Sonic Solutions 'Medianet' was one. Film industry (Hollywood) and some bigger mastering houses used it.
http://www.digitalprosound.com/Htm/TechStuff/May/BitstreamMix.htm
It depends, of course, on your definition of 'widely deployed'
(I'm still using it now and then, btw.)
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Sonic Solutions 'Medianet' was one. Film industry (Hollywood) and some bigger mastering houses used it.
http://www.digitalprosound.com/Htm/TechStuff/May/BitstreamMix.htm
It depends, of course, on your definition of 'widely deployed'
(I'm still using it now and then, btw.)
In the early days before ethernet switches were developed local nets of up to 25 or so computers were bridged to other nets by dedicated computers. Really could get slow from collisions and quite simply lack of bandwidth. But you had to start from somewhere.
Now for a bit of new old stuff. I am determined to finish my power supply article/book before the end of the year.
I just redid my diode switching measurements and here is the plot.
It shows the current into the power supply diode bridge. You can see the switch on, the rise in current, tapering off, the noisy switch off spike and even the line noise coming in while the diode is conducting. This was done with a small ferrite core being used for the current transformer.
I just redid my diode switching measurements and here is the plot.
It shows the current into the power supply diode bridge. You can see the switch on, the rise in current, tapering off, the noisy switch off spike and even the line noise coming in while the diode is conducting. This was done with a small ferrite core being used for the current transformer.
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"The eye was in the thumb, looking at Cain" (©Bible)
The eye of God, or those who think they are.... ;-)
Got, though it is subtle. The tested preamp is opamp + BUF634, gain 2x
1) OPA627+BUF634
2) OP27+BUF634
See test signal (Y scale calibrated) and measurement of OP27 and OPA627 versions (Y scale relative, but same for both versions). There is a difference tone cluster in the OP27 version spectrum, the cluster reveals instability of one of the oscillators. The OPA627 version is free of difference tones.
Behind the preamp there is a 15kHz double RC filter to protect soundcard input from HF frequencies. Without that filter, the soundcard makes its own intermodulation products.
Should be noted that at the preamp input there is a cascade of two RC filters, 680R+68pF and 1k+330pF.
1) OPA627+BUF634
2) OP27+BUF634
See test signal (Y scale calibrated) and measurement of OP27 and OPA627 versions (Y scale relative, but same for both versions). There is a difference tone cluster in the OP27 version spectrum, the cluster reveals instability of one of the oscillators. The OPA627 version is free of difference tones.
Behind the preamp there is a 15kHz double RC filter to protect soundcard input from HF frequencies. Without that filter, the soundcard makes its own intermodulation products.
Should be noted that at the preamp input there is a cascade of two RC filters, 680R+68pF and 1k+330pF.
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That supports the notion that FET inputs (such as in the OP627) are much less susceptible to HF IM compared to bipolars, which has been my experience as well. And the OP27 is a pretty decent bipolar. I suspect if you were to try a (bipolar) part with considerably lower input stage current you could get a good deal more energy at the difference frequency.
A consultant who did the clean-sheet-of-paper designs of automotive amps for Harman migrated to exclusively-JFET-input amps after a while, as the customers got more and more picky about susceptibility to RF, and while the RF environment got worse and worse.
Sonic Solutions 'Medianet' was one. Film industry (Hollywood) and some bigger mastering houses used it.
http://www.digitalprosound.com/Htm/TechStuff/May/BitstreamMix.htm
It depends, of course, on your definition of 'widely deployed'
(I'm still using it now and then, btw.)
Interesting, I never heard of it (not surprisingly). The article is 15 years old and a bit confused in spots. File locking and access is not properly part of a LAN protocol, but an OS or application issue. It sounds like Medianet was more of a Netwrok Operating System, like NetWare but optimized for media files. Like NetWare I assume they could later leverage better physical layer protocols to deliver more raw performance. QoS is now everywhere but a little higher up the stack, and IPv6 should make it even more ubiquitous.
Thanks for the link.
My intention is to use the actual HF signal which is right after the DAC' output and run it to an amplifier and see how the filtered vs unfiltered affects any audio thd/IM. That HF is well within the band width of most audio PA amps. Also, same with HF thru wideband amp to tweeter and if the tweeter distortion changes.
Now that everyone knows the levels and freq of the HF, as shown on the spectrum/network analyzer, those with the test equipment can also work on it and not wait for me.
THx-RNMarsh
Now that everyone knows the levels and freq of the HF, as shown on the spectrum/network analyzer, those with the test equipment can also work on it and not wait for me.
