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Re: Audible differences

Good post.

I don’t disagree with you really. We are maybe talking about semantics.

“”Suppose some person is a designer and he believes it's possible for audible differences between power amplifiers to exist without there being any measurable difference between them. You might think this would make him a better designer than someone who thought otherwise.””

YEEP! And why?

Because he probably have made a lot of listening tests alongside with the electrical distortion measurements he also made. I have great respect to guys like John Curl and his likes with a lot of years of experience regarding audio amplifier design.

“”measuring everything we know how to measure””

This is actually one of my main points. Do we know how to measure the audible differences we experience? Are we really measuring the right things? Suppose again that we have two amplifiers A and B and both measure the same when measured with a purely resistive load with ordinary THD measurements and two tone IM measurements.

But the designer of amplifier A have also made measurements with LCR networks that simulate the overall impedance of real loads and also with real loudspeakers. And he has also made measurements with multitone test signals (witch actually resembles a real music signal much better than a single sinus tone, because the probability density functions are more like each other). And above that also made a lot of listening during the design process. The designer have adjusted his design according to this.

Meanwhile designer of amplifier B have only made ordinary THD measurements and two tone IM measurements with a purely resistive load.

And suppose that at a scientific listening test the listeners can determine that amplifier A is audibly superior to amplifier B, then I believe that there are differences when we start to do the extensive tests made to amplifier A.

My point is that we maybe are doing the wrong tests and because of that can’t see the differences experienced during listening. How many manufacturers have you seen that provide these extended measurements?

Sometimes (and especially with revivers) there are a expectance effect saying that the more expensive amplifier should be better, BUT as an designer/manufacturer you really want the cheaper solution to be the better to be able to compete on better terms.

“”So while having the view that it's possible for audible differences to exist without any measurable differences might make a designer appear very open-minded, there really is little practical application of such a view. “”

Experience my friend, experience. That is very important because a skilled designer (In my book) have learnt trough the years that audible differences may exist without any measurable differences, and adjusted his design according to this. But someday we might find a solution to this and learn how to measure the differences.


Enjoy Creating / Mad Man Harju


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