how would you use an oscilloscope to measure a sine wave?

[Tim R]

There is an old paper where a musician claims to have used an oscilloscope to measure a particular trumpet tone and proved it was a pure sine wave. There is no date available but probably late 50s, the company was started in 1956. So we're talking whatever scope technology would have been available then.

I've always been a bit skeptical about the claims because there are some other aspects that don't make sense to me.

However, my question is about how you would use a 1950s era scope to determine a sine wave or the degree of harmonics present. Most musical tones have a series of harmonics above the fundamental that add the characteristic tone.

 

On Tuesday, December 22, 2015 at 8:59:55 AM UTC-5, Tim R wrote:

There is an old paper where a musician claims to have used an oscilloscope to measure a particular trumpet tone and proved it was a pure sine wave. There is no date available but probably late 50s, the company was started in 1956. So we're talking whatever scope technology would have been available then.

I've always been a bit skeptical about the claims because there are some other aspects that don't make sense to me.

However, my question is about how you would use a 1950s era scope to determine a sine wave or the degree of harmonics present. Most musical tones have a series of harmonics above the fundamental that add the characteristic tone.

Seems doubtful, I mean I can play a pure sinewave into a speaker and I know
what that sounds like. A trumpet sounds different.

George H.

 

[Tim R]

On Tuesday, December 22, 2015 at 11:39:49 AM UTC-5, Phil Hobbs wrote:

On 12/22/2015 11:02 AM, c4urs11 wrote:
On Tue, 22 Dec 2015 05:59:52 -0800, Tim R wrote:

However, my question is about how you would use a 1950s era scope
to determine a sine wave or the degree of harmonics present.

Scopes from that era easily reached several MHz of bandwidth.
That should be considered adequate to inspect audio signals.

Cheers!


The eyeball is a really lousy detector of harmonics, though, especially
odd harmonics.

Plus he had to use a 1950s-era microphone, so the scope bandwidth is
irrelevant.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

I've used an RTA, but those hadn't been invented yet. Before my time, but wasn't there something called octave filters?

The experimenter wasn't real detailed but supposedly he could tell from looking at the scope that it was a pure sine without harmonics. I was very skeptical that 1950s technology allowed that. He is a believer that the material a trumpet is made from determines the sound, whereas many of us believe it is the shape of the air column.

I will quote the article:
******
At one time we ran an experiment in which we used steel, aluminum, various plastics, glass, silver, various combinations of brass and the last one we used was lead. To demonstrate results as quickly as possible, I will choose the two extremes. The steel bell, which we tempered so it was extremely hard, gave possibly one of the most interesting results. Many people test a bell by tapping it with their finger or knuckle and in tapping the steel bell, it would emit a very ringing sound, truly like a bell. However, when we played this instrument, the quality of sound was extremely dead. On searching for the reason for this, we looked at the oscilloscope when the performer played on the instrument and found the sine pattern very faint but the distortion pattern, coming from the vibration of the bell itself, going through at a very jagged and rapid rate, killing the brilliance of sound of the true tone. At the other extreme was the lead bell. This bell, if rapped with your knuckle, emitted an extremely dead sound like rapping on a piece of wood. However the sound that emanated when it was blown was extremely brilliant, brilliant to the point of being mechanical. This showed up on the oscilloscope as a perfectly true sine pattern, there being no distortions in the harmonics either above or below, and, as a result, the sound was absolutely pure but not usable musically, except for a general effect such as a percussion instrument would give. The voice, you know, registering on an oscilloscope, gives harmonics both above and below the note. These distortions, if we may call them such, give warmth to the tone. We have to have that "distortion" in order to have the sound acceptable to our ears as a musical sound.

 

[Tim R]

On Tuesday, December 22, 2015 at 12:53:50 PM UTC-5, amdx wrote:

To do that you need to know the shape of a sine wave... perfectly.
You could use a dual trace and compare a sine wave to your trumpet note.

Or use your computer sound card and see what you really have.

Yes, in 2015 I can do this, and have.

My suspicion was that it was not really possible in 1956 to have done what he claimed to have done. I figured in the time domain the most you would see is a tiny ripple on a scope trace, maybe not detectable. But I asked the question here because you all actually know how to use scopes (and some of you may be old enough to remember 1950s scopes).

 

[Tim R]

On Tuesday, December 22, 2015 at 12:04:12 PM UTC-5, Phil Hobbs wrote:

It's both.


Changing the material also moves all the mechanical resonances, which
will have a huge effect.

