OK, What is a DAC? seriously.

[edward]

I know I know dont call me seriously.
All jest aside what is a DAC and is it better than a DVD audio,
CD player or SACD player?
it is time for a new music player, the old CD player is from 1995
So for 2 channel listening and providing the best reproduction for about $400.00 what do you gentelmen recommend?
:huge:

thanks
edward

[Hugh]

May I suggest you check out the Onix CD-10 from my ad.

http://www.tweakcityaudio.com/forum/showthread.php?t=610

Thanks,

[dvenardos]

I am guessing your current cd player does not have a digital output?

[NekoAudio]

An outboard DAC is usually only comparable with a CD or DVD player, and not a DVD-Audio or SACD player. For the reason that outboard DACs will not decode DVD-Audio or SACD signals from a player (I'm talking 99% here).

DAC stands for Digital to Analog conversion and refers to the tiny chip inside of receivers, CD/DVD players, or your PlayStation 3 that turns the digital information on a CD or other source into an electrical signal to drive your speakers.

But when most people talk about a DAC they mean a box that has one or more of those chips inside, and all of the associated electronic circuitry there to support optimal performance of said chip.

I've got a little more information on my forum in the D100 FAQ.

For $400 I'd recommend looking at Audiogon and finding something you like, or find a used Benchmark DAC-1 if you stretch your budget a bit. I have D100 measurements posted, which you could use as a starting point for understanding how you could compare DACs without listening yourself.

[zductive]

Wes

Would you fill us in a little bit about how your reconstruction filters work with the transformer coupled output? Your Jensen datasheet shows how you would integrate the transformer into the circuit while using opamps. I wonder how you would handle the out-of-band impedance of the filter with the transfer,

You don't talk about the reconstruction filter much - is it a 3 stage Bessel?

You don't talk about the upsampling that would be performed by the dac. Any comments about how you traded off upsampling v. filter requirements.


Curious about the technical trades that go into a high performance product.
Thanks

[NekoAudio]

Would you fill us in a little bit about how your reconstruction filters work with the transformer coupled output?
...
You don't talk about the reconstruction filter much - is it a 3 stage Bessel?

There's actually no additional low-pass filter. Since the output stage is 100% passive, there's nothing to alter the signal that is coming out of the PCM1794. The chip itself contains a very sharp low-pass filter (see Figure 1 on page 8 of the PCM1794 datasheet).

The result is pretty clear, as seen in the frequency response and steep THD+N drop around 7kHz.

You don't talk about the upsampling that would be performed by the dac. Any comments about how you traded off upsampling v. filter requirements.

The D100 is a non-upsampling DAC. Higher sample rates actually result in worse performance (see the datasheets of any DAC chip). But if you want to feed a higher sample rate it'll accept it and output the higher frequencies too.

Curious about the technical trades that go into a high performance product.

One obvious trade-off is the use of a passive output stage instead of an active one. As a result, the THD+N measurements are higher than in a DAC that would employ op-amps and lots of negative feedback. The output signal is also -6dB from typical balanced and -3dB from typical unbalanced. The output impedance is a bit higher than you can achieve with other methods.

But removing active components means there aren't any additional devices that can interfere with the sound. The noise floor is extremely low (around -140dB). Linearity remains very good without the use of negative feedback. There aren't any op-amps playing "catch-up" with the input signal, so one of the noticeable things is the quick transient response. (Although you can argue modern op-amps are very good at doing what they need to do.) There's also no smearing of one sound into the next.

There aren't really any trade-offs in the other parts of the D100. I didn't spare any expense on components or the chassis (well, I didn't make the enclosure so fancy that you're paying more for looks than performance). Tantalum capacitors instead of electrolytic. Components with low variance as a function of temperature. Lots of power capacitance and pi filters on every power input. Toroidal transformer and a big line filter, separated by a shield. Based on typical margin, a unit like the D100 would cost a lot more from a dealer.

So while in some ways it doesn't measure as well as other DACs, it sounds amazing. That's why Neko Audio is "uncompromising audio electronics". :D