On Wed, January 23, 2013 12:20 pm, Joe Hartley wrote: 44.1k, it would be likely that it would not be as good as 48k. Just that a good 48k setup is much easier/cheaper than 44.1k unless the 44.1k is band limited to 18khz audio pass band or so. I have a Delta 66 (like a 1010 with fewer channels) and from what I have read about the quality of parts used and some other design decisions, I would stick with 48k. I have been reading what I can on audio interfaces... I am thinking there are very few good ones. I am thinking that some parts of the system are vastly over priced like ADAT and MADI interfaces, both of which seem to cost about 10X (at least) what they should cost... like how come a Gb NIC is well under $100 and MADI PCI(e) card (100Mb) is $800? Even figuring in scale that is way too much. ADAT (even slower... only 8 channels in one direction at a time) which uses the same parts as s/pdif is $500 (and up)... though I guess one could call that the price of keeping obsolete interfaces around.... right in there with vintage gear :) I would suggest that any PCI(e) card that has ADC/DACs on the card is less than a great quality card, even dealing with sample clock (or power) on the card seems less than optimal. For audio quality, it seems FW, USB and ethernet _could_ give better results if designed right. -- Len Ovens www.OvenWerks.net

On Wed, Jan 23, 2013 at 5:10 PM, Len Ovens <len(a)ovenwerks.net> wrote: Gb NIC sales: in the millions MADI PCI(e) card sales: low thousands if you are lucky, hundreds if not results if designed right. none of them live "on the bus" the way a PCI card can. all of them are subject to a separate clock, in addition to the audio sample clock and the PCI bus clock (which is so high a frequency as to be mostly irrelevant).

On Wed, 2013-01-23 at 19:14 -0600, Charles Z Henry wrote: Power supplies don't have that much impact. The capacitors of very good overdone audio gear power supplies will dry out and then they are as all the other power supplies. Most of the people who claim that they need overdone power supplies don't replace those capacitors, since they don't realize that the very good power supplies became averaged power supplies. Everything near to a computer, that is able to do it, will receive electric smog, so it's very likely that there is some "digital" noise received by gear connected to PCI(e) cards. OTOH ADAT cables can't receive this electric smog ;). Regards, Ralf

On Wed, January 23, 2013 6:31 pm, Paul Davis wrote: Yes... Building a general purpose computer from the ground up is a lot of work. Not only are you trying to make it work with whatever os and applications are out there but whatever other (badly designed) peripherals are around. Then you have to redesign it ever 6 months or yearly anyway to keep up with whatever is new. With a network/firewire/USB box, things are more static. If a network audio interface had been designed 10 years ago with only 2 i/o at 10M. It would still work today. There can be control of what is in that box... to the last diode and every part placement can be done for audio. Extra shielding is possible. So yes, an external audio box is in effect it's own little computer, but it only does one thing and it makes sense to take care of the audio. It doesn't have to have the latest processor or run the newest version OS. Have you ever opened a $15 network switch? 3 main chips, Arm cpu, multi-ethernet and memory.... hmm, all the stuff needed to make an ethernet to MADI interface. Just change the rom and add the right drivers/plugs for the MADI end. The only problem is the cost of the MADI stuff to plug in. -- Len Ovens www.OvenWerks.net

