Dither Agony

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The "Merging Cellar" is the place where you can share your tasting experiences and discuss everything from technique, artistic matters or even business practices, but not necessarily about Pyramix. Feel free to pick the brains of the talented Merging forum users. Enjoy.

Dither Agony

Postby Perfect Record » Thu Oct 27, 2011 19:25

You may enjoy this.
I've been working on a CD of a classical duo for the last many weeks. I've been sending them roughs as we go along for approval. The CD's were always made directly from projects in Pyramix using the internal dither.

When I finished the CD, I spent hours in iZotope RX fixing clicks and rumbles. Since I like iZotope's MBit dither, I dithered down in RX when saving all the tracks.

We delivered the finished CD for approval, and to my amazement, the flute player complained that the master didn't sound like the roughs- and that she preferred the roughs.

Yesterday I spent 2 hours with the producer comparing every which way imaginable. Yes there was an audible difference. Yes the two versions nulled almost completely, other than the dither noise, and of course the places where I de-clicked.

The MBit sounds closer to the 32 bit mixes, but now I get to go back and re-build the master so that I can use the Pyramix dither. Mind you, both versions sound very good. Good enough where there's no point in wasting my time arguing.

The artists loved everything I did in the mix, which was done un supervised. I'm kind of amazed that I'm re-doing the master because of a very subtile difference in dither!
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Re: Dither Agony

Postby Perfect Record » Thu Nov 03, 2011 04:57

Re made the production master, and the client is delighted.

This was a healthy exercise. It made me sit down and compare various forms of dither. Amazing how something so small can make an audible difference.
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Re: Dither Agony

Postby Bernhard Guettler » Thu Nov 03, 2011 13:03

Interesting, what were your exact dither settings in both cases?

Cheers
B.
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Re: Dither Agony

Postby Perfect Record » Thu Nov 03, 2011 23:05

When I was making the edit reference discs for the client I was applying the 8th order dither that's available in the Generate CD window. The dither in the version the client didn't care for was standard iZotope MBit dither without any modification.

I certainly could have had a long discussion and demonstration of various dither settings with the artist, but the producer thought it would be best to merely re-create what I had done for the quickie edit refs. And that's the sound that made her happy.

The MBit dither had a bit more stereo depth and a slightly cleaner sounding noise floor to my ear. Like I said in an earlier post, it was very interesting taking the time to compare the differences, as well as listening via different CD players and converters.

Even at the end of this process I'm still quite surprised that the artist was able to hear a difference in dither, even on a very modest CD player. I wonder how this story would have ended if I'd been using MBit on the early reference CD's?
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Re: Dither Agony

Postby Perfect Record » Thu Nov 03, 2011 23:07

I had a thought. I wonder if she was using an older player with poor zero crossing performance? Perhaps a higher dither level helped the performance of the CD player?
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Re: Dither Agony

Postby Bernhard Guettler » Fri Nov 04, 2011 00:23

It would be interesting to know her listening system. Headphones or Speakers?
And also her audiograms, but that's hard to get probably :-)
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Re: Dither Agony

Postby Perfect Record » Fri Nov 04, 2011 05:24

Bernhard Guettler wrote:And also her audiograms, but that's hard to get probably :-)


That might be a little beyond what I'd ever want to ask a client. :oops:
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Re: Dither Agony

Postby Bernhard Guettler » Fri Nov 04, 2011 11:36

I would go out on a limb and speculate she liked the noise from more level the 8th order has around 9 kHz - perceived as a pseudo brilliance - more than the cleaner an warmer MBit dither. Either way it would be an extremely subtle effect.
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Re: Dither Agony

Postby fl » Fri Nov 04, 2011 17:06

Intrigued by this discussion, I took some screen shots of the frequency spectra of various flavours of dither that I have available, using the most excellent (and free) VST Plug-in, Voxengo SPAN http://www.voxengo.com/product/span/

These images compare Dither settings from Pyramix, Voxengo's Elephant Plug-in, and the Izotope Dither found in the Ozone 4 Plug-in (as well as in RX2 and other programs which license this technology). To even the playing field somewhat, these are all Triangular Probability Density (or 2 bit dither as it's called in Ozone), dithering to a 16 bit word length. I did two images for each instance - one while running a 96 kHz. SR session, and the other while running a 44.1 kHz. session. Most of the time, the differences between Sample Rates are as you'd expect, but notice the change between the Pyramix Acoustic setting between a the two sample rates.

