DAC discussion

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^ found the cable on Amazon

my mobo has spdif in/out pins only. No adapter was there with board.

My speakers AL VS4121 take analog stereo input. Don't know whether it filters sound or not.
 
What is your motherboard model - I'll tell you if it has a SPDIF out header if there isn't any jack on the panel. But what's the point - the VS4121 accepts only analog input.

If you need better sound, the decoding has to happen on a DAC other than your motherboard audio chip - either on a external DAC (like a VALAB DAC) or a sound card's DAC!
 
Most dedicated CD players will have a digital output on them as well as the analog output. If you connect the digital output of your CD player to a DAC then you will bypass the CD player's "internal DAC" (digital-to-analog portion of your CD player) and the external DAC will then be responsible for the conversion process.

This is an extremely effective way of upgrading a CD-based hi-fi system and can make an extreme impact on the quality of playback. Later, you can then consider whether or not to upgrade your CD player to a dedicated CD transport.
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Quick question: What's the difference between connecting a DAC to a CD player's digital-out and a dedicated CD transport? Is a dedicated CD transport a CD player without an analogue-out at all? If so, what are the advantages over a CD player with the option of a digital and analogue out?

Another point of discussion regarding DACs: Sample Rates.

According to what I have studied in DSP, for an analog signal to be converted into a digital format, the signal has to be read (sampled) at a rate greater than two times the highest desired frequency of the analog signal so as to avoid aliasing of the converted signal.

Example: Supposing you have a simple analog sine wave with a frequency of 1000Hz, in order to convert it to a digital signal, it must be sampled at >2000Hz to avoid aliasing.

Since the human ear is meant to be responsive in the range of 20Hz to 22¬24KHz, most recordings are sampled at 22*2 = 44KHz or 24*2 = 48KHz. This bit I understand.

What really confuses me, is when there are audio files which are sampled at 96KHz. This translates to a Nyquist frequency of 48KHz which is well outside the auditory range of any human being no matter how leet he claims his audiophilia is.

What is the point of sampling an analogue frequency at such a high level? Does it hold some real world significance other than just 'winning' in the numbers game? Does it somehow manifest itself in the same way as playing a first-person-shooter at 100 FPS instead of 30 FPS which is the threshold of the eye's ability to resolve discrete images? Although the eye may not be able to discern the difference, scientifically, it is noticeable when a first person shooter runs at 30 and 100 fps respectively.
 
Grease Monk said:
Is a dedicated CD transport a CD player without an analogue-out at all?
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Yes.

If so, what are the advantages over a CD player with the option of a digital and analogue out?
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Design budget is allocated solely at minimising read errors and reducing jitter. This is a non-trivial exercise.

What is the point of sampling an analogue frequency at such a high level?
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It's not just about hearing limits - Nyquist theorem has its practical limits.

When the Nyquist frequency is close to the perception frequency, you need a brickwall filter with a steep slope which can itself cause aliasing in the passband (assuming 1/3f). Increasing the sampling frequency allows you to use gentler filters.

Using a higher samplerate (the resampling numbers game) without using a gentler filter slope (it's not automatically deployed, not all converters have multiple slopes) may hurt the sound more than help, though the increased perception of higher frequencies may lead to some people liking the results.

Edit: For ADC, the logic is to be applied in reverse :) We record at higher samplerates to ensure better fidelity when being played back.
 
Cranky, what's the advantage of using a M2Tech hiface usb to spdif interface over a regular coax spdif interface? Chaos was mentioning the reduction of jitter. Does this mean a USB DAC will have absolutely no jitter during the transmission then?

And for long distance signal transmission, is the optical preferred over the coaxial? Or the other way round?
 
Onboard sound typically has very high levels of jitter. Chaos is correct. Please read my long-ass reply up above - I've pointed out clearly that all USB are not equal when it comes to audio :) USB DACs are mostly 1.1, and they are not so great - even the nuForce is one of the same.

For long-distance digital transmission, the preferred formats are HDMI, Displayport and DVI-D. Consumer level digital audio is not meant to be transmitted over long distance. It was not built for that. If one absolutely needed to, optical would be preferred if one was reasonably confident that the cable would not bend and turn too much. This is why coax is a safer bet, but in any case performance will be poor. Whether you can hear the difference or not is debatable.
 
so if a cd output is considered to be bit perfect, then the best way for me to get good d-a audio conversion is to use this method -

CD (digital out to spdif in on mobo) --> Nuforce uDac?

Does Nuforce udac accept spdif input? I read it has spdif out (if vol is zero), nothing about input mentioned.

Or am I thinking wrong here. Is it like I don't have to connect cd digital output to mobo and the Nuforce udac will do the work? :S

If a discrete DAC is better than sound card, is there anyway to get all audio I play on a comp, come through a 3rd party DAC?

Came across another type of DAC - A non oversampling DAC or known as Zero DAC.

