how is it measuring?

[fumihiko]

MINASAN KONNICHIWA

how is it measuring?
my measuring ,play test CD and am measuring a spot with the distortion-analyzer.
It is only 1KHz and 10KHz.

I can not buy the AP and RS.

 

[Bernhard]

I can not buy the AP and RS.

Ebay spectrum analyzer can find for cheaper.

 

[banana]

I suggest RMAA and a decent soundcard, such as "ESI Wave Terminal 192X" or "Echo MIA".

 

[Bernhard]

I am afraid a soundcard is limited to 20kHz ???

 

[fumihiko]

KONNICHIWA banana SAN

I suggest RMAA and a decent soundcard, such as "ESI Wave Terminal 192X" or "Echo MIA".

I tried RMAA wirh Roland UA-30 but,can not measuring DAC
It measured the performance of ADC
To measure surely, the performance of ADC becomes a problem.



thanks

 

[Bernhard]

If you like to measure 0dB signal you will have big problem because distortion is very low and maybe souncard is worse.
If you use standalone analyzer you need one with 100dB dynamics which cost $$$$$

Better use -60dB signal from Pedja`s website.

I have Nicolet 446B with only 75dB dynamics and works fine.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=49778

 

[Jocko Homo]

A -60 dB test tone will tell you a lot more about your DAC than a 0 dB tone.

Jocko

 

[banana]

I don't have very good experience with stand alone Dynamic Signal Analyzer, the oldish HP analyzer in my work place seems to have too high noise floor.

But I have good results working with HP8903B analyzer. Though no FFT feature, its low noise preamp allow me to see -90dBFS signal. Below is the -90dBFS signal from my diy AD1853 DAC, 30KHz bandwidth, ignore vertical scale.

An externally hosted image should be here but it was not working when we last tested it.

And I'm planning to build a diy low noise preamp and a 30KHz LPF, so that I can skip the 8903.

 

[Bernhard]

HI Banana,

this looks like only last two bits are switching.
Measuring such a signal is useless, exept maybe for MSB adjustment, but not to see the result.
-60 dB is better.

 

[fumihiko]

KONNICHIWA Bernhard SAN

I try again measurement with +20dB amplifier and Roland UA-30.

-60dB 997Hz sin-wave 16bit/44.1KHz input,
It is a result of measurement.
The vertical scale,please subtract 20dB.


The result of measurement is very good.

 

[banana]

Hi Bernhard,

Yes, to measure THD, -90dBFS signal would be useless.
-90dBFS signal is useful for analyzing the noise floor.

John Atkinson used to publish -90dBFS measurement in Stereophile. Below are some.

-90dBFS "47Lab 4715D/A"

-90dBFS "Linn Unidisk 1.1"

-90dBFS "MSB Plantinum Link Plus"

 

[Bernhard]

I try again measurement with +20dB amplifier and Roland UA-30.

-60dB 997Hz sin-wave 16bit/44.1KHz input,
It is a result of measurement.
The vertical scale,please subtract 20dB.

Can You do 128 x averaging ? The noise ...

 

[Jocko Homo]

-90 dB is usless for distortion, but the more the signal looks like something that you can recognise, the better.

The AD1862 was good in that regard. The B-B DACs, wihtout a MSB trim.........no comment.

Jocko

 

[Bernhard]

-90 dB is usless for distortion, but the more the signal looks like something that you can recognise, the better.

The AD1862 was good in that regard. The B-B DACs, wihtout a MSB trim.........no comment.

Jocko

I found 10% of tested PCM56 very good with adjustment and maybe 2% without, regardless of grade.
They vary a lot.
PCM58 all were a mess, 10 pieces tested.
Differences between TDA1541 are not so big, but the chip is not very good in this respect.

 

[fumihiko]

Hi Bernhard

Can You do 128 x averaging ? The noise ...

averaging 300times
noise is DITHER
my system is CS8412-SM5842(dither on)-PCM63PKx8/ch

 

[Bernhard]

averaging 300times
noise is DITHER
my system is CS8412-SM5842(dither on)-PCM63PKx8/ch

What would you say where the noise floor is ? xxdB below measured signal ?

Do You prefer parallel PCM63 ?

 

[fumihiko]

KONNICHIWA

What would you say where the noise floor is ? xxdB below measured signal ?

Do You prefer parallel PCM63 ?

noise floor -120dB
measuring 34401A with A-filter

I don't have AUDIO ANALYZER

 

[philbyx]

I don't have very good experience with stand alone Dynamic Signal Analyzer, the oldish HP analyzer in my work place seems to have too high noise floor.

But I have good results working with HP8903B analyzer. Though no FFT feature, its low noise preamp allow me to see -90dBFS signal. Below is the -90dBFS signal from my diy AD1853 DAC, 30KHz bandwidth, ignore vertical scale.

An externally hosted image should be here but it was not working when we last tested it.

And I'm planning to build a diy low noise preamp and a 30KHz LPF, so that I can skip the 8903.

Hi Banana

How do you generate the -90dbfs signal ?
I have Cool Edit pro, and a spdif output on my PC card (creative Audigy) but it makes -80dbfs, not less...

Philippe

 

[banana]

Hi Banana

How do you generate the -90dbfs signal ?
I have Cool Edit pro, and a spdif output on my PC card (creative Audigy) but it makes -80dbfs, not less...

Philippe

I generate -90dBFS signal using "DAC Tester", which is kindly provided by a nice guy called Ulas on this forum.

I have problem using the SPDIF out of my cheapo Zoltrix soundcard. So I burn the test track onto a CDR and play it through my DVD player.