On Wed, January 23, 2013 11:53 pm, Florian Faber wrote: MADI (or ADAT) are as you say, audio transport protocols. For that purpose they are fine, and it seems come for free... or if they don't come for free, the ADC/DAC does. (There seem to be a number of FW/USB Audio IFs that have not only have 8 channels of audio in and out of the computer, but also ADAT i/o... all for the same price as a PCI(e) ADAT only card) Both MADI and ADAT make sense if they are used as a transport medium. I think however, when they are used as a computer interface method they stop making sense. There is a digital snake available (Black Mamba) that uses cat5 cable to join the ends and the ethernet protocol to transfer data. It sends sync over the same cable just the same as other digital audio transports. Because it is layered on top of the net, things are a bit easier to see. It is very hard to get stable sync out the second end and takes a lot of CPU time to do so. Someone has used it in this manner (look up jack mamba with google) and was able to build a jack backend that would talk with it. It used a lot of CPU and it was hard to get a low jitter sync, but in case of the use transport was a major part of the need and so the cpu load was considered acceptable. I think if one computer was dedicated to act as an end of the transport and deal with just the sync and data, the cpu load would be less... or not really matter (it wouldn't matter because it would be constant load as audio lines don't change in load for transport) A second Ethernet connection could go from that box to the computer that was generating signal or recording it. That second link does not have to have sample sync as it just sends 32 or 64 sample packets that are reasonably in time and so the cpu load would be less. Also, the general running of the computer would have less impact on the audio. What I am trying to say, is that transport protocols are not the best thing for computer interface use. I think sync should be totally external to the computer box (though it may/will have it's own dedicated computer). I am not sure that ethernet is the best thing either, but, it is available, cheap, and easy to hack. Netjack does give a usable interface protocol that spans OSs and (so far) I have found it to be stable. I think though the future is in USB3 (unless something else shows up real quick) as it effectively brings the PCIe bus outside of the computer case. The problem in the past with the PCI bus has been it's flexibility. Each audio card was interfaced to the PCI bus in a different manner and so each had a different driver. AC97 and HDA are attempts standardize the audio interface, but really USB1.1 and USB2.0 audio standards are a bigger step in the right direction than they appear (from looking at Linux support for these devices). It might be interesting to use USB3 with the HDA chipset and a good set of ADC/DACs on top of that. I don't know how much intelligence would be needed in such a box.... Or if it would just work with the HDA driver. Just a note on external sync/clock. The TV stations have been doing it for years, Master sync with failover to hot backup goes to every video source in the building (Our sync was colour black). Cable lengths (includes the length from the video source to the switcher as well) were all the same (or had delays to look that way) to make things line up. The problems with jitter from long cables don't go away from adding sync to the computer interface, they just get worse. Learning to deal with external sync is the answer. -- Len Ovens www.OvenWerks.net

On Thu, January 24, 2013 5:43 pm, Fons Adriaensen wrote: Our on air was 2" machines. 5 of them. A very busy place during commercial breaks. For out of station feeds we had a (at the time very expensive) frame store unit for sync. And the frame which is actually two vertical scans... at least over here in NTSC land. (NTSC = Never Twice the Same Colour) Yes for audio (MADI, ADAT, AES3 or whatever else) phase is not the problem it once was for video. I would imagine the video world has added frame store to all the inputs of the switchers by now. This is the difference from video. Video can actually be somewhat out frequency wise as the frame store can "cheat" during the V retrace to keep things aligned. Audio can't do that, it has to be the same frequency (if not phase) or there are artifacts. -- Len Ovens www.OvenWerks.net

On Fri, Jan 25, 2013 at 06:44:31AM -0800, Len Ovens wrote: Know that :-) We had Ampexes on-air, and RCAs in the editing suites. Those were really lovely machines. All moving parts were controlled by pneumatic actuators, it was phssst, pfff, pssssst all the time while editing. Below the actual tape deck there was something like a cubic meter of electronics. For slow motion playback (mainly used for soccer) there was an analog hard disk recorder. The disk was around 40cm diameter and the whole thing was packaged in a glass case, you could see the heads moving. Twice that (8 fields, 4 frames) for PAL... Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow)

On Fri, January 25, 2013 11:14 am, Ralf Mardorf wrote: Pictures opposite to captions I think. The tape machine looks 1 inch-ish to me. Too big for 3/4 inch. (I have seen 3/4 inch open reel) You have to realize though that my experience is all North American, there may be standards I never met. I was surprised at the large number of different PAL standards in the link you gave for that. We touched on both PAL and SECAM in school, but more of an awareness that NTSC was not the only thing in the world than any real study of them. -- Len Ovens www.OvenWerks.net

