Why We Measure Audio Equipment Performance

[captrajesh]

Found this interesting article while browsing.

Why We Measure Audio Equipment Performance | Audioholics

Check it out. Forum open for comments.

Disclaimer: I do not subscribe to the views of the writer; in fact I contest some of what is written but nevertheless posting the article and soliciting healthy debates

 

[square_wave]

I think we are beating a dead horse.

Without measurements and careful analysis and study, none can design audio gear. But one needs to think beyond all these with a holistic and open mind once these engineering criteria are attained. These arguments are definitely valid when dealing with folks who try to sell you lemons which does not meet basic engineering criteria. But not at all valid when dealing with gear designed by folks who have gone beyond.

Many a times, I have seen websites like these dismissing anything which is beyond their comprehension or because they have an extremely closed mindset. Please keep in mind that all these websites have something to sell you philosophies and then products that ride on it. But of course, it is a good place to hangout - to understand the important engineering basic s in audio so that one is not taken for a ride by charlatans. But when they say that there is nothing beyond, it is hard to digest.

 

[captrajesh]

Great post Square_wave, thank you for putting across your point very articulately.

 

[Thad E Ginathom]

Interesting article, and possibly more balanced than most on the topic.

I've passed by Audioholics previously, but have now read some of their articles due to your links. It's a great food-for-thought site

 

[captrajesh]

I expected some sparks to fly but none of that sort happened! Time to revive the thread.

 

[keith_correa]

soliciting healthy debates

I expected some sparks to fly but none of that happened!

Paradoxical

 

[captrajesh]

Paradoxical

Not really. While as a moderator I was soliciting healthy debate, it is quite common for sparks to fly (It is happening right now in another thread)

Wanted to sensationalise la Indian media; egging upon members to participate.

 

[Nikhil]

I'll bite ... the subjectivist vs objectivist debate is one that consumes a fair bit of internet bandwidth so will not get into all of that. However, here are some interesting experiences I've had recently.

A cable manufacturer has a cable which is the rage right now and I am considering it along with a fellow audio enthusiast. My friend wrote to the designer and asked about the specs being followed for the manufacture of the cables. To my surprise the reply that came back was that the cables that were made to spec did not sound very good in tests. So as a result the cable is made with a particular sound in mind which of course makes it deviate from specifications. At least the designer was up front in admitting that he actively voiced the cables to something he felt was desirable.

Another interesting example is a software that I am using right now. The developer makes no bones about explaining how he gets the sound clearly stating on his website that he can't provide any scientific basis for the sound. But the sound from this player is really right up there with among the best software out there.

Regards.

 

[Fantastic]

Basic tests on audio systems is useful,to get an 'idea' about what it might be like. Once above a certain level of specs it is necessary to listen to the system to evaluate it as current tests are not able to 'reveal' some differences.
Maybe we aren't looking at the right places. However people keep coming up with special test signals hoping that it will reveal'everything' about the sound of a system.I haven't seen one that is perfect, yet.

Take for example , if the HF rolls off after 10 Khz by measurement. In some systems it could sound 'soft' or slightly 'dull'. But there are many tube systems that start rolling off by 10 or 15 Khz and have no audible loss of HF .
Same thing with damping factor. Some systems with a damping factor of say 500 don't have as much control over large bass drivers as other systems with just 50 as a damping factor. But if the damping factor is 4 you could expect issues with the bass response. So some measurements reveal only 'some performance factors'.

So while current measurements can't reveal all about the system, it can tell us in what ballpark area it is in now.So , yes, measurements can be helpful.

As always the 'ear' is the final judge. A system that measures poorer than others might end up being the best sounding one.This also means that you can "pick" a great system without any measurements at all ! If it "sounds" the best to you , then it is the best ...for you !That's all that matters.

Currently measurement results are like the 'cover of a book' . 'Marketing people' try to tell you that the system is 'great' by publishing great looking numbers. You could also be taken up by it. Like frequency response 0Hz to 1 Mega Hertz ! Distortion 0.0000001% etc. Did that excite you ? It could be an average sounding amp ! In the 80's the Japs made amps with vanishingly low distortion figures and most didn't sound too good. That trend has now changed. It's like a book with a black cover or no cover at all ! You wouldn't even notice it or pick it up. But the contents could be amazing. You need to 'spend time with it' to discover what's great about it ! Same with audio systems. Don't get carried away by looks or specs. LISTEN to them. Many great sounding Single Ended tube amps have distortion figures of a few percent ! Did that distortion figure tell anyone how it would sound ?

