[jagwap]

HMMMM. Are you guys saying I should wrap my opamps in a shield?!

Joking aside: Some gear does. Although it also can be for marketing/confidentiality reasons.

For example the Marantz HDAM modules we legitimate discrete opamp circuits in a copper can, which helped screen them, and hide what's inside. They were a nice JFET input MOSFET output class A circuit. However another company I won't name, with a similar reputation did similar with a PSU regulator circuit. But rather than it hiding a discrete regulator circuit, it was hiding a $0.10 TO-220 linear regulator and trying to make it look special.

However with modern SMT opamps, on a multi-layer PCB, good decoupling, sensible RF filtering, and most importantly great layout, you have a good chance of making the unit nearly imune.

But remember, all of the above only reduces effects, never eliminates them. So it is a matter of knowledge, experience, often backed up by measurement and learning by listening, to know when how much reduction is enough. Some RF fixes increase ground currents between units, which bring other issues.

RF is like a game of wack-a-mole. Push it down in one place, and it pops up in another.

 

[redrol]

I have 2 modified devices with opamps jacked way above the circuit board via adapters. Prolly the worst case scenario. I'll consider shielding them.

 

[bigshot]

If it ain’t broke, don’t fix it. I don’t think this is an issue for most people. If you hear interference, then track it down.

 

[gregorio]

All gear has RFI rejection standards: FCC in US, CE in Europe and CCC in China for example.

All consumer equipment has legal limits for the amount of RF they produce but are there standards, which include consumer audio gear and analogue interconnect cables, for RF rejection?

This from very competent design teams, that learnt from the experience for next time, but did not necessarily share their in-house experience with professional bodies like the AES etc.

Is it really “from very competent design teams” though, or is this just another example of common audiophile marketing, where something is supposedly extremely complex/difficult to achieve and only expensive audiophile equipment manages it, such as jitter rejection to below audibility or USB noise rejection for example?

I’m not saying it’s not complex or difficult to achieve, just that as it can be achieved by some/many cheap units, why should it be such an apparent problem for vastly more expensive audiophile gear and wouldn’t that be a case of incompetent design teams, without enough knowledge/experience? The example given of CDMA cellphones for instance; CDMA has been around for over 50 years and a N. American standard for cellphones for over 25 years. Wouldn’t you expect a design team even of only basic competency to know this and have the knowledge/experience to mitigate it?

G

 

[jagwap]

All consumer equipment has legal limits for the amount of RF they produce but are there standards, which include consumer audio gear and analogue interconnect cables, for RF rejection?

Yes. In some markets (EU for example). It is called Susceptibility. But it does not guarantee that audio equipment is isolated well enough for optimum performance. It maybe just keep the local taxi radio from coming through your speakers.

Is it really “from very competent design teams” though, or is this just another example of common audiophile marketing, where something is supposedly extremely complex/difficult to achieve and only expensive audiophile equipment manages it, such as jitter rejection to below audibility or USB noise rejection for example?

May I re-iterate, I am not in or have any relation to marketing. I am an engineer with over 30 years design experience and I have worked in and alongside many very competent teams (and some who were less so, and assisted them when I was able). I have not stated that "only expensive audiophile equipment manages it", as have worked in budget audio and pro audio, where there isn't the money to mess around.

I’m not saying it’s not complex or difficult to achieve, just that as it can be achieved by some/many cheap units, why should it be such an apparent problem for vastly more expensive audiophile gear and wouldn’t that be a case of incompetent design teams, without enough knowledge/experience? The example given of CDMA cellphones for instance; CDMA has been around for over 50 years and a N. American standard for cellphones for over 25 years. Wouldn’t you expect a design team even of only basic competency to know this and have the knowledge/experience to mitigate it?

G

Because: for general EMI

1: People miss things, as EMI can be rather elusive. The regulations do not cover all the product requirements, only the compliance requirements.
2: People sometimes do not know what to measure for, until they listen, and hear an issue, then go looking for it in novel measurable areas.
3: Nobody knows everything. That includes everyone here too, including you and I.
4: Mitigate: Let's be clear - these things can only be reduced, never removed. It is an attenuation of interference. How much reduction required is not tightly defined, and some companies are are more particular than others.
5: Every now and then something gets in and gets demodulated at a point and/or frequency no one on the team has seen before, and needs addressing. However that has also happened to be found in the field after the product has been released. This does not make them incompetent, just lacking a specific obscure knowledge, which perhaps no one has ever seen before.

Your view that all electrical audio problems have been solved is optimistic. We are always learning new stuff. Which is good, because the world is throwing more RF at us all the time.

