Yet another bold claim...

Paul Ranson said:
The 'null test' was demonstrated by Peter Baxandall and David Hafler in two different forms way back in the 70s. The intent is to show 'subjectivists' that an amp that measures well also performs well in actual use with actual programme.l
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Precisely, Paul!
My test, is a refinement of the David Hafler test , with the added bonus that you can even null test Op Amps .


[[ The fact that many 'hifi' amps are actually very poor (but obviously they 'sound' good) is really beside the point.]]

This is a very interesting point ,but if you put the pot of the amp under test in the null position (voltage at the input of the pot equal to voltage at the output of the amp ) and with another amp connected to a speaker , you can compare the sound that come from the CD , to the sound at the output of the amp.
That way , you will see (ear) that the sound at the output will be warmer ...more euphonic that the input, because the harmonic distortion will add to the signal, as they are indeed harmonics of the original frequencies. And some people like this added warm.

[[ The statement that all competently designed amps operated within their limits sound the same isn't challenged.]]

Of course ...two amps with a very good null (only thermal noise ) obviously will sound the same.

[[ TD should tell us how big the residue is relative to the output, after all being able to measure something doesn't imply that it's audible.]]

As i have shown to Michael and BD , in my best amp , the null playing music and connected to the speaker is only thermal noise... :MILD:

[[ You've clearly completely missed the point of the null test ]]

Happily you don't...fine!


[[ The elegance is that crap test gear means you get a worse null.]]

Yes Paul...you nail it...


Regards

Jorge
 
wadia-miester said:
an indicator.
Like the clear ones that Bimmers use to frighten old farts on bikes
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When do Bimmer drivers use these, that's not in the handbook, they only time I've seen bimmers with their indicators on is double parked with hazards on to save the lazy sod from walking 20 yards up the road.
 
bottleneck said:
Does anyone else see this as a flaw in reasoning?
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I do!

[[ You then have a pair of speakers and a CD player that were not purchased with a flat frequency response and zero distortion in mind.]]

All the speakers manufacturers try to achieve a flat frequency response and virtually all CD players are ruler flat in the audible frequencies...

So if for you measures means nothing , how if the man don't use the meter and the multiple Km, what was the meaning of me saying that England is far from Portugal...I can also say that Portugal is far from Spain and is much closer...

Without measuring we are only guessing...
 
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bottleneck said:
The fact that he is unlikely to do so is surely because he LIKES the sound of his speakers and CD player. This completely undermines the methodology of using Null testing as a method of picking hifi components. After all, if the philosophy applies to one audio component it surely applies to the entire system.

Does anyone else see this as a flaw in reasoning?
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No. I can see what you're driving at but I don't agree. It might seem like an attractive idea that you can somehow mix and match components so that their respective distortions cancel each other out and the end result is distortion free but that's surely a recipe for madness. IMO you should never choose any component to act as a "tone control" to compensate some other bit of equipment in the chain. That way lies never ending box swapping and never being satisfied with what you've got.

Null testing, AFAIK, can only be practically applied to devices which have an analog input and an (electrical) analog output. That basically means amps, preamps and cables. Still if you can get those bits to be "perfect" that IMO would be an excellent start. Then you've at least narrowed down the number of variables in your system to just the source and speakers.

It is, in theory, possible to do a form of null test equivalent on CDPs and even speakers. Keith Howard explored this a little in a couple of articles for HiFi News a while back (May/June 2003). Basically, the idea is to use an ADC to convert the analog signal at the end of the chain back to digital and then compare it with the original WAV file on the CD and, since you're clearly never going to get exactly the same data back, do a statistical analysis to compare the two to come up with a value for how different they are.

In theory this could even go as far as including speakers (and therefor the room) into account, but then you've also got to take include the mic recording the in-room sound into the equation. KH used just a CDP on its own, digitially recording the analog output of it. He used the technique to demonstrate that a Townshend Seismic Sink and a special mains cable he tested had no significant effect. OTOH (and surprisingly) it showed that the Ringmat "Statmat" used on a CD did have a measurable effect, and what's more that the effect lasts for some time even after the statmat is removed.

There were still a number of problems with the technique but, if perfected, it could indeed be a very powerful tool for measuring pretty much any hifi component assuming you're starting with a CDP as a source. It has the same benefits as the null test as it's measuring in real world conditions with real music.

