"High Fidelity"

[dave walsh]

Hi, I'm not sure you'll get an answer to the question-put that way anyhow! The previous responses on the thread and reading around suggested the term being used as far back as the 20's [but in relation to radio] after the initial enquiry about a thirties film recording. Then there is the possible mid forties diversion. I rather went with the notion that as home audio boomed in the US it spread to Britain [ie demos at the Royal Albert Hall] and it was then that High Fidelity became a popular term on both sides of the Atlantic.
So the "high" point seems to be from around the time of your tape machine. Whether it was denoting clearer/superior sound a wider Fr range, or an opinion, I suspect it was a response to better quality kit being available in the domestic enviroment. There are definitions and measurements but I'm not sure that there was ever an absolute standard set down by anyone in the way you seem to mean but perhaps I'm very wrong on this. It wasn't just a technical developement but also a consumer fashion so there was room for artistic license! On the other hand, something marked High Fidelity in the 50's might well have been superior to a predecessor, say a wire recorder or a fairly crude Tape Recorder [without the bias] or using a permanent magnet for erase. Anything getting up to 9k seemed pretty good at one time. In that sense "when did it actually mean something" covers whenever someone felt they were hearing something that sounded much better. No doubt Vinyl will be another story. Dave W

[Kat Manton]

Hi,

Intrigued, I've just had a look at the promotional leaflet I've received for this microphone:

The M.R. Piezo-Crystal Microphone is a high-fidelity instrument possessing many advantages over carbon and other types of microphones.

The frequency response is remarkably uniform throughout the musical scale, responsible tests showing that the characteristic is practically level from 25 to 10,000 c.p.s.

I've as-yet been unable to pin a definite date on this microphone but the same leaflet shows a schematic for a suitable preamplifier using an HL 210 triode. Early thirties is probably a reasonable guesstimate.

"Practically level" - well, I've had it connected up briefly and, while it seems rather good, my ears in 2010 say the response is "a bit lumpy."

"25 to 10,000 c.p.s." - The Marconi-Reisz carbon microphone as used by the BBC was within 2dB from 100Hz to 8kHz, so the M.R. Piezo-Crystal was "high-fidelity" in comparison. But the Marconi-Reisz was "high-fidelity" compared to earlier microphones...

Cheers, Kat

[fidobsa]

Ah, perhaps we should read "High Fidelity" in vintage literature to indicate that the equipment is "State of the Art".

[GrimJosef]

I'm not aware of any general definition of "high fidelity". However in the 40's and 50's there was a discussion in the literature of what was required of amplifiers. Among the most important papers were Design for a High-Quality Amplifier by D T N Williamson (Wireless World, April & May 1947) and Amplifiers and Superlatives by D T N Williamson and P J Walker (Wireless World, September 1952). Williamson listed 6 requirements for a high-quality amp in the first of these papers and these were expanded to 7 in the second. You can read the full text here http://www.dc-daylight.ltd.uk/Valve-...S-WW-1952.html where the requirements are discussed in detail. But just to summarise, they were:

1. Negligible nonlinearity distortion up to the maximum rated output. (A figure of 0.1% was suggested by the authors since this was undetectable in listening tests. It seems to have been widely accepted - for example it was also the figure after which the Leak "Point One" series of amps was named.)

2. Linear frequency response within the audible frequency spectrum of 10Hz-20kHz.

3. Negligible phase shift within the audible range.

4. Good transient response.

5. Low output resistance.

6. Adequate power reserve.

7. Hum and noise at least 80dB below maximum output.

We should remember of course that these were set out in the context of the audio world as it was then - music in mono, recordings on shellac 78's, and speakers with a decidedly bumpy frequency response and limited frequency range (albeit impressive sensitivity). Even now though it's a struggle (perhaps impossible ?) to find speakers which get anywhere near meeting the first two requirements. So I, for one, am still happy to settle for amps which satisfy these criteria. Indeed I'm listening to George Gershwin through a pair of Quad IIs as I write this .

Cheers,

GJ

[brenellic2000]

"Audio Biographies" relates the story of how Henry Hartley defined "high fidelity" in 1927 (and in so doing coined the phrase 'hi-fi') when describing the truthful sound ("fidelity") from his new Hartley-Turner loudspeaker when compared to the 'growling sound' (of a lion) from the long-in-the tooth "Lion" loudspeaker, inferring that the "Lion" was was "low-fidelity". There was no scientific criterion laid down.

The marketing criteria for hi-fi tape recorders regularly changed with technology especially in regards to wow and flutter and frequency response: for example, it used to be 15ips and better than 10,000Hz... then was redefined as 7-1/2ips and better than 14,000Hz... then better than 18,000Hz... but that is all very subjective, as the ear's ability (and one's bone structure) to pick up sound waves degenerates very quickly... (pardon?)

Then you have to consider the acoustics of a concert hall; that of a recording studio and that of one's lounge full of toys, furniture and reflective glass windows. Defining hi-fi is, surely, impossible?

Barry

[MarcoBerti]

On the Hallicrafters S 27, which is I believe the oldest (fall 1939) mass-production set able to receive today's FM band, the tone control, on the linear position, says "High Fidelity".