"Nothing new under the sun"? The challenge of evaluating audio equipment

[HUG-1]

This thread relates to the challenge of evaluating audio equipment. We may think that this is a new challenge, but turning the written technical specification into an universally agreed subjective score is a very old problem indeed - as we will show.

[HUG-1]

A reader of HiFi News writes about the poor correlation between the manufacturers technical specifications and how a loudspeaker actually sounds. The author comments that since his first interest in audio in the 1940s scant attention has been given to this subject.

It's shocking how little progress has been made since 1970 (or even 1940s) despite the millions of words written by journalists over that period.

(The Harbeth company was founded in 1977. In 1970 the current BBC monitor would have been Dudley Harwood's LS5/5, and the LS3/5a had not been invented.)

[Paul G Smith]

It's shocking how little progress has been made since 1970 (or even 1940s) despite the millions of words written by journalists over that period.

It's interesting to note that the content of the letter from the MCPS immediately above Mr. Harms' is also still as pertinent.

[A.S.]

It's interesting to note that the content of the letter from the MCPS immediately above Mr. Harms' is also still as pertinent.

And again, from the archives, I stumbled across this letter from the highly regarded audio engineer, Reg Williamson - who knew a thing or two about amplifier design.

"The language of hi-fi" - a reader's letter from Wireless World magazine October 1977, the year of Harbeth's founding. What's changed? And is it just the audio industry which is deeply conservative? Mr. Williamson's plea about the responsibilities of journalists to convey technical matters may have gone unheard. Regarding the point he makes in his closing lines about chasing absurdly low distortion figures we are covering distortion here.

To illustrate his comment, harmonic distortion of several percent is very normal and an unavoidable by-product of wiggling a diamond on the end of a rod in a channel hot-cut into a plastic disc - i.e. the gramophone record. But it doesn't seem to bother those who enjoy vinyl and hence, achieving 0.0004% distortion is an exercise in futility.

>

[EricW]

Terrific letter, that.

It makes me wonder. In the past, you've added noise to a digital track to simulate the sound of an LP. But there's a difference between noise, which is random, and harmonic distortion, which is by definition non-random.

Would it be possible to add a carefully contoured amount of harmonic distortion to a clean digital recording to more closely simulate the LP experience? And might some listeners actually prefer the sound to that of a completely undistorted signal?

("Distortion" is such a negative word - maybe we should call it "harmonic enhancement".)

[Labarum]

Try this

http://www.izotope.com/products/audio/vinyl/

[HUG-1]

Anyone able to pass some audio through this software device and let us hear degrees of 'enhancement'?

[EricW]

It seems to offer control over a number of parameters, but not - unfortunately - harmonic distortion. Maybe there's a business opportunity here! (But if there is, I claim trademark rights over the term "harmonic enhancement".)

[Labarum]

Try the AddDistortion App here

http://www.audiosignal.co.uk/freeware.html

and read

http://www.aes-uk.org/category/past-meeting-reports/

Which I have not yet had time to digest.

[Paul G Smith]

And again, from the archives, I stumbled across this letter from the highly regarded audio engineer, Reg Williamson - who knew a thing or two about amplifier design.

"The language of hi-fi" - a reader's letter from Wireless World magazine October 1977, the year of Harbeth's founding. What's changed? And is it just the audio industry which is deeply conservative? Mr. Williamson's plea about the responsibilities of journalists to convey technical matters may have gone unheard. Regarding the point he makes in his closing lines about chasing absurdly low distortion figures we are covering distortion here.

To illustrate his comment, harmonic distortion of several percent is very normal and an unavoidable by-product of wiggling a diamond on the end of a rod in a channel hot-cut into a plastic disc - i.e. the gramophone record. But it doesn't seem to bother those who enjoy vinyl and hence, achieving 0.0004% distortion is an exercise in futility.

>

but distorted distortion is surely worse again?
One lot of distortion may be acceptable, perhaps that of the microphone, but in my experience it's the combined effect of added distortions that needs to be kept to a minimum for a life-like listening experience. For distortion read anything that makes a difference between the original sound and the reproduced sound. It's not only harmonic distortion that matters. I find intermodulation distortion to be even more offensive.

[Taxman]

A reader of HiFi News writes about the poor correlation between the manufacturers technical specifications and how a loudspeaker actually sounds. The author comments that since his first interest in audio in the 1940s scant attention has been given to this subject.

It's shocking how little progress has been made since 1970 (or even 1940s) despite the millions of words written by journalists over that period.

(The Harbeth company was founded in 1977. In 1970 the current BBC monitor would have been Dudley Harwood's LS5/5, and the LS3/5a had not been invented.)

It's nice to see Wilfred Harms' name in print again. When he retired from Civil Engineering he worked for Malcolm Jones at Falcon Acoustics in Bexhill for a number of years, and was unusually helpful with customer correspondence.