I agree the material will have a huge effect on the mechanical resonances. It is not so clear that the mechanical resonances have any appreciable effect on the contained wind column resonances. There is no obvious theory why they should, and a couple of centuries of experiments have really failed to show much in the way of effect, whether done with listening tests or lab measurements.

 

[Tim R]

On Tuesday, December 22, 2015 at 2:02:19 PM UTC-5, Sjouke Burry wrote:

On 22.12.15 19:48, Tim R wrote:
On Tuesday, December 22, 2015 at 12:53:50 PM UTC-5, amdx wrote:
To do that you need to know the shape of a sine wave... perfectly.
You could use a dual trace and compare a sine wave to your trumpet note.

Or use your computer sound card and see what you really have.

Yes, in 2015 I can do this, and have.

My suspicion was that it was not really possible in 1956 to have done what he claimed to have done. I figured in the time domain the most you would see is a tiny ripple on a scope trace, maybe not detectable. But I asked the question here because you all actually know how to use scopes (and some of you may be old enough to remember 1950s scopes).

Just use a signal generator on the second scope channel,
switch to x/y mode, and produce an ellipse/circle slowly
rotating.
Distortions will show up quite well.
Even in 1950.

I wondered about that. There was a long ago physics lab where we made Lissajous figures, but so long ago I didn't remember details.

 

[Ralph Mowery]

"Tim R" <timothy42b@aol.com> wrote in message
news:08de2443-cf3c-4789-9b30-ab353a31ae82@googlegroups.com...

There is an old paper where a musician claims to have used an oscilloscope
to measure a particular trumpet tone and proved it was a pure sine wave.
There is no date available but probably late 50s, the company was started
in 1956. >So we're talking whatever scope technology would have been
available then.

I've always been a bit skeptical about the claims because there are some
other aspects that don't make sense to me.

However, my question is about how you would use a 1950s era scope to
determine a sine wave or the degree of harmonics present. Most musical
tones have a series of harmonics above the fundamental that add the
characteristic >tone.

An easy way would be to use a high pass filter or a notch filter to filter
out the frequency of the note and then look to see if anything is left.

Look for a SINAD or distortion meter.

When you filter out the origioinal wave (first harmonic) anything that is
left is from a frequency that is not the sine wave.
It could be distortion or a harmonic. The scope could be used to determin
what frequency or which harmonic is left over.

 

[Phil Hobbs]

On 12/22/2015 10:26 AM, ggherold@gmail.com wrote:

On Tuesday, December 22, 2015 at 8:59:55 AM UTC-5, Tim R wrote:
There is an old paper where a musician claims to have used an
oscilloscope to measure a particular trumpet tone and proved it was
a pure sine wave. There is no date available but probably late
50s, the company was started in 1956. So we're talking whatever
scope technology would have been available then.

I've always been a bit skeptical about the claims because there are
some other aspects that don't make sense to me.

However, my question is about how you would use a 1950s era scope
to determine a sine wave or the degree of harmonics present. Most
musical tones have a series of harmonics above the fundamental that
add the characteristic tone.

Seems doubtful, I mean I can play a pure sinewave into a speaker and
I know what that sounds like. A trumpet sounds different.

George H.

Well, given that the trumpet is driven by a relaxation oscillation of
the player's lips, it would be quite strange if there weren't a lot of
harmonics. Odd harmonics would be nearly resonant, I think, though the
shape of the bell means that the resonance isn't really an organ-pipe mode.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[c4urs11]

On Tue, 22 Dec 2015 05:59:52 -0800, Tim R wrote:

However, my question is about how you would use a 1950s era scope
to determine a sine wave or the degree of harmonics present.

Scopes from that era easily reached several MHz of bandwidth.
That should be considered adequate to inspect audio signals.

Cheers!

 

[Phil Hobbs]

On 12/22/2015 11:02 AM, c4urs11 wrote:

On Tue, 22 Dec 2015 05:59:52 -0800, Tim R wrote:

However, my question is about how you would use a 1950s era scope
to determine a sine wave or the degree of harmonics present.

Scopes from that era easily reached several MHz of bandwidth.
That should be considered adequate to inspect audio signals.

Cheers!

The eyeball is a really lousy detector of harmonics, though, especially
odd harmonics.

Plus he had to use a 1950s-era microphone, so the scope bandwidth is
irrelevant.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Phil Hobbs]

On 12/22/2015 11:53 AM, Tim R wrote:

On Tuesday, December 22, 2015 at 11:39:49 AM UTC-5, Phil Hobbs
wrote:
On 12/22/2015 11:02 AM, c4urs11 wrote:
On Tue, 22 Dec 2015 05:59:52 -0800, Tim R wrote:

However, my question is about how you would use a 1950s era
scope to determine a sine wave or the degree of harmonics
present.