What software are you talking about Nikhil ?

 

[captrajesh]

Nikhil & Fantastic, you both have validated the fundamental principles which I too believe firmly. But many of the forum members don't seem to have enough faith on their own ears. How do we deal with the situation!?

 

[jls001]

Nice article, though a bit dumbed down at times.

Measurement is essential but unfortunately insufficient to quantify the whole audio phenomena. The article itself clearly says,

Quote:
Even if we measure a loudspeakers listening window (on/off axis response) and power response (frequency response 360 degrees around the loudspeaker), it still doesnt give you all the information on how it will play or more importantly sound in a real room. Its often difficult or near impossible to quantify in measurements the airiness and depth in soundstage a loudspeaker can portray in a room.
Unquote

(emphasis mine)

It is part science, part art. Case in point - The Blowtorch preamplifier is often attributed as a design of electronics designer John Curl. But he was helped by two important collaborators - one guy listened and chose the best sounding components. Presumably they would have made many prototypes, cycled through different makes/models of a particular components then chose the best sounding one for that particular application. The third guy designed the layout.

The circuit topology is John Curl's, but the voicing is someone else's. The topology and handpicked parts may not have worked so well were it not for the optimised layout by yet another person.

Circuit theory is sufficient to describe the design part. Good layout practices are now well known. But now, how would one quantify "best sounding" parts in numbers and physically measurable attributes? A Dale resistor probably measures the same as a Kiwame resistor, and both probably have the same tight tolerances. But many designers and DIYers are of the opinion that they somehow sound different.

Pure "objectivist" is naive. As is pure "subjectivist". It's a judicious mix of both. IMHO, of course.

 

[sidvee]

Pure "objectivist" is naive. As is pure "subjectivist". It's a judicious mix of both. IMHO, of course.

Well said, and I subscribe to that school of thought also.
Cheers,
Sid

 

[captrajesh]

Circuit theory is sufficient to describe the design part. Good layout practices are now well known. But now, how would one quantify "best sounding" parts in numbers and physically measurable attributes?

Very valid point Joshua. Hope some "Objectivist member" can answer.

A Dale resistor probably measures the same as a Kiwame resistor, and both probably have the same tight tolerances. But many designers and DIYers are of the opinion that they somehow sound different.

Based on actual listening experience, their opinions I'm sure are not misplaced.

Pure "objectivist" is naive. As is pure "subjectivist". It's a judicious mix of both. IMHO, of course.

Considering that the experience of listening to music (for most of the living things) is purely "subjective", it can't be brushed aside as naivity.

When I got into the hobby, I first experienced it subjectively before my good friend Sashi attributed the experiences to measurements.

I'll quote a couple of examples from my experiences.

My first hifi speakers that were driven by Denon PM520 sounded with much better midrange clarity when paired with the CDA254 Class D Audio amplifier. When Sashi explained that it is due to the better THD, I learned what THD is.

The loose bass when paired with the Class D amp totally disappeared when it was replaced with a Nacamichi preamp and Rotel Power amp combo. When Sashi attributed it to the Rotel's superior damping factor, I learned what damping factor is.

My point is, since music listening is connected to your heart (being an emotional experience) rather than the brain, one can pick a good sounding system without analysing it objectively.

 

[square_wave]

Honestly, I object to the word subjectivism being used in an absolute manner. The fact remains that there is no absolute consensus between different audio makers (experts) about the parameters that contribute to the resulting musical experience of a piece of equipment or combination of equipment. This means that the jury is still out on objectivism in audio manufacturing to some extent at least.

The subjectivity in human perception adds to the confusion.

Till date I have not heard a spectacular music system that was assembled based on objective parameters alone. An objectivist can argue that all high performing gear are indeed manufactured based on objective parameters. The counter argument is that beyond a certain price point, such difference cannot be heard in a DBT ( the mainstream veriety) which is the tool of an objectivist. This means that if a manufacturer has gone beyond that point of arbitration of DBT while manufacturing gear, you have pretty much entered the realm of ART so such gear cannot be used by an objectivist while assembling a system.

