WiiM Amp

[Steve Woodhouse]

Honestly I think that the THD+N doesn't define an amplifier and tells you almost nothing about how it will sound, nonetheless it is a parameter to be taken into consideration (especially in case of weird values).

It’s certainly not the only parameter, but it’s a very important one. If one amp’s distortion and/or noise levels are high and well within human audibility, and the next one has very low levels, outside the limits of human audibility, then the latter amp will sound better, if by better we mean more transparent to the source - if anyone means something different, they have a responsibility to flag up a massive government health warning on all their comments.

Ideally, an amp shouldn’t sound like anything. It should take the signal it receives, increase it to a level high enough to drive your speakers, and do nothing else.

The measurable parameters we can measure are frequency response (is it flat and full range), what's the total harmonic distortion, is there an issue with crosstalk, what’s the level of noise. We also need to know how much power it can chuck out before any of the above become noticeable.

And that’s it. All of the above have been scientifically proven to show to what extent any amp colours the signal. Nothing else has been shown to do so (my apologies if I’ve missed anything),

If anyone knows of any other parameter, please let us know, and provide documented evidence that there’s a measurable factor that shows how an amp will sound.

 

[Mr Ee]

The price tag

 

[onlyoneme]

And that’s it.

It's just a beginning.

For example:

(Suggestion on) Testing power amplifiers according to IEC 60268-3 standard

(Suggestion on) Testing power amplifiers according to IEC 60268-3 standard I would like to start the debate on ASR power amplifier testing and suggest some degree of conformance with current standards. --------------------------------------------------- The part 3 of IEC 60268 applies to...

www.audiosciencereview.com

Handling a complex load by power amplifiers

Handling a complex load by power amplifiers A power amplifier’s job is to supply a voltage to a loudspeaker and then to deliver whatever current the loudspeaker needs to move its voice coil, producing airwaves with a sound pressure level up to what is specified for the speaker and/or...

www.audiosciencereview.com

And also:

Distortion Surface: old measurement, new approach

Distortion Surface: old measurement, new approach The following metric is typically included for amplifier manufacturers’ specifications: THD+N <...

www.superbestaudiofriends.org

"We need to move on and use distortion measurements that are perceptually meaningful."

An updated post

www.audiosciencereview.com

 

[Steve Woodhouse]

It's just a beginning.

For example:

(Suggestion on) Testing power amplifiers according to IEC 60268-3 standard

(Suggestion on) Testing power amplifiers according to IEC 60268-3 standard I would like to start the debate on ASR power amplifier testing and suggest some degree of conformance with current standards. --------------------------------------------------- The part 3 of IEC 60268 applies to...

www.audiosciencereview.com

Handling a complex load by power amplifiers

Handling a complex load by power amplifiers A power amplifier’s job is to supply a voltage to a loudspeaker and then to deliver whatever current the loudspeaker needs to move its voice coil, producing airwaves with a sound pressure level up to what is specified for the speaker and/or...

www.audiosciencereview.com

And also:

Distortion Surface: old measurement, new approach

Distortion Surface: old measurement, new approach The following metric is typically included for amplifier manufacturers’ specifications: THD+N <...

www.superbestaudiofriends.org

"We need to move on and use distortion measurements that are perceptually meaningful."

An updated post

www.audiosciencereview.com

I’m not sure most of the points there are saying what you think they say.

I’m quite in agreement that, beyond a certain level (a level we may well have passed a long time ago), there’s little difference in many modern amps for THD+N (for example).

That doesn’t mean it’s not a parameter we can measure, and which we know sounds bad in the worst circumstances.

I personally feel that, unless something is badly broken, within the constraints of trying to get an underpowered amp to drive difficult speakers, most amps are much of a muchness.

What I'm talking about, and warning against, is the idea that some high-end manufacturers have managed to (a) discover some previously unthought of parameter which makes a difference to an amp’s sound (b) they’ve sorted the problem, (c) sorting it costs a fortune, (d) they're not telling anyone what it is, and (e) it’s not measurable.

 

[canard]

pour rappel à l'utilisateur il est déjà possible de faire un joli montage en passe haut en utilisant le mode peq...

 

[onlyoneme]

I’m not sure most of the points there are saying what you think they say.