Scopes from that era easily reached several MHz of bandwidth.
That should be considered adequate to inspect audio signals.

Cheers!


The eyeball is a really lousy detector of harmonics, though,
especially odd harmonics.

Plus he had to use a 1950s-era microphone, so the scope bandwidth
is irrelevant.


I've used an RTA, but those hadn't been invented yet. Before my
time, but wasn't there something called octave filters?

The experimenter wasn't real detailed but supposedly he could tell
from looking at the scope that it was a pure sine without harmonics.

Well, he was wrong about that. Even 10% third harmonic isn't easy to
spot unless you have a comparison sine wave on the screen at the same
time. (I'm thinking about zero degrees relative phase, so the peaks are
symmetrical. It's a bit easier to see at other phases.)

> I was very skeptical that 1950s technology allowed that.

Unless he had a really expensive ribbon mic, his 1950s microphone had a
heavy diaphragm and rolled off really badly above about 5 kHz. (One of
the audio guys will correct this, but it's roughly right.) None of the
nice 40-kHz piezo film mics you can get nowadays. (I have a matched set
of Earthworks omni mics from about 15 years ago--their impulse response
is about 15 microseconds wide.)

He is a believer that the material a trumpet is made from determines
the sound, whereas many of us believe it is the shape of the air
column.

It's both.

I will quote the article: ****** At one time we ran an experiment in
which we used steel, aluminum, various plastics, glass, silver,
various combinations of brass and the last one we used was lead. To
demonstrate results as quickly as possible, I will choose the two
extremes. The steel bell, which we tempered so it was extremely
hard, gave possibly one of the most interesting results. Many people
test a bell by tapping it with their finger or knuckle and in tapping
the steel bell, it would emit a very ringing sound, truly like a
bell. However, when we played this instrument, the quality of sound
was extremely dead. On searching for the reason for this, we looked
at the oscilloscope when the performer played on the instrument and
found the sine pattern very faint but the distortion pattern, coming
from the vibration of the bell itself, going through at a very
jagged and rapid rate, killing the brilliance of sound of the true
tone.

Changing the material also moves all the mechanical resonances, which
will have a huge effect.

At the other extreme was the lead bell. This bell, if rapped with
your knuckle, emitted an extremely dead sound like rapping on a piece
of wood. However the sound that emanated when it was blown was
extremely brilliant, brilliant to the point of being mechanical. This
showed up on the oscilloscope as a perfectly true sine pattern, there
being no distortions in the harmonics either above or below, and, as
a result, the sound was absolutely pure but not usable musically,
except for a general effect such as a percussion instrument would
give.

The voice, you know, registering on an oscilloscope, gives harmonics
both above and below the note. These distortions, if we may call them
such, give warmth to the tone. We have to have that "distortion" in
order to have the sound acceptable to our ears as a musical sound.

Cheers

Phil "Not an audio guy" Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[whit3rd]

On Tuesday, December 22, 2015 at 8:39:49 AM UTC-8, Phil Hobbs wrote:

On 12/22/2015 11:02 AM, c4urs11 wrote:
On Tue, 22 Dec 2015 05:59:52 -0800, Tim R wrote:

However, my question is about how you would use a 1950s era scope
to determine a sine wave or the degree of harmonics present.

Scopes from that era easily reached several MHz of bandwidth.
That should be considered adequate to inspect audio signals.

The eyeball is a really lousy detector of harmonics, though, especially
odd harmonics.

Not always; I have no trouble looking at a filtered triangle-wave type "sine"
and seeing the distortion, which is presumably under 1%.
"Pure" to the ear doesn't require a spectrum analyzer with parts-per-million
resolution and logarithmic display. I think the researchers were applying
a loose definition.

Plus he had to use a 1950s-era microphone, so the scope bandwidth is
irrelevant.

Carbon microphone, maybe, but dynamic microphones were very well
developed by then. A lot of early recordings were transcribed onto DVD,
and the sound quality improved because the SINAD of microphone and tape were better
than the rest of the phonograph process.

 

[amdx]

On 12/22/2015 7:59 AM, Tim R wrote:

There is an old paper where a musician claims to have used an oscilloscope to measure a particular trumpet tone and proved it was a pure sine wave. There is no date available but probably late 50s, the company was started in 1956. So we're talking whatever scope technology would have been available then.

I've always been a bit skeptical about the claims because there are some other aspects that don't make sense to me.