 

[Nikhil]

I don't think most who are new to audio are very objective so to speak.

Objective analysis is an 'advanced' subject which forums like Hydrogen Audio preach and revel in - most of us would get banned in a heartbeat on there.
I like to think that most of us have a predisposition towards the subjective side of things.
The technical specs are mentioned usually when they are in agreement with our opinions.

 

[keith_correa]

My point is, since music listening is connected to your heart (being an emotional experience)rather than the brain,...

It probably affects your "heart" medically. But with what you implied, the reference to the heart is actually a reference to the brain too since the "heart" is incapable of "emotions" in isolation. So, it's the brain in tandem with the heart. Now where does that leave us? And the effect on the heart is a reaction. It's AFTER the listening is processed. Aren't we talking of DURING the listening? Does the heart come into play at this time? Am I nitpicking? Yes!

one can pick a good sounding system without analysing it objectively.

And do you agree that one can pick a good sounding system by analyzing it objectively?

 

[raghupb]

Measurements initially are required to match equipment to a certain extant.
After that it is just the subject and content.
Music to you may be noise to me and vice versa. So strike out content too. It is just the subject.
In the end, Keith's signature sums it up nicely.

Cheers,
Raghu

 

[captrajesh]

It probably affects your "heart" medically. But with what you implied, the reference to the heart is actually a reference to the brain too since the "heart" is incapable of "emotions" in isolation. So, it's the brain in tandem with the heart. Now where does that leave us? And the effect on the heart is a reaction. It's AFTER the listening is processed. Aren't we talking of DURING the listening? Does the heart come into play at this time? Am I nitpicking? Yes!

Looks like you've taken the literal meaning literally to heart.

I'm sure you know this already but for record; both emotions and logical reasoning are parts of brain function but are processed at different parts of the brain. Music would have no direct effect on heart IMO.

So be it Subjective or Objective analyses, they all happen at the top story vonly; No confusions there I hope.

do you agree that one can pick a good sounding system by analyzing it objectively?

I don't know. I'm a true believer of subjectivism.

 

[philipreji]

An audio chain involves the source, preamp, power amp and speakers. The strength of a chain is only as good as its weakest link - that we know. As of today, an expert designer can design and implement excellent audio equipment purely on objective grounds. If finally it doesn't turn out to be as good as expected, it simply shows that the expertise of the designer was insufficient.

Nice article, though a bit dumbed down at times.

It is part science, part art. Case in point - The Blowtorch preamplifier is often attributed as a design of electronics designer John Curl. But he was helped by two important collaborators - one guy listened and chose the best sounding components. Presumably they would have made many prototypes, cycled through different makes/models of a particular components then chose the best sounding one for that particular application. The third guy designed the layout.

The circuit topology is John Curl's, but the voicing is someone else's. The topology and handpicked parts may not have worked so well were it not for the optimised layout by yet another person.

Circuit theory is sufficient to describe the design part. Good layout practices are now well known. But now, how would one quantify "best sounding" parts in numbers and physically measurable attributes? A Dale resistor probably measures the same as a Kiwame resistor, and both probably have the same tight tolerances. But many designers and DIYers are of the opinion that they somehow sound different.

Pure "objectivist" is naive. As is pure "subjectivist". It's a judicious mix of both. IMHO, of course.

While circuit design and layout are the domain of the Objectivist, preferring certain components/manufacturers over others is certainly the Subjectivist area. To what extent does this modify the sound - 2%, or even 5%? Perhaps John Curl's associate really had those "golden" ears. But can such minute modifications be proved in a double-blind test involving sufficient number of experienced listeners ? I am not so sure!

I hope someone starts a thread where we list out our subjective requirements for an excellent audio system, and also the ways of designing the same objectively. For example, "airy" may be equated to "extended high frequency response", "sound staging" to "phase coherent crossing over of the drivers well below the cone breakup frequency of the woofer", etc.

cheers,
Reji

 

[keith_correa]

I'm sure you know this already but for record; both emotions and logical reasoning are parts of brain function but are processed at different parts of the brain. Music would have no direct effect on heart IMO.

So be it Subjective or Objective analyses, they all happen at the top story vonly; No confusions there I hope.

I used to think that too till I read that new research has found that the heart too plays a literal role in emotions. Google is your friend.