How good does a DAC need to be for ASR approval?

[Blumlein 88]

Hope Amir doesn't mind me starting this thread. Since he is building up a list of DACs measured I wondered how good measurements should be to not worry anymore. Amir mentioned he would like a list of ASR approved gear. So a chance to discuss it.

To kick it off I suggest we talk about his jitter measurements because that is usually the first thing he shows. You also get some idea of the noise floor of the DAC and PS leakage in that graph. So what parameters should be good enough?

 

[RayDunzl]

Keeping it objective, maybe a big comparison checklist including things like:

Inputs - coax/optical/AES/USB
Number of Channels
Has DSP or Bass outputs
RCA/XLR Outputs
Undistorted output voltage
PCM rates
DSD or other rates if applicable
MQA
Method of Volume Control
Headphone Outputs
Remote Control
Power Supply
Construction Quality
Country of Origin
Street Price

Maybe also:

Digital Outputs/pass through
Analog Input

In other words, many things other than A/P measurements of inaudible faults

 

[Blumlein 88]

One thing is the noise floor. While arbitrary I think one should manage the '16 bit' noise floor of - 96 db. I believe Amir uses 64K FFT's so that shows noise floors if they are close to flat about 45 db lower than the noise floor for the whole bandwidth at 48 khz. So if a you add 45 to 96 you'll get 141 db. So shall we say the base noise level in a J-test needs to be in or around -140 db? Or does Amir use a smaller FFT size.

 

[amirm]

I use 32K FFT although I am playing with deeper one in Matlab for the future.

 

[NorthSky]

 

[Blumlein 88]

I use 32K FFT although I am playing with deeper one in Matlab for the future.

Okay so then we're talking noise floors around - 138 db for that.

 

[Wombat]

This good?

https://people.xiph.org/~xiphmont/demo/neil-young.html

 

[watchnerd]

It just needs to be audibly transparent.

 

[Blumlein 88]

It just needs to be audibly transparent.

Oh yes I agree. I think standards could perhaps allow us to know (with a high degree of probability) when that has been achieved without doing actual listening tests.

The other consideration is if excess capability is available for peanuts, then you might as well get it.

I feel for most possible issues, if a device keeps all the various distortions below -80 db relative to the signal level you'll have transparency. Is this blanket choice good enough you think?

Take the Uphoria used as a DAC. It is a little short of a noise level I mention above. Yet it probably is low enough you'll not hear it or have it compromise into being audible under any reasonable use of the device.

 

[Thomas savage]

Buy the most expensive one you can afford but treat it like it’s the cheapest one so extra mains filtering and phat cable plus all the usb filtering you can grab...

Technology moves on though so be prepared to feel a deal of anxiety about ‘ missing out’on the next mega $ DAC.

 

[Sal1950]

Buy the most expensive one you can afford but treat it like it’s the cheapest one so extra mains filtering and phat cable plus all the usb filtering you can grab...

Technology moves on though so be prepared to feel a deal of anxiety about ‘ missing out’on the next mega $ DAC.

You itching for a banning?

 

[watchnerd]

I feel for most possible issues, if a device keeps all the various distortions below -80 db relative to the signal level you'll have transparency. Is this blanket choice good enough you think?

For listening over speakers in a room that isn't an anechoic chamber, that sounds about right.

For listening over sensitive IEMs (or horns?), maybe a bit lower.

 

[mindbomb]

I think it just has to stand out relative to similarly priced items.

 

[watchnerd]

I think it just has to stand out relative to similarly priced items.

Stand out in what way?

 

[sergeauckland]

I feel for most possible issues, if a device keeps all the various distortions below -80 db relative to the signal level you'll have transparency. Is this blanket choice good enough you think?

That would be pretty much my criterion, however, with modern chipsets and a decent implementation, I would be worried if any DAC, even the cheapest, couldn't manage 10dBs better.

I use whatever DAC comes with the kit and don't have an external DAC in my main system, but use ADC/DACs a lot for recording and testing, and if an ADC/DAC pair can't manage -90dB back-to-back, then I wouldn't use it as something isn't done right.

S.

 

[amirm]

Maybe this should be a subjective decision I make based on measurements, price, fidelity, features and build quality.

 

[RayDunzl]

Maybe this should be a subjective decision I make based on measurements, price, fidelity, features and build quality.

 

[fas42]

Oh yes I agree. I think standards could perhaps allow us to know (with a high degree of probability) when that has been achieved without doing actual listening tests.

The other consideration is if excess capability is available for peanuts, then you might as well get it.

I feel for most possible issues, if a device keeps all the various distortions below -80 db relative to the signal level you'll have transparency. Is this blanket choice good enough you think?

Take the Uphoria used as a DAC. It is a little short of a noise level I mention above. Yet it probably is low enough you'll not hear it or have it compromise into being audible under any reasonable use of the device.

When one leaves the semi fantasy world of measuring equipment in highly prescribed ways, and looks at what the gear does in the real world, then that 80dB looks very, very ambitious. The exercise I doing in examining the real outputs of various pro gear in simple DA/AD paths demonstrates misbehaviour at only about 20dB down in the poorer cases - there is a large divergence of competence, in the real world, and looking at what the waveform does in the "tricky areas" shows up the winners, and losers.

I was hoping to post some pics by now, but the new version of Audacity is exploding on me - I'm "dithering" on whether to revert to an older version, or push for answers on what's happening.

 

[Wombat]

Maybe this should be a subjective decision I make based on measurements, price, fidelity, features and build quality.

I haven't seen output parameters mentioned e.g. impedance and dc offset.

 

[Sal1950]

Maybe this should be a subjective decision I make based on measurements, price, fidelity, features and build quality.

And the size of the check that accompany the device submitted for review.
At the very least the device should be donated to ASR