On Sat, January 26, 2013 1:41 am, Ralf Mardorf wrote: The audio carriers are at different frequency offset from the main carrier... depending on the type of PAL (maybe NTSC too, but there are only two countries I can receive from and our standards are the same) SO there may even be some sources where you get no audio. South America has a PAL/NTSC mix, but the PAL is 60hz so it sort of works no matter which receiver you use. (this probably has something to do with why PAL is more popular than SECAM) It was interesting to find out the the same company now owns all three companies that developed the three standards. -- Len Ovens www.OvenWerks.net

On Sat, January 26, 2013 7:26 am, Ralf Mardorf wrote: "PAL was developed by Walter Bruch at Telefunken in Germany.... Telefunken was later bought by the French electronics manufacturer Thomson. Thomson also bought the Compagnie Générale de Télévision where Henri de France developed SECAM, the first European Standard for colour television. Thomson, now called Technicolor SA, also owns the RCA brand and licenses it to other companies; Radio Corporation of America, the originator of that brand, created the NTSC colour TV standard before Thomson became involved." -> from the PAL wiki page. Technicolor owns them all it seems. -- Len Ovens www.OvenWerks.net

On Fri, Jan 25, 2013 at 05:44:32PM -0800, Len Ovens wrote: Word clock only at 48 kHz seems to be a limitation of some particular equipment. It's not clear to me why things should be that way, I can't see a good technical reason for it. AES3 inputs (at least the balanced ones) are rare or semi-pro equipment anyway. Those that have them will be capable of syncing to them, the inputs would be useless otherwise. Syncing to AES may have some advantages as you sync to the data clock which has a much higher frequency than the sample rate. The inverse, regenerating a higher frequency from a lower one, is usually a bad idea, phase noise is mutiplied by the square of the ratio. I don't think there is a 'standard practice' for audio clock distribution, it will very much depend on the nature of the installation. If there's anything video in house as well the primary source is likely to be video, with audio derived from it. I a large facility with many studios the system will be layered - a GPS driven master with an atomic standard as backup driving a second level master generator in each studio. In such a case the signal between the primary and secondaries could be video or just 1, 5, or 10 MHz if no video sync is needed. A lot of master clocks only provide word clock, these tend to be the 'audiophile' ones used to 'make the sound more transparent' or some such nonsense. Pro equipment will always have AES3 outputs in addition to word clock. A few years ago that could have made sense as there were few MADI routers. But e.g. <http://www.directout.eu/en/products/m.1k2.html> will allow per channel routing between 16 MADI ins and outs. Of course a wall of AES3 connectors looks cool... In practice the choice may be driven by any existing wiring and in-house standards if e.g. a studio is upgraded. Probably yes, AES3 (known as AES/EBU here) surely is free. AES 3 allows unbalanced connections using coax and BNC, this may be a good option for installations that have existing video wiring. But if the connector is XLR the signal MUST be transformer balanced. S/PDIF pro is a variation of the consumer S/PDIF format, some of the extra bits take another meaning. This is also the AES3 format. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow)

On Sat, Jan 26, 2013 at 09:08:40AM -0800, Len Ovens wrote: Video and audio would be derived from a common source, so that any video pull-up/down is also applied to the audio sample rate. Frequency standards (GPS, atomic) are not application specific and usually provide 10 MHz (1 and 5 MHz are also used but less popular). All serious laboratory measurement equipment (oscillators, frequency counters, spectrum analysers, digital scopes, ...) accepts 10 MHz as an external reference, as does most RF equipment. Satellite ground stations usually derive the hundreds of frequencies they need from a single 10 MHz reference, etc. It's an industry standard. Deriving e.g. 48 kHz from 10 MHz is no more difficult or less accurate than using an exact multiple. Professional A/V master clocks will accept 10 MHz as one of the possible references. AFAIK there is no license fee for using MADI. The AES wants your credit card for *everything*, even for papers published 40 years ago ($25 for non-members, for a download). Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow)