Speed Racer Posted June 8, 2017 Share Posted June 8, 2017 12 minutes ago, Teresa said: I agree with Speed Racer perhaps new DACs should move away from USB. Maybe something like Thunderbolt. Does Thunderbolt have the same issue as USB? I don't know and I need to get educated on that. I still think an Ethernet to AES/EBU or S/PDIF coax connection is the way to go based on what we have today. That can be an Ethernet to AES/EBU DDC or a low noise audio streamer/end point on Ethernet outputting AES/EBU or S/PDIF coax. This eliminates the sinkhole that is USB.... Link to comment
Popular Post Miska Posted June 8, 2017 Popular Post Share Posted June 8, 2017 5 hours ago, Teresa said: I agree with Speed Racer perhaps new DACs should move away from USB. Maybe something like Thunderbolt. Ethernet? plissken, 4est and AudGuy 3 Signalyst - Developer of HQPlayer Pulse & Fidelity - Software Defined Amplifiers Link to comment
mansr Posted June 8, 2017 Share Posted June 8, 2017 3 hours ago, Miska said: Ethernet? Ethernet using what protocol? Unless you're using a dedicated link, you need to deal with address assignment, device discovery, etc before you can even think about sending audio data. But you obviously know all that. Link to comment
Jud Posted June 8, 2017 Share Posted June 8, 2017 12 hours ago, jabbr said: Instead of a protocol analyzer I'd invest in: 1: (generally) a good high speed oscilloscope (can do eye patterns) 2: high resolution spectrum analyzer 3: vector signal analyzer Re number 2, was poking around and ran across this: http://www.specs-zurich.com/en/high-resolution-oscilloscope-and-spectrum-analyzer-_content---1--1548--259.html I noticed it features a "1 MS/s sampling rate." So how, if at all, does it affect measurements we want to do if the measuring device is sampling at a lower rate than some of the clock rates we're dealing with? Use this tool only for measurements where that isn't a factor, I assume? (I'm supposing the answer to that may well be "Yes, fool." ) So what sorts of audio system measurements would number 2 and number 3 be useful for? One never knows, do one? - Fats Waller The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein Computer, Audirvana -> optical Ethernet to Fitlet3 -> Fibbr Alpha Optical USB -> iFi NEO iDSD DAC -> Apollon Audio 1ET400A Mini (Purifi based) -> Vandersteen 3A Signature. Link to comment
jabbr Posted June 8, 2017 Share Posted June 8, 2017 56 minutes ago, mansr said: Ethernet using what protocol? Unless you're using a dedicated link, you need to deal with address assignment, device discovery, etc before you can even think about sending audio data. But you obviously know all that. The Ethernet->I2S/DSD interfaces will generally run ARM perhaps with an associated FPGA (e.g. Zynq), but not necessarily (e.g. rPi). Or another SoC such as ClearFog (Armada). Lots of options. Each DAC needs an ALSA driver. A remote network protocol such as netJACK->ALSA or @Miskas NAA would connect. The interface would run some version of Linux, typically. Presumably one could do the same type of thing for Windows IoT. Custom room treatments for headphone users. Link to comment
plissken Posted June 8, 2017 Author Share Posted June 8, 2017 1 hour ago, mansr said: Ethernet using what protocol? Unless you're using a dedicated link, you need to deal with address assignment, device discovery, etc before you can even think about sending audio data. But you obviously know all that. Vendors can solve that by just not being typical developers in that regard: 1. Statically assign a default IP Address. Sonic Wall and others do this with their firewalls. Use something like 172.16.100.254/24 2. Have a simple web server for management of the IP stack built in. If you can get this in a $100 Printer/Copier/Fax you can get this in a $500/$1000/$5000 DAC. Post a 5 minute video on how to configure your computer. I have to take Auralic to task for a hands down stupid implementation. Link to comment
kilroy Posted June 8, 2017 Share Posted June 8, 2017 13 hours ago, Speed Racer said: Why would we want to invest in this? If we were smart, we would be looking for ways to get away from USB. That's the future anyway. Explain how it's the future. What's around the corner we'll all be using in a year or three. Link to comment
mansr Posted June 8, 2017 Share Posted June 8, 2017 7 minutes ago, Jud said: Re number 2, was poking around and ran across this: http://www.specs-zurich.com/en/high-resolution-oscilloscope-and-spectrum-analyzer-_content---1--1548--259.html I noticed it features a "1 MS/s sampling rate." So how, if at all, does it affect measurements we want to do if the measuring device is sampling at a lower rate than some of the clock rates we're dealing with? Use this tool only for measurements where that isn't a factor, I assume? (I'm supposing the answer to that may well be "Yes, fool." ) It also has only 18-bit resolution and 100 kHz analogue bandwidth. This is just barely enough for audio signals. If you want to measure digital signals, look elsewhere. For analogue audio purposes, you might as well use a $500 recording interface such as those from Focusrite, RME, and Tascam. 7 minutes ago, Jud said: So what sorts of audio system measurements would number 2 and number 3 be useful for? I don't know what you'd use a vector signal analyser for here. Those are typically used to study complex modulations in RF signals. Jud 1 Link to comment
