fill35u
Super Member
"Often"? Examples of some CDs with significantly different low bass between channels?
Hello, is 1 dB difference large?
- Thread starter vintagetree
- Start date
"Often"? Examples of some CDs with significantly different low bass between channels?
The reason I ask is you quoted very specific percentages. I'd like to see the theory.
Depends on whether it is a point or line source. A point source will drop 6dB at every doubling of distance. A line source will only drop 3dB for each doubling of distance.
Also- the scientific definition of one dB, in audiological context, is the smallest increment that is RELIABLY audible as a difference in level, by an average human being. Also, by the same definitions, 10dB is a perceived doubling of level, by a human.
Doing the math (logarithms/powers of 2 vs. powers of 10, in essence), it is possible to extrapolate, that a 1dB difference is about a 7% "perceived" change in volume level. Here is a calculator, listing all the formulas needed, showing these relationships:
http://www.sengpielaudio.com/calculator-levelchange.htm
And, indeed, if you put in a 1dB increase- you get a loudness increase of a factor of 1.07, or 7%.
Regards,
Gordon.
Quadman2
Lunatic Member
I do the same at times. Might be the source. A slight move of one speaker. A loose connection
Sometimes I hear this happen with lower amplitudes more so than when at higher levels.
Q
the skipper
Professional Curmudgeon
...or speaker placement in the room.
Doug G.
Lunatic Member
You have to consider the tolerances of components in equipment, too 10% or even 20% tolerances are common. Usually, in preamplifier circuits the tolerances in critical components like gain determining resistors are kept at 1% but still..
A 1 dB difference is really no big deal.
Doug
A 1 dB difference is really no big deal.
Doug
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fill35u
Super Member
Anecdote of detectability of 1dB difference:
In the late 80's I had a Realistic STA-2380 receiver. I kept getting the nagging feeling that the balance was off, so of course I turned the "balance" knob a couple clicks to one side to compensate. Eventually, as a sanity check, I ran a frequency response check on both channels. Sure enough, the o-scope showed a 1dB difference with the balance knob centered, and my tuning by ear had perfectly corrected it. And this was with my first DIY speakers, probably the worst any of us have ever heard!
My later experiences setting channel trims on multichannel systems, then verifying with C-weighted SPL meters and mics, have been that my ears do a good job of balancing levels to within 1dB.
In the late 80's I had a Realistic STA-2380 receiver. I kept getting the nagging feeling that the balance was off, so of course I turned the "balance" knob a couple clicks to one side to compensate. Eventually, as a sanity check, I ran a frequency response check on both channels. Sure enough, the o-scope showed a 1dB difference with the balance knob centered, and my tuning by ear had perfectly corrected it. And this was with my first DIY speakers, probably the worst any of us have ever heard!
My later experiences setting channel trims on multichannel systems, then verifying with C-weighted SPL meters and mics, have been that my ears do a good job of balancing levels to within 1dB.
fill35u
Super Member
@toddalin , excellent example! Although, of course, I'd say it's an exception that proves the rule.
The original question was about *digital* sources of stereo bass. Your example raises a lot of questions:
Was the low bass faithfully preserved as stereo on the original Meddle LP's? Cassette? What about later releases on CD? The YouTube vid linked?
My only copy of "One of These Days" is on my DSOT CD. I wonder if the FOH at the venue supported stereo bass, and if so, was it utilized that way? What about the recording setup? Subsequent mastering of the CD? LP? Cassette? VHS? DVD? I wouldn't be surprised if the stereo low bass was converted to mono in at least some of those formats.
Not like it matters much,t he higher frequencies that let us localize will still be appropriately panned.
And since we're also in a thread about 1dB differences, I might as well mention a recent post in another thread where I pointed out a pervasive 1dB difference between channels in the low bass in another album:
https://audiokarma.org/forums/index...akers-sound-great.945756/page-3#post-14467618
The original question was about *digital* sources of stereo bass. Your example raises a lot of questions:
Was the low bass faithfully preserved as stereo on the original Meddle LP's? Cassette? What about later releases on CD? The YouTube vid linked?
My only copy of "One of These Days" is on my DSOT CD. I wonder if the FOH at the venue supported stereo bass, and if so, was it utilized that way? What about the recording setup? Subsequent mastering of the CD? LP? Cassette? VHS? DVD? I wouldn't be surprised if the stereo low bass was converted to mono in at least some of those formats.
Not like it matters much,t he higher frequencies that let us localize will still be appropriately panned.
And since we're also in a thread about 1dB differences, I might as well mention a recent post in another thread where I pointed out a pervasive 1dB difference between channels in the low bass in another album:
https://audiokarma.org/forums/index...akers-sound-great.945756/page-3#post-14467618