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Very basic question on computer audio vs CD playback


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Friends:

I was hoping someone could explain a question I have--I hope in asking that I do not decrease the intellectual environment of this great forum.

 

Basically, I am wondering why computer audio requires software playback? With a CD player, a laser reads a CD and sends the digital bits to a "internal" DAC then out to a preamp (or receiver). Why then does the data on a hard drive require processing by playback software before it is sent to an external DAC. Isn't digital data, digital data --regardless of the source on which it is stored (i.e., CD disc versus hard drive)?

 

Tom

 

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Hi Tom,

 

"...With a CD player, a laser reads a CD and sends the digital bits..."

 

The part you left out, between "a laser reads" and "sends" is extensive and may be the answer to your question.

 

What is stored on a CD is not at all the same as what is stored in a file on a computer. First, it might help to know that the binary data (i.e. "ones and zeros") is not what is written to the CD. Instead, that data is encoded, using a process called "8:14 modulation". This is used to create the pits on the CD, which come in nine different lengths.

 

The data (those ones and zeros) is written redundantly, so if the laser has trouble reading one part of a disc, it can (hopefully) recover that part from another place on the disc. The recovered 8:14 information must be demodulated, error correction must be applied and then the signal is passed to the DAC.

 

So, in effect, there is software (more properly, firmware) in the CD player, which performs the tasks necessary to create something the DAC can understand.

 

An oversimplification perhaps but I hope it helps.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

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Barry:

Thanks for the clarification. The origin of my question stemmed from me thinking about how different, in some regards, distinct playback software sounds in my computer audio chain. For example, I cannot hear a "significant" improvement over say iTunes using Amarra or Decible; however, Pure Music (PM) has for me audible sonic improvements. Likewise, Audirvana offers significant sonic improvement, though sounding notably distinct from PM. This has me thinking to what degree do these programs "color" the sound and how far is this away from the original source recording. By contrast, my Rega Apollo CD player and Ayre CX-7eMP sound very different, with the Ayre winning in every respect (it also cost ~2500 more and has MP filtering). I imagine both players have different firmware etc. that in turn impacts its own sonic signature. One of the many advantages with computer audio is that we have the flexibility to test numerous playback software that sounds best to our ears. Whether this takes us closer too or further away from the "absolute" sound of a live acoustic recording, is a matter of personal preference.

 

Tom

 

 

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I teach for a living, and it seems like some of the best questions get asked by people who think they are asking too basic a question.

 

It is a really good, fundamental question. I sure as hell didn't know the answer.

 

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"This is used to create the pits on the CD, which come in nine different lengths."

Hi Barry

I didn't realise that either.

Thanks for the interesting explanation, even if it was abbreviated .

 

Kind Regards

Alex.

 

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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Hi Tom,

 

"...I imagine both players have different firmware etc. that in turn impacts its own sonic signature..."

 

While their firmware has an effect, the circuit topology in the players will impact their sonic performance was well. Analog stage design, clocking, etc. will all impact how a player sounds.

 

"...Whether this takes us closer too or further away from the "absolute" sound of a live acoustic recording, is a matter of personal preference..."

 

In my view, whether a person likes how a given software application (or hardware component) makes music sound is a matter of personal preference. But whether it is closer or further from the sound of the recording itself, is not.

 

For example, there are many highly regarded DACs which to my ears, superimpose a "character" or color on everything that passes through them. This might be "enhanced detail" or it might be a "warmth and smoothness", etc. Many other types of components, also have a distinct sonic profile.

My feeling is there is nothing wrong with any of these if they provide what a given listener seeks but I would not confuse this with truth to input.

 

There are some components in my experience that just seem better at getting out of the way. Whether software or hardware, one way I've found to identify them is by the fact that differences between different recordings are more pronounced via these apps/devices than they are with devices with more "color". (When a device adds a flavor, it adds it to everything, hence diminishing the inherent, quite wide differences between all recordings.)

 

So while I'd agree that "better" is in the ear of the behearer ;-}

I find there are almost as many definitions of the term as there are listeners.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

 

 

 

 

 

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