Why 1Khz sine wave?

[mulletchuck]

How did this frequency become the default frequency to test with?  Why not 440hz or some other musical frequency?

 

[joaquins]

One followed by zeros always makes the math easier, I don't know the history behind this but also ear measurements as dBA or Munson-Fletcher curves are also referenced at 1kHz, it's a reasonable mid point of human hearing (the most centered one followed by zeros) and the ear behaves quite linear (in logarithmic perception) at that frequency compared with lower frequencies. Also the ear has the better pitch sensitivity at 1kHz (not level, that's about 4Khz depending on the actual level)

I don't know which of this facts made this the standard reference frequency or at which point it was picked though.

JS

 

[pucho812]

well if it is anything else we do in audio, we probably borrowed the notion from the telephone guys.

Since 1K( as far as octaves goes) is middle of the speech frequency range seems to me they would use it and we adopted it much like when we first started using hand me down radio equipment as consoles in studios long before the console as we know it today.

but that's a guess.

 

[PRR]

Telephone is 300cps to 3kcps. What is the geometric mean?

Speakers and radio transformers more often used 400Hz. This is a low-point on a typical speaker impedance curve, and also the geo-mean of 50Hz and 3KHz, the useful range of AM radio.

Bass/treble tone controls in wide-range gear often puts the transition around 700Hz. Perhaps a geo-mean of 50Hz-10KHz (what you can hear well) or 20Hz-20KHz (nice round numbers which by the 1960s were used to define "hi fi").

If the system is any good, the exact frequency does not matter. (I expect a flat-amp's gain to be the same at 400 or 1K.) If the system is not flat, a single-freq number isn't enough information.

 

[kambo]

i tried calibrating couple of equipment back in past with
lower frequencies to c whats happening...
lowering test signal frequency made calibration harder and harder... and more unstable...

 

[Rob Flinn]

I always find 100Hz signals at low levels are better to check signal  flow through a console.  If  you're checking connections/switches a +4db 1khz tone can punch through crap on the contacts  & not highlight issues in that department.  Also an average level audio signal is usually not +4db like a constant tone is.

Another big plus is that it's a lot easier on the ear .........

 

[pvision]

I always find 100Hz signals at low levels are better to check signal  flow through a console. 
Another big plus is that it's a lot easier on the ear .........

Amen to that.  I discovered a few years ago that I can whistle 1 KHz tone.  I've heard so much of it that the exact frequency is stuck in my head

My 10 KHz is a bit sketchy, though

Nick Froome

 

[JohnRoberts]

I always find 100Hz signals at low levels are better to check signal  flow through a console. 
Another big plus is that it's a lot easier on the ear .........

Amen to that.  I discovered a few years ago that I can whistle 1 KHz tone.  I've heard so much of it that the exact frequency is stuck in my head

My 10 KHz is a bit sketchy, though

Nick Froome

I won't burden you all with more opinions about the rationale for 1kHz but back in the '70s I became pretty proficient at whistling 1kHz because that was the pitch we used to calibrate tape speed with on cassette decks we modified for variable speed.

Years later when I was designing recording consoles I learned how to whistle at 10kHz or above. Then it was purely for fun, to stand in the back of a crowded studio control room and start whistling quietly, to see how long it would take for the studio owner to dive for the power amp power switch, fearful that something was oscillating and about to release smoke from his tweeters.  ;D

JR

PS: FWIW  IIRC the Dolby level calibration tapes used 400 Hz for setting NR playback levels. I suspect with cassette heads, minor alignment errors may have less effect at 400 Hz than 1 kHz (but just another speculation). 

 

[DaveP]

" I learned how to whistle at 10kHz or above. Then it was purely for fun, to stand in the back of a crowded studio control room and start whistling quietly, to see how long it would take for the studio owner to dive for the power amp power switch, fearful that something was oscillating and about to release smoke from his tweeters"


I find it very hard to imagine you ever being naughty JR
DaveP