The Computer Audiophile Posted June 8, 2017 Share Posted June 8, 2017 10 hours ago, Speed Racer said: Does Thunderbolt have the same issue as USB? I don't know and I need to get educated on that. I still think an Ethernet to AES/EBU or S/PDIF coax connection is the way to go based on what we have today. That can be an Ethernet to AES/EBU DDC or a low noise audio streamer/end point on Ethernet outputting AES/EBU or S/PDIF coax. This eliminates the sinkhole that is USB.... The DAC designers I've talked to about Thunderbolt all say it's a terrible interface compared to USB because it's so high speed that the noise is off the charts. Teresa 1 Founder of Audiophile Style | My Audio Systems Link to comment
Popular Post AJ Soundfield Posted June 8, 2017 Popular Post Share Posted June 8, 2017 16 hours ago, Miska said: ...that's why I always prefer sticking to measure the DAC output Crazy talk, but I agree. Should funding include cost of an audiophile power cord for the analyzer, else the results lack resolution and revealingness? plissken, crenca and mav52 3 Link to comment
jabbr Posted June 8, 2017 Share Posted June 8, 2017 39 minutes ago, Jud said: So what sorts of audio system measurements would number 2 and number 3 be useful for? Regarding 1,2 and 3 (scope , spectrum analyzer. vector analyzer) there is overlap among the 3 and each tool is used for different applications or may have specs that are tuned for a specific measurement. (short answer : lots of stuff) a high resolution scope can do eye-patterns for example. Maybe you'd do 4 gsps for 1-2 Ghz resolution but at 8 - 12 bits. : realtime info spectrum analyzer: FFT plots so my old HP 3561a 125 microHz to 100 kHz at 640 micro Gz intervals -- thus also forms part if a really really close in phase noise measurement (using a really good phase comparitor) -- generally great for looking at harmonics : non realtime info vector analyzer: eg HP 89441a -- all in one phase noise much faster & quicker & easier newer packages are digital & have special software modules to automate measurements -- this is less than scratching the surface Custom room treatments for headphone users. Link to comment
mav52 Posted June 8, 2017 Share Posted June 8, 2017 39 minutes ago, AJ Soundfield said: Crazy talk, but I agree. Should funding include cost of an audiophile power cord for the analyzer, else the results lack resolution and revealingness? Crazy talk , yep The Truth Is Out There Link to comment
Popular Post Wavelength Posted June 8, 2017 Popular Post Share Posted June 8, 2017 Ok guys a few things... First Audio Jitter/Phase Noise is measured from 10Hz down. Most jitter analyzers you see like the microsemi is used for communications or other stuff. Good high speed scopes with EYE pattern and differential probes will tell you a lot about USB, Ethernet and other protocols. Still need a 5x scope for that with a lot of storage. Ethernet is a good protocol, not great for streaming but non the less it is isolated and capable at 100Mhz speeds. The controllers are good at 10/100 and some of them Microchip MZ, i.MX6, Renesas RZA1 etc.. are good choices as they have I2S capable outputs. A number of the ARM processors do not have good I2S interfaces. The processors listed above have very good I2S. The other ARM processors do not have good I2S and need to have FPGA's or other logic to lower the I2S jitter. The problem with more powerful processors such as say an A53 which has 10/100/1000 Ethernet is now you have processor noise to deal with. Isolation becomes and issue and expense. Ethernet does require a protocol and even tough there is AVB, in our case the Roon code is probably best. UPnP/DLNA is hit or miss in most setups. I have a Thunderbolt license and designed a few things. I have the v1, v2 development system here chips and so forth. Thunderbolt is basically a wired extension of PCIe. Some companies in the pro industry are basically doing USB and Thunderbolt. They have a USB multiplexer on board and a USB Host controller hooked up the the Thunderbolt bridge and can select one or the other interface and then that goes to usually an ARM processor and or DSP (can be FPGA) to do all their stuff. Is this better? Well you could argue that Thunderbolt could be a more controlled setup and I bet it would be. USB, USB3, USB-C we made USB easy to work with. We created platforms that allowed digital and analog designers easy access to build their