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JohnSwenson

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  1. Can you guys get together and define what you mean by "longer", and please specify what the length refers to ie "tip to tip" or some other reference. I'm not guaranteeing this will happen soon, I am working VERY hard on the etherREGEN. Things like this just add to the wait time. John S.
  2. JohnSwenson

    It *cannot* just be about 1's and 0's - surely?

    One possibility is actually the cable length. I have measured error rates with different lengths and found that many 3m and longer cables do in fact have significant error rates. As has been mentioned this MAY cause something in the system to be changing state which is responsible for the loudness difference. Or it could be that whatever you are using to measure the volume is getting confused by the dropped packets and what that does to the waveform. Do you have a scope or any way to look at the waveform coming out of the DAC? It would be interesting to see if you are getting any waveform distortion. John S.
  3. Depends on what you mean by "isolation". The Ethernet connection just has data lines, there is no "ground" (unless you are using shielded cable with a metal plug that connects to ground). The issue is leakage flowing through the data lines. For the 4 copper jacks on the "dirty side", there are normal transformers on each port. These provide galvanic isolation between each port, and low impedance leakage isolation. They do not provide high impedance leakage isolation. That is where the "grounding' comes in. The ground connection shunts the high impedance leakage to the safety ground (assuming it is properly connected), bypassing the switch. Remember the SMPS that UpTone provides is already grounded. If you use a non-grounded PS, and don't ground the switch, high impedance leakage going into one of the dirty ports will be coupled to all of them. The "clean" port will always isolate leakage current (both types) from any of the "dirty" ports. John S.
  4. That's only necessary for some existing switches. The leakage shunting will work on all copper ports in any order for the etherREGEN. The components were specifically chosen in order to allow that to happen. John S.
  5. Let's just say that all of the parts can be had from places like Digikey, but we are using them together in ways not normally considered for these components. Unfortunately many of these components are pretty expensive. The synergy between devices simply does not work with less expensive devices. We are not spending LARGE sums to have custom made components, but the ones we do need are not cheap. John S.
  6. First off some clarifications about the differences between SMPS and DC/DC switching regulators. An SMPS plugs into the mains, it chops up the mains voltage into high frequency pulses, feeds that through a transformer, on the other side rectifies the high frequency pulses coming from the transformer, filters it into fairly clean DC, measures the DC and sends a feedback signal through another transformer or optical coupler to the front end to modify the pulse width so the DC output voltage is correct. These have low level high frequency noise on the output AND input, but also have both high impedance and low impedance leakage current from the AC line to the DC output. This is what causes a lot of the issues with SMPS, NOT the high frequency noise on the output. A DC/DC converter does NOT connect to the AC mains, its input is DC from some other power supply. Their purpose is to convert one DC voltage to another (either up or down). Their big advantage over a linear regulator is that the POWER is constant, not the current. With a linear regulator the current going in is the same as coming out. With a switching DC/DC converter the current going in depends on the power on the output. Say for example you have 10V coming in and you want 1 volt coming out. If your load takes 1 amp, a linear regulator will need 10V at one amp on the input, that means 9 watts of power are dissipated in the regulator (ie a BIG heat sink). With a DC/DC converter the power on the output is 1 watt (1V x 1A = 1W). So on the input it takes 1W / 10V = 0.1A. Now in reality the converters are not 100% efficient, maybe say 85%, so the power needed by the input will be a little higher, in this case 1.15W, so the input current is 0.15A. This means the DC/DC converter is dissipating 0.15W instead of 9W, 60 times lower! The DC/DC converter DOES have high frequency output noise, but it is usually at a much higher frequency than an SMPS. SMPS usually run at 40KHz to 70KH, DC/DC converters usually run at 500KHz to 1MHz. This is a big difference. At 60KHz a filter is fairly large and costs some money. The same amount of attenuation at 1MHz takes very small very inexpensive components. The result is that IF you use a filter on the output, you can get a huge attenuation for very small board space and cost when using a DC/DC converter. Of course you DO have to spring for the filter, very cost constrained devices usually don't. The DC/DC converter does NOT create any extra leakage since it is not connected to the mains. Whatever leakage exists from the power supply is still there, the DC/DC converter does not attenuate it, but it doesn't increase it either. With a DC/DC converter you can always add a linear regulator after the converter, good ones can decrease the high frequency noise from the converter by 80-100dB. So a combination of the filter AND a linear regulator reduces the high frequency output to much less than the inherent noise of the regulator, it is essentially gone. So if properly implemented a DC/DC converter does not have any down side and it drastically reduces the amount of heat that has to be dissipated. All that said, very low cost devices are not going to go to any of those measures, they are going to use a cheap DC/DC converter and and feed the output directly to the chips. On the etherRegen, there ARE a few DC/DC converters in the design. But they have the good filters and very good linear regulators after the converter. I have tried using some very sensitive test equipment and have not seen ANY sign of the DC/DC converter on the final DC. One other issue with DC/DC converters is EMI, the converter can radiate high frequency signals that can be picked up by other traces on the board. I am using some very special converters that have extremely low EMI, I can JUST barely measure it, where I can measure strong emission from other converters. Even though the EMI is so low I am laying out the board so that pickup by other signals is quite small. Again I have not been able to see any hint of this in prototypes. The whole reason for using the DC/DC converters is to drastically cut down on the amount of heat the box has to dissipate, AND the high cost of getting the heat from the regulators TO the heatsinks. I'm quite confidant that this is done in such a way that there will be NO impact of this on the operation of the device. John S.
  7. JohnSwenson

