80 replies to this topic

[Pulse-R]

This is a screen dump from the Audison disc - track 1. As you can see, very badly overdriven... People that do this on 'Audiophile' discs should be shot.

Attached Files

•  Track_1_2.jpg   89.17K   18 downloads

Edited by Pulse-R, 31 January 2008 - 08:08 PM.

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[Pulse-R]

not only this track either - after track 4, all the tracks are overdriven - even the 1812 overture cannons sound like someone popping a paper bag too close to the mic.

otherwise it's got some nice stuff on there. I don't think it will replace the UDD as 'disc of choice' for tuning.

[Luke352]

Overdriven? I'll admit to not knowing what that term means, coulld you explain it a bit better.

Have to say though I prefer the Audison disc to the Chesky discs, but thats me, i can't stand the Chesky discs nor can I tune with them, I have other Cd's I find so much easier to tune with.

I found the In phase, Out of phase sections very interesting as I've never heard such good examples before.

[~thematt~]

Overdriven means they dont cap at 0dB. The peak of the sounds are actually above that.

I dont like the sound of that at all Simon. So much for Audiophile.

[ProClass]

May I suggest that the CD is ment for amplifiers with head room.

Just a thought.

[Captn_Awesome]

as long as your transport can handle it though. I dont know of too many CD players that can truely deal with much over ref. Simon you got a VU for the peaks?

Also what media is it coming from before being put onto CD obviously it wasnt recorded digitally originally

[Luke352]

~thematt~, on Jan 31 2008, 09:56 PM, said:

Overdriven means they dont cap at 0dB. The peak of the sounds are actually above that.

So is this the same as when they refer to a recording being too hot, or the opposite being to cold.

Komodo, on Jan 31 2008, 10:19 PM, said:

as long as your transport can handle it though. I dont know of too many CD players that can truely deal with much over ref.

Along that line, I'm sure somewhere in the literature it mentions something about 120db of dynamic range in certain areas, yet I was under the impression that CD players don't even have the ability to play/read that large a range. Obviously there must be some that do but seems odd to produce a CD with that large a range especially when you consider it's use is for in car where you'll never be able to appreciate it.

[fuddbutter]

could you rip the music as wav files and port them into something like sound forge and bring the levels down a tad?

[Matt VIP]

shouldnt have to do that with a reference disc surely...

Edited by VIP318, 01 February 2008 - 01:21 PM.

[fuddbutter]

VIP318, on Feb 1 2008, 02:20 PM, said:

shouldnt have to do that with a reference disc surely...

well yeah..

[~thematt~]

Luke352, on Feb 1 2008, 09:19 AM, said:

So is this the same as when they refer to a recording being too hot, or the opposite being to cold.

Dunno. I've always used the 'hot' terminology to refer to too much compression.

Quote

Along that line, I'm sure somewhere in the literature it mentions something about 120db of dynamic range in certain areas, yet I was under the impression that CD players don't even have the ability to play/read that large a range. Obviously there must be some that do but seems odd to produce a CD with that large a range especially when you consider it's use is for in car where you'll never be able to appreciate it.

It may be theoretically possible, but not actually. Most CD's these days dont have a DR greater then 30dB. And some CD's less then 10.

[Pulse-R]

The term "too hot" usually refers to the average level of the music, which in this particular case isn't too bad. The peaks are where the dynamics are, and in a good production should be either soft-limited or the whole program level brought down to allow the peaks to occur at -1dB or lower.

The problem in this case, is that the waveform peaks are lost - once you get up to 0dB in a digital format, it just clips the tops off the waves. the sound is gone. it's nothing to do with the transport, or the DAC - once the signal hits 0dB it can't go any higher.

CD (44.1kHz, 16 bits stereo) is limited to 96dB dynamic range, but often 'high end' players have a signal to noise ratio (SNR) of over 100dB. This means that the quietest sound on the CD should be audible over the players in-built noise. In a car CD player, 'zero bit mute' noise gates are often used to make this figure look better, meaning the average CD player really has a usable dynamic range of only 80dB or so, the equivalent of 14 bits of resolution. a good ($2k+) home CD player will be better than this. The lowest level signal represented by a single bit of CD data is -96dB, and goes in 6dB steps for each bit of data...
i.e.
15 bit = 90dB
14 bit = 84dB
13 bit = 78dB
etc.

the reason why we don't suddenly have 6dB louder per step of the DAC is because the output is filtered to 'round off' the steps, and so smooth the sound, giving smaller increments than the 6dB. There are other issues related to this phenomena, if you want to find out try google "NOS DAC" and oversampling I think is in Wikipedia.

anyway, here's a closeup of the above peaks, to illustrate what I'm describing:
Firstly is a sample of the distorted track at the level on the CD. notice that the right channel (lower part of display) is much higher level - these peaks are in the right channel.
 Track_1a.jpg   91.92K   28 downloads

Next, we reduce the level of both channels (left and right).
 Track_1b.jpg   84.07K   25 downloads

Now we can see that the level ohas been reduced by 3dB in both channels. Notice that the right channel which is clipped still shows the cut-off tops of the peaks... That is the music which is lost, this kind of clipping cannot be 'undone' by re-sampling the CD.
The only way to fix it is to get it right from the master and reduce the level of the whole recording before it even gets to the stage of being a CD.

Edited by Pulse-R, 01 February 2008 - 06:28 PM.

[Luke352]

Ok it all makes sense now, thanks for explaining all that.

[abmolech]

Bang on.
Sometimes the sound engineer(?) is over exuberant with the use of the limiter.

Best way to get an audiophile recording is from people who care about their music.

Go classic.

No way would this recording make it into a classical collectors repository.

We could finish the "slam dunk" with the way some of these are not even recorded in stereophonic. (IE 8 track monophonic and "mixed" to stereo, or have a debate over which microphone configuration is stereophonic)

Point
Just another recording in a cultural waste land.

[Pulse-R]

This particular track is all synthesiser and horn sounds, so no point trying to get stereo. it is, however creatively phase shifted and panned to give a 3D-type illusion.

I'll try and find the original of this track to compare.