Testing audiophile claims and myths

[Ryokan]

he’s come out with classic claims such as being able to hear distortion at -300dB.

G

I thought the decibel scale started at zero? where rustling leaves is 20dB. Is there another scale for testing sensitive equipment? Thank you.

 

[castleofargh]

McGowan is interesting as he is joint CEO of a Hi fi manufacturer and co designs a lot of their products so he obviously knows electronics but he does make claims that I’m guessing will wind people on this forum up - for example PS Audio no longer make bespoke mains cables yet he claims expensive ones make a difference- im guessing that view is like a red rag to a bull here

Any direct link between money and sound quality is a problem IMO. It smells a lot like heuristics solving complex multivariable questions about fidelity, electrical laws of physics and audibility, with a one fit all solution: "expensive=better". It's even more of a problem for "audiophile" cables, as they have some of the biggest markups in the audio industry, making the relation between physical properties (sound) and pricing quite mysterious or even nonexistent most of the time.


Beyond that, I'm a simple guy. If I see an actual method used to get a conclusive result, I tend to trust that result. It's the lack of proper method and long lists of empty claims that get my spider sense tingling. Controversial conclusions do require more evidence, already proved ideas don't need much of anything. It's a belief system I like.

I'd ask you to show me evidence that the laws of physics don't apply to cables. But there's no point. You have no evidence. You are simply faith-based.

I started watching The 3 Body Problem TV adaptation and right at the start someone says that "physics doesn't exist". ^_^

I thought the decibel scale started at zero? where rustling leaves is 20dB. Is there another scale for testing sensitive equipment? Thank you.

He means -300dB on a digital signal (as it's discussed by Rob in statements about absurd levels of noise shaping), where full scale signal is 0dB.
But even considering that you'd listen super loud with peaks at 120dB SPL, with 0dB SPL being about where people stop hearing (it can go lower in an anechoic chamber but not by much), it still sounds ludicrous. It's another example of an expert in something talking nonsense once he's outside his area of expertise.

 

[gregorio]

I thought the decibel scale started at zero? where rustling leaves is 20dB. Is there another scale for testing sensitive equipment? Thank you.

There are roughly 50 different decibel scales, however we only refer to about 5 of them here (as many of the others are for measuring other things, such as radio or radar power). Most commonly we use only 2 of the dB scales though: dB SPL (sound pressure level) for measuring acoustic sound waves and dBFS (digital Full Scale) for measuring the level of digital audio. We often just say “dB” though because it’s usually obvious which scale we’re talking about from the context.

Typically the analogue, power and acoustic dB scales do not start at zero, zero is just a defined reference point. So for example 0dBm is referenced to 1mW into 600Ohm impedance but you can of course have less than 1mW. The dB SPL scale effectively starts at about -23dB SPL but 0dB is referenced to 20 microPascals, roughly the threshold of human hearing at 1kHz (given near ideal conditions). This isn’t the case with the digital audio dBFS scale though, you can’t have higher than 0dBFS (in practice).

You stated a 20dB level for rustling leaves (we’ll ignore the fact this would only be true under specific conditions), what you actually meant was 20dB SPL, because the context is acoustic sound and you can’t have 20dBFS any way. Nearly always here, if you see a negative dB value then it’s a pretty safe bet we’re talking about the dBFS scale.

Although we covered it here years ago: If 0dBFS were the sound level of a truck driving past at 50mph from ~3m away, then the sound at -144dB (the limit of 24bit audio) would be roughly the sound level of 2 hydrogen atoms colliding. Although that’s just theoretically, because it wouldn’t actually produce sound, not enough acoustic energy to propagate a sound wave. Rob Watts claim of hearing -300dBFS would be roughly 100 million times lower in level than the “sound” of 2 hydrogen atoms colliding!

G

 

[Ryokan]

There are roughly 50 different decibel scales, however we only refer to about 5 of them here (as many of the others are for measuring other things, such as radio or radar power). Most commonly we use only 2 of the dB scales though: dB SPL (sound pressure level) for measuring acoustic sound waves and dBFS (digital Full Scale) for measuring the level of digital audio. We often just say “dB” though because it’s usually obvious which scale we’re talking about from the context.