I’m quite in agreement that, beyond a certain level (a level we may well have passed a long time ago), there’s little difference in many modern amps for THD+N (for example).

That doesn’t mean it’s not a parameter we can measure, and which we know sounds bad in the worst circumstances.

I personally feel that, unless something is badly broken, within the constraints of trying to get an underpowered amp to drive difficult speakers, most amps are much of a muchness.

What I'm talking about, and warning against, is the idea that some high-end manufacturers have managed to (a) discover some previously unthought of parameter which makes a difference to an amp’s sound (b) they’ve sorted the problem, (c) sorting it costs a fortune, (d) they're not telling anyone what it is, and (e) it’s not measurable.

You don't know what I think so you cannot be sure at all.

All these sources provide conclusions that simple sinad measurements are not enough, they are meaningless or even useless. Especially when talking about perceptual aspects of the audio.

 

[Steve Woodhouse]

You don't know what I think so you cannot be sure at all.

All these sources provide conclusions that simple sinad measurements are not enough, they are meaningless or even useless. Especially when talking about perceptual aspects of the audio.

No they don’t.

Again, the onus is on you to state specifically what other aspects of amplifier make a difference, scientific evidence that they do make a difference, and evidence as to how some models have solved the problems caused whilst others haven’t.

By ‘perceptual’ you just mean “I can hear it”. That’s not actually adding anything to the discussion at all.

 

[onlyoneme]

No they don’t.

Again, the onus is on you to state specifically what other aspects of amplifier make a difference, scientific evidence that they do make a difference, and evidence as to how some models have solved the problems caused whilst others haven’t.

By ‘perceptual’ you just mean “I can hear it”. That’s not actually adding anything to the discussion at all.

If you want to talk about 'how X sounds' then you will have to consider perceptual aspects. And, again, I think I know better what I mean or what I think.

And I would say that quotes like below are quite self-explanatory:

"There isn't much controversy about THD+N noise measurements being of limited use. It's been known for some time but people continue to use them because they are easy to make. We need to move on and use distortion measurements that are perceptually meaningful."

Of course you can disagree. You can even think that sinad equality means audio sound equality.
So, all I will point out is that for some people the measurements you noted as "and that’s it" are in fact just a beginning.

 

[musig]

It’s certainly not the only parameter, but it’s a very important one. If one amp’s distortion and/or noise levels are high and well within human audibility, and the next one has very low levels, outside the limits of human audibility, then the latter amp will sound better, if by better we mean more transparent to the source - if anyone means something different, they have a responsibility to flag up a massive government health warning on all their comments.

Ideally, an amp shouldn’t sound like anything. It should take the signal it receives, increase it to a level high enough to drive your speakers, and do nothing else.

The measurable parameters we can measure are frequency response (is it flat and full range), what's the total harmonic distortion, is there an issue with crosstalk, what’s the level of noise. We also need to know how much power it can chuck out before any of the above become noticeable.

And that’s it. All of the above have been scientifically proven to show to what extent any amp colours the signal. Nothing else has been shown to do so (my apologies if I’ve missed anything),

If anyone knows of any other parameter, please let us know, and provide documented evidence that there’s a measurable factor that shows how an amp will sound.

I agree on the whole line, I was just meaning that unless THD+N has very anomalous values, it becomes a measure with little impact on the final experience. Unfortunately, in the end, we don't hear the sound of the amplifier but the whole chain which starts with a source and ends in speakers which are placed in room with many other aspects that inject sensible impact on the listener experience. Back to your list, I would also add to the list of the useful parameters the electrical relationship between the output stage of the amp and the impedance of the speakers which is often named "dumping factor" as it gives a (rough) idea of the dynamic of the system.

Enjoy the music!

 

[Smartplug]

Let’s take a look frequency response its ruler flat but when you listen to them it has its own house signature. Denon/marantz vs yamaha/onkyo for instance. I owned both brand and even on untrained ear could hear the difference between brands. So, if frequency is flat as ruler are they supposed to sound identical? All these measurements on asr are good but are they audible? Can someone tell difference between snr 150 vs 160? The measurements can but can the human ear tell that? They all look good on paper but once cross the threshold human hearing all that stuff is just a moot.

 

[harkpabst]

@Steve Woodhouse, @onlyoneme, it doesn't look to me like your positions are really that far apart. You agree on the importance of objective measurements in general, don't you? You're both not into the golden ears paradigm at all.

