Right on, Wayne.
Locally, in Serbia, we have this annual meeting of trumpet players. It's probably the bigges festivity in the country.
Some years ago, when Miles Davis listened to the recordings, he is said to have commented than he never knew a trumpet could be played like that. Totally different to what a typical Westener is exposed to.
So, I believe the number of possible variation on the very style of playing musical instruments is, practically speaking, infinite, or the next thing after it. Thus, the definition of what the sound should be like is likewise practically limitless.
Who's to say that his way is the only proper way?
And it's all our human race heritage, it belongs to no-one in particular, it belongs to all of us and our children.
I only have to look at my own nation. We Serbs are not known for level headedness in general, but in music, they don't come any more tolerant then we ourselves. If it were not so, there would be none of us left, because every 30-40 miles' distance, musical taste and form change, sometimes radically. It's a bit scary sometimes (because of the musical style changes), but very beautiful as well.
And the ruling musical democracy in power locally is absolute, if it's music, nobody objects. If it has folk music roots, be it ours or from the 21 minorities living in Serbia today, it's welcome. From larger minority such as the Rumanians and Bulgarians and Hungarians, to small minority notes, such from say Slovaks.
Musically speaking, it's a lot of FUN living here. Most rewarding. Any traditional restaurant worth its salt will have a decent live band each and every evening. Even in cities.
the point is dvv, it doesnt matter how you tune it, even the perfectly tuned differential filter will do very little to stop common mode noise of any power...its also more expensive than a single x2y SMD cap, which replaces an X filter and 2 x Y filters with a single part ie. X+2Y, is far less inductive, takes up less space etc etc.
I dont fancy using my ears for listening for RF, I dont have your skills clearly...
I dont fancy using my ears for listening for RF, I dont have your skills clearly...
you talking to me?
class A will lower the load on the local reservoir caps, so they can be reduced, not so much the decoupling for preventing noise entering the system.
dont mistake X2Y for something like X7R or NP0, X2Y is not a thermal coefficient, its a capacitor construction type/format. just guessing in the case you were referring to that.
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Actually, Qusp, I have only three skills, one of which is congenital, to me a Godsend:
1. I have an ear for languages, a natural talent,
2. I have developed an ability to integrate many details into one whole, and
3. I like to think more than most - not a talent, more of a stretching of mental muscles on a regular basis.
2) is not a gift, just a lot of practice, and can therefore be learnt. 3) is a choice I wish many more would make, and the key reason why I come to this forum - birds of feather flock together.
sorry, you missed the cheeky sarcasm 
despite your natural gift for language hehe 
nobody can listen for RF and VHF, so you dont have that skill either.
Even if you can make audible chirps fade, thats not an indication that you have gotten rid of the problem. the audible chirps are simply what is folded down into the audible range and show themselves obviously; there will still be problems and distortion thats not so obvious. Given a GSM chirp of the type i'm talking about, I find highly unlikely you can get rid of it by adjusting a cap between 220-680nf, perhaps you have it easier over there for the bands your telcos have chosen.
its no surprise that the audio in the mids cleared up though, the interference will have been using up some of the gain bandwidth.
I really recommend you check out the X2Y stuff, honestly its fun stuff, you dont always get rid of the 100uf or whatever, but the other 2 are nolonger needed and performance is superior, better even than a common mode choke, or matched caps and inductors.
despite your natural gift for language hehe nobody can listen for RF and VHF, so you dont have that skill either. Even if you can make audible chirps fade, thats not an indication that you have gotten rid of the problem. the audible chirps are simply what is folded down into the audible range and show themselves obviously; there will still be problems and distortion thats not so obvious. Given a GSM chirp of the type i'm talking about, I find highly unlikely you can get rid of it by adjusting a cap between 220-680nf, perhaps you have it easier over there for the bands your telcos have chosen.
its no surprise that the audio in the mids cleared up though, the interference will have been using up some of the gain bandwidth.
I really recommend you check out the X2Y stuff, honestly its fun stuff, you dont always get rid of the 100uf or whatever, but the other 2 are nolonger needed and performance is superior, better even than a common mode choke, or matched caps and inductors.