Typically the analogue, power and acoustic dB scales do not start at zero, zero is just a defined reference point. So for example 0dBm is referenced to 1mW into 600Ohm impedance but you can of course have less than 1mW. The dB SPL scale effectively starts at about -23dB SPL but 0dB is referenced to 20 microPascals, roughly the threshold of human hearing at 1kHz (given near ideal conditions). This isn’t the case with the digital audio dBFS scale though, you can’t have higher than 0dBFS (in practice).

You stated a 20dB level for rustling leaves (we’ll ignore the fact this would only be true under specific conditions), what you actually meant was 20dB SPL, because the context is acoustic sound and you can’t have 20dBFS any way. Nearly always here, if you see a negative dB value then it’s a pretty safe bet we’re talking about the dBFS scale.

Although we covered it here years ago: If 0dBFS were the sound level of a truck driving past at 50mph from ~3m away, then the sound at -144dB (the limit of 24bit audio) would be roughly the sound level of 2 hydrogen atoms colliding. Although that’s just theoretically, because it wouldn’t actually produce sound, not enough acoustic energy to propagate a sound wave. Rob Watts claim of hearing -300dBFS would be roughly 100 million times lower in level than the “sound” of 2 hydrogen atoms colliding!

G

So much to learn, thank you @gregorio and @castleofargh .

 

[gregorio]

So much to learn, thank you @gregorio and @castleofargh .

Yep, the different dB scales and the fact they’re all logarithmic can occasionally catch out even experienced engineers. Having said this, in practice the two scales we use here mostly (dBFS and dBSPL) are fairly easy to relate, even though there’s no common reference.

In cinema systems, 0dBFS = 105dBSPL but with consumer audio systems 0dBFS equals whatever dBSPL you set your amp “volume” to. However, the ratio is always correlated. Let’s say you set you amp so that 0dBFS = 100dBSPL from your speakers. If you play a digital audio signal at -40dBFS, what you’ll get out of your speakers is 100 - 40 = 60dBSPL. If you set your amp so that 0dBFS = 80dBSPL from your HPs, then our -40dBFS digital signal will result in 80 - 40 = 40dBSPL.

Hope that helps a bit.

G

 

[bigshot]

I've noticed with YouTube videos that when a high end audio expert/salesman prevaricates, it isn't subtle. It's rarely just fudging around the edges to sweeten his argument, it's a great big honkin' falsehood that flies in the face of fundamental principles of digital audio and physics. And when they cite studies, it's always a questionable outlier, not studies that have been peer reviewed and verified by others before becoming generally accepted. I guess if you're going to lie, you might as well lie big. It's surprising there are any cherries left to be picked!

 

[Dogmatrix]

My experience of CEOs in audio manufacturing is the role is predominantly marketing

 

[Dogmatrix]

Found this recently a short paper on tribalism, it talks about political aspects but I think it is easily transferable to our context

https://www.researchgate.net/publication/333673884_Tribalism_Is_Human_Nature

 

[castleofargh]

As a kid, my stepfather explained this to me with Coca-Cola VS Pepsi, and Canon VS Nikon. I didn't get it at first, as I thought that only monsters could willingly pick Pepsi.

 

[Moonglum]

As a kid, my stepfather explained this to me with Coca-Cola VS Pepsi, and Canon VS Nikon. I didn't get it at first, as I thought that only monsters could willingly pick Pepsi.

I've spent a lot of my academic career working on group dynamics and in particular prejudice and discrimination. One of the key theories I deployed in my work was called social identity theory and it shows we have a natural tendency towards categorising the world into in versus outgroups and that the ingroups come to form part of our self and identity, meaning we link our self esteem to our groups. I teach a class about social psychology and I also discuss evolutionary approaches in the lecture on prejudice - I think they are compelling when it comes to "tribalism" - evolutionary approaches postulate, with some evidence, that banding together in communities carried clear survival value for early humans, and distrusting strangers made sense in this context where it wasn't worth taking the risk that an unknown human might cleave your skull in. So it made sense to be hostile towards outsiders, stereotype them all as potential deadly threats, and so on. And to revere the ingroup because the ingroup looked after you and your survival depended on them. Evolution shows humans are pretty slow to change. These feelings we have to distrust outsiders are deep seated evolutionary remnants in my view. At least that is part of the picture. Interestingly research also shows that virtual environments can exacerbate feelings of social identity and so you can sometimes get more prejudice expressed online - it's not just the anonymity offered by fake names and avatars, it's something to do with how social identity can be stronger online. I frequent a lot of photography forums and have noted the tribalism associated with brands - Sony vs Canon vs Nikon vs Fuji etc