However, my question is about how you would use a 1950s era scope to determine a sine wave or the degree of harmonics present. Most musical tones have a series of harmonics above the fundamental that add the characteristic tone.

To do that you need to know the shape of a sine wave... perfectly.
You could use a dual trace and compare a sine wave to your trumpet note.

Or use your computer sound card and see what you really have.

Free sound card spectrum analyzers.

http://www.nch.com.au/wavepad/fft.html?gclid=CMuPysOD8MkCFdgHgQodztEKYA

http://www.qsl.net/pa2ohh/04audio.htm

http://www.qsl.net/dl4yhf/spectra1.html

Mikek

 

[Sjouke Burry]

On 22.12.15 19:48, Tim R wrote:

On Tuesday, December 22, 2015 at 12:53:50 PM UTC-5, amdx wrote:
To do that you need to know the shape of a sine wave... perfectly.
You could use a dual trace and compare a sine wave to your trumpet note.

Or use your computer sound card and see what you really have.

Yes, in 2015 I can do this, and have.

My suspicion was that it was not really possible in 1956 to have done what he claimed to have done. I figured in the time domain the most you would see is a tiny ripple on a scope trace, maybe not detectable. But I asked the question here because you all actually know how to use scopes (and some of you may be old enough to remember 1950s scopes).

Just use a signal generator on the second scope channel,
switch to x/y mode, and produce an ellipse/circle slowly
rotating.
Distortions will show up quite well.
Even in 1950.

 

[Jeff Liebermann]

On Tue, 22 Dec 2015 10:48:39 -0800 (PST), Tim R <timothy42b@aol.com>
wrote:

>My suspicion was that it was not really possible in 1956 to have done what he claimed to have done. I figured in the time domain the most you would see is a tiny ripple on a scope trace, maybe not detectable. But I asked the question here because you all actually know how to use scopes (and some of you may be old enough to remember 1950s scopes).

Heathkit intoduced its first oscilloscope, the O-1, in 1947 (for $50).
<http://www.nostalgickitscentral.com/heath/products/test.html#o>
The "O" series went from O-1 to O-12 with the bandwidth going from
about 150Khz to 5 MHz. I couldn't find a time line, but here's an O-2
schematic dated Jan 1948.
<http://www.nostalgickitscentral.com/heath/schematics/heathkit_schema_o2.pdf>
Offhand, I would say that it would have been possible in 1956.

Back in the stone age of signal analysis, the usual method of looking
at harmonics was to notch out the fundamental, and look at what was
left. At audio, notch filters are fairly easy to build with bug
discrete parts. In effect, an early distortion analyzer. I don't
have a date, but looking at the schematic of the first Heathkit
distortion analyzer, the HD-1, methinks the choice of tubes puts it in
the same time frame as the O-1:
<http://www.nostalgickitscentral.com/heath/schematics/heathkit_schema_hd1.pdf>
So, it might also have been possible to inspect the horns harmonic
content, if the player could hold a steady note.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Tue, 22 Dec 2015 12:31:21 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

No brain today (especially while talking on the phone).
The dates are on the web page, right two columns:
<http://www.nostalgickitscentral.com/heath/products/heathkit_test.html>
The Heath O-1 was sold from 1947 to 1947. By 1956, there were
probably a dozen scopes produced by Heathkit. The HD-1 distortion
analyzer went from 1948 to probably 1948. My guess(tm) is that Howard
Anthony ran out of WWII surplus parts and was forced to design a
modern replacement.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[MJC]

In article <i1cj7bhpur6bafo0i83h6eba1muf81bt2p@4ax.com>,
jeffl@cruzio.com says...

So, it might also have been possible to inspect the horns harmonic
content, if the player could hold a steady note.

Which reminds me that in a holiday job between school and college I
spent some time chatting up the test engineers who were checking an
audio amplifier. They just used a sine wave signal and listened on
speakers. So I leant on the speaker and whistled a beating note. The
technician spent a minute or two hunting for the source of the beats
until I ran out of breath and got chased out of the test bay...

Mike.

 

[Phil Hobbs]

On 12/22/2015 05:07 PM, whit3rd wrote:

On Tuesday, December 22, 2015 at 8:39:49 AM UTC-8, Phil Hobbs wrote:
On 12/22/2015 11:02 AM, c4urs11 wrote:
On Tue, 22 Dec 2015 05:59:52 -0800, Tim R wrote:

However, my question is about how you would use a 1950s era scope
to determine a sine wave or the degree of harmonics present.