If anyone who owns the POW-R dither key and has access to the SPAN plug-in wishes to take similar images, I'd be happy to add them to my online storage for display in this list.

Here are the images in an online Gallery, which can be viewed as a Slideshow:
http://www.dropbox.com/gallery/743443/1 ... s?h=4c8405

Here are the individual images for download:
http://dl.dropbox.com/u/743443/Dither%2 ... %20Off.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... %20Off.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20Pass.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20Pass.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... oustic.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... oustic.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... %20Off.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... %20Off.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Equal.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Equal.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... lassic.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... lassic.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20None.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20None.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Simple.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Simple.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Clear.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Clear.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Psych5.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Psych5.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Psych9.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Psych9.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20None.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20None.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Simple.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Simple.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Clear.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Clear.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Psych5.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Psych5.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Psych9.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Psych9.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20None.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20None.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Light.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Light.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Medium.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... Medium.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20High.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 20High.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Ultra.jpg
http://dl.dropbox.com/u/743443/Dither%2 ... 0Ultra.jpg
Frank Lockwood, Toronto, ON, Canada
http://LockwoodARS.com
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Re: Dither Agony

Postby tas » Sun Apr 22, 2012 11:24

HI Frank

you don't have those pictures available anymore or has just the location changed?

thanks
PMX 8.0.12 Native, Windows 7 Ultimate, MacPro, Bootcamp 4.0, RME MadiFX
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Re: Dither Agony

Postby fl » Sun Apr 22, 2012 14:54

Oh, I cleared out my DropBox when the thread appeared to die last fall - sorry.

I've uploaded a single zip file of all of them: http://dl.dropbox.com/u/743443/Dither%20Images.zip
Frank Lockwood, Toronto, ON, Canada
http://LockwoodARS.com
Native 11.0.5/Native Music 9.1.10
Win7 Pro SP1 64/32
Bootcamp 5.1.5621/4.0.4033
Mac Mini 6.2 (Quadcore i7)/MacBook Pro 3.1 (Core2Duo)
RME Fireface 800, driver version 3.122
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Re: Dither Agony

Postby fl » Thu Nov 22, 2012 19:20

There seems to be some renewed interest in my images of the frequency response of various types of Dither, made using Voxengo's SPAN plugin. I only was able to make images of those types of dither I own, which include all those found in Izotope products, those found in Voxengo's Elephant plug-in, and also those available within Pyramix 7.1.10. I do not own the license for POWr dither, so could not make an image of those.

The images are available here:
https://dl.dropbox.com/u/743443/Dither%20Images.zip

This time, I included a more recent series I created showing the flavours found when using the options found in the Pyramix Mixdown or Create CD Image windows, as opposed to those found in the Mixer. Unsurprisingly, there is some overlap:

Mixer Window 1st Order Dither appears to be the same as the Mixer's Triangular High Pass.
Mixer Window 8th Order Dither appears to be the same as the Mixer's Triangular Acoustic.
Mixer Window 49th Order Dither appears to be a smoother curve than found in the 8th Order Dither, and is not available in the Mixer.

Looking at the waveform displays in Pyramix at 64x vertical zoom, it appears that there is some difference in the overall level of these Dithers - 1st Order being the quietest, then 49th Order, then 8th Order as the loudest - but this could just be a quirk of the waveform display routines in Pyramix causing it to appear louder because more energy is concentrated in specific frequency areas than others.

When using the Mixer's Dither, there seems to be an issue when running at sample rates other than 44.1 kHz. - the frequency contour shifts with the sample rate (like vari-speeded playback), so that the peaks and notches shift by an octave or more. As I understand it, the whole point of Shaped Dither is to exploit the sensitivities and deficiencies of human hearing at specific frequencies, so use of these shaped dithers at sample rates above 48 kHz. should probably be avoided (although I suppose the question could be asked as to why anyone would need a noise-shaped-dithered 16 bit, 96 or 192 kHz. file in the first place).
Frank Lockwood, Toronto, ON, Canada
http://LockwoodARS.com
Native 11.0.5/Native Music 9.1.10
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