Historically, too may engineers did not really follow good engineering practice when it comes to audio: If what your modesl predicts and your measurements don't align with reality (and reality is human hearing), the you should update them. Human hearing might be individual to a certain degree, but if the reproduction equals the original perfectly, if the sound pressure waves surrounding the listener are exactly as in the original sound event, then the reproduction will be perfect for every listener, regardless of individual perception.

Human perception of sound is also measurable, of course. Not in the sense of directly taking technical measurements. But there are scentifically proven psychometrical methods and concepts like double blind ABX testing are no secret.

 

[onlyoneme]

I wouldn't waste my time on measurements if I didn't think they were important. But I'm also against oversimplification and unjustified conclusions, which are quite common in the measurements world.
But yes, if I say that something is a beginning then I do not contradict it itself, so my position cannot be too far apart

 

[onlyoneme]

but if the reproduction equals the original perfectly, if the sound pressure waves surrounding the listener are exactly as in the original sound event, then the reproduction will be perfect for every listener, regardless of individual perception

The physical reproduction, yes, but not the perceived reproduction. Not everyone consider a perfect fidelity as an attribute of the perfect sound quality.

 

[harkpabst]

The physical reproduction, yes, but not the perceived reproduction. Not everyone consider a perfect fidelity as an attribute of the perfect sound quality.

Right, but that's personal taste then.

Everyone is entitled to have that, of course. As long as everyone doesn't mix up taste and facts.

 

[onlyoneme]

As longs as everyone doesn't.mix up taste and facts.

You are demanding too much. Most of the people calls the system which better suits their taste, simply as better sounding.

 

[harkpabst]

You are demanding too much. Most of the people calls the system which better suits their taste, simply as better sounding.

I'm pretty sure that I have fallen into this trap myself on more than one occasion.

 

[Mr Ee]

'dumping factor"

Well, I suppose it does dump sound into the speakers!

I was reading about this a week or two back on one particular manufacturer's blogs (tbh, can't recall which one), and (again, iirc) they pretty much stated that once it got to about 350, any more was irrelevant.

 

[harkpabst]

I was reading about this a week or two back on one particular manufacturer's blogs (tbh, can't recall which one), and (again, iirc) they pretty much stated that once it got to about 350, any more was irrelevant.

Almost 50 years ago, Floyd E. Toole concluded that almost no advantage could be gained from a damping factor higher than around 25.

The argument is built on the rationale that the voice coil's DC resitance is actually limiting how match damping of the fundamental electro-mechanical resonanance can be achieved. If the amplifier's output resistance was exactly zero, the equivalent electrical circuit describing the entire arrangement still includes RDCVC as the limiting factor.

Cable length can be a different story, but usually rather in pro audio (or maybe very complex HT installations). Having a little extra margin by means of low amplifier output impedance doesn't hurt in this case. But it's by far not as efficient as one might assume, because it won't help with cable inductance (becoming meaningful with long runs of cable).

Here's a link to a somewhat more recent paper (published in 2015) summing things up quite nicely.

https://www.l-acoustics.com/wp-content/uploads/2021/10/RS2015-Cable_Effects.pdf

We haven't even touched the influence (or not) of frequency dependancy of the DF.

And still I'm not sure if the dumping factor could be much more important and maybe becoming the next hot shiit of Audiophilia.

 

[wiimamp user]

Yes, put your headphones into pairing mode, then set the Amp's audio output to Bluetooth

I did connect my Dali headset via the app to my Dali. It says connected.I can see it on the app.

I hear the music through my Dali headset.
But the music keeps randomly falling out for a second or so. Music keeps playing but then randomly is fall out again.
Do i do something wrong? Could this be an issue with the wiiamp?

 

[Brantome]

I did connect my Dali headset via the app to my Dali. It says connected.I can see it on the app.

I hear the music through my Dali headset.
But the music keeps randomly falling out for a second or so. Music keeps playing but then randomly is fall out again.
Do i do something wrong? Could this be an issue with the wiiamp?

It’s possibly an issue for a few WiiM models given reports here and elsewhere. Submit a ticket - the more who do, the better chance they have of fixing it. Make sure you identify the make and model of the headphones.