products. Full Speed sure is ceiling is pretty low at 32/96 being the max stereo sample rate. High Speed sure is limited to sixteen channels @ 32/192. USB SS is pretty much wide open. The big problem here is isosynchronous is not error correcting. You could create a custom protocol that is error correcting but really with the error rates on a well constructed system being pretty low there really is no need. ~~~ Were at a point in audio were we are moving sideways. The DAC chips really are having enough problems at 384 going to 768 is just silly. So we are giving the customer base different connection options. There will always be ways and products that will better the listening experience. Really I have boxes of shit all the way back to college. Who remembers the sharpie product that you would apply to the outside rim of a CD. Basically the green was suppose to inhibit stray laser bouncing that would effect the receiver and cause less errors. This is a niche market area of high end audio that will never go away. No company can be sure that they get everything perfect in computer audio. They can't because there are too many variables. Some do better than others, that's the way it is. Buying and knowing how to use test equipment is something you should leave to Stereophile. John has spent decades working with Ap, Prism and other companies creating test suites. Buying inside a group to do testing would first require that you totally understand what it is you are testing. Just think of what would happen if you guys did testing and the results were XYZ. Do you think that this would be argued over and over again and really what would that accomplish? Probably nothing... Thanks, Gordon darkless, AudGuy, Superdad and 3 others 6 J. Gordon Rankin Wavelength Audio http://www.usbdacs.com/ http://www.wavelengthaudio.com/ http://www.guitar-engines.com/ Link to comment
jabbr Posted June 8, 2017 Share Posted June 8, 2017 59 minutes ago, The Computer Audiophile said: The DAC designers I've talked to about Thunderbolt all say it's a terrible interface compared to USB because it's so high speed that the noise is off the charts. That and other reasons ! Not widely integrated into motherboards so forget about SoCs (cpus with integrated I/O etc) No reason to think it would be better than Ethernet Custom room treatments for headphone users. Link to comment
AJ Soundfield Posted June 8, 2017 Share Posted June 8, 2017 6 minutes ago, Wavelength said: Full Speed sure is ceiling is pretty low at 32/96 being the max stereo sample rate. High Speed sure is limited to sixteen channels @ 32/192. Could you define "low" and "limited" in terms of audio? Most "high end" audio rigs are 2ch. Just think of what would happen if you guys did testing and the results were XYZ. Do you think that this would be argued over and over again and really what would that accomplish? Probably nothing... Unless the point is arguing? Link to comment
The Computer Audiophile Posted June 8, 2017 Share Posted June 8, 2017 Thanks for the info @Wavelength Founder of Audiophile Style | My Audio Systems Link to comment
jabbr Posted June 8, 2017 Share Posted June 8, 2017 @Wavelength -- hey neighbor ! < 10 Hz phase error -- yep hence HP 3048a ... need to resurrect a 486 slow enough to run the software !! Zynq can do Ethernet and I2S both in FPGA side and logic/drivers in ARM side -- so equal facility with USB and SGMii (SFP -> fiber) ... better phase error than eg Marvel Armada Custom room treatments for headphone users. Link to comment
Popular Post Wavelength Posted June 8, 2017 Popular Post Share Posted June 8, 2017 Ok, Quote Not widely integrated into motherboards so forget about SoCs (cpus with integrated I/O etc Some of the top end SOC's have PCIe and SATA. I have worked with the ARMADA 7040 which has both. Quote Zynq can do Ethernet and I2S both in FPGA side and logic/drivers in ARM side -- so equal facility with USB and SGMii (SFP -> fiber) ... better phase error than eg Marvel Armada The larger ARM chips like the Armada, double digit ARM like the A53 the 64 bit units and so forth are great for network bridges, NAS drives and stuff like that. They are not very good at Audio. Doing Ethernet in an FPGA is not something I would try. I bet if they are using an ARM processor on the board the Ethernet is probably going there. Quote Could you define "low" and "limited" in terms of audio? Most "high end" audio rigs are 2ch. As I said low in terms of sample rate. Full Speed is limited to 32/96 stereo or 2ch. High Speed USB is limited to 16 channels at 32/192. Or 8 stereo channels at 32/192 or higher rates with less channels. 4 stereo channels at 32/384 or two stereo channels (4 ports) at 32/786. But remember with higher sample rates, means more data being pushed through which does equate to more USB errors. Thanks, Gordon Teresa and Jud 2 J. Gordon Rankin Wavelength Audio http://www.usbdacs.com/ http://www.wavelengthaudio.com/ http://www.guitar-engines.com/ Link to comment