 

[The Jester]

Or when you open the box of a piece of equipment and it‘s supplied with a power cord with a moulded ferrite bead at one or either end ?
Manufacturer going a little bit further or without such a cable the unit may just fail mandatory testing, so a redesign or just pop a correctly tuned ferrite on the supplied power cable,
Given that, if a standard or even an “audiophile quality” cable is substituted it could possibly sound worse ?

 

[jagwap]

Or when you open the box of a piece of equipment and it‘s supplied with a power cord with a moulded ferrite bead at one or either end ?
Manufacturer going a little bit further or without such a cable the unit may just fail mandatory testing, so a redesign or just pop a correctly tuned ferrite on the supplied power cable,
Given that, if a standard or even an “audiophile quality” cable is substituted it could possibly sound worse ?

I am not asserting any facts here, but my opinion based on having been a while in the industry, is that any cables in the box that have added ferrites on them, usually co-molded on, are not there for fun. 95% at least are because they are necessary to pass EMC compliance in a market with that plug. It is possible that the manufacturer got some cheap, lower cost than non-filtered cables, due to some clearance sale, but unlikely. It really suggests they couldn't fix it in time or within budget internally so kludged this on. So it would be recommended to use the in box cable. Or a better product. It could even be some marketing, because marketing follows little logic when observed from a technical view point.

However it may be fixing immunity from outside EMI that doesn't exist in your environment, so then you will never notices a difference.

As to your last point, there are so many permutations, I cannot find the time here to list them. The answer is a VERY conditional yes.

 

[Ghoostknight]

im kinda wondering about the studys in the first post the conclusion if often something like "49% of the listeners could tell them apart" but what actually does this mean?

1. each listener was giving one chance and in the end 49% guessed right
2. each listener had multiple chances and 49% were able to guess consistently right

this is a huge difference imo if 49% can tell reliably the difference then the study disproofs nothing since there will always be people that dont hear a difference and people that are, just because around 50% couldnt doesnt make this a coinflip and disproofs the myth
same goes kinda for both points tho unless everyone guessed 50% right

 

[bigshot]

Yes. In some markets (EU for example). It is called Susceptibility. But it does not guarantee that audio equipment is isolated well enough for optimum performance. It maybe just keep the local taxi radio from coming through your speakers.

I've never found any RF interference to be a problem unless it is an obvious problem, like the local taxi radio coming through my speakers. Unless you can detect a problem, it isn't a problem. Too much of audiophile stuff is finding solutions to problems that don't exist. RF isn't normally a subtle thing. And if it is subtle, as long as it's subtle enough to not be heard, it doesn't matter.

 

[gregorio]

Because: for general EMI
1: People miss things, as EMI can be rather elusive. The regulations do not cover all the product requirements, only the compliance requirements.
2: People sometimes do not know what to measure for, until they listen, and hear an issue …

The tendency here on head-fi is to look at a relatively tiny segment of the market and consider that to be the whole world. For example, audiophiles tend to view the world of audio only in terms of the audiophile world and even here in this subforum we tend to discuss the recording/reproduction of audio almost exclusively in terms of the music industry. Just to put this into perspective, the global music recording industry had revenue in 2021 of around $26 billion, while the global film/TV/video industry had revenue of around $600 billion. Abbey Road Studios, one of the biggest music recording studios, has 3 main studios, plus the Penthouse Studio, two smaller “budget” studios and employs around a dozen music engineers. Todd A/O, the biggest film/TV audio post facility for many years, had 17 mix stages, over 100 sound edit suites and employed around 250 sound engineers. The overwhelming majority of professional audio recording/production in the world is done in the TV/film world, music is a relatively tiny corner of the commercial audio content creation world.

What relevance does this have? I won’t go into all the details of film/TV audio creation because it’s far more complex and diverse than music recording but I’ll mention two pertinent areas: Film/TV is recorded in many different locations, sometimes “on set”, in purpose built “sound stages” and sometimes “on location”; in airports, kitchens, factories, hospitals, military bases, train stations and pretty much anywhere you can think of. This “production sound” has to be edited and cleaned by editors spending many hours a day, day in, day out, studying spectrograms (and other analysis tools), identifying and dealing with pretty much every source of EMI (and other unwanted sounds) known to man. There’s probably tens of thousands of sound engineers/editors around the world doing this right now. Another area is “Foley”, where we have to record masses of extremely quiet sounds. For example, most films have 2 or more tracks of “Cloths”; clothes rustles, cloth rubs, scratches, swooshes, etc. This is far more demanding on audio equipment than what we encounter in the music industry because we need to massively amplify these tiny signals, 60dB of gain is very common and 80dB is not unheard of. So even tiny amounts of EMI or other mic, amp or digital conversion noise/distortion can become an easily audible issue (and has to be identified and dealt with). We commonly have to hold our breath while recording and be very careful of the clothes we’re wearing because these noises can be far louder than what we’re trying to record. Again, there are thousands of Foley artists/editors doing this around the world right now (and have been for generations).

There’s not much which is “elusive” with 60-80dB of gain or in all the shooting locations used, plus all the filming equipment (cameras, computers, lighting and monitoring equipment and power generators, radio mics, etc.)!

Your view that all electrical audio problems have been solved is optimistic.

For consumer audio reproduction, sure they have (assuming that “solved” means reduced to inaudible). Of course, this doesn’t rule out the possibility that some boutique audiophile manufacturers simply miss something or even deliberately ignore it, because marketing is more important than actual performance. Think about the Apple dongle for example; here we have a bit of cable, two connectors and a DAC/Amp all physically connected to a device which is an actual radio, bluetooth and wi-fi transmitter/receiver, plus various CPUs/GPUs/processors chugging along just a couple of inches away. Yet all this close proximity EMI/noise is reduced to inaudibility by a dongle that costs ~$9. Is it really such a difficult/impossible task to design a DAC/amp with similar isolation for a 10x-100x (or more) higher price?

G

 

[jagwap]

The tendency here on head-fi is to look at a relatively tiny segment of the market and consider that to be the whole world. For example, audiophiles tend to view the world of audio only in terms of the audiophile world and even here in this subforum we tend to discuss the recording/reproduction of audio almost exclusively in terms of the music industry. Just to put this into perspective, the global music recording industry had revenue in 2021 of around $26 billion, while the global film/TV/video industry had revenue of around $600 billion. Abbey Road Studios, one of the biggest music recording studios, has 3 main studios, plus the Penthouse Studio, two smaller “budget” studios and employs around a dozen music engineers. Todd A/O, the biggest film/TV audio post facility for many years, had 17 mix stages, over 100 sound edit suites and employed around 250 sound engineers. The overwhelming majority of professional audio recording/production in the world is done in the TV/film world, music is a relatively tiny corner of the commercial audio content creation world.

What relevance does this have? I won’t go into all the details of film/TV audio creation because it’s far more complex and diverse than music recording but I’ll mention two pertinent areas: Film/TV is recorded in many different locations, sometimes “on set”, in purpose built “sound stages” and sometimes “on location”; in airports, kitchens, factories, hospitals, military bases, train stations and pretty much anywhere you can think of. This “production sound” has to be edited and cleaned by editors spending many hours a day, day in, day out, studying spectrograms (and other analysis tools), identifying and dealing with pretty much every source of EMI (and other unwanted sounds) known to man. There’s probably tens of thousands of sound engineers/editors around the world doing this right now. Another area is “Foley”, where we have to record masses of extremely quiet sounds. For example, most films have 2 or more tracks of “Cloths”; clothes rustles, cloth rubs, scratches, swooshes, etc. This is far more demanding on audio equipment than what we encounter in the music industry because we need to massively amplify these tiny signals, 60dB of gain is very common and 80dB is not unheard of. So even tiny amounts of EMI or other mic, amp or digital conversion noise/distortion can become an easily audible issue (and has to be identified and dealt with). We commonly have to hold our breath while recording and be very careful of the clothes we’re wearing because these noises can be far louder than what we’re trying to record. Again, there are thousands of Foley artists/editors doing this around the world right now (and have been for generations).

There’s not much which is “elusive” with 60-80dB of gain or in all the shooting locations used, plus all the filming equipment (cameras, computers, lighting and monitoring equipment and power generators, radio mics, etc.)!

I know this. I've designed equipment in this field. I've delt with these issues. What's your point? You are trying to contradict me, but how?

For consumer audio reproduction, sure they have (assuming that “solved” means reduced to inaudible). Of course, this doesn’t rule out the possibility that some boutique audiophile manufacturers simply miss something or even deliberately ignore it, because marketing is more important than actual performance. Think about the Apple dongle for example; here we have a bit of cable, two connectors and a DAC/Amp all physically connected to a device which is an actual radio, bluetooth and wi-fi transmitter/receiver, plus various CPUs/GPUs/processors chugging along just a couple of inches away. Yet all this close proximity EMI/noise is reduced to inaudibility by a dongle that costs ~$9. Is it really such a difficult/impossible task to design a DAC/amp with similar isolation for a 10x-100x (or more) higher price?

G

Isolation of 100x is only 40dB. That would be very poor for anyone wanting good performance. I assume you didn't mean that.

You have also said in the past you deal in large scale audio systems. This can be where problems add rather than cancel. Particularly bad can be stadiums, or large multi building or multi generator truck systems.

I do not yet see what your position is yet except to take a contrary one.

