max peaks of 85dB and the LFE could be at 95dB. Shawn Quote Link to comment Share on other sites More sharing options...
Don Richard Posted January 19, 2009 Share Posted January 19, 2009 The decibel is simply a ratio, and on its own without a reference is meaningless. There is a reference for power amplifiers, not very popular, called the dBW, where 0dB=1 Watt. Therefore, 10 dBW=10 Watts and 20 dBW=100 Watts. The equipment in question in the OP is obviously not calibrated to this standard. It may be an arbitrary number, or it may reference a certain power output. Perhaps the manual would shed some light. Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 19, 2009 Share Posted January 19, 2009 "The decibel is simply a ratio, and on its own without a reference is meaningless." That is why the system needs to be calibrated properly. That gives a reference to the 0dB settings on the receiver/pre-pro. Shawn Quote Link to comment Share on other sites More sharing options...
Groomlakearea51 Posted January 19, 2009 Share Posted January 19, 2009 Some number of years ago I asked a factory (Sansui) engineer at a trade show in Germany why their high end amps volume controls were marked "-70db" to "0db". He explained (he was an honest man...) that that "scheme" was more marketing than anything else, but that the numbers were, in fact, "real". At "0", the amp will produce it's rated power with a dynamic (speakers attached) 8 ohm load. He then explained that at any volume setting less than "0", say -42dB, etc, corresponded to the level of power expressed in minus dB of the "reference" level for that amp, with -70db being virtually 0 watts. There's a formula that relates to dB and power produced (every increase or decrease of power is relational). He also explained that the numbers on the volume knob are also positioned based upon the type of volume pot used on that amp. On the Sansui AU-11000, -42dB is about the 10:00 oclock position. On the "a" version, it's about 9:00 o'clock position. Heres what Bruce Rozenblit wrote (Transcendent OTL; Audio Reality; p.34, et.al) A 1 dB increase in loudness requires 10% more amplifier power and a 3 dB increase requires 100% more amplifier power. This means that for the average person, an amp putting out 50 watts doesn’t sound any louder until it outputs 100 watts. For sound to be perceived as sounding twice as loud, an amplifier is required to increase its output by 10 times, or 1000%, an increase of 10 dB. The application of decibels relating to amplifier power and apparent loudness are a 10- log function. When the decibel is applied to voltage gain, it is a 20-log function. That means if you double the voltage, the decibels increase by 6 dB. Similarly, if you reduce the voltage gain by a factor of two, it decreases by 6 dB. This is double the amount just stated for power. A voltage gain of 10 times is 20 dB, and 100 times is 40-db. Hope that helps from one aspect at least. Quote Link to comment Share on other sites More sharing options...
Groomlakearea51 Posted January 19, 2009 Share Posted January 19, 2009 I think I'm following you. If I recall, the tech also mentioned that the markings were related to to sensitivity, and measured based upon a standard input level, etc. Which would be why "-42dB" would be loud on some input signals, vs low on others. Correct? Quote Link to comment Share on other sites More sharing options...
laager Posted January 19, 2009 Share Posted January 19, 2009 "Who said anything about THX?" The original poster, that is what Reference Level refers to. That's an entirely subjective interpretation of 'Reference Level' and its application to the question posed. Further, if a receiver is not 'THX certified' then the calibrated 0dB = 'THX Reference Level' argument falls to pieces unless you're further arguing that regardless of the certification or not, all receiver manufacturers are intending that 0dB on the display is to be 'THX reference Level'. That would be an ambit assertion indeed. Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted January 19, 2009 Share Posted January 19, 2009 "Who said anything about THX?" The original poster, that is what Reference Level refers to. That's an entirely subjective interpretation of 'Reference Level' and its application to the question posed. Further, if a receiver is not 'THX certified' then the calibrated 0dB = 'THX Reference Level' argument falls to pieces unless you're further arguing that regardless of the certification or not, all receiver manufacturers are intending that 0dB on the display is to be 'THX reference Level'. That would be an ambit assertion indeed. Hmmmm. I learned a long time ago that when Shawn shares his expertise, it is usually best to listen to him. After that, if something does not make sense, it is probably best to then politely ask for further clarification. But that is just me..... Having smart folks answer your questions is a valuable thing. Why be caustic and unecessarily argumentative? It doesn't make sense. Again, that is just my simple-minded opinion, -Tom Quote Link to comment Share on other sites More sharing options...
Groomlakearea51 Posted January 19, 2009 Share Posted January 19, 2009 mdeneen (mark): Curiouser and curiouser.... On the 11000's, the "detents" are 0, -3, -6, etc all the way back to -60 and the final one is "infinity symbol". At the first detent off infinity (-60) the amp volume is pretty much at a normal listening level... provided you are listening and not doing anything else. Underneath the volume knob however, is a rotating ring/ slider that allows 0db (no effect), -10db (SWMBO just walked in the room...), and -20db (Talk on the phone and really not listen at all). That does not include the normal -20dB mute switch which when used is the same as the slider at -20dB. They can be used in combination, although at a minumum -60dB setting, and with -10dB on the slider, -20db on the main mute, it is very quiet. While barely audible, it's still clear. The 11000a's are detented at -1, -2, -3, -4, then at -2 increments, then -3 increments until - 28, then increments of -4, -5, -6, -7, -10, -10, -10 down to -70db and then to "infinity". There is no ring slider on the "a" models. Using any source, e.g. a CD, both the 11000 and the 11000a, exhibit the same SPL at the same volume settings, so it's just the weird design of the volume pot assembly. Curiouser and curiouser.... and I can't find the "cheat sheet" the tech gave me many years ago (as in 1977...) that showed the approximate output at each detent level for the nominal "test" load. Pre-out and main-in sensitivity is 700mV at 100k-ohms; nominal input into the pre is 130mV. Power RMS is rated 110 wpc, but I just had one of the 11000's rebuilt. According to the tech, Warren Bendler (www.sansui.us), the amp tested out at 115 wpc + 0.05 watts into an 8 ohm load at 1khz (which is apparently the factory method of testing on the bench). Knowing that... and not using any controls except the volume control, how do you calculate the power that it would be producing for each detent? If you could guide me on the formula, I can use an Excel sheet and do one for each of my amps at the test load.[8-|] Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 19, 2009 Share Posted January 19, 2009 "if a receiver is not 'THX certified' then thecalibrated 0dB = 'THX Reference Level' argument falls to pieces " Notin the least. If one calibrates the unit as I said above it makes nodifference if the receiver is THX certified or not. It will still becalibrated such that 0dB on the volume control is THX Reference level. Onecan calibrate *anything* to THX reference level, even a basic 2 channelpre-amp. Simply play the -30dB channel balance noise and turn up thevolume until you measure 75 dB at the listening position. Mark thatposition on the volume knob, that is THX Reference level. What youloose doing this is the nice reference to how many dBs above or belowyou are from reference level. "unlessyou're further arguing that regardless of the certification or not, allreceiver manufacturers are intending that 0dB on the display is to be'THX reference Level'. " Itis a reference, if one calibrates as stated above it results in THXreference level. Before THX certification just about no receiver had volumecontrols that became less negative as you turned up the volume. After THXcertification popularized the idea of reference level within a few years pretty much all of them did.Shawn Quote Link to comment Share on other sites More sharing options...
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