Wavelength Posted June 8, 2017 Share Posted June 8, 2017 1 hour ago, jabbr said: Regarding 1,2 and 3 (scope , spectrum analyzer. vector analyzer) there is overlap among the 3 and each tool is used for different applications or may have specs that are tuned for a specific measurement. (short answer : lots of stuff) a high resolution scope can do eye-patterns for example. Maybe you'd do 4 gsps for 1-2 Ghz resolution but at 8 - 12 bits. : realtime info spectrum analyzer: FFT plots so my old HP 3561a 125 microHz to 100 kHz at 640 micro Gz intervals -- thus also forms part if a really really close in phase noise measurement (using a really good phase comparitor) -- generally great for looking at harmonics : non realtime info vector analyzer: eg HP 89441a -- all in one phase noise much faster & quicker & easier newer packages are digital & have special software modules to automate measurements -- this is less than scratching the surface I have a mint 3561A yea with the bubble memory. It's a great piece for testing low noise analog stuff. I also have a Stanford SR760 which is a little better. The problem is getting the phase noise into these. I have a Symmetricom phase noise analyzer that we use for testing crystals and oscillators. It's got a custom downloadable FPGA in it and a 10MHZ super low phase noise reference in it. We get good plots to 1Hz with this. Before we had that it was kind of hit and miss using a boat load of reference stuff. Thanks, Gordon Jud 1 J. Gordon Rankin Wavelength Audio http://www.usbdacs.com/ http://www.wavelengthaudio.com/ http://www.guitar-engines.com/ Link to comment
AJ Soundfield Posted June 8, 2017 Share Posted June 8, 2017 9 minutes ago, Wavelength said: As I said low in terms of sample rate. Full Speed is limited to 32/96 stereo or 2ch. I see. So a 48kHz playback upper end is "low" for 2ch audiophiles, many 60-70+. Fascinating. I may have to rethink my supertweeter designs Thanks Gordon Link to comment
crenca Posted June 8, 2017 Share Posted June 8, 2017 2 hours ago, AJ Soundfield said: Crazy talk, but I agree. Should funding include cost of an audiophile power cord for the analyzer, else the results lack resolution and revealingness? Bah!! Hey MQA, if it is not all $voodoo$, show us the math! Link to comment
jabbr Posted June 8, 2017 Share Posted June 8, 2017 2 hours ago, Wavelength said: I have a mint 3561A yea with the bubble memory. It's a great piece for testing low noise analog stuff. I also have a Stanford SR760 which is a little better. The problem is getting the phase noise into these. The HP 11848a is the phase noise interface but no doubt a modern FPGA based device is vastly easier to use. The Stanfords are just a little bit too pricey for me . I scavenge for stuff being given away Custom room treatments for headphone users. Link to comment
jabbr Posted June 8, 2017 Share Posted June 8, 2017 2 hours ago, Wavelength said: Doing Ethernet in an FPGA is not something I would try. I bet if they are using an ARM processor on the board the Ethernet is probably going there. Actually off the shelf nowadays. You can hang a SFP cage on the 3.3v IO lines and run the low level logic in the PL and send the packets to the ARM for the TCP/IP stack. The same clock domain crossing logic is used to send the bits back to the PL for output as DSD and PCM. Custom room treatments for headphone users. Link to comment
Ralf11 Posted June 8, 2017 Share Posted June 8, 2017 23 hours ago, wgscott said: If the product isn't all smoke and mirrors, they would have a 30 day return policy emblazoned on their web page. ;-) I am tempted to 'love' this post too, as I agree with the general direction of the comment, but this is test gear. How often can you return test gear? That is more common for consumer items. I've never seen a mass spectrometer that could be returned for example. Link to comment
Popular Post Miska Posted June 8, 2017 Popular Post Share Posted June 8, 2017 8 hours ago, The Computer Audiophile said: The DAC designers I've talked to about Thunderbolt all say it's a terrible interface compared to USB because it's so high speed that the noise is off the charts. Well, it is pretty much just PCIexpress on a cable. Companies like RME, Lynx and many others have been making sound cards that perform better than many audiophile DACs and sit inside the computer connecting to the PCIe... Focusrite, Universal Audio and many others already have Thunderbolt interfaces for studios. It allows low latency and huge number of channels at the same time. Of course audiophiles can keep worrying about the noise and all that, while not knowing that the music they've been listening to has been recorded using Thunderbolt connected ADC... crenca and Teresa 2 Signalyst - Developer of HQPlayer Pulse & Fidelity - Software Defined Amplifiers Link to comment
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