 

[jagwap]

The tendency here on head-fi is to look at a relatively tiny segment of the market and consider that to be the whole world. For example, audiophiles tend to view the world of audio only in terms of the audiophile world and even here in this subforum we tend to discuss the recording/reproduction of audio almost exclusively in terms of the music industry. Just to put this into perspective, the global music recording industry had revenue in 2021 of around $26 billion, while the global film/TV/video industry had revenue of around $600 billion. Abbey Road Studios, one of the biggest music recording studios, has 3 main studios, plus the Penthouse Studio, two smaller “budget” studios and employs around a dozen music engineers. Todd A/O, the biggest film/TV audio post facility for many years, had 17 mix stages, over 100 sound edit suites and employed around 250 sound engineers. The overwhelming majority of professional audio recording/production in the world is done in the TV/film world, music is a relatively tiny corner of the commercial audio content creation world.

What relevance does this have? I won’t go into all the details of film/TV audio creation because it’s far more complex and diverse than music recording but I’ll mention two pertinent areas: Film/TV is recorded in many different locations, sometimes “on set”, in purpose built “sound stages” and sometimes “on location”; in airports, kitchens, factories, hospitals, military bases, train stations and pretty much anywhere you can think of. This “production sound” has to be edited and cleaned by editors spending many hours a day, day in, day out, studying spectrograms (and other analysis tools), identifying and dealing with pretty much every source of EMI (and other unwanted sounds) known to man. There’s probably tens of thousands of sound engineers/editors around the world doing this right now. Another area is “Foley”, where we have to record masses of extremely quiet sounds. For example, most films have 2 or more tracks of “Cloths”; clothes rustles, cloth rubs, scratches, swooshes, etc. This is far more demanding on audio equipment than what we encounter in the music industry because we need to massively amplify these tiny signals, 60dB of gain is very common and 80dB is not unheard of. So even tiny amounts of EMI or other mic, amp or digital conversion noise/distortion can become an easily audible issue (and has to be identified and dealt with). We commonly have to hold our breath while recording and be very careful of the clothes we’re wearing because these noises can be far louder than what we’re trying to record. Again, there are thousands of Foley artists/editors doing this around the world right now (and have been for generations).

There’s not much which is “elusive” with 60-80dB of gain or in all the shooting locations used, plus all the filming equipment (cameras, computers, lighting and monitoring equipment and power generators, radio mics, etc.)!

For consumer audio reproduction, sure they have (assuming that “solved” means reduced to inaudible). Of course, this doesn’t rule out the possibility that some boutique audiophile manufacturers simply miss something or even deliberately ignore it, because marketing is more important than actual performance. Think about the Apple dongle for example; here we have a bit of cable, two connectors and a DAC/Amp all physically connected to a device which is an actual radio, bluetooth and wi-fi transmitter/receiver, plus various CPUs/GPUs/processors chugging along just a couple of inches away. Yet all this close proximity EMI/noise is reduced to inaudibility by a dongle that costs ~$9. Is it really such a difficult/impossible task to design a DAC/amp with similar isolation for a 10x-100x (or more) higher price?

G

OK, let me propose another arguement. We come from different positions because of where we are in the industry.

You put together professional systems, and as such you need to assume the gear you are using works perfectly together, unless it proves not to. Otherwise you are going to go mad with paranoia.

I need to think the opposite way. I need to assume the gear I am designing potentially has significant problems for a small percentage of the hundreds of thousands of customers a year, until we prove they don't. Otherwise we could lose our customers' confidence.

You NEED to believe in it, and that is why you will not take on board what I am saying.

I NEED to assume things can go wrong, or we won't spot them in time.

Does that help with you understanding of my position?

 

[gregorio]

Isolation of 100x is only 40dB.

Err, 100x $9 is $900.

We come from different positions because of where we are in the industry.

You put together professional systems, and as such you need to assume the gear you are using works perfectly together, unless it proves not to.

No, the position I come from is having to deal with audio which has been recorded in locations from extremely quiet, almost anechoic studios to exceptionally hostile environments (high noise and/or high EMI), recorded on anything from $60 prosumer recorders to the highest end amps and ADCs costing many thousands. And “dealing with” means all kinds of unusual things, such as round trips through DACs and very common things, such as applying extreme amounts of gain to very quiet signals and then having to carefully analyse and reduce all the noise/interference revealed by applying such amounts of gain. So, I get to clearly hear, see and process all those things that are completely inaudible to consumers, for hours a days and for days on end. From the sound of Daniel Craig’s tongue against his teeth to EMI from virtually every source, to all those distortions from amps and ADCs/DACs that are way below audibility.

G

 

[bigshot]

I don’t generally worry about problems that haven’t proven to be problems. I find my time is better spent on other things. I understand the ‘just in case” mindset, and I guess it’s OK if there are no real problems to address, but I don’t see it as having much of an impact on improving sound at the end of the day.

 

[Dogmatrix]

Apart from tubes I have not had issue with noise since about 1986