I know it's not scientific, but unshielded speaker cables sound better.
If you require them to be shielded you are in a SERIOUSLY bad area.
If you have long runs of speaker cables, shielding or putting RF chokes on them will help keep out interference from nearby stations. Not a bad idea, but make sure to use quality cables / chokes that won't show a reactive load for audio.
Funny thing is, I've seen simple coaxial cable used for speaker runs in TV stations and a recording studio. Something like that is beyond the pale to many home theater people...
Funny thing is, I've seen simple coaxial cable used for speaker runs in TV stations and a recording studio. Something like that is beyond the pale to many home theater people...
Every comment that each of you made about the shielded speaker cables fits exactly along with what I always thought which is based on nothing but personal experience. Most places there is not any more noise with unshielded cables but some places it does make a difference. Often it is places very near truckstops which is not the RF per say causing it. Or it wouldn't if it were clean and legal anyway. It is the overmodulation and non-linear (non linear is almost an understatement because they are mega non linear) amplifiers which ironically they call linears that CB people love and improperly tuned antennas and other things. I call their amps splatter boxes. They love powered mics that can really overmodulate badly plus they scream into them to get the maximum amount possible. You can hear them all over the band and usually in 10 meters too and also on everybodies televisions and even doorbells and yes bands equipment if they are very close at all. Shielded speaker cables do help in that situation. I am not saying it is the only situation where they help but one of the main ones you will actually run into some day if you run around doing live gigs.
The frequency that television channel 5 is on here is a harmonic of a frequency in the 11 meter band so if you are running a clean legal station (which is rare) and you aren't overmodulating too bad maybe your next door neighbor will hear it on his TV if he is watching channel 5 but it won't wipe out his show. It will be in the background. But the way most of these guys run theirs everybody in their neighborhood hears them no matter what channel they are watching and it wipes out what is on the TV. It even gets into the cable and all kinds of other things. I have heard CBrs on my doorbell before. Somebody might wonder how I know they were CBrs. If you have ever heard them you will know believe me. Nobody else that stupid is allowed to transmit on any radios.
CB people are the only ones I know of who will deliberately cause that kind of problem. HAM operators will not overmodulate and splatter all over the band on purpose (and rarely at all) and neither will any commercial radio stations that I know of. But get near a truckstop or anywhere else CB people congregate and it is terrible. They wipe out anything RF that is close and sometimes not so close to them. Drive through windows. Anything. I mean here is how smart these kind of people are. They all dream of having a HAM license and consider anybody with one God. Well since they came out with no code licenses they still dream of having a HAM license but don't have them. If you really wanted a HAM license a long time ago but couldn't get one it was a little sad but if you can't get a no code HAM license and you want one that is very sad. These are the kind of people who use cheap delays (they call them echo boxes) on radios. I am not making this up. They also use sound effects like trains and pingers and reverb and all kinds of really stupid junk like powered mics on 10 in vehicles with the windows down to make double sure nobody can understand them but everybody can hear them no matter what frequency they are on.
If you are close to one of these guys I doubt it is possible to stop them from interfering without shutting them down. But shielded speaker cable will help a lot provided that the other equipment is properly shielded too.
The frequency that television channel 5 is on here is a harmonic of a frequency in the 11 meter band so if you are running a clean legal station (which is rare) and you aren't overmodulating too bad maybe your next door neighbor will hear it on his TV if he is watching channel 5 but it won't wipe out his show. It will be in the background. But the way most of these guys run theirs everybody in their neighborhood hears them no matter what channel they are watching and it wipes out what is on the TV. It even gets into the cable and all kinds of other things. I have heard CBrs on my doorbell before. Somebody might wonder how I know they were CBrs. If you have ever heard them you will know believe me. Nobody else that stupid is allowed to transmit on any radios.
CB people are the only ones I know of who will deliberately cause that kind of problem. HAM operators will not overmodulate and splatter all over the band on purpose (and rarely at all) and neither will any commercial radio stations that I know of. But get near a truckstop or anywhere else CB people congregate and it is terrible. They wipe out anything RF that is close and sometimes not so close to them. Drive through windows. Anything. I mean here is how smart these kind of people are. They all dream of having a HAM license and consider anybody with one God. Well since they came out with no code licenses they still dream of having a HAM license but don't have them. If you really wanted a HAM license a long time ago but couldn't get one it was a little sad but if you can't get a no code HAM license and you want one that is very sad. These are the kind of people who use cheap delays (they call them echo boxes) on radios. I am not making this up. They also use sound effects like trains and pingers and reverb and all kinds of really stupid junk like powered mics on 10 in vehicles with the windows down to make double sure nobody can understand them but everybody can hear them no matter what frequency they are on.
If you are close to one of these guys I doubt it is possible to stop them from interfering without shutting them down. But shielded speaker cable will help a lot provided that the other equipment is properly shielded too.
