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In Reply to: Create your own ... posted by Christine Tham on December 27, 2004 at 22:14:43:
Not a bad idea if you have the time and the knowledge and the equipment. (If I had the time and the knowledge and the equipment, I would build a time machine!)It would be even easier to simply make a copy of the Ayre disc. Unlike the RIAA, I promise that we won't sue you (unless you start selling them).
Is your homemade disc "better" than the Ayre disc? It's possible, but not because the level is 1 dB lower than the Ayre disc. Many players will clip a 0 dBFS *square* wave (due to overshoot in the digital filter), but I don't know of any players that will clip a 0 dBFS *sine* wave.
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I won't, though, simply because I don't have the original to make a copy from!
PS - you can get 0dBFS+ issues with sine waves. check out my article in the URL below. However, in this case they won't because I have not amplified the signal in any way.in theory, white noise can generate 0dBFS+ signals as well - that's the primary reason for staying below -1dBFS. I guess I could have mastered the disc at 0dBFS except for the white noise track, but i like being consistent!
PPS - what's the reason for initially creating the signals at 88.2/24? 44.1/24 i can understand, but 88.2 seems to be to be a waste.
Incidentally, your promotional material mentions the disc was mastered using 0.5 dither and a triangular pdf. I take it you must be using Adobe Audition, since that's the software that allows you to do this. Can I suggest that you might want to try Apogee UV22HR instead (available on Wavelab)? I've found it to be the best dithering algorithm i've experienced - giving "pseudo" 24 bit quality in 16 bits, albeit with an increase in noise above 20kHz.
PPPS - the signals on my disc were created directly in 44.1/16 - I chose not to apply dithering.
PPPPS - trying out the disc in "burn in" mode on a Denon DVD-3910 at the moment that I'm reviewing - I'll let you know whether it results in an improvement in the sound after 48-72 hours.
I read your linked article, which was very interesting and well presented. I had not ever heard of this problem. It's definitely not a problem for our player. I simply cannot imagine designing a circuit that didn't have some "headroom". (I normally shoot for 100% "headroom" so that the circuit can handle at least twice the signal level normally present.)I was surprised to see that *any *players had a problem with the (admittedly unusual) test signal. But there you go...
In any event, there won't be any problems like this with the Ayre IBE disc. All of the noise tracks were recorded well below 0 dBFS. The software was Cool Edit Pro (I think that's what it's called), which was subsequently purchased by Adobe and renamed "Audition".
There was a specific reason for dithering the signals. It seems to be successful, as there are many postings on the Audio Asylum that state that the Ayre IBE produces better results than other similar (and typically more expensive) discs.
... I can send you some files that will allow you to test whether there is a problem in your player or not. Based on email exchanges I've had with several manufacturers, the problem appears to be in the digital filter implementation rather than the analog stage, which - as you've correctly pointed out - usually has some headroom.If your players use "off the shelf" digital filters, you may have the problem, since the only player I have that handles 0dBFS+ (sony xa777es) uses a Sony-proprietary digital filter.
In terms of dithering - it won't do any harm, but it most likely won't deliver any real benefit either. Dithering is often useful for computer generated test signals, as the addition of noise helps mask any artificial harmonics generated by the perfectly regular bit patterns. However, in this case, 5 of the tracks are noise, therefore dither is just adding noise to noise and arguably making the pink and brown noise samples "less pure."
For the sine wave sweeps, since the frequency of the sine wave is continuously changing, there is no regular bit pattern, therefore no real need to dither. Having said that, it probably won't do any harm (except cause you to lose about 1 bit in resolution - big deal).
Looking forward to reading your review Chris. Any idea when it will be published?As you may know, I recently bought a 3910. At the moment, the Sony SCDXB790 is more open, relaxed and altogether more true to the ear than the Denon, which seems "pinched" and lacking something with SACD's. Same comparison holds when comparing DVD-Audio with the Toshy SD900E - the Denon just doesn't have the depth and presence I am used to CD's do sound quite nice though at this stage.
Do you expect things will change over time?
if your player is brand new, i would suggest doing a burn in period by playing a m-ch dvd-a or sacd in "repeat disc" mode for 48-72 hours and see if it improves.also, try setting "source direct" on, which bypasses bass and time management. i believe on this player, source direct will preserve dsd, otherwise dsd will be converted to pcm.
feel free to drop in one of these days and check out the player on my system. it should be okay by the weekend - currently it's still playing my version of the IBE disc in "repeat" mode.
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