I don't think we have anyone doing any of that here. We do have some people who believe in some things that others are very skeptical about. Like possible effects of different types of cables, for example. However, poorly designed cables or poorly designed equipment could exhibit symptoms in some cases. It's not impossible.
Regarding Bybee devices, John Curl has not been making the same claims Jack Bybee does. John has said the effects are subtle and that devices need to be closely coupled to circuitry to have the effects he has observed. He also said sometimes they make equipment sound worse rather than better.
Edirol UA-25ex
Behringer UCA202
PCM2704 MINI USB Sound Card DAC
and others I forget or never noted.
I thought all asynchronous DACs did this by means of FIFO registers, local oscillator and PLL.
Suggestions/schematics on DAC optimal treatment of D+/D- lines please.
Mark, I have done enough blind AB testing with myself as the subject or the other party as the subject to verify audibility, no question.
Dan.
Yes, well said.
I am going to catch up with this guy qdl.com.au next week and see what we can flesh out.
Dan.
Some use two PLLs in series to reduce jitter even more. Even that isn't perfect, it's why some newer DACs use a fixed clock and SRC of the incoming data so that it can be clocked out of SRC to the DAC using the DAC's fixed clock.
People on the forum here are starting to play around with the latest ES9038 DAC using Chinese modules from ebay. Improving the fixed clocks is one mod people sometimes do, but it's probably not too bad as is.
The earlier ES9018 DACs reportedly had an issue where they sometimes sounded better with the SRC turned off if the incoming data was already very clean. Some people say that is fixed in the 9028 and 38, and SRC always sounds okay.
Keeping the USB interface galvanically isolated is also something some people favor, although it isn't always practical.
I think the point is what has been found is that for people who's brains pick out distortion so they hear even very small amounts of it, making a clean DAC is not trivial. But, if the DAC is supposed to work with USB then it needs to be insensitive to cables. Otherwise there is no way to be sure you are ever hearing it the way it's supposed sound. You may never have a perfect cable, or perfect USB transmitter in your computer, so relying on fiddling around with those things is a fundamentally flawed approach.
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Lots of companies use words in the company name that don't have anything to do with how the product works. How about Apple computers?
This week I have been headhunted by these guys www.audiotechnik.com.au to lob in two days per week in addition to my job servicing and crewing stage lighting.
Take a good look at the inventory, that's the gear I will be working on/studying/auditioning.
The QDL EMC lab just happens to be around the corner, I didn't choose the name.
Dan.
Mark, I'm with you, ie which cable is the 'right' one.
Are the twin PLL dacs totally insensitive to USB cables ?.
Dan.
Why do you need PLL's or SRC's at all? BIG FIFO and the best clock you can muster, is the latency really that big an issue?
Thought experiment, let's say some DSP guru invented a process to upscale 44.1/16 to a 24/192 file that everyone agreed blows everthing else away but takes 2-3hr. to process a CD.
For replay, latency is of course zero issue...a vinyl needle drop takes a second or two before the first sounds appear, I have never heard complaints about that.
Sony made a range of Walkman CDP's with switchable 2 second or so FIFO for vibration immunity.
The first few seconds after hitting play/track skip were as per normal, after that with the long FIFO operating the sound output was nicely better than standard mode.
I think most NAS/Music Server or PC Audio users would be perfectly fine with that.
Dan.
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They used to run the DAC clock on one or two-in-series PLLs. The difference is now the DAC runs on a fixed crystal clock and the PLLs are to servo the SRC digitally.
And, yes, SRC is just a way to approximate what you would want from a big FIFO. Some people do use a big FIFO, but they reset it between songs or wherever there is a gap of silence so it doesn't overflow. For DACs that may be used with continuous streaming there is no guarantee there will be a good place to reset the FIFO. Also, there could be unwanted latency as the FIFO fills up to make sure enough data is buffered to prevent underflow. SRC is a way to use a fixed clock without problems a big FIFO might have.
Also, upsampling has its uses. Sometimes helpful with some kinds of DSP. Also, it can help avoid reconstruction filter audibility that otherwise can be hard to do well at 44.1
In addition, if you have a DAC with a sweet spot at 24/96, say, you can already do a very good job of offline SRC. Weiss Saracon is probably the best available, with spurs as low as -160dB depending on the conversion settings. SARACON | Weiss Engineering Ltd.
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I found my system is audibly immune to anything they do. But I left them on anyways. It's probably not a super resolving system, but it's one I'm completely familiar with, other than recently changing a phono cartridge.
What problems? EAC can usually run at 8 to 10X in ripping even a bad CD, filling up a FIFO so that there is no possibility of either under or overflow in several hours is trivial and the memory costs nothing. How much can clocks vary and have the recording still be worthwhile fussing over? At CD rates 1% off is not even 7M bytes an hour.
Ok, so you are now completely familiar with the sound of your system with the ferrites in place, all good, take them out and see if you detect fine changes.
Charles Hansen had some strong words (negative) about the subjective effects of ferrite.
Dan.
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