Michael.
 
Tube_Dude said:
That way , you will see (ear) that the sound at the output will be warmer ...more euphonic that the input, because the harmonic distortion will add to the signal, as they are indeed harmonics of the original frequencies. And some people like this added warm.
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I think that's the point for me. I am not ridiculing the null test at all. I simply cannot see that it should be used as an arbiter of whether the user will actually like the results. I happen to like my music sweetened up a bit. The vast majority of commercial recordings exhibit surprising levels of digital clipping distortion that I find unpleasent to listen to on a truly revealing system.

So if the software contains objectionable distortion, why should I want to replay that in it's full glory?
 
Michael,

I remember the article you refer to. I seem to recall that the conclusion was that the test procedure was flawed, and unable to show the differences that were audible. Was that not the case?
 
merlin said:
I think that's the point for me. I am not ridiculing the null test at all. I simply cannot see that it should be used as an arbiter of whether the user will actually like the results. I happen to like my music sweetened up a bit. The vast majority of commercial recordings exhibit surprising levels of digital clipping distortion that I find unpleasent to listen to on a truly revealing system.
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Ok...I see your point!...Nothing to argue , against a personal , subjective preference.

Cheers

Jorge
 
merlin said:
I remember the article you refer to. I seem to recall that the conclusion was that the test procedure was flawed, and unable to show the differences that were audible. Was that not the case?
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merlin - I don't remember that to be the case, but I have both articles here with me and will give them a quick browse through again.

I happen to like my music sweetened up a bit
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Nothing wrong with that, but then you can't claim to be interested in ultimate fidelity.

Michael.
 
michaelab said:
Nothing wrong with that, but then you can't claim to be interested in ultimate fidelity.

Michael.
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Nor can any of you without extensively treated listening rooms or digital room correction ;)
 
Robbo said:
No. He's probably more interested in enjoying music, which after all, is what it's all about. Or is it?
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Well, I can enjoy music on the kitchen tranny or on the car stereo or on my iPod. Ultimate fidelity isn't a prerequisite for musical enjoyment at all. However, the whole point of spending an arm and a leg on a "high fidelity" system is to get..erm...high fidelity reproduction and therefore (one would hope) much greater musical enjoyment.

Michael.
 
Robbo said:
He's probably more interested in enjoying music, which after all, is what it's all about. Or is it?
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I can enjoy the music that I like , even with my portable radio , in the shower...

But crap radios ,are not what Zero Gain is all about.

Or is it?
 
michaelab said:
merlin - I don't remember that to be the case, but I have both articles here with me and will give them a quick browse through again.
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Well, you were right. He said that the test system failed to show any difference when using his Perp. Tech P1A upsampler, the "resolution enhancement" feature was switched on or off. A difference he claims (and so do many others) is "quite marked".

So, he concludes that the test methodology is not yet mature enough, or doesn't yet have the resolution to identify some changes which are (apparently) clearly audible.

Still - the results he obtained were interesting and the methodolgy certainly has the potential to be a fantastically useful tool.

Michael.
 
Robbo said:
No. He's probably more interested in enjoying music, which after all, is what it's all about. Or is it?
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Robbo,

You would be surprised how close related the two things are:

Enjoying music => Accuracy. You only can enjoy music with accuracy... unless you like your equipment as being part of the music.

However, accuracy doesn't necessarily means enjoying music...
 
I'd like to know why you think it is. Let me guess, becuase it uses FETs and not bi-polar output devices, which apparently measure worse. That may be, but I wouldn't want to make a claim about the amp as a whole without measuring the amp as a whole.

Michael.
 
BerylliumDust said:
Robbo,

You would be surprised how close related the two things are:

Enjoying music => Accuracy. You only can enjoy music with accuracy... unless you like your equipment as being part of the music.

However, accuracy doesn't necessarily means enjoying music...
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I don't know if I missunderstand your words but they are millions of people who enjoy music without accuracy. And I would bet they enjoy music more than others who look for accuracy in their or others reproduction system.

For me a valid reference point for finding out how much someone is really enjoying music, is how much he talks about music and not technical analysis of hardware. ... for example if he ever posts messages in the music section... :rolleyes:
 

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