Scopes from that era easily reached several MHz of bandwidth.
That should be considered adequate to inspect audio signals.

The eyeball is a really lousy detector of harmonics, though, especially
odd harmonics.

Not always; I have no trouble looking at a filtered triangle-wave type "sine"
and seeing the distortion, which is presumably under 1%.

You're looking at the residual cusp, though, not the smooth details of
the peak, right?

"Pure" to the ear doesn't require a spectrum analyzer with parts-per-million
resolution and logarithmic display. I think the researchers were applying
a loose definition.

Plus he had to use a 1950s-era microphone, so the scope bandwidth is
irrelevant.

Carbon microphone, maybe, but dynamic microphones were very well
developed by then.

Sure, but they have big heavy diaphragms and coils, so their high
frequency response stinks. (Velocity sensitivity helps, but low
resonant frequency wins.)


A lot of early recordings were transcribed onto DVD,

and the sound quality improved because the SINAD of microphone and tape were better
than the rest of the phonograph process.

I don't doubt that one bit. Record cutters especially.

Cheers

Phil Hobbs



--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Bennett Price]

On 12/22/2015 8:53 AM, Tim R wrote:

On Tuesday, December 22, 2015 at 11:39:49 AM UTC-5, Phil Hobbs wrote:
On 12/22/2015 11:02 AM, c4urs11 wrote:
On Tue, 22 Dec 2015 05:59:52 -0800, Tim R wrote:

However, my question is about how you would use a 1950s era scope
to determine a sine wave or the degree of harmonics present.

Scopes from that era easily reached several MHz of bandwidth.
That should be considered adequate to inspect audio signals.

Cheers!


The eyeball is a really lousy detector of harmonics, though, especially
odd harmonics.

Plus he had to use a 1950s-era microphone, so the scope bandwidth is
irrelevant.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

I've used an RTA, but those hadn't been invented yet. Before my time, but wasn't there something called octave filters?

The experimenter wasn't real detailed but supposedly he could tell from looking at the scope that it was a pure sine without harmonics. I was very skeptical that 1950s technology allowed that. He is a believer that the material a trumpet is made from determines the sound, whereas many of us believe it is the shape of the air column.

I will quote the article:
******
At one time we ran an experiment in which we used steel, aluminum, various plastics, glass, silver, various combinations of brass and the last one we used was lead. To demonstrate results as quickly as possible, I will choose the two extremes. The steel bell, which we tempered so it was extremely hard, gave possibly one of the most interesting results. Many people test a bell by tapping it with their finger or knuckle and in tapping the steel bell, it would emit a very ringing sound, truly like a bell. However, when we played this instrument, the quality of sound was extremely dead. On searching for the reason for this, we looked at the oscilloscope when the performer played on the instrument and found the sine pattern very faint but the distortion pattern, coming from the vibration of the bell itself, going through at a very jagged and rapid rate, killing the brilliance of sound of the true tone. At the other extreme was the lead bell. This bell, if rapped with your knuckle, emit
ted an extremely dead sound like rapping on a piece of wood. However the sound that emanated when it was blown was extremely brilliant, brilliant to the point of being mechanical. This showed up on the oscilloscope as a perfectly true sine pattern, there being no distortions in the harmonics either above or below, and, as a result, the sound was absolutely pure but not usable musically, except for a general effect such as a percussion instrument would give. The voice, you know, registering on an oscilloscope, gives harmonics both above and below the note. These distortions, if we may call them such, give warmth to the tone. We have to have that "distortion" in order to have the sound acceptable to our ears as a musical sound.

Could you give a citation, reference (or even a URL) to the article.
I'd love to read it.
Thanks

 

[Phil Allison]

Tim R wrote:

There is an old paper where a musician claims to have used an oscilloscope to measure a particular trumpet tone and proved it was a pure sine wave. There is no date available but probably late 50s, the company was started in 1956. So we're talking whatever scope technology would have been available then.

I've always been a bit skeptical about the claims because there are some other aspects that don't make sense to me.

However, my question is about how you would use a 1950s era scope to determine a sine wave or the degree of harmonics present.

** The same way you might use a modern scope.

A sine wave has a distinct shape and the addition of harmonics visibly alters that shape. Instruments like the clarinet produce near square waves when playing most notes. Guitar strings vibrate with a series of harmonic frequencies, depending how the string is struck. You can clearly see them on a scope screen if you plug an electric model into the vertical input.

Check out U-Tube vids.

Most musical tones have a series of harmonics above the
fundamental that add the characteristic tone.

** Scopes show the time domain picture of a wave.



..... Phil