What is multi bit DAC?

B

bluegrassphile

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I have a few basic computer questions.

1. I know a DAC is a digital to analog converter. Is it the same thing as a computer interface?

2. I have an RME Baby Face (considered a very good interface) as my home recording studio computer interface.

3. Do I still need to purchase a DAC for my audio system?

4. What is a multi bit DAC? How is it different from a DAC?

5. When do you need a multi bit DAC?

Thank you!
 
bluegrassphile said:
I have a few basic computer questions.

1. I know a DAC is a digital to analog converter. Is it the same thing as a computer interface?

2. I have an RME Baby Face (considered a very good interface) as my home recording studio computer interface.

3. Do I still need to purchase a DAC for my audio system?

4. What is a multi bit DAC? How is it different from a DAC?

5. When do you need a multi bit DAC?

Thank you!
Click to expand...
Looking up details on your RME Babyface, it includes a DAC as well as ADC functionality, parametric EQ, mixing, mic preamps, headphone outputs, MIDI, reverb, etc. In the high end audio market DACs are most commonly stand alone units, not incorporating all of the functionality which your RME BF does. RME appears to be aimed more at the professional music market which doesn't mean that its performance is necessarily at a lower level. I've heard some good things about their very reasonably priced DACs like their model ADI-2. So if the inputs and outputs support your requirements and are performing your DAC needs, then there is nothing to require you to pursue another DAC. Of course there are always opportunities to upgrade and potentially improve your system's sound quality, so if you found a higher performing DAC you could choose to upgrade.

DACs have been around for many decades, so like with most things their technology has evolved. The differences between multibit and single bit DACs are technical in nature, but either can accomplish the same function... converting your digital music files into an analog signal which can be played back through analog amplification. There are some listeners that prefer the sound quality of multibit DACs while others may choose single bit designs. Some argue that one is inherently better than the other, and multibit designs are more expensive to manufacture and are becoming harder to find. There are many articles getting into the technical differences between the two designs, and you can see several of them here if interested for further reference.

Hope that helps!

- Bill
 
audio.bill said:
Looking up details on your RME Babyface, it includes a DAC as well as ADC functionality, parametric EQ, mixing, mic preamps, headphone outputs, MIDI, reverb, etc. In the high end audio market DACs are most commonly stand alone units, not incorporating all of the functionality which your RME BF does. RME appears to be aimed more at the professional music market which doesn't mean that its performance is necessarily at a lower level. I've heard some good things about their very reasonably priced DACs like their model ADI-2. So if the inputs and outputs support your requirements and are performing your DAC needs, then there is nothing to require you to pursue another DAC. Of course there are always opportunities to upgrade and potentially improve your system's sound quality, so if you found a higher performing DAC you could choose to upgrade.

DACs have been around for many decades, so like with most things their technology has evolved. The differences between multibit and single bit DACs are technical in nature, but either can accomplish the same function... converting your digital music files into an analog signal which can be played back through analog amplification. There are some listeners that prefer the sound quality of multibit DACs while others may choose single bit designs. Some argue that one is inherently better than the other, and multibit designs are more expensive to manufacture and are becoming harder to find. There are many articles getting into the technical differences between the two designs, and you can see several of them here if interested for further reference.

Hope that helps!

- Bill
Click to expand...


Thank you so much, Bill. Very informative.
 
bluegrassphile said:
I have a few basic computer questions.

1. I know a DAC is a digital to analog converter. Is it the same thing as a computer interface?

2. I have an RME Baby Face (considered a very good interface) as my home recording studio computer interface.

3. Do I still need to purchase a DAC for my audio system?

4. What is a multi bit DAC? How is it different from a DAC?

5. When do you need a multi bit DAC?

Thank you!
Click to expand...

Just to add to what Bill said, multibit DACs is a different engineering and mathematical (the digital "filter") approach to convert digital music files to analog. The vast majority of DACs are not multibit DACs, but "delta-sigma" DACs (with all due respect to Bill, I don't think D/S DACs are "single-bit"). These DACs use an "approximation" in the "math" to convert digital bitstream into analog output signal. Companies that make multibit DACs, notably MSB, Chord, Schiit, etc, are of the general view that multibit DACs provide a more "analog than digital" musical presentation than D/S DACs.

In my personal experience, I would agree; I considerably prefer multibit DACs to D/S DACs, they sound more "analog" to me, on the whole. That does not mean I've not heard D/S DACs that I did not like; in particular, the Bricasti M1 is a very good-sounding DAC.

For a thread on Head-Fi (that is closed now); you can read this: http://bit.ly/2McXEzi

I also found this on Linus Tech Tips:

"Our music is encoded using pulse-code modulation (PCM), which represents audio as samples of the signal amplitude. However, the vast majority of DACs these days actually perform their decoding using a pulse-density modulation (PDM) signal, using a technique called delta-sigma modulation. These kinds of DACs are commonly referred to simply as "delta-sigma" to differentiate from multibit.

The supposed problem is that delta-sigma DACs, in order to do their decoding, much discard the original PCM samples when they convert to PDM. Further, delta-sigma DACs are typically 1-5 bits, making up for the lost dynamic range with extremely high oversampling - e.g. in the MHz range.

Multibit solutions overcome these supposed drawbacks by decoding the audio signal with a true 16+ bit DAC, preserving the original PCM samples.

On top of this, Schiit has layered a proprietary closed-form, frequency- and time-domain optimized digital filter. Digital filters are necessary to perform upsampling of the audio signal, which moves aliasing distortion out of the audible band. Some typical methods for this are the minimum-phase and linear-phase filters. Some people claim that minimum phase filters are better because they avoid pre-ringing, while other prefer linear phase because they avoid phase-distortion. I'm not sure how Schiit's closed-form filter differs from linear-phase, other than it is supposed to preserve all of the original samples."
 
Good posts here. I would add that multibit DACs were the original digital implementation with the advent of PCM recordings and later the CD. Delta sigma came later.

As I understand it, delta sigma also came to the forefront with 24 bit depths of 'hi res' audio. It is very hard to make multibit 'ladder' DACs above 18 or 20 bit resolution. The question is if higher resolution than 20 bit is even necessary, apart from headroom during processing in the digital domain. It is practically almost impossible to make a DAC of actual resolution of more than 20 bit at its analog output, the reason being inherent noise of its electronic components. I was told that the dynamic headroom of an entire system is usually hardly above 80 dB, less than the 16 bit dynamic range of a CD of 96 dB. Again, the issue of inherent noise floor.
 
Al M. said:
Good posts here. I would add that multibit DACs were the original digital implementation with the advent of PCM recordings and later the CD. Delta sigma came later.

As I understand it, delta sigma also came to the forefront with 24 bit depths of 'hi res' audio. It is very hard to make multibit 'ladder' DACs above 18 or 20 bit resolution. The question is if higher resolution than 20 bit is even necessary, apart from headroom during processing in the digital domain. It is practically almost impossible to make a DAC of actual resolution of more than 20 bit at its analog output, the reason being inherent noise of its electronic components. I was told that the dynamic headroom of an entire system is usually hardly above 80 dB, less than the 16 bit dynamic range of a CD of 96 dB. Again, the issue of inherent noise floor.
Click to expand...

You are correct sir. Hans Beekhuzen has a very good video on his YouTube channel about this.
 
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