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Audio Hardware / Re: "Only few percents of FIDELITY"
Last post by DVDdoug -
Quote
Could you explain why my subwoofer is under 1% of THD...
Put me down as "skeptical".   ;)  If it's an active (powered) subwoofer, that's probably just the amplifier  spec (when it's not clipping).

There are also frequency response non-linearities.  Possibly even resonance/ringing.   Room acoustics have a HUGE effect on frequency response and resonances. 

And, you can get rattling, buzzing, or port noise, etc.  

You could get intermodulation distortion (but I don't think that's a big problem with subwoofers).

It's also possible to overdrive the speaker or the amplifier, especially at very-low or subsonic frequencies (in which case you'll exceed the distortion spec).


P.S.
What subwoofer is this?
3
Opus / Re: What is the bitrate of your Opus files?
Last post by IgorC -
If you're fine with that bitrate you may as well just use a time domain subband codec like MusePack or hell, even MP2, and enjoy the perfect temporal resolution. Throwing more bits at a transform codec doesn't do much to fix their fundamental shortcomings beyond 192 kbps.
Is there any  recent blind test which  indicates superiority of MPC over other codecs?

I've found only these old tests:
https://hydrogenaud.io/index.php/topic,36465.msg321547.html#msg321547


And  this old one
http://listening-tests.freetzi.com/html/Multiformat_128kbps_public_listening_test_results.htm



4
Audio Hardware / Re: "Only few percents of FIDELITY"
Last post by greynol -
I've split the above post from the original discussion because it was off-topic.

Could you explain why my subwoofer is under 1% of THD and at the same time totally unable to reproduce a complex audio signal in a range of only few percents of FIDELITY ?
I'm not sure I know what "few percents of fidelity" means.

Would you be able to provide data from controlled listening tests that demonstrate whatever problem it is that you're trying to describe is audible?
9
Scientific Discussion / Re: Wav volume changing FLAC sizes
Last post by DVDdoug -
I did an experiment in Audacity- Interesting results...

Original 0dB-normalized FLAC = 20,571 KB
-6dB FLAC = 18,648 KB
Re-boosted FLAC with default dither = 20,769 KB
Re-boosted FLAC with no dither = 20,667 KB

There was some "funny" rounding because when I re-boosted, Audacity would only allow me to boost by 5.999dB (unless I allowed clipping) so I boosted by 5.999.

And, I think  6dB is not an exact factor of two...   The calculator says it's not, but I don't know how much precision the calculator gives me with logs...  
10
Scientific Discussion / Re: Wav volume changing FLAC sizes
Last post by bmcelvan -
A better approach might be to create a 24-bit WAV, open in Audacity and amplify or normalize, then export to 16-bit FLAC.  That way you wouldn't have to guess the gain/amplification setting.
That's a good idea...the not having to guess about the gain part. The 24bit wav is what what I've been doing already. However since the 0dB outputted file is smaller anyway I think I'll stick with it and use a replaygain tag.

What I don't know is if the foo_input_sacd component creates a pcm file and then changes it's amplitude after the fact (like what I would be doing using Audacity), or if that +6dB option actually happens during the conversion itself thus making the 0dB and 6dB files actually different. Then it would make a difference whether to use it or not.
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