Looking for signals for test CD/ready-to-burn image

[ReDFoX]

Hi! Inspired by NTTY's recent posts, I decided to measure my CD and DVD players, but that rises 2 questions:

1. What signal types should I burn onto a CD?
2. Is there an "industry standard" CD that I can just copy and be good to go?

From my point of view, a simple test CD have to consist at least:

• 0dBFS 1kHz sine tone (single freq. THD)
• 32 tones multitone signal (ENOB + multitone distortion)
• J-test (jitter, obviously)
• 0dbFS white noise (antialiasing filter out of band attenuation)
• SMPTE/AES 2-tone signal (intermodulation + stop band performance)
• 20-20000Hz 0dBFS sine sweep (FR)

All signals are non-dithered (should they?)

---

Am I right/wrong about this? Any feedback appreciated!

 

[staticV3]

Dithering should be applied to most of these to suppress quantization noise.

Technically, the MT and white noise signals already contain frequency response, making a separate frequency sweep somewhat redundant (unless you care about passband ripple).

 

[ReDFoX]

Dithering should be applied to most of these to suppress quantization noise.

Ah, ok, got it! I wanted to use REW for signal generation. Do I just check "add dither 16bits" box in generator?

Technically, the MT and white noise signals already contain frequency response, making a separate frequency sweep somewhat redundant (unless you care about passband ripple).

Yes, but I will white noise give sufficient resolution as a FR linearity measure? I suppose I should use something like 1/48 smoothing with that

 

[staticV3]

Ah, ok, got it! I wanted to use REW for signal generation. Do I just check "add dither 16bits" box in generator?

Try different levels of dithering and see which one gives you optimal results.

To do this, simply save the tones to a file using the REW Generator, then drag them onto the RTA Window to analyze.

IIRC, last time different levels of dithering gave me the cleanest results, depending on signal type (1K vs MT vs IMD etc).

Yes, but I will white noise give sufficient resolution as a FR linearity measure? I suppose I should use something like 1/48 smoothing with that

Again, do your own tests and see if MT and white noise alone are sufficient.

If not, add an REW measurement sweep (also exportable as file from REW's Generator).

 

[ReDFoX]

drag them onto the RTA Window to analyze

Whaaaat!? You can do that?
This may sound stupid, but I can't understand how to get FR from sweep... I thought it would plot it like frequency VS level, but that's not the case(
Thank you so much for dithering advice!

 

[staticV3]

Whaaaat!? You can do that?
This may sound stupid, but I can't understand how to get FR from sweep... I thought it would plot it like frequency VS level, but that's not the case(
Thank you so much for dithering advice!

For an REW measurement sweep, use Import->Import sweep recording

When measuring this sweep being played by a CD Player, use the standard Measure dialog and choose Playback from file.

Click Start and REW will listen for the chirp signal indefinitely and start once the CD player starts playing.

 

[ReDFoX]

For an REW measurement sweep, use Import->Import sweep recording

Wow, that's... counterintuitive. I always assumed that it does "sweep import" on drag and drop (what else you can drag and drop? aside from graphs)

Click Start and REW will listen for the chirp signal indefinitely and start once the CD player starts playing.

Yeah, that's the easiest way, though I'm more interested in offline analysis since I'll be doing other measurements alongside

 

[kchap]

A bit basic, but you may be interested in the Focal Tools CD.

 

[AnalogSteph]

Yes, but I will white noise give sufficient resolution as a FR linearity measure? I suppose I should use something like 1/48 smoothing with that

It's hard to beat MLS signals (like RMAA uses) or traditional sweeps for this indeed. That being said, you could test this with white noise and DeltaWave and see whether you like the results.
(You could probably do worse than putting complete test signals for typical measurement apps like RMAA, REW and Multitone on there in general.)

Your "1 kHz" "0 dBFS" test signal can be undithered if the exact frequency is chosen appropriately, see discussion

Yamaha CDX-393 Review (CD Player)

This is a review and detailed measurements of the Yamaha CDX-393 (MKI) CD stereo player. By the looks of it, you can guess this is one more old CD player, and you're right, it's from 1999. My first review of the Onkyo C-733 here contains information about my measurements which I align with...

www.audiosciencereview.com

onward. I would pick either 1000.003 Hz or 999.9991 Hz, with a fallback option of 999.91 Hz.

Also see this for amplitude considerations:

Orpheus Zero Review (CD Player)

You're right @restorer-john. John always starts his reviews with this information and I'm happy to include it. In reality there's no reason why I did not do it earlier. I'll update accordingly. EDIT: The balanced outputs of The Orpheus Zero invert absolute polarity. That said, the interface...

www.audiosciencereview.com

Undithered you could go up to a generator amplitude of 0.999969, dithered about 0.9996. I would generally consider 0.999 "close enough".

