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aurgathor
join:2002-12-01
Lynnwood, WA

aurgathor

Member

Very short history on digital audio

Found this on head-fi. Interesting read, especially the cost cuts.
»www.head-fi.org/t/701900 ··· 10629122

This may be somewhat biased and not fully accurate, however.

camper
just visiting this planet
Premium Member
join:2010-03-21
Bethel, CT

camper

Premium Member

said by aurgathor:

not fully accurate

 
Understatement.

The author of that article tells a nice story, though.
daveinpoway
Premium Member
join:2006-07-03
Poway, CA

daveinpoway to aurgathor

Premium Member

to aurgathor
If I understand correctly, the whole thread takes up 380 pages!

aurgathor
join:2002-12-01
Lynnwood, WA

aurgathor

Member

I was referring to a single post, and perhaps maybe to this rebuttal: »www.head-fi.org/t/701900 ··· 10629393

I could quote them here, but why bother -- read only the very first articles in the links.

There is a bunch of other stuff in that thread, some may be relevant to varying degrees (like the discussion about digital filtering) but a good portion is mostly or completely irrelevant.

The author of the first article is one of the head honcho of Schiit audio (maker of audio DACs) so he does know a bit about the subject, although one could argue that this is part self-promotion.

camper
just visiting this planet
Premium Member
join:2010-03-21
Bethel, CT

1 edit

camper

Premium Member

said by aurgathor:

The author of the first article is one of the head honcho of Schiit audio (maker of audio DACs) so he does know a bit about the subject,

 
Perhaps he knows the subject but he has an interesting (and I'd agree with you, self-serving) spin on history.

For example, "First cost cut: digital filtering (oversampling). That allowed manufacturers to throw out the analog brick wall filter, which was wwayyyyy cheaper" could be stated differently.

Oversampling was done because the early brick wall filters rang like a bell on transients.

When I bought my first CD player in the spring of 1984, there were two main options: Sony (using brick wall filter) or Philips (using oversampling and a more gently-sloped filter).

The reviews of the Sony consistently knocked it for the ringing in its output, ringing that simply was not present in the Philips CD players. That's one of the reasons why Meridan's first CD player in the 1980's was based upon the Philips transport and digital electronics, and Meridan substituted their analog electronics.

Even the "better" brick wall filters used in the mastering process rang. I have quite a few early CDs where the ringing on transients is so pronounced that it reduces my enjoyment of the music.

Oversampling allowed for more gently sloped (and non-ringing) analog filters initially.

[edit: add the following] Additionally, at the time, oversampling was more expensive than brick wall filters (which is why many manufacturers used brick wall filters in the first place). The digital electronics needed to process the higher frequency digital signal required by oversampling was bleeding-edge for audio equipment in the early 1980's.

aurgathor
join:2002-12-01
Lynnwood, WA

aurgathor

Member

said by camper:

Even the "better" brick wall filters used in the mastering process rang. I have quite a few early CDs where the ringing on transients is so pronounced that it reduces my enjoyment of the music.

The filters weren't good enough. There are filters (i.e. Bessel) that has maximally flat phase response; unfortunately, they are not very steep.

Not listed here, but looking at these curves it can be seen that there is a big difference between various filter types. (there are more than what's listed there)

IMHO, designing a really good, audio quality brick-wall filter is almost like art mixed with some black magic, so I'm not surprised that people quickly went for oversampling instead.

camper
just visiting this planet
Premium Member
join:2010-03-21
Bethel, CT

camper

Premium Member

said by aurgathor:

IMHO, designing a really good, audio quality brick-wall filter is almost like art mixed with some black magic, so I'm not surprised that people quickly went for oversampling instead.

 
The brick wall filter design is just as you say. You have too many things working against you (a couple of which fall under "The Laws of Physics"), all of which need to be balanced precariously in order to get mediocre sound quality.

The studio side of things moved to digital filtering more quickly than the consumer equipment side, as the studios were less concerned about price points and more interested in quality.

The consumer equipment side stayed with brick wall filters far too long, mostly because they were cheaper and because they could get away with the sound quality.

As a result of this thread, I fired up my old Philips CD player yesterday and gave it a listen to. Still no ringing, but wow, the analog section needs a lot of help. I suspect some components have deteriorated over the three-plus decades since I first got it.