THx-RNMarsh
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I tried the method with "real HF noise", without success. No result, no difference. But the "real HF noise" is quite undefined and hardly repeatable. And it differs with player and with signal as well. There should be a clear HF test method that would be defined and repeatable. The CCIF method at hundreds of kHz is well defined, similar one was proposed by Bob Cordell in the past.
I have also measured one of my power amplifiers with pure 100kHz and 200kHz sine signals. All I get is the same distortion as that of the generator and measuring instrument itself. These measurements are not easy to perform well, if you have a good amplifier. Neither HF CCIF, nor THD 200kHz.
I have also measured one of my power amplifiers with pure 100kHz and 200kHz sine signals. All I get is the same distortion as that of the generator and measuring instrument itself. These measurements are not easy to perform well, if you have a good amplifier. Neither HF CCIF, nor THD 200kHz.
It takes a volt or more typically to get appreciable rectification, biased bipolars are on the edge all the time.
OK. Thats is telling me something about your amplifier. Then it does Not have the rising thd distortion seen in many amps.... it is wide band and low distortion at HF to begin with.
Do you have any amps with the typical rising thd at the high freq. at 20KHz and test one of those for distortion with 50-100KHz HF.
Typical being of this distortion curve shape:
The question I had for myself to answer is the typical GNFB amplifier with its falling nfb and increasing distortion, cause more distortion in audio range when HF is present?
I might not have to do that test myself
THx-RNMarsh
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I have some amps that would fail in a HF test. One of them is a chip amp based on OPA549 (power opamp) with high cross-over distortion and very low slew rate (9V/us). It will perform badly, but what does it say? No one today would design an amplifier the way like OPA549, same as no one would use uA741.
I do have one or two another amplifiers that have THD rising with frequency and with not very low distortion, maybe I'll try one of them.
I do have one or two another amplifiers that have THD rising with frequency and with not very low distortion, maybe I'll try one of them.
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It isnt just old amps... you still see this distortion shape in T&M reviews and in receivers etc. Many do not have low distortion at HF.
Let's contrast those typical curve shapes with a modern amp design that I did for a well known company. This amp barely reaches .005% thd at 250W/8 at 20KHz. Using 80KHz analyzer filter.
I have no HF issues with it or similar.
Then we can go to tweeters.
THx-RNMarsh
,,
Let's contrast those typical curve shapes with a modern amp design that I did for a well known company. This amp barely reaches .005% thd at 250W/8 at 20KHz. Using 80KHz analyzer filter.
I have no HF issues with it or similar.
Then we can go to tweeters.
THx-RNMarsh
,,
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It is also a question of slew rate. IMO if slew rate of the input HF interference signal, considered after passing through input RC filter, multiplied by gain, approaches to or exceeds amplifier's slew rate, then the problem is born and HF will cause issues. In case that amplifier has high enough slew rate an low HF distortion, then output HF noise from digital sources will make no problem.
yes, of course. That amp I refer to - A-P graph from 2003. BTW - this amp also used FET OPS.
View attachment CFA PA.pdf
But that shows prototype at .01% at 20KHz and 250W/8... approaching clipping. At less power, less distortion of course. This was commercialized in 2004... and sold until the Crash in the economy.
Maybe you read some of the things we were talking about on another forum last year about CFA designs.... what i used for decades now. High SR is its trademark. Ultimately this lead to many other design forums. One was by DADOD. His design got prototyped and sent to me. i tested it and listened to it. Even better than my 2003 design !! And, higher SR.
He listened and gave me what my criteria was. His design is an amazing amplifier by any T&M and by listening. But I would still filter the input to this anyway due to tweeter distortion. Or limit use to CD players which do not have the HF in the analog output (but whose are those?).
THx-RNMarsh
View attachment CFA PA.pdf
But that shows prototype at .01% at 20KHz and 250W/8... approaching clipping. At less power, less distortion of course. This was commercialized in 2004... and sold until the Crash in the economy.
Maybe you read some of the things we were talking about on another forum last year about CFA designs.... what i used for decades now. High SR is its trademark. Ultimately this lead to many other design forums. One was by DADOD. His design got prototyped and sent to me. i tested it and listened to it. Even better than my 2003 design !! And, higher SR.
He listened and gave me what my criteria was. His design is an amazing amplifier by any T&M and by listening. But I would still filter the input to this anyway due to tweeter distortion. Or limit use to CD players which do not have the HF in the analog output (but whose are those?).
THx-RNMarsh
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