 

[Moonglum]

My experience of CEOs in audio manufacturing is the role is predominantly marketing

Not Paul, he helps design the products as well - he's actually a nice guy whatever you think about his support of products that you may think are dubious - I know people who have toured the PS Audio facility and spoken to him and he is a real fan of music and hi fi and a gracious host

 

[bigshot]

There's a history behind this group. The people in this forum used to be part of the in group, but we were forced to create an out group for ourselves. We used to participate in all of the forums on Head-Fi. But apparently advertisers weren't happy with discussions of double blind testing and bias. Bad for business. So they banned discussion of those topics from the whole site... except for our little banishment group where we can discuss that without disturbing the delicate sensibilities of high end audio salesmen. We aren't a tribe by choice. It was enforced upon us. This little group is the only place we're allowed to speak freely. That's why we're a bit protective of it. You can also see why we're sensitive to the smell of snake oil.

I'm sure that salesman is a very nice guy. Why doesn't he stop in and graciously share some of his friendliness with us here in Sound Science? We could have a party! Invite him next time you see him.

 

[Moonglum]

There's a history behind this group. The people in this forum used to be part of the in group, but we were forced to create an out group for ourselves. We used to participate in all of the forums on Head-Fi. But apparently advertisers weren't happy with discussions of double blind testing and bias. Bad for business. So they banned discussion of those topics from the whole site... except for our little banishment group where we can discuss that without disturbing the delicate sensibilities of high end audio salesmen. We aren't a tribe by choice. It was enforced upon us. This little group is the only place we're allowed to speak freely. That's why we're a bit protective of it.

I'm sure that salesman is a very nice guy. Why doesn't he stop in and graciously share some of his friendliness with us here in Sound Science? We could have a party! Invite him next time you see him.

Interesting I was unaware of that history. of course you also have an entire website that focuses on measurement, ASR, and the tables are turned there for anyone who is not committed to a measurement approach. The sarcasm about Paul from PS Audio is a bit uncalled for tbh - have you met him yourself? Is there some default position on this forum that anyone associated with an audio manufacturer is an evil charlatan?

 

[castleofargh]

I've spent a lot of my academic career working on group dynamics and in particular prejudice and discrimination. One of the key theories I deployed in my work was called social identity theory and it shows we have a natural tendency towards categorising the world into in versus outgroups and that the ingroups come to form part of our self and identity, meaning we link our self esteem to our groups. I teach a class about social psychology and I also discuss evolutionary approaches in the lecture on prejudice - I think they are compelling when it comes to "tribalism" - evolutionary approaches postulate, with some evidence, that banding together in communities carried clear survival value for early humans, and distrusting strangers made sense in this context where it wasn't worth taking the risk that an unknown human might cleave your skull in. So it made sense to be hostile towards outsiders, stereotype them all as potential deadly threats, and so on. And to revere the ingroup because the ingroup looked after you and your survival depended on them. Evolution shows humans are pretty slow to change. These feelings we have to distrust outsiders are deep seated evolutionary remnants in my view. At least that is part of the picture. Interestingly research also shows that virtual environments can exacerbate feelings of social identity and so you can sometimes get more prejudice expressed online - it's not just the anonymity offered by fake names and avatars, it's something to do with how social identity can be stronger online. I frequent a lot of photography forums and have noted the tribalism associated with brands - Sony vs Canon vs Nikon vs Fuji etc

Off topic. Amazon deciding to close DPReview made me almost as sad as when learning that someone I admire was dying.

 

[FunkyBassMan]

they banned discussion of those topics from the whole site...

This is a lie. There are plenty of discussions of these topics all over this site.