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Tony's Player
192.19.218.100 |
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Posted on July 13, 2012 at 00:15:47 | ||
Posts: 2422
Location: No. California Joined: October 13, 2002 |
Below Tony was talking about an interesting concept in a player, I would like to explore this a little bit. Basic concept: simple device that uses ethernet or some other remote mechanism to fill large amount of memory with data, remote interface gets disconnected and anything having to do with it gets physically powered down, simple system takes data from memory and clocks it into some form of DAC with as simple a path as possible using ultra low jitter clocks and ultra low noise power delivery. If possible the player would not have any form of DSP or digital filtering at all, this would be performed by the computer before sending the data to the player. Of course that means the amount of data can be very large. But memory is cheap and and ethernets are fast. If I understand correctly the reason for doing this is to completely remove the computer from having anything to do with real time affects on sound quality. I agree, I think this would be the best candidate I have heard of for doing this. One interesting aspect of this post was that Tony proposed using DSD, while this can mean a very simple DAC part, I am surprised that Tony brought this up given some of his previous posts expressing some rather negative thoughts on DSD. Tony, have your thoughts on DSD changed? I personally am not a big fan of DSD, but I have never played with the 128 version so maybe that makes a big difference. On detailed impelementation, I have actually already designed about 80% of this for another project. I am working on a high end squeezebox design with an FPGA, large memory, ethernet "chip" that talks to the FPGA, ultra low jitter clocks and a PCM1704 based DAC circuit (I REALLY like 1704s). The ethernet part is the same XMOS chip used for UAC2 implementations, but XMOS also has a nice network stack for it. I have most of this already done. Digital filters would be implemented in the FPGA. Tony's concept could use most of this as is, I would have to add relays to the power for the XMOS chip and a relay on the cable connection. I would have to increase the memory significantly, but that is not too hard, DDR memory chips are designed to be used in large arrays. I already have the DDR interface in the FPGA so this is mainly a board layout challenge. I already have the digital side and DAC side completely isolated from each other with the low jitter clocks on the DAC side feeding the digital side to clock out the data. It will be two boards with LVDS interface between them with a each board in it's own shielded section of the box. Of course each secction gets it's own separate power supply. (actually 5 separate power supplies) The concept of having the computer perform the reconstruction filter and sending the resulting data to the memory is an interesting one. I did some experimentation on that last night. I already have a DAC that has an FPGA driving the 1704 (with reclocking via the local clock of course) in which I can implement my own digital filter or send the data through direct. I tried applying a software filter on the file and sending it to the DAC at 192, this worked very well, vastly better sounding than hardware filters such as the DF1704. I was not able to tell for sure if the software filter sounded better than the filter in the FPGA, but I know for sure they were different filters, I was just trying a couple upsampling routines in some wave editors I had. So the concept sounds viable. Of course the user interface on this box is going to be very primitive. I'm thinking of a play, pause, restart and connect buttons. You use the computer to choose a playlist, do any filtering etc, then download it into memory, then the box disconnects from the network and runs stand alone playing the playlist. You can start and stop but that is about it. If you want to change the playlist you have to do that on the computer, reconnect the box to the network and download the data. With a giga-bit ethernet connection the download won't take TOO long, but you do have to live with it. Anybody interested in actually doing this? I don't have the cash to actually build this right now, but I can do all the design and prototype building if I can get some others to invest in it. I'll let someone else figure out how the computer software side of this is going to work. Whether it's a new program or a plugin to something else we can discuss. Any thoughts? John S. |
RE: Tony's Player, posted on July 14, 2012 at 02:52:38 | |
Posts: 2426
Joined: July 11, 2007 |
John. I'd approach the thing differently. What we need is a DAC with the best possible signal recovery/restauration on it's input. It should be an external standalone device. The Transport side should become kind of irrelevant. It shouldn't matter If I use my PC,SBT,iPad,Android as long as the signal is bit perfect. Working on the transport side is much too complex. What IMO matters is a device which can talk to all those commonly used devices and comes up with the same SQ from all of them. When is comes to usability ( two button control !?!?!): I've been presenting my stuff feeding an Anagram DAC on a DIY-fair. We compared it to ec-designs SD-player. The majority in the room (all audiophile nuts - including me) prefered the iPeng control of the simplistic SD player control. The differences in SQ were subtle. The differences in operating the devices were unacceptable to all of them. I think spending more work on SB kind of projects is waste of time. Buy a Rasberry PI at 35$ that runs squeezeplayer at up to 192khz and hook up a USB DAC to it. BTW: Have you checked out "IANcanada"'s reclocker project @ DIY-audio- digital section?? Perhaps a nice building block to make a better DAC. Good luck. ----------------------------------------------------------------- blog latest >> The Audio Streaming Series - tuning kit pCP |
RE: Rasberry PI at 35$ , posted on July 14, 2012 at 04:07:51 | |
Posts: 2426
Joined: July 11, 2007 |
Yep. I know. They do prepare currently for mass production. You don't need a box. You can easily put it in your DAC box. It's credit card format. There's another quite new very interesting 4-core, 1,4GHz, 1GB RAM device at 129$. Hardkernel Odroid-X. The Samsung SIII is based on the same stuff. Ubuntu 12.0.4 runs on it. And you can use it even for DSP work and/or video. You can also plan for RAM playback. Cheers ----------------------------------------------------------------- blog latest >> The Audio Streaming Series - tuning kit pCP |
Recurses! Foiled Again!!! (nt), posted on July 14, 2012 at 08:16:32 | |
Posts: 144
Location: Hollister, CA Joined: November 20, 2005 |
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perhaps my memory is faulty but, posted on July 14, 2012 at 09:10:06 | |
. I thought you reported a while back that your system sounded better with the thunderbolt drive? . |
Oh Well this thread is dead before it even started....Half baked Ideas go nowhere..nt, posted on July 15, 2012 at 15:44:13 | |
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John, I think it's called PlayGo, posted on July 16, 2012 at 12:55:01 | |
Posts: 1846
Joined: March 31, 2008 |
Having DLNA might solve a lot of interface problems:
The Well Tempered Computer |
Interesting - how about MEASUREMENTS?, posted on July 22, 2012 at 17:30:02 | |
Posts: 821
Joined: January 18, 2002 |
Fascinating idea John and I hope someone offers to help with the building of such a device... Would make a great "Extreme Ultimate Music Transport / DAC" article! However, the operation of such a device as you've alluded to will be very "user-unfriendly" in terms of convenience. For that price, just how much audible difference do you hope this device will deliver compared to an excellent DAC like say a Weiss? Although I don't think I could ever live with the inconvenience of a "primitive" interface, objectively, what do you think such a device will accomplish? How much jitter reduction do you expect and how would you measure this? Do you think the extreme isolation will lower the noise floor audibly? Will the frequency response change whatsoever; any more "flat" compared to a good orthodox DAC design? I think it would be awesome to have such a device built and experience the state-of-the-art sound; but I think it'd be just as interesting academically to get some measurements out of the beast and see the results of some blind testing to see if anyone notices :-) ------- Archimago's Musings: A 'more objective' audiophile blog. |
Don't Hold Your Breath...., posted on September 27, 2012 at 14:03:41 | |
The DIY spirit is not alive here. Plenty of talk and expert opinion though. |