28 May
2010
28 May
'10
2:36 p.m.
Hello all,
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
(Free beer at the next LAC for the best analysis)
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !
28 May
28 May
3:35 p.m.
On 05/28/10 14:31, fons(a)kokkinizita.net wro
<http://www.kokkinizita.net/linuxaudio/quiz.html>
Jitter or power supply. Is it on all ports?
Flo
--
Machines can do the work, so people have time to think.
public key DA43FEF4 x-hkp://wwwkeys.eu.pgp.net
4:36 p.m.
On Friday 28 May 2010, fons(a)kokkinizita.net wrote:
Hello all,
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
(Free beer at the next LAC for the best analysis)
Ciao,
My guess is that it could be related to crosstalk, and the nominally 100hz
component is the digitization delay.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
I never liked you, and I always will. -Samuel Goldwyn
4:53 p.m.
On Fri, May 28, 2010 at 1:31 PM, <fons(a)kokkinizita.net> wrote:
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
Why 1015 Hz?
Chris
5:27 p.m.
On 05/28/2010 05:05 PM, Ralf Mardorf wrote:
Chris Cannam wrote:
Slew-rates of op-amps are higher by at least an order of magnitude:
off-the shelf cheap op-amps have ~ 10V/us. Fons' test signal may be
~50mV peak-to peak.
In reply to Olivier message Fons already stated that it's not an issue
with sampling. Besides there's usually a low-pass filter on each analog
input.
He probably choose 1015 Hz for aliasing: 48000/1015 or 44100/1015 is not
a common ratio. ~1000 Hz is also in the middle of the card's spectrum
and there's rarely sth. around your house that oscillates at frequency.
There may be more to it, though. Fons?
Why 1015 Hz?
Slew rate of card x's input op-amps?
5:05 p.m.
On 05/28/2010 02:31 PM, fons(a)kokkinizita.net wrote:
Hello all,
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
(Free beer at the next LAC for the best analysis)
Ciao,
Well, interpreting an 'experiment' that one has not conducted
him/herself without knowing _all_ parameters of the setup is not
something to encourage doing..
Did you use symmetric (XLR) connections? Are the sample-rate settings of
both cards identical? what was the physical distance between the devices
(cross-talk)? Was there any ground-lift equipment (built-in?) in place
or maybe you simply forgot to switch off phantom-power?
Anyway, good that you've labeled it 'quiz'; so here's my guess:
You're encountering reflections (or even standing-waves) in the cable.
(did you uncoil it? or was it a very short one?)
Did you repeat the measurement? using different cables for example.
Cheers!
robin
5:39 p.m.
On Fri, May 28, 2010 at 05:05:19PM +0200, Robin Gareus wrote:
Well, interpreting an 'experiment' that one
has not conducted
him/herself without knowing _all_ parameters of the setup is not
something to encourage doing..
Did you use symmetric (XLR) connections?
Where possible, yes. Note that we are seeing a *modulation*
effect, the level of the spurious signals is proportional
to the wanted signal. It's not additive.
Are the sample-rate settings of both cards identical?
Shouldn't matter, as the connection is via an analog signal.
what was the physical distance between the devices
(cross-talk)?
It's absolutely not crosstalk.
Was there any ground-lift equipment (built-in?) in
place
or maybe you simply forgot to switch off phantom-power?
All those would create additive effects, which is not what
we see. Phantom power, where available, was off. Card X
has both line and mic inputs, all show the same result.
Mic inputs are driven via a balanced passive attenuator
with an output impedance of 50 ohm.
Anyway, good that you've labeled it
'quiz'; so here's my guess:
You're encountering reflections (or even standing-waves) in the cable.
(did you uncoil it? or was it a very short one?)
Did you repeat the measurement? using different cables for example.
No differnece seen between a cable of 3 m and on of 18 m.
This will answer most other posters, except Chris:
Why 1015 Hz ?
To clearly separate the signal from any 50 Hz harmonics.
One more hint: card X is a very high end one. It should
be 'perfect', or at least much better than card A.
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !
6:54 p.m.
Fons,
One more hint: card X is a very high end one. It
should
be 'perfect', or at least much better than card A.
So card A produced the effect and cancelled it out when measuring itself.
Flo
--
Machines can do the work, so people have time to think.
public key DA43FEF4 x-hkp://wwwkeys.eu.pgp.net
7:22 p.m.
On 05/28/2010 05:34 PM, fons(a)kokkinizita.net wrote:
good; those charge-pumps that are used to create 48V from 5 or 12V
often cause ripples in the supply voltage.. which in turn can influence
the oscillator.. resulting in signal modulation.
On Fri, May 28, 2010 at 05:05:19PM +0200, Robin Gareus
wrote:
a 2nd measurement showing a measurement at - let's say 1215Hz would have
made that clear in the first place. Anyway I take your word for it.
Thanks for /organizing/ this little quiz; it's quite fun!
Well, interpreting an 'experiment' that
one has not conducted
him/herself without knowing _all_ parameters of the setup is not
something to encourage doing..
Did you use symmetric (XLR) connections?
