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On my HK 635 the volume level is usually in the minus range, ie -25. What does this mean exactly? Is the minus rating a way to know how much strain you have on the receiver? For example if I up it to 0 is that getting toward the power limit of the receiver? I was wondering how much I can push it without starting to clip my speakers.
 

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It USED to mean the pre-amp section was attenuating the signal. In other words, assume you took the analog signal straight from the source component (such as a CD player) and plugged it directly into an amplifier, bypassing any volume control. This would be considered the "0db" mark on the pre-amp/receiver. When a pre-amp attenuates an analog signal, it simply drops the voltage, so the higher the negative number, the greater the voltage drop, and the lower the volume. Beyond the "0" mark and the voltage is being raised and making the volume louder than it would be when plugged directly into an amp.


Notice I said "used to". This is all pretty much out the window in the days of digital processing. Digital signals are attenuated differently and most receivers and pre-amps don't do passive attenuation to analog signals either, but they kept the basic concept to provide something to relate to, I suppose. The numbers on modern volume controls are usually fairly meaningless.
 

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In "theory", if you calibrated your system to reference using a DB meter, 0 would be Dolby reference level, or 105db. The negative numbers are the db below this reference. Once again, in "theory" any 2 systems so calibrated would be at the same volume level at the same number. In practice, they would only be similar at 0, because I doubt the neg numbers translate the same between brands.
 

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As far as I know there are two numbering systems being used these days. One has 0 dB as the “all the way up†figure, the other runs a few (+) numbers above 0 dB.


With the former, the numbers refer to the pre amp section’s voltage output. Zero dB is maximum output voltage, settings below that are essentially “so-many dB below maximum output.†Thus the volume control really doesn’t turn volume up; it’s attenuating from maximum output. As noted, the dB figures refer to voltage, not actually loudness (dB SPL).


The latter I think is specific to THX-certified receivers - not sure how their calibration scheme works.


Regards,

Wayne A. Pflughaupt
 

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Quote:
Originally Posted by jdcrox
In "theory", if you calibrated your system to reference using a DB meter, 0 would be Dolby reference level, or 105db. The negative numbers are the db below this reference. Once again, in "theory" any 2 systems so calibrated would be at the same volume level at the same number. In practice, they would only be similar at 0, because I doubt the neg numbers translate the same between brands.


0dB on the receiver readout may or may not be related to Dolby "Reference Level" output.


Some units actually do calibrate the volume readout to mean that. Most do not do so. Most units just let you determine the readout number that is equal to the "Reference Level" SPL setting.


One person's -10dB volume setting could be equal to anther person's 0dB setting (or any other number). By equal I mean equal SPL levels.


This issue relates to playback volumes that people claim to use. When people say that they play their system at "reference level", who knows what they really mean!
 
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