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Thread: Understanding relative volume and 0db on my receiver.

  1. #11
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    Default Re: Understanding relative volume and 0db on my receiver.

    +15 is an arbitrary limit...as you set what what SPL 0db on the volume knob.

    I get it, with all the variables involved, you are looking for the safe volume limit. The AVR isn't going to do that for you. You will not get a definitive answer for that. Nobody knows how loud you like to listen. You have to be smart about how you use the system and how loud you play it.
    -curtis

  2. #12
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    Default Re: Understanding relative volume and 0db on my receiver.

    Hey Jimb! Welcome!

    Thank you for your insights! Yes, maximum non-clipped volume setting from a digital source. Bingo.

    Yep, from your input and Curtis's and Mike's, I see that I need to speak with these AVR manufacturers directly. Hopefully I can get some kind of answer for this. I will report back with what I learn.
    Thanks, guys!!
    Last edited by j0nnyfive; 11-10-2019 at 06:41 PM.

  3. #13
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    Default Re: Understanding relative volume and 0db on my receiver.

    j0nnyfive,

    I think you are misunderstanding volume control and how it relates to a receiver's or amplifier's "power output"....

    First off, as others have mentioned - "0dB" is just an arbitrary number - it is meaningless and has no relationship to the output volume of your speakers or how much wattage your receiver or amplifier is producing.

    That said, if you calibrate your receiver using its built in auto speaker setup it takes measurements of your speakers and will then set "0dB" to typically refer to 75 or 85dB spl output from one speaker at the microphone position. (there is no standard, some receivers calibrate to 75, others to 85, others to whatever the user wishes). This then translates such that +3dB on your volume control would then mean 78dB from one speaker at the same mic position (if the auto level calibrated to 75db). However, this is not precisely accurate.

    The receiver has no idea how much power it is sending to the speakers at any volume control level. Volume controls control "gain". As such, the receiver does not know when it is clipping or when it has reached maximum output. It is complicated because every speaker model has a unique sensitivity rating and unique impedance profile. At what output volume level from the speakers your receiver will start to clip will dramatically vary from one model speaker to another.

    There are some receivers/amplifiers out there that do measure ripple current from the power supply and thus initiate some form of limiter or compression circuit to reduce gain in order to reduce clipping - but this is quite rare and these limiting circuits often come at a cost of a reduction in dynamics.

    While we understand what you want to accomplish -- the only way to do this is as follows.

    Your receiver must be connected to the speakers and you must check your AC line voltage to confirm proper voltage.

    With the receiver connected to the speakers, connect an oscilloscope across the receiver's speaker output (+ and -) so that you can view the waveform.

    Play some music or pink noise, and gradually increase the volume level of the receiver while monitoring the waveform on the scope. At this first hint of "clipping" - (a squaring off of the crest and trough) - using a voltage meter (or the scope) - jot down the peak voltage level and there you have it, your maximum safe peak voltage output from the receiver connected to this particular set of speakers. Or, but somewhat less accurate, using an SPL meter take a peak spl measurement at the first sign of clipping -- this would then be the maximum safe volume level you can reach. If your receiver is calibrated, note the dB level of the volume control and simply do not exceed this....

    I'm afraid that if you call your receiver manufacturer and ask to speak to a tech, they are not going to even understand what you are asking or even worse, provide you with wrong information.
    Last edited by davef; 11-11-2019 at 04:57 PM.
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  4. #14
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    Default Re: Understanding relative volume and 0db on my receiver.

    Hey Dave!

    Thank you for your technical insight! (And thank all of you for yours!) I appreciate it. Unfortunately... (drum roll)... I have more questions. lol

    "0dB" is just an arbitrary number - it is meaningless and has no relationship to the output volume of your speakers or how much wattage your receiver or amplifier is producing."

    My impression of the volume knob control system is that they try to make it smooth and predictable, roughly correlating to 1db change per "tick" of the knob. It seems to me that, given a certain impedance profile, they (engineers) should be able to roughly predict how much electricity can be delivered to each speaker at each "tick" of the volume knob. Is this not possible?

    And, since the sources are decoded inside the AVR itself, this would seem to give us even more predictability.

    I'm not an audio expert, but surely.... surely!... there must be some system at play here (even if only the engineers know) that would at least give us a rough estimate of how loud the volume knob can be turned for most 8-ohm speakers, most of the time? Maybe? Maybe just a rough guess? I don't know. I don't need a super exact number. I'm just looking for "rough" guess. Also, does anyone know why they make the positive numbers go up to +15? +16.5? +18? Is there a technical reason for this?

    " At what output volume level from the speakers your receiver will start to clip will dramatically vary from one model speaker to another."


    How dramatically are we talking here? Could 2 different 8 ohm bookshelf speakers (MT, 2-way) clip at 2 dramatically different points on the volume knob? Like "-10" on one speaker and "+5" on another speaker? Is it this dramatic? I'm just trying to get a sense of scale here. And maybe hold on to irrational optimism. lol

    Thanks again!

    P.S. Thank you for your advice about the oscilloscope and SPL meter. Also, I'm listening to the Sierra-2EX right now! I'm loving them! My ears have to adjust to the difference for now, but I'm loving them. Man, you weren't kidding about the bass. lol Talk about PUNCH! I'm hearing some singers breathing in the background when they're not singing (jazz). Awesome!
    Last edited by j0nnyfive; 11-12-2019 at 05:08 PM.

