GWklipsch Posted February 14, 2001 Share Posted February 14, 2001 Could someone please explain how it works? My Onkyo receiver (TX-SV545) has volume numbered in db that goes from -58 to 0 then from 0 to +12. Does 0 represent full volume and is everything to +12 the headroom more or less? I would like to know what the 0 represents on that scale. Thanks for you help! George Quote Link to comment Share on other sites More sharing options...
Andy W Posted February 15, 2001 Share Posted February 15, 2001 Typically negative dB indicates attenuation (or cut) and positive dB indicates gain (or boost). -Andy W Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted February 15, 2001 Share Posted February 15, 2001 If the Onkyo engineers actually intended the "0dB" indication to be a reference to some standard of some sort, the only things I can think of are (a) it refers to one of the Dolby reference levels (THX? AC-3? Surround?) and puts out that reference volume level given a reference line level signal (2 volts?) through a standard speaker sensitivity (?) and input impedence (?) in a typical (?) room. Or, (, the 0 dB level is where the preamp is at "unity gain": that is, a CD player putting 0.567 volts into the CD input causes the preamp to put exactly 0.567 volts into the amplifier modules. Or, and more likey, the guys in marketing thought it looked cooler to go from -58 through 0 to +12 and it did to go from -70 to 0. Ray Quote Link to comment Share on other sites More sharing options...
toots mutant Posted February 15, 2001 Share Posted February 15, 2001 My receiver goes from -66 to +18, all of which just makes me think its designers were inspired by something they saw in Spinal Tap. Quote Link to comment Share on other sites More sharing options...
boa12 Posted February 16, 2001 Share Posted February 16, 2001 toots, lol. that's what I was thinking. great movie line. do the mondial amps go to 11? Quote Link to comment Share on other sites More sharing options...
Guest BobG Posted February 16, 2001 Share Posted February 16, 2001 dB is a log scale measurement used to make comparisons of things. Level, illumination, distance, height. Anything can be described in dB if it can be expressed as a ratio. For example, if you go twice as far, that's a 6dB change in distance. dBW is an increase in level as compared to 1 watt. dBM is an increase relative to 1 milliwatt. Since most human senses are sensitive to proportional changes in the stimulus, it is best to express those stimuli in dB. To convert measurements to dB, first compare the two measurements by creating a ratio like Quantity A/Quantity B next compress the ratio by converting to a log scale. if the ratio is 1:100 convert to scientific notation for log 10. 100 in log 10 is 2 since 100 is 10 to the second power. this is the measurement in Bels. To get decibels, multiply by 10 if it's power you are measuring or multiply by 20 if it's pressure (voltage, distance, etc) I know this is complex and likely more than you wanted, but it comes from a cool training I attended and I wanted to show you how bright I am. On the volume control, it doesn't mean a heck of a lot other than how much LESS than full output, relative to some voltage level (either 1 v or .775 for pro gear) your current setting is. Has nothing to do with sound pressure level in the room. I apologize. BobG Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted February 16, 2001 Share Posted February 16, 2001 BobG (and welcome back again!!! )... The problem here is that the scale doesn't simply show you the attenuation in dB from maximum output at 0dB down to some arbitrary floor at, say, -70dB... the scale goes from -58dB to 0dB to +12 dB. The question is, what does the 0dB reference point mean? 0dB relative to WHAT? +12dB above WHAT? I still think the marketing guys just thought it looked cool... Ray Quote Link to comment Share on other sites More sharing options...
GWklipsch Posted February 19, 2001 Author Share Posted February 19, 2001 Thanks guys for you help with this. I think your response has helped me look at this is a way I haven't yet considered. This was just one of those things that buged me for some time. Again thank you! George Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.