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Topic: "Problem sample" question.. (Read 3399 times) previous topic - next topic
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"Problem sample" question..

This has been something on my mind for awhile.. I just want everyone's opinion on this:

A good friend of mine builds amplifiers in his spare time, and is a genius at it.  He used to work for Cary Audio Design(world-class tube amps, etc).  His way of tuning an amplifier with different components is all by ear.  Me and my brother help him out sometimes when he brings new projects over.  We've never done a blind test or anything like that, but can undoubtly tell when something sounds better than something else.  For example, we recently swapped in some better audio-grade caps in my brother's amplifier(over the "5000 in a roll" type caps ), and the sound was distinguishingly less harsh than before.  That was unmistakable, and there were no "samples" to be had, it was the overall sound that was different.

So my question is, are codecs ever tuned by the overall sound of them?  Some differences I hear aren't in a specific sample, or maybe undetectable in a specific sample, but range over the whole piece of audio.  As in, "Yeah, that sounds less harsh overall."  Instead of "That specific hi-hat sounds less "tizzy."" 

When I switched to MPC over from MP3, I WANTED my mp3s to sound better so I wouldn't have to go back and re-rip/encode all my CDs again.  Much to my surprise, MPC sounded distinguishingly better, though I couldn't come up with a small sample of music to prove this.  Perhaps I could do it with a minute or two of music, but nothing as small as 10 seconds.

Anyone get my mean?

"Problem sample" question..

Reply #1 –
Quote
That was unmistakable, and there were no "samples" to be had, it was the overall sound that was different.

Don't know about the codecs.  But one observation: The ear, applied diligently, will never lie.  Assuming you have one, and it certainly sounds like you have a good one.   

"Problem sample" question..

Reply #2 –
Quote
Don't know about the codecs.  But one observation: The ear, applied diligently, will never lie.  Assuming you have one, and it certainly sounds like you have a good one.   

The brain, though, likes to play tricks, even if the ear doesn't lie.

I know from experience, having actually performed blind listening tests and found that I'm occasionally fooled by what I think I hear.

Blind tests don't have to be performed on short samples, although they typically are done that way for convenience.

ff123

"Problem sample" question..

Reply #3 –
Quote
A good friend of mine builds amplifiers in his spare time, and is a genius at it.  He used to work for Cary Audio Design(world-class tube amps, etc).  His way of tuning an amplifier with different components is all by ear. .. We've never done a blind test or anything like that, but can undoubtly tell when something sounds better than something else.

The difference is, psychoacoustic encoders are not aimed to sound "better", like a warm tube amp, that in fact "adds" something to the sound. "Better" is something always subjective. Instead, they are aimed just to sound as transparent as possible, adding as little as possible to the sound. By the way, that is what I want an amp to do too, but this is again something subjective.

"Problem sample" question..

Reply #4 –
There's an idea I have about this:

Some people listen closely with ABX and hunt down artefacts.
Some people listen to entire pieces of music, and speek of an overall impression, but no actual artefacts.

Sometimes, the latter is placeabo. But when it isn't, I think it's just another way of looking at the same thing. For very small artefacts, if you don't concentrate on them, they'll effect the overall character of the music. If you do concentrate, then you can hunt them down, find a small part of the track where there's a particularly obvious difference, and ABX it.

In other words, the change which an encoder brings to a track, which some people say is an "overall" change of character - this is the sum total impression of lots and lots of very small artefacts. But each of these artefacts in ABXable with time, patience, and care.


Or, to put it yet another way: All the artefacts that are just ABXable with care and concentration are the exact changes which give rise to a vague feeling of there "being something wrong" when you're just listening to the music (rather than the artefacts).


I don't know how you ABX an amplifier when you only have one unit, and you've just soldered in new capacitors! But I do know that whenever you do something to your stereo that you expect to improve the sound, then that change will improve the sound to you. I also know that most cheap capacitors exhibit terrible objective performance measurements! Some of the best circuits avoid putting capacitors in the signal path altogether; other manufacturers prefer a simple circuit with the best capacitors they can find.


Cheers,
David.

"Problem sample" question..

Reply #5 –
To elaborate a bit on KikeG's excellent point - tube gear (most high-end "audiophile" designs, anyway) has a characteristic sound signature due to the euphonic distortion valves introduce. The increased harmonic content colors the sound in a musical, warm, sweet, what-have-you manner. A great many of pleasant-sounding vacuum tube amps are not high-fidelity devices, regardless of the countless praise you may see in various audio mags, whose staff does not seem to be able to differentiate between "musicality" and "fidelity".

That said, I'd imagine that at low bitrates, when sufficiently transparent encoding isn't possible, there's quite a number of tuning trade-offs to be made. Perhaps then the developer decides which type of distortion sounds more agreeable to the average person's ear. This is speculation, so anyone familiar with low-bitrate codec tuning is welcome to comment/correct/enlighten.

"Problem sample" question..

Reply #6 –
Quote
this is the sum total impression of lots and lots of very small artefacts.

What 2Bdecided says applies to some of the tests I've made.

In the Transwave MPC test, I first noticed the track sounding wrong as a whole. Then, after several listenings to a short part, since it was difficult to ABX, I counted the beats until a stronger artifact appeared, and then listened only to this artifact.
I didn't concentrate on a given artifact in a blind test on FhG 192 CBR stereo with a Rebecca Pidgeon audiophile sample. there were just here and there some smeared attacks.
There are some tracks with transients all along (Amnesia, Transwave, Spahm (?), Ravebase (?)), and therefore artifacts all along.

But on the other hand, I would rather consider distortions like frequency response or noise to really fit Ben's definition of an overall problem, rather than artifacts, or for example clipping.

But after all, the difference is not so wide, I remember when I ABXed the vinyl vs CD sample of the legendary pink dots, with 1 db more treble, I also concentrated on a very single spot in order to differenciate the coloration of each sample. It was an overall problem, but I isolated one sound to spot it.