Multi-tone audio testing?

[Music1969]

Keep it at 4.5v.

I think I figured why.

So I am outputting DSD256 (HQPlayer) from the DAC.

So the output level will be half of PCM? So I am getting the equivalent of 4.3V/2 = 2.1V ?

So now I've changed Cosmos ADC to 1.7Vrms dip switch setting.

HQPlayer also has -3dB volume attenuation.

These numbers now seem to make sense (assuming my above makes sense?)

Thoughts? This is iFi Zen DAC Signature V2

 

[pkane]

I think I figured why.

So I am outputting DSD256 (HQPlayer) from the DAC.

So the output level will be half of PCM? So I am getting the equivalent of 4.3V/2 = 2.1V ?

So now I've changed Cosmos ADC to 1.7Vrms dip switch setting.

HQPlayer also has -3dB volume attenuation.

These numbers now seem to make sense (assuming my above makes sense?)

Thoughts? This is iFi Zen DAC Signature V2

View attachment 193923

Not sure. If you have a voltmeter, that would be the best way to determine what’s actually coming out of the DAC. DSD level can be lower than equivalent PCM by about 6dB. HQPlayer -3dB can turn this into -9dB, so sounds about right, but a voltmeter will be the way to make sure.

 

[Music1969]

Not sure. If you have a voltmeter, that would be the best way to determine what’s actually coming out of the DAC. DSD level can be lower than equivalent PCM by about 6dB. HQPlayer -3dB can turn this into -9dB, so sounds about right, but a voltmeter will be the way to make sure.

And 6dB down means half output level right?

I have a Fluke multimeter. Any general tips how and where to connect it to XLR pins

I've only used it for continuity checks with things unplugged

SINAD of 100dB

And multitone approx. 100dB of range distortion and noise free. Not state of the art but not crap !

Jitter is clean !

 

[Music1969]

Ok @pkane I survived the voltage measurement

500Hz tone measured by the Fluke at 0.77 Vac

And that's with a -9.72dBFS showing below

Cosmos ADC dip switch 1.7Vrms

So what does this all mean ?

 

[pkane]

Ok @pkane I survived the voltage measurement

500Hz tone measured by the Fluke at 0.77 Vac

And that's with a -9.72dBFS showing below

Cosmos ADC dip switch 1.7Vrms

So what does this all mean ?

View attachment 193940

Sorry, maybe I missed it, but what is it that you are trying to do? That might help with the answer

Click the Show Distortion button to see harmonic distortion, noise levels, THD, THD+N, etc.

 

[Music1969]

Sorry, maybe I missed it, but what is it that you are trying to do? That might help with the answer

Click the Show Distortion button to see harmonic distortion, noise levels, THD, THD+N, etc.

LOL ok before we get to that.

I changed HQPlayer to PCM output. I played 500HZ 0dBFS tone and measured voltage between pin 2 and 3.

I measured 2.1Vac.

That's half the spec.

There's no Cosmos here - just DAC output.

Spec is 4.2V RMS.

No DSD input involved either.

 

[Music1969]

And HQPlayers -3dB volume increased to 0dB in the above too.

 

[Music1969]

And I even skipped HQPlayer.

I use REW to play direct to the DAC using the tone generator.

Measured 2.1V ac again - curiously half the balanced output spec.

I'm using iFi's own 4.4mm Pentaconn to XLR cable and measuring XLR pin 2 and 3 @pkane

 

[Music1969]

Argh it was Blumlein 88 's image here that confused me:

How do I measure DAC output voltage?

Hi all, I'd like to measure the output voltage of my SMSL M500 DAC at various volume levels via the XLR and RCA outputs. How do I go about doing this? Will my multimeter (below) suffice? Your shared knowledge, as always, is much appreciated :)

www.audiosciencereview.com

This pic got me the correct voltage values.

 

[Music1969]

So it is measuring 4.3V straight from REW tone generator.

But DSD256 output will half that, and then -3dB HQP attenuation, so I think leave the dip switch to 1.7Vrms is correct.

So those measurements above are about as correct as I will get

 

[pkane]

So it is measuring 4.3V straight from REW tone generator.

But DSD256 output will half that, and then -3dB HQP attenuation, so I think leave the dip switch to 1.7Vrms is correct.

So those measurements above are about as correct as I will get

Change overlap to 87.5% in REW, otherwise all looks OK to me.

 

[Rja4000]

Argh it was Blumlein 88 's image here that confused me:

How do I measure DAC output voltage?

Hi all, I'd like to measure the output voltage of my SMSL M500 DAC at various volume levels via the XLR and RCA outputs. How do I go about doing this? Will my multimeter (below) suffice? Your shared knowledge, as always, is much appreciated :)

www.audiosciencereview.com

This pic got me the correct voltage values.

On Neutrik connectors, pin numbers are engraved on both sides.

 

[-Matt-]

I know this is an old thread but it still seemed like an appropriate place for this random thought...


Is there already a clever way of choosing which frequencies to use when doing these multitone measurements?

If you use evenly spaced tones then there is a good chance that harmonics will be masked by your other test tones.

There are a lot of prime numbers between 20 and 20,000. If you have decided to use 32 tones, is there an equation to find the 32 frequencies that will mask each other the least? I.e. They will be spaced non-uniformly to minimise overlap between harmonics and test tones.

 

[pkane]

There are a lot of prime numbers between 20 and 20,000. If you have decided to use 32 tones, is there an equation to find the 32 frequencies that will mask each other the least? I.e. They will be spaced non-uniformly to minimise overlap between harmonics and test tones.

That's been available in Multitone Analyzer for a few years as Decoherent Frequencies in multitone settings. Quoting my own post:

The algorithm is designed not to place any of the fundamental tones where they would:

• Overlap any of the harmonics from any of the tones
• Overlap any ot the even-order IMD products (2nd, 4th, 6th, 8th, 10th, etc.)
• May reduce overlap with odd order IMD products starting with 3, but will not eliminate these

 

[-Matt-]

That's been available in Multitone Analyzer for a few years as Decoherent Frequencies in multitone settings. Quoting my own post:

Thanks.

Is this used for @amirm's tests?

 

[pkane]

Thanks.

Is this used for @amirm's tests?

He uses APx555 and multitone tests are constructed differently there.

 

[Rja4000]

He uses APx555 and multitone tests are constructed differently there.

I suspect they are built with same goals.
And lowering crest factor, of course.

They also use some tricks, like centering all tones to FFT bins, then multiplying FFT size by 2: all odd order FFT bins may only contain noise then. So they are able to get a noiise measurement durectly from the multitone.

Read here: https://www.ap.com/technical-library/using-multitones-in-audio-test/

 

[pkane]

I suspect they are built with same goals.
And lowering crest factor, of course.

They also use some tricks, like centering all tones to FFT bins, then multiplying FFT size by 2: all odd order FFT bins may only contain noise then. So they are able to get a noiise measurement durectly from the multitone.

Read here: https://www.ap.com/technical-library/using-multitones-in-audio-test/

Yes, AP does something a bit different. Their type of measurement will not work with unsync'ed clocks which is mostly how I measure things. MTA is fully capable of measuring noise from any multitone signal up to 32 tones, as long as a proper FFT window is used with clocks or sample rates that are not the same between the generator and the ADC.