Using shaped dither can be useful in teasing out a better approximation of the analog noise floor (at least up to ~6 kHz) even when you're limited to 16 bits. The variety employed by Audacity is quite handy in this regard. (Perceptively, the shaped dither as employed by Foobar2000 wins out, but that's not as well-suited for measurement purposes.)

Test tones for overs would still be quite handy, i.e. 5512.5 Hz +0.69 dB, 7350 Hz +1.25 dBFS and 11025 Hz +3 dBFS.

Teac VRDS-20 Review (CD Player)

Nice report, test and an even nicer device. I also own a Teac VRDS-25x, an absolute tank among CD players. I still need a VRDS-20 for my pleasure, if only because of the look and construction. Not even one of the Teak developers could explain to me at an event what Teak was thinking with the...

www.audiosciencereview.com

 

[ReDFoX]

It's hard to beat MLS signals (like RMAA uses) or traditional sweeps for this indeed. That being said, you could test this with white noise and DeltaWave and see whether you like the results.
(You could probably do worse than putting complete test signals for typical measurement apps like RMAA, REW and Multitone on there in general.)

Your "1 kHz" "0 dBFS" test signal can be undithered if the exact frequency is chosen appropriately, see discussion

Yamaha CDX-393 Review (CD Player)

This is a review and detailed measurements of the Yamaha CDX-393 (MKI) CD stereo player. By the looks of it, you can guess this is one more old CD player, and you're right, it's from 1999. My first review of the Onkyo C-733 here contains information about my measurements which I align with...

www.audiosciencereview.com

onward. I would pick either 1000.003 Hz or 999.9991 Hz, with a fallback option of 999.91 Hz.

Also see this for amplitude considerations:

Orpheus Zero Review (CD Player)

You're right @restorer-john. John always starts his reviews with this information and I'm happy to include it. In reality there's no reason why I did not do it earlier. I'll update accordingly. EDIT: The balanced outputs of The Orpheus Zero invert absolute polarity. That said, the interface...

www.audiosciencereview.com

Undithered you could go up to a generator amplitude of 0.999969, dithered about 0.9996. I would generally consider 0.999 "close enough".

Using shaped dither can be useful in teasing out a better approximation of the analog noise floor (at least up to ~6 kHz) even when you're limited to 16 bits. The variety employed by Audacity is quite handy in this regard. (Perceptively, the shaped dither as employed by Foobar2000 wins out, but that's not as well-suited for measurement purposes.)

Test tones for overs would still be quite handy, i.e. 5512.5 Hz +0.69 dB, 7350 Hz +1.25 dBFS and 11025 Hz +3 dBFS.

Teac VRDS-20 Review (CD Player)

Nice report, test and an even nicer device. I also own a Teac VRDS-25x, an absolute tank among CD players. I still need a VRDS-20 for my pleasure, if only because of the look and construction. Not even one of the Teak developers could explain to me at an event what Teak was thinking with the...

www.audiosciencereview.com

Wow! Thank you so much, although I'm just a silly foxxo and this kind of math is well above my level at the moment... I'll certainly try to educate myself, but stick to using REW for the moment)

 

[AnalogSteph]

I quite like using Audacity as a tone generator as well. In 2.1.3 you still had to turn off dithering for high-quality conversions if you wanted straight undithered 16 bit output, but otherwise it seems to work just as well as later versions. (UI changes over the years have been a rather mixed bag in my opinion, so my approach to updates has generally been "don't fix what isn't broken".)

 

[NTTY]

A bit basic, but you may be interested in the Focal Tools CD.

I already tested these a while ago and wrote to the engineer who created them to ask if the fact they included shaped noise was intentional. He replied he'd have a look and the files were removed from the site. I didn't know they were back. Here is a view of the 1kHz test tone:

It's not suitable for CD player measurements, except in very specific case. Also note the -14.01dBFS attenuation, again not wanted in our case.

Cheers

 

[NTTY]

Hi! Inspired by NTTY's recent posts, I decided to measure my CD and DVD players, but that rises 2 questions:

1. What signal types should I burn onto a CD?
2. Is there an "industry standard" CD that I can just copy and be good to go?

Hi, I created this thread for the purpose, as you were not the only one to ask.

 

[NTTY]

I quite like using Audacity as a tone generator as well. In 2.1.3 you still had to turn off dithering for high-quality conversions if you wanted straight undithered 16 bit output, but otherwise it seems to work just as well as later versions. (UI changes over the years have been a rather mixed bag in my opinion, so my approach to updates has generally been "don't fix what isn't broken".)

And under your influence, I must say it became my preferred way to create single test tones with no, rectangular or shaped dither

 

[ReDFoX]

Hi, I created this thread for the purpose, as you were not the only one to ask.

I already burned a CD and measured my Marantz...
UPD: I checked your article, but some pics aren't showing, and I can't see a link to excel table