Urgon, nobody can. Well I can't either anyway. I don't know for sure that nobody can. I think it is 20 or 30 minutes. What will really frustrate you is if you edit one a lot and add a bunch of stuff to it and then when you go to post it instead of telling you it has been too long it just dumps it then tells you it has been too long.
In most SS amps the output connects more or less directly to the input pair via the NFB loop. To help the RF signal get there, most designers thoughtfully add a capacitor across the feedback resistor. Whatever RF is picked up on the speaker cables is presented almost unattenuated to the input.
Some valve amps are similar, except the RF is dumped onto the cathode of the input stage. Fortunately a typical valve can cope with more RF than a typical BJT.
In either case a simple solution is to split the feedback resistor and put the capacitor across only one of them. Some designs do this; many do not.
About 35 years ago (can you say Smokey and the Bandit) I lived in a rental duplex that had the Florida Turnpike in the back yard. I had to ditch my old SS Pioneer stereo because it kept telling me that there was a Smokey in the bushes at the 16. I lived at mile marker 16. The Pioneer picked up CB real good, even my totally unmodified Motorola Mocat CB set (a very clean radio). My neighbor who also had a pioneer, had the same problem.
The answer was simple. Turn the CB on, set it on channel 19 and put a rubber band on the mic. The pioneer did not respond to an unmodulated carrier, only modulation or worse overmodulation. The "good buddies" usually don't talk if they can't hear. More than once I left the Mocat in my van (hey it was 1976) keyed all night long. It didn't fry and I still have it somewhere.
I don't know anyone who would build a CB rig using a plate modulated 4-400 on 2500 volts for the final......do you?
Just to take another angle on this RF noise issue, I wanted to introduce this from the digital side of things - mainly to emphasise that RF may be some of the explanation for other phenomena i.e what we call jitter.
This is from a post by JosephK on an interesting thread he started over on Diyhifi.org.
The point being - would RFI be a likely explanation for the above & perhaps for some/most of what is called jitter?
This is from a post by JosephK on an interesting thread he started over on Diyhifi.org.
The point being - would RFI be a likely explanation for the above & perhaps for some/most of what is called jitter?
I think RFI could not be a cause of deterministic jitter (by which I assume he means jitter which relates to the signal). Non-deterministic jitter could be caused by RFI, but n-d jitter mainly just adds noise so is not so harmful.
The jitter reduction depends on the nature and time constants of the clock recovery circuit. There is a compromise between lock time and LF jitter reduction.
The jitter reduction depends on the nature and time constants of the clock recovery circuit. There is a compromise between lock time and LF jitter reduction.
No, I think he means it the opposite way around - the mechanism by which DJ effects sonics might be through RFI.
OK. I guess it is possible. The transition edges, being high frequencies, could get to parts of the circuit where they are not wanted. There they could be rectified and appear as distortion. This would be in addition to their direct effect on timing in the DAC.
Another reason to be careful about op-amps near DACs??
Another reason to be careful about op-amps near DACs??
It's a bit loose, for my liking, to just characterise a phenomenon as deterministic jitter.
Deterministic jitter is clock jitter or signal jitter that is predictable, i.e it can be seen to be related to some other aspect of the signal. This includes periodic jitter, data dependent jitter, and duty-cycle dependent jitter.
So what kind of deterministic jitter is he talking about, or is he just waffling? This is a typical audiophool ploy, to throw in some fairly esoteric technical term which is outside most people's usual experience, in the hope that it will induce brain-fade and superstitious awe in the audience.
My money's on waffling. Otherwise why not give a clear definition of how the jitter is comprised, and how it relates to the signal.
w
Deterministic jitter is clock jitter or signal jitter that is predictable, i.e it can be seen to be related to some other aspect of the signal. This includes periodic jitter, data dependent jitter, and duty-cycle dependent jitter.
So what kind of deterministic jitter is he talking about, or is he just waffling? This is a typical audiophool ploy, to throw in some fairly esoteric technical term which is outside most people's usual experience, in the hope that it will induce brain-fade and superstitious awe in the audience.
My money's on waffling. Otherwise why not give a clear definition of how the jitter is comprised, and how it relates to the signal.
w
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All possible yes, but differential mode is less of an issue IMO than common-mode RF.
Yep, they don't mix too well.
OK, I looked at both threads.
The issue of deterministic jitter is unrelated to RFI.
JosephK does give a more satisfactory description of what he means by deterministic jitter, he is talking about data-dependent jitter.
The jitter he is talking about is of the order of tens of pS.
Why not read this:-
Detection threshold for distortions due to jitter on digital audio
Abstract: Detection threshold for distortions due to time jitter was measured in a 2 alternative forced choice paradigm with switching sounds. Music signals with random jitter were simulated on the digital domain. The size of jitter was arbitrary controlled so that the detection threshold could be estimated. Professional audio engineers, sound engineers, audio critics and semi-professional musicians participated as listeners. The listeners were allowed to use their own listening environments and their favorite sound materials. It was shown that the detection threshold for random jitter was several hundreds ns for well-trained listeners under their preferable listening conditions.
http://www.jstage.jst.go.jp/article/ast/26/1/50/_pdf
This tends to indicate that to be audible, jitter, admittedly random, requires to be of the order of hundreds of nanoseconds.