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here, check this out for some reading on x2y and gsm, sponge-like constant research is part of my obsession too, good stuff on this site even if its promoting their product to a degree, there are also some excellent calculators. caps of this type have been licensed to 3 companies I think. Johanson, Syfer and one other I cant remember. its not just good for GSM, its simply a better, lower inductance capacitor type as well.
I often use high end and very sensitive, low impedance, in ear stage monitors for listening late at night and use digital volume control (input is not attenuated), so its of particular interest to me keeping this stuff out of the system. my stuff is all balanced, so it gets rid of a fair bit, but the common mode has secondary differential effects that need targeting
I often use high end and very sensitive, low impedance, in ear stage monitors for listening late at night and use digital volume control (input is not attenuated), so its of particular interest to me keeping this stuff out of the system. my stuff is all balanced, so it gets rid of a fair bit, but the common mode has secondary differential effects that need targeting
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I was responding to your post , Not specifically at you.....
OK well that clears that up then ... Class A doesnt seem in any way relevant to the problem we are discussing TBH
sorry, you missed the cheeky sarcasm
Even if you can make audible chirps fade, thats not an indication that you have gotten rid of the problem. the audible chirps are simply what is folded down into the audible range and show themselves obviously; there will still be problems and distortion thats not so obvious. Given a GSM chirp of the type i'm talking about, I find highly unlikely you can get rid of it by adjusting a cap between 220-680nf, perhaps you have it easier over there for the bands your telcos have chosen.
its no surprise that the audio in the mids cleared up though, the interference will have been using up some of the gain bandwidth.
I really recommend you check out the X2Y stuff, honestly its fun stuff, you dont always get rid of the 100uf or whatever, but the other 2 are nolonger needed and performance is superior, better even than a common mode choke, or matched caps and inductors.
I said I do well with languages, not reading of minds from Europe to Australia and New Zealand. Moreover, I don't know you even a bit.
As for "listening to RF", I mentioned only birdies, which are a common sign that it's picking up RF from somewhere, given that it occurred at my home and in an urban envirnoment, meaning nothing RF active in the nearer vicinity. The fact is that once the decoupling was improved, it disappeared as an effect.
On basis of that, I assumed the cause was RF, but I have no way of making sure. If you have another idea, I'd like to hear it.
Quite frankly, I have no idea what "x2y" means - please explain, if you feel it pollutes the forum, a PM will be just fine.
I should mention that by deafult, my input and VAS stages run off fully electronically regulated stages, with generous CRC decoupling. So, we are talking about high power current stages only.
Those parts are interesting especially for the very high frequencies. I see that as applied to inamp inputs they show 1nF parts, and 100nF for power connections.
Years ago when David McCorkle was doing design work for Harman-Motive, now Harman-Becker, he found an amplifier for BMW a particular challenge. Among other things he more-or-less stopped using bipolar input opamps altogether, and transitioned to JFET input ones, with their appreciable lower susceptibility to RF envelope detection. It would be interesting if the X2Y parts might allow use again of bipolars. Nowadays most of the equalization is done in the digital domain, so it's much less of an overall susceptibility problem as it is.
The one product I designed the electronics for that was remarkably robust against cellphone interference turned out to be so fortuitously. As it was a multimedia/computer audio oriented one there was not as much concern about RFI --- at the price points and without an iron-clad spec to meet about such, people pretty much lived with what they got. However, because I needed a very low-noise front end with differential outputs for a surround-synthesis scheme, which allowed the smooth adjustment of the envelopment from maximum to plain stereo, I ran a fair amount of current through discrete-component stages. There was also a pretty good ground plane in the vicinity. It was a happy surprise that the resulting system was almost completely immune to cell interference in the vicinity.
the problem is, without a couple of revisions, these type of effects can be very unpredictable and can easily just couple into and modulate the ground plane. many of the devices impedances arent modeled well (not for the general public anyway, you may have had more luck), if at all and its a whole system interaction thing, the simulation tools are inaccessible, expensive and still only get you part way there.
indeed the possible use of bipolars is a driving factor for me too. johanson dont really make much by way of larger capacity, but syfer make up to 1uf I think (might be the other way around) I just got some in a few values and sizes and have actually applied them to part of that project ive been talking to you about.