  5. #15
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    Default Re: Understanding relative volume and 0db on my receiver.

    Quote Originally Posted by j0nnyfive View Post
    Hey Dave!

    Thank you for your technical insight! (And thank all of you for yours!) I appreciate it. Unfortunately... (drum roll)... I have more questions. lol

    "0dB" is just an arbitrary number - it is meaningless and has no relationship to the output volume of your speakers or how much wattage your receiver or amplifier is producing."

    My impression of the volume knob control system is that they try to make it smooth and predictable, roughly correlating to 1db change per "tick" of the knob. It seems to me that, given a certain impedance profile, they (engineers) should be able to roughly predict how much electricity can be delivered to each speaker at each "tick" of the volume knob. Is this not possible?

    And, since the sources are decoded inside the AVR itself, this would seem to give us even more predictability.

    Perhaps this explanation will make more sense. Basically, there are 3 main sections to a modern AVR. section 1 is where all the DSP processing occurs. Section 2 is the pre-amp. Section 3 is the amplifier.

    An audio amplifier has a fixed gain, typically a gain of 28. An amp does not have variable gain. The pre-amp section sends a variable low voltage signal to the amp section, and the amp amplifies this analog signal. For example, put in 1 volt, get 28 volts out.

    The DSP section does the various processing and in the last stage of this section, the digital signal is converted to analog (an audio signal - AC current). This is sent to the pre-amp section. The signal source and type, or where it is decoded makes no difference at all. If decoded outside, then generally the signal bypasses the DSP section and just hits the pre-amp section.

    Speakers have varying impedances and efficiencies. An 8 ohm speaker might dip as low as 3 ohms at say 100Hz, while another speaker might have a 30ohm impedance at 100Hz. Impedance rating of a speaker is a bit like an overall average.


    Quote Originally Posted by j0nnyfive View Post
    I'm not an audio expert, but surely.... surely!... there must be some system at play here (even if only the engineers know) that would at least give us a rough estimate of how loud the volume knob can be turned for most 8-ohm speakers, most of the time? Maybe? Maybe just a rough guess? I don't know. I don't need a super exact number. I'm just looking for "rough" guess. Also, does anyone know why they make the positive numbers go up to +15? +16.5? +18? Is there a technical reason for this?
    There is no special system at play here, if you want to properly estimate how loud you can play before clipping for any speaker, I gave you the procedure. Or, you can simply do the math and get a decent estimate using a calibrated SPL meter at your listening position. Those dB increments on your volume control are purely arbitrary. If you calibrate, then you set 0dB to = a specific SPL at the mic position from 1 front speaker.

    With a speaker rated at a sensitivity of 85 and an 80 watt receiver, and with a listening distance of ~30 feet - calibrate the receiver such that 0dB = 85dB, and you will be clipping your receiver at the 0dB volume control level. Your receiver does not know this...

    Quote Originally Posted by j0nnyfive View Post
    P.S. Thank you for your advice about the oscilloscope and SPL meter. Also, I'm listening to the Sierra-2EX right now! I'm loving them! My ears have to adjust to the difference for now, but I'm loving them. Man, you weren't kidding about the bass. lol Talk about PUNCH! I'm hearing some singers breathing in the background when they're not singing (jazz). Awesome!
    Happy to hear you are enjoying the Sierra-2EX. I can't continue answering your questions regarding the 0dB setting though as I and others here have done our best.
    .
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  6. #16
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    Default Re: Understanding relative volume and 0db on my receiver.

    I want to thank you guys for your help. I was going to say to please ignore my last post because I know you guys are busy doing what you do, and I appreciate it. You even responded faster than I could stop you (which is awesome)! Thank you for the oscilloscope and SPL meter method advice. I know you have much more understanding than I do regarding these things, and I will take your advice. Thank you also for your explanation of how the receiver works. You guys aren't even in the AVR business and here I am asking AVR questions!

    Thank you for the GREAT speakers. I love them. Thank you also to Curtis, Jimb, and Mike for your contributions. I have some learning to do.

  7. #17
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    Default Re: Understanding relative volume and 0db on my receiver.

    Okay, I just want to thank you guys again and say sorry for bugging ya'll so much. lol And...

    I think I've figured out what I'm going to do! I feel compelled to at least tell you guys my plans, for good or bad. You don't have to respond, but if you feel it's a bad idea, please don't hesitate to let me know!


    Here's my logic:

    IF dynamic range peak loudness = max wattage,
    THEN proportionally lower dynamic range loudness = proportionally lower wattage.
    SET speaker output @ 1 meter to equivalent of proportionally lower wattage.

    The resulting volume setting will be what I'm looking for. This represents the "theoretical danger zone". I will stay well south of this volume setting.


    What does this accomplish for me? A little more piece of mind. It's not super accurate like the Oscilloscope method, but it will satisfy me enough. (This is my creative interpretation of Dave's "do the math")


    Again, thanks guys for your help! You all got me thinking in a better direction. And, if this is a dumb idea and my logic is completely convoluted or just plain stupid, please let me know!! lol
    Thanks again.

    Edit: If you have any concerns or additional ideas to add to this approach, please feel free!
    Last edited by j0nnyfive; 11-14-2019 at 07:22 PM.

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