Jitter is simply flavour of the month as regards features of audio systems which can be seized upon by the marginally-informed or the dissembling to blame for imaginary deficiencies or differences in systems. Nobody seems to notice or care that the recordings are made using systems whose performance is no better than the playback systems they are complaining about.
I think that what is driving DiyHifi is, for the large part, narcissism. Most of what they are doing is ego-driven. Very little on the site is about finding solutions, most of it is about finding problems, and they're not fussy about whether they're real or not. It's a lot easier to sit in the audience and heckle than it is to get on stage and perform.
Audio frequency design is the 4rse-end of electronic design. Even a SMPS is harder to build than an audio amp. All the guys with two braincells to rub together go into advanced telecomms, DSP or imaging. Cellular phones. Satellite communications. Wireless broadband. HD video.
These guys have found a little niche for themselves, lording it (as they see it) over their sycophantic little group of amateur audio builders, who are easy to impress.
If I want to talk to some RF experts, I can call them up on the phone. Men and women who are working on the design of leading-edge digital wireless, antennas, predistorted transmit amplifiers, SDR receivers, CDMA spread spectrum, VOFDM, not guys who are faffing around trying to drag the limits of their expertise into the spotlight to generate themselves a coterie of adulants amongst the ill-informed. And, I might add, continuously harping on about their own brilliance.
Why not simply move on from this fruitless discussion of RFI and jitter in obsolescent systems and concentrate on the appreciation of low-jitter solid state players or buffering burst-download USB3 DACs which will inevitably replace the current generation of systems as night follows day. The easiest way out of this argument is not to settle it by blind testing, but by making widely available systems in which jitter is reduced below the point of any imaginable audibility.
With a similar rationale I look forward to the day when 24/192 will be adopted as the standard for audio, not because I think that it will sound any better than 16/44.1 but because I think there'll be a lot less opportunity for this kind of obsessive bitching.
w
The issue of deterministic jitter is unrelated to RFI.
JosephK does give a more satisfactory description of what he means by deterministic jitter, he is talking about data-dependent jitter.
The jitter he is talking about is of the order of tens of pS.
Why not read this:-
Detection threshold for distortions due to jitter on digital audio
Abstract: Detection threshold for distortions due to time jitter was measured in a 2 alternative forced choice paradigm with switching sounds. Music signals with random jitter were simulated on the digital domain. The size of jitter was arbitrary controlled so that the detection threshold could be estimated. Professional audio engineers, sound engineers, audio critics and semi-professional musicians participated as listeners. The listeners were allowed to use their own listening environments and their favorite sound materials. It was shown that the detection threshold for random jitter was several hundreds ns for well-trained listeners under their preferable listening conditions.
http://www.jstage.jst.go.jp/article/ast/26/1/50/_pdf
This tends to indicate that to be audible, jitter, admittedly random, requires to be of the order of hundreds of nanoseconds.
Jitter is simply flavour of the month as regards features of audio systems which can be seized upon by the marginally-informed or the dissembling to blame for imaginary deficiencies or differences in systems. Nobody seems to notice or care that the recordings are made using systems whose performance is no better than the playback systems they are complaining about.
I think that what is driving DiyHifi is, for the large part, narcissism. Most of what they are doing is ego-driven. Very little on the site is about finding solutions, most of it is about finding problems, and they're not fussy about whether they're real or not. It's a lot easier to sit in the audience and heckle than it is to get on stage and perform.
Audio frequency design is the 4rse-end of electronic design. Even a SMPS is harder to build than an audio amp. All the guys with two braincells to rub together go into advanced telecomms, DSP or imaging. Cellular phones. Satellite communications. Wireless broadband. HD video.
These guys have found a little niche for themselves, lording it (as they see it) over their sycophantic little group of amateur audio builders, who are easy to impress.
If I want to talk to some RF experts, I can call them up on the phone. Men and women who are working on the design of leading-edge digital wireless, antennas, predistorted transmit amplifiers, SDR receivers, CDMA spread spectrum, VOFDM, not guys who are faffing around trying to drag the limits of their expertise into the spotlight to generate themselves a coterie of adulants amongst the ill-informed. And, I might add, continuously harping on about their own brilliance.
Why not simply move on from this fruitless discussion of RFI and jitter in obsolescent systems and concentrate on the appreciation of low-jitter solid state players or buffering burst-download USB3 DACs which will inevitably replace the current generation of systems as night follows day. The easiest way out of this argument is not to settle it by blind testing, but by making widely available systems in which jitter is reduced below the point of any imaginable audibility.
With a similar rationale I look forward to the day when 24/192 will be adopted as the standard for audio, not because I think that it will sound any better than 16/44.1 but because I think there'll be a lot less opportunity for this kind of obsessive bitching.
w
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