    Faith-Based Sound Issue..

    Hi K-Man, I've been doing church sound for a very long time (over 40 years) and am well versed in the issues you are talking about. I have used an X-32 extensively, if you would like to ask questions or share stuff, PM me and I'll be glad to help. A few thoughts on your situation: A worship leader has no business whatsoever setting house sound levels during a service. What he hears on stage is VERY different than what the congregation hears. If he insists that he is the ONLY person that can get the sound right during a service (while leading the service), then he is an arrogant jerk and and should not be a Christian worship leader. Try and find a nicer way to say that! In many cases I have found that what you are experiencing is actually caused by an improperly tuned sound system, the results are that people cannot hear what they want to hear, so they insist it be turned up, but that usually just makes things worse. The problem is the sound system is not allowing people to hear distinctions between instruments, voices etc, ie it is a thick gooey mess they are hearing. Once the sound is cleaned up significantly and everyone can hear a wonderfully clear sound there is no need for the excessive loudness and they are perfectly fine with a lower level. Even the "rocker types". Performer monitoring is a whole different can of worms. The same thing applies there, if the monitors are not clean, the performers insist on a louder level, which just makes it worse. IEMs can help a lot, but again things have to be setup so the performers can clearly hear what they want to hear. Fortunately the X-32 system has a large array of tools for getting this right, getting these setup right for your situation can make a huge difference. I usually try and approach this with the worship leader and pastor as a team effort, explaining that my job is to properly transmit their artistic talents to the congregation. If we work together we can make this happen. So far this has worked. So it is up to you, are you willing to work on tuning your system, I can help you work through that if you are interested. You can either do it without telling anyone you are doing it and see if things improve and the worship leader and pastor will accept a lower level without even knowing it, or let them know up front what you are trying to do. I have seen many times that this approach does work, getting the system tuned properly does in fact get rid of almost all the issues of "too loud" and "too soft". The only real problem after that is overloading hearing aids of people who need them. They are usually set for fairly high gain so the person can hear fairly soft conversations around them. The louder sound from the music (even if clean) can overload the hearing aid. One way we found to deal with that is to have the people use a hearing aid with telecoil, and then use a hearing assistance wireless receiver with a telecoil loop, they don't need to put on headsets etc, the signal gets fed directly into the hearing aid. The mixer can setup a signal that gives a fairly consistent level feed to these devices so it doesn't overload. Or you can forget about all this and leave. But if you want to stay I think it's possible to work things out so everybody is happy. John S.
  8. 100Mbit Ethernet can easily handle 2 channels of DSD512. If you want to do 8 channels of DSD512, forget it, but two is fine. As long as the DSD512 is the only connection going over that interface. You can have all kinds of stuff going over the gigabit connections on the other side, it is just the "clean" connection that is limited to 100Mbit. And yes, it is assumed that the clean port of the etherRegen will be the last device plugged into the player/renderer, hence there should be no over traffic on that connection. John S.
  9. JohnSwenson

    USB audio transmission isn’t bit true

    There actually IS a difference. Music uses isochronous transmission which has NO error correction. Most other forms of data use transmission protocols which DO have error correction, thus transmission errors get corrected so the end user never sees an error. With music there is no correction so transmission errors DO show up at the DAC. Per my previous post transmission errors are very rare with shorter cables, but do happen a LOT with longer cables. So while in some sense data is data, how music data gets sent over USB is very different. John S.
  10. JohnSwenson

