Bits and Hertz Influence on your CDP Purchase

[El Hefe]

Hi all,

Just want to hear some views from all of you whether you take into account the CD player bits and frequency spec when choosing a CD player. For me personally, I dont. If that CD player sounds good on my set up, then it sounds good to me without asking whats the spec like. However, if you do take into account the specs, which one would you choose from the following scenario without demoing the unit?

1. Same price between 2 models. CDP A offers 24 bit with upsampling to 192 kHz. CDP B offers 32 bit with upsampling to 192 kHz.

2. And what if CDP B is cheaper but CDP A has more reputation?

 

[the record spot]

Don't really take that into account. FWIW I'd include a standard non-upsampling CDP and put it into your analogy too. Otherwise I'd probably listen to both and then decide.

 

[matthewpiano]

I actually have no idea what the specs are for my CD player. What I do know is that it sounds incredible.

 

[toyota man]

I have no idea what the sampling rate or whatever is on my cdp when Ihad my dems it was what they sounded like that mattered

 

[MajorFubar]

Don't see the point of any CDP with anything but a 16/44 DAC unless it can either play HDCDs or it can play HD audio from a computer (etc) via a digital input. If it can do either/both of those things and you have HD media of some sort then yeah the specs are important.

 

[El Hefe]

Thanks all for the feedback... Thats what I thought when it comes to CDP. For the main duty of spinning 16 bit/ 44.1 kHz CD, why do we need a CDP with upsampling DAC in it? Unless it comes with digital inputs like Audiolab 8200 CDQ and Musical Fidelity M6, then it can be used with hi res files.

However, I believe when you are paying more for one CDP over another, its the quality of components used that you are paying for.

 

[andyjm]

Increasing the sample rate doesn't add any new information over information that is already on the CD (how can it?), what it does do is add samples between the existing samples. There are a number of ways of doing this, usually by some form of interpolation.

While this may seem pointless, by increasing the sample frequency it moves the aliases further up the frequency spectrum and allows much gentler anti-ailiasing filters to be used on the output of the D2A converter chip.

This in turn has positive benefits to sound quality.

 

[MajorFubar]

by increasing the sample frequency it moves the aliases further up the frequency spectrum and allows much gentler anti-ailiasing filters to be used on the output of the D2A converter chip.

This in turn has positive benefits to sound quality.

Isn't this what manufacturers used to call oversampling...

 

[shooter]

Technically you need a DAC chip that has a resolution of 18 - 20 bits, anything less adds distortion and noise. Its impossible to exceed a 24 bit DAC chips performance at room temp without smothering the lower bits in noise, its just a marketing clap trap that a 32 bit DAC chip will work flawlesly.

 

[plastic penguin]

Don't give a monkeys about specs - if it sounds good I'll buy it...

 

[The_Lhc]

Don't care, I've never bought a CD player and I never will.

 

[the record spot]

And no wonder, when that dang gramophone does the business so well!

 

[shooter]

Don't give a monkeys about specs - if it sounds good I'll buy it...

To true, i still love the Sony PS1 which is 14 bit playback. I've heard better clarity, detail, seperation etc but its still a reference point for me on vocal and strings, wonderful. 8)

 

[shafesk]

Don't care about the specs, frankly I'm sick of it and I wish manufacturers would stick to the natural 16/44 khz of cds than upsampling or oversampling it just to sell their cdps. Marketing pish posh if you ask me.

 

[SteveR750]

I took this with me when buying my last CDP.

http://en.wikipedia.org/wiki/Upsampling

Noe quite sure how it is different from this though:

http://en.wikipedia.org/wiki/Oversampling

 

[andyjm]

by increasing the sample frequency it moves the aliases further up the frequency spectrum and allows much gentler anti-ailiasing filters to be used on the output of the D2A converter chip.

This in turn has positive benefits to sound quality.

Isn't this what manufacturers used to call oversampling...

Yes, and it explains why even though the CD was recorded at 16/44.1 there are benefits to having the digital to analogue conversion take place at a higher sample frequency, even if the samples are interpolated.

There is a more complex argument as to why greater bit depth could improve the sound. In order to interpolate the samples the CD player has to do some internal math. By doing the math at a higher resolution (20 bits say), some of the truncation inherent in 16 bit math can be avoided.

So while the CD is still 16/44.1, there is apparently merit in having a CD player with greater bit depth and sample frequency.

 

[shooter]

Upsampling is used to simplify the design of the analogue reconstruction filter and oversampling moves the noise that needs to be filtered out up to higher frequencies. I think :?

 

[shooter]

Don't care about the specs, frankly I'm sick of it and I wish manufacturers would stick to the natural 16/44 khz of cds than upsampling or oversampling it just to sell their cdps. Marketing pish posh if you ask me.

From what i can gather the reconstruction of the digital signal needs some headroom to convert to analog, it otherwise add noise in doing so, thats why the process occurs.

The difference in oversampling and non-oversampling (NOS) is that the NOS filtering is in the analog domain (after the DAC chip) unlike the up/oversampling in that the bulk is done in the digital domian (befor the DAC chip), but some NOS dont use filters at all.

:wall:

 

[oldric_naubhoff]

Don't care about the specs, frankly I'm sick of it and I wish manufacturers would stick to the natural 16/44 khz of cds than upsampling or oversampling it just to sell their cdps. Marketing pish posh if you ask me.

From what i can gather the reconstruction of the digital signal needs some headroom to convert to analog, it otherwise add noise in doing so, thats why the process occurs.

The difference in oversampling and non-oversampling (NOS) is that the NOS filtering is in the analog domain (after the DAC chip) unlike the up/oversampling in that the bulk is done in the digital domian (befor the DAC chip), but some NOS dont use filters at all.

:wall:

but don't forget that oversampling and digital filtering introduces ringing to the signal. so yes, you've got Nyquist frequency moved further up the spectrum, but at the same the signal does not maintain the ultimate fidelity.

 

[shooter]

Isn't it the job of the low pass filter to remove any noise created from the up/oversample?

Input signal > 16 bit raw data > up/oversample [quantization] > DAC chip > Low Pass Filter [noise shaping] > Output

Rather crude but...

 

[El Hefe]

From what I can understand here, the upsampling etc does have a technical explanation behind it to improve the sound. However, in general when purchasing a CDP, people tend not to really bother with the spec as long as it sounds good.

 

[oldric_naubhoff]

Isn't it the job of the low pass filter to remove any noise created from the up/oversample?

Input signal > 16 bit raw data > up/oversample [quantization] > DAC chip > Low Pass Filter [noise shaping] > Output

Rather crude but...

not quite right. oversampling makes the DAC has lover noise floor and also aliasing artifacts go higher up the freq spectrum. still any DAC will create aliasing artifacts at half of sampling frequency, i.e. for 96kHz signal aliasing will appear at 48kHz - way above human hearing threshold. for Red Book it'll be only 22kHz so just outside audible spectrum which makes it quite tricky to create the right filters. low pass is better but it'll have to start to attenuate within audio range. there's no such problems with oversampling. oversampling DACs will have a ruler flat freq response as an effect. but oversampling also introduces ringing of the outputted signal and that's a completely different story. check this picture below. maybe it'll tell you more than my words.