btw just saw your email earlier, it got buried in other stuff that came in in the last 24hrs, thanks, i'll have a look and reply tomorrow. i'll show you what i've come up with so far and it uses these parts. interesting layout challenges with leveraging them to best advantage with floating shield PCB layer.
dvv, as you can see above, I explained and linked to materials already in post #9054 where you can read much more comprehensive info than I can give, but if you are interested I can maybe show you how i'm using them for audio privately.
dont read too much into the sarcasm, it wasnt really subtle, what else could it be, nobody can hear RFI directly and I left a little ... sarcasm is no fun if you have to hilight the fact you are being sarcastic, recognizing it is something that comes from frequent conversation in English (or alternatively other languages) and even then its not possible for some people to see it, particularly if its not part of the culture necessarily.
I just couldnt help but hilight the irony, I meant no harm.
btw regulation is not relevant either, regs dont have the bandwidth and it would need to have differential sensing to begin to see it.
indeed the possible use of bipolars is a driving factor for me too. johanson dont really make much by way of larger capacity, but syfer make up to 1uf I think (might be the other way around) I just got some in a few values and sizes and have actually applied them to part of that project ive been talking to you about.
btw just saw your email earlier, it got buried in other stuff that came in in the last 24hrs, thanks, i'll have a look and reply tomorrow. i'll show you what i've come up with so far and it uses these parts. interesting layout challenges with leveraging them to best advantage with floating shield PCB layer.
dvv, as you can see above, I explained and linked to materials already in post #9054 where you can read much more comprehensive info than I can give, but if you are interested I can maybe show you how i'm using them for audio privately.
dont read too much into the sarcasm, it wasnt really subtle, what else could it be, nobody can hear RFI directly and I left a little ... sarcasm is no fun if you have to hilight the fact you are being sarcastic, recognizing it is something that comes from frequent conversation in English (or alternatively other languages) and even then its not possible for some people to see it, particularly if its not part of the culture necessarily.
I just couldnt help but hilight the irony, I meant no harm.
btw regulation is not relevant either, regs dont have the bandwidth and it would need to have differential sensing to begin to see it.
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What one can detect fairly easily, and it's a good way to sensitize your hearing to some of the more subtle distortion effects, is the impact of RF on the behaviour of the audio system, making it misbehave. Whereabouts, and how precisely the misbehaviour is triggered is another topic, but the ears have no trouble picking it happening.
There is a fairly generic quality to this distortion "sound", in everything I've heard it happen with. Obviously, the system has to be running pretty cleanly in the first place, and key is that the treble is pure, there is no edge or unpleasantness there, the sound is very "sweet", and sparkles in the best sense. That is the state with no RFI; then with a system susceptible to this - which in my experience so far is nearly all of them - add a RF generator nearby, and virtually instantly the sound dulls, deadens to a degree, loses that sparkle, a very distinct edginess, an uncomfortable tonality, permeates the sound. Switch off the RFI generator, and the sound is virtually instantly restored to its former premium state.
Solo violin is good for testing this on, where the tone has a soaring, inspiring sheen to it: with RFI in the picture the sheen evaporates to a large degree, is replaced by an irksome scratchiness which starts to grate very quickly.
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Should be no trouble to show it in measurements. I look forward to seeing it.
Do you know what the problem is here? It's the dilemma of the observer effect, which necessitates having to jump through some hoops to get meaningful results ...
Most straightforward measurement devices these days use high speed, digital circuitry for their innards, which create ... wait for it ... RFI. I've already tried a simple sound capture of the speaker output, and heard the SQ degenerate as the AD circuitry was busily sampling the sound, which was being damaged by the AD circuit busily sampling ...
Of course there are ways of getting around this, but now it's become a far more complex process, it's no longer relatively trivial to do ...
Most straightforward measurement devices these days use high speed, digital circuitry for their innards, which create ... wait for it ... RFI. I've already tried a simple sound capture of the speaker output, and heard the SQ degenerate as the AD circuitry was busily sampling the sound, which was being damaged by the AD circuit busily sampling ...
Of course there are ways of getting around this, but now it's become a far more complex process, it's no longer relatively trivial to do ...
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