    USB audio transmission isn’t bit true

    I have done same tests that Gordon did and get similar results. Under some conditions you can get lots of data errors (many per second) with USB audio, under other conditions you can get no errors for days. The biggest correlation I got was with cable length. With a cable greater than 3m you have pretty good chance of getting a large number of errors. Under 2m errors are few and far between (days between errors). Between 2m and 3m is where the fun happens, you can trade off cable length and cable quality. For example with Supra cables you can go with significantly longer cables than cheap cables. In this range hardware has significant impact. For example my SuperMicro motherboard is error free with longer cheap cables than my cheap laptop. I also did a lot of listening to the audio with different error rates on the USB. At low error rates the sound is identical. As error rates increase you start hearing the infamous clicks and pops. If you are getting say a click per minute, the sound quality in between clicks doesn't change. As the clicks come more often they get so annoying its impossible to tell if the sound quality is changing or not. At some point the errors come so often the system just shuts down, it can't handle that many errors. (a 5m cheap cable has a high probability of doing this). So my conclusion was that if you stay with cables less than 2m you can be pretty sure you are essentially error free. These rare bit errors do not seem to cause any sound change (other than a possible click). John S.
  11. JohnSwenson

    SMPS and grounding

    Mains born RF noise IS a separate issue. The leakage I'm talking about is primarily line frequency, 50/60Hz and harmonics. How much of an issue it is and what to do about it are very system dependent. Again no simple generalizations possible. One problem is that several common solutions for RF actually increase leakage loops. At least for me and my my systems it is better NOT to use these attempts at RF attenuation. I haven't spent a lot of effort on RF issues, for me they have been much lower importance than leakage. John S.
  12. JohnSwenson

    SMPS and grounding

    Partially. Connecting AC safety ground connects the SMPS negative output will connect the negative output to the AC neutral IF as in the US the neutral is connected to the safety ground. This CAN lead to a traditional ground loop and or a leakage loop. Remeber the two loop types: Traditional ground loop: caused by current flowing through the AC wires magnetically coupling to the safety ground. Longer wires generally have greater potential developed this way. Very small difference if everything plugged into a single power strip. Large difference if say preamp and poweramp plugged into sockets at opposite end of large room. Leakage loop: leakage that goes AC, through power supply, through various wires either to safety ground or another power supply. A strategically placed connection to safety ground can prevent a leakage loop from going through a audio devices power supply. The impedance of the safety ground connection is much lower than going through another power supply. The result is there is NO simple "always do it this way" approach. You need to take into account how the the AC wiring is done and how you want the system setup. A system where EVERYTHING is connected to the saftey ground in a single power strip can possibly be the best system. All leakage currents wind up being shunted through the single safetey ground. But add just one NON-grounded supply (say a computer) and all bets are off. As is common in many systems today where you have some boxes grounded and some not you really have to sweat the details and figure out where leakage currents are going and work to prevent them from flowing through the most sensitive points (DACs, preamps). John S.
  13. LMS definitely does NOT use HTTP for sending audio data. SlimProto is actually a very simple protocol and is used for sending the audio data. It supports several "native" formats, which are essentially the audio data in common file formats. (WAV, FLAC, MP3, probably a couple more). The rest of the file formats get converted in the server into one of these. The only thing HTTP is used for is talking to the web server GUI that is part of the server. If you are using any of the other controllers (hardware or software) HTTP is not used at all. LMS also uses UDP multicast to coordinate servers, controllers and players finding each other on a network, but after they are found the rest happens through SlimProto. John S.
  14. JohnSwenson

    SMPS and grounding

    If the grounded SMPS is powering an LPS-1.2 (or -1), it will provide isolation for what is left over on the output of the SMPS. If you are powering network equipment the builtin transformer will also do a good job of blocking what is left. The issue is if you are powering something else (such as a renderer, preamp, poweramp etc) where the ground of the SMPS MAY provide a path for a leakage loop that you don't want. It may not provide such a loop, it is going to be very situation specific. John S.
  15. The LPS-1.2 already has two LT3045 regulators in parallel. It is theoretically possible to use the same techniques to parallel 2 boxes together, BUT that is a different design. It takes a different board and several connections between boxes, it is NOT trivial. The existing LPS-1.2 design is VERY carefully tuned, doing anything to the design is guaranteed to break SOMETHING, it would take several prototypes and months of development work to get right. I do NOT want to do that. I want to focus on the new developments we are working on now, any modifications to existing designs are just going to slow down the new developments and I really don't want to do that. John S.
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