This is quoted from a seller from an ebay page. Putting it here cause he's managed to put it out in simple lay man terms.

Why non-oversampling DAC? ------ 'oversampling' kill music!



You may not know, the actual digital signal recorded on your CD title is 16bit/44.1k format. Yes, never doubt it! Then why almost all modern DAC feature 24bit/96k or even 192k specification? In modern digital recoding studio, music will be recorded in new 24bit/192k format but when they need to 'write' onto CD, these information rich formation must be degraded into old format. These 'New' DACs will try 'restore' the degraded back to more informative format using some talent algorithm work out by smart mathematician. ----- That is problem! why? All music you hear from CD will be processed by some smart algorithm, then you hear the artifact sound ---- actually bad sound!

My over-opinion? No! If you are a experienced audiophiles, you will find if these cd players or DACs use the same dac chip inside, they all will have very closer sound features, even their analog circuits designs are quite different. Why? You hear the same artifact derived from the same talent algorism.
These artifacts contamination did hurt your audio enjoyment! Why, they mask real tone color and even 'atmosphere' of music player. You do not believe!? Try to find CD records which also have vinyl LP version, compare music from vinyl and CD. You will know how bad these artifact sound is!
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Some links related to this:

http://www.sakurasystems.com/articles/Kusunoki.html

As the new generation of CD format is appearing on the horizon, I thought the basic concept should be "To Confirm the Original 44.1kHz/16bit Format". A CD in our hands has exactly the same data, every bit to bit, as to the one that left the studio. To recall this dreamy fact, the above theme would be quite appropriate. Any high-bit or high-sampling does not have its raison d'être unless it surpasses this level of accuracy.

About Non-Oversampling

After examining the following two aspects, I came to a conclusion that 'it is quite difficult to carry out oversampling as theoretically under the current technology'.
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So does this mean that theoretically, even the normal DAC's cannot oversample music?

I found a place where people were debating on what the guy in the above site said.

http://www.dsprelated.com/showmessage/13474/1.php

And while searching for zero dac's I came across this on ebay where the upgrade mentioned is a transistor setup. Considering that DAC was meant to replace transistors in the first place...

http://cgi.ebay.com/ZERO-Tianyun-24-192-DAC-Headphone-Amp-OPA627-USB_W0QQitemZ260422597983QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ca2657d5f

The same or another piece reviewed on hifi I think.
 
6pack said:
so if a cd output is considered to be bit perfect, then the best way for me to get good d-a audio conversion is to use this method -

CD (digital out to spdif in on mobo) --> Nuforce uDac?

Does Nuforce udac accept spdif input? I read it has spdif out (if vol is zero), nothing about input mentioned.

Or am I thinking wrong here. Is it like I don't have to connect cd digital output to mobo and the Nuforce udac will do the work? :S

If a discrete DAC is better than sound card, is there anyway to get all audio I play on a comp, come through a 3rd party DAC?
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CD Drive reads are assumed to be bit perfect. It'll differ from drive to drive. A Pioneer DVR-110D, or a Plextor Premium is noticed to perform better than your average optical drive. Also consider some error correction software while ripping your discs as even with sufficient dampening around the optical drive there will vibrations and instrumentation errors considering its a mechanical device.

IINM the nuforce will be connected to a USB port and not the optical/coax out of your mobo. Using the onboard out will simply be contempt on your part after starting and going through this thread :P.
 
Thanks for the link Nuke. The discussion there bolstered Cranky's lovely explanation.

Slightly OT, but found a nice Java app to fool around with Fourier transforms: Fourier Series Applet

Edit: If you are using the link above, please be sure to reduce the volume on your speakers before you hit the 'Sound' button. Unless you're in the mood to dislodge your woofers.
 
nukeu666 said:
from head-fi:

For playback, 24/96 is overkill. For recording and mixing, it is not, 16/44 is enough.

Also 24/96 is increasing resolution, not doubling frequency range. (?)

link: 96/24 vs 44/16 vs analogue - Gearslutz.com
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wrt the above, at what playback resolution should I set my computer mixer to?

44kHz, 24 bit? or 16 bit?

Also will setting it at 24bit resample say a 16bit audio cd file being played through a media player?

Also saw that a mp3 file says just the resolution its encoded at. So playback can be at any bit depth?
 
nuForce is a USB input only DAC.

As long as your default windows device is set to the external DAC/sound card/other conversion, all the sounds will play through that. For people like me, there is an onboard soundcard that handles all the gaming and general PC audio tasks, and there is a dedicated sound card for music, that Foobar is set to output to.
 
no.. DS and WASAPI also do the job.( the USB DAC or transport should have its own drivers or windows should be able to detect it properly )
 
It was taken as an example since I've heard a lot of reviews of it. Another reason is that I haven't seen any other DAC priced at that point. All the other dac's are priced in the USD 150+ range making them out of budget to lots of people here.
 
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