Where possible, yes. Note that we are seeing a *modulation*
effect, the level of the spurious signals is proportional
to the wanted signal. It's not additive. Are the
sample-rate settings of both cards identical?
Shouldn't matter, as the connection is via an analog signal.
what was the physical distance between the
devices
(cross-talk)?
It's absolutely not crosstalk.
Was there any ground-lift equipment (built-in?)
in place
or maybe you simply forgot to switch off phantom-power?
All those would create additive effects, which is not what
we see. Phantom power, where available, was off. Card X
has both line and mic inputs, all show the same result.
Mic inputs are driven via a balanced passive attenuator
with an output impedance of 50 ohm.
OT: I would not trust any consumer-grade audio-interface for signal
differences larger than 80dB anyway. I'm amazed that card A shows such a
low noise-floor in the loop-back test.
Anyway, good that you've labeled it
'quiz'; so here's my guess:
You're encountering reflections (or even standing-waves) in the cable.
(did you uncoil it? or was it a very short one?)
Did you repeat the measurement? using different cables for example.
No differnece seen between a cable of 3 m and on of 18 m.
This will answer most other posters, except Chris:
Why 1015 Hz ?
To clearly separate the signal from any 50 Hz harmonics.
One more hint: card X is a very high end one. It should
be 'perfect', or at least much better than card A. Ciao,
10:07 p.m.
On Fri, May 28, 2010 at 07:22:24PM +0200, Robin Gareus wrote:
OT: I would not trust any consumer-grade
audio-interface for signal
differences larger than 80dB anyway. I'm amazed that card A shows such a
low noise-floor in the loop-back test.
Not OT at all. Don't mistake the -140 dB noise line on that plot
for the S/N ratio... changing the analyser bandwidth (i.e. the FFT
length) in JAAA you can put this line almost everywhere you want it.
The more frequency bins you have, the less noise there is in each of
them, and that is what the plot shows.
The really interesting value is the noise density shown in the upper
left corner (for the marker at 1100 Hz): noise density is -137.9 dB/Hz
Add 43 dBHz (for 20 kHz), and the resulting S/N ratio is -94.9 dB.
Which is 16-bit performance, even if the card is 24-bit.
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !
10:52 p.m.
On Fri, 2010-05-28 at 22:02 +0200, fons(a)kokkinizita.net wrote:
The really interesting value is the noise density
shown in the upper
left corner (for the marker at 1100 Hz): noise density is -137.9 dB/Hz
Add 43 dBHz (for 20 kHz), and the resulting S/N ratio is -94.9 dB.
Which is 16-bit performance, even if the card is 24-bit.
Not quite. With a 16 bit card you wouldn't be able to pick up anything
at all @ -96 dB ... zilch!
Assuming this card otherwise works as promised (?), you will still be
able to pick up a conversation drenched in 24 dB of noise @ -120 dB.
So 20 "useful" bits - approx.
11:12 p.m.
On Fri, May 28, 2010 at 10:51:03PM +0200, Jens M Andreasen wrote:
So 20 "useful" bits - approx.
Where do you get this ? What the plot shows is that the
S/N ratio is around 95 dB, that's all. Even if the ADC
has 20 effective bits, they are useless as the analog
noise dominates. OTOH, that doesn't mean you can't detect
lower signals. It's not difficult to detect e.g. a -200 dB
sine signal in -95 dB of noise - it just depends on the
bandwidth.
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !
11:34 p.m.
On Fri, 2010-05-28 at 23:07 +0200, fons(a)kokkinizita.net wrote:
I get this from the difference between a piano-like signal fading out
into a squarewave vs fading out way below the noisefloor. The former is
unbearable.
So 20
"useful" bits - approx.
Where do you get this ? What the plot shows is that the
S/N ratio is around 95 dB, that's all. Even if the ADC
has 20 effective bits, they are useless as the analog
noise dominates.
29 May
29 May
12:05 a.m.
On Fri, May 28, 2010 at 11:33:35PM +0200, Jens M Andreasen wrote:
I get this from the difference between a piano-like
signal fading out
into a squarewave vs fading out way below the noisefloor. The former is
unbearable.
Absolutely, and that why there's dithering, which in its
simplest form is just adding noise.
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !
12:31 a.m.
On Sat, 2010-05-29 at 00:00 +0200, fons(a)kokkinizita.net wrote:
Absolutely, and that why there's dithering, which
in its
simplest form is just adding noise.
Great ;)
Now you please go add some noise to a 16 bit signal and keep that
theoretical -90 dB noisefloor also, will you ...
In any case, the noisefloor on a 16 bit card will now be considerably
higher than the -95dB you had on the 24 bit card-A you compared it to.
Which was my point.
/j
28 May
28 May
8:55 p.m.
Just thinking about what I had wrote and remembered the semantics used here...
One more hint: card X is a very high end one. It
should
be 'perfect', or at least much better than card A.
... which might suggest that Card X is not performing well. Since it has been stated the
card x is not USB, it is possible that this card has it's audio clock derived from the
PC clock which is likely dithered - they call it spread spectrum to help reduce radiated
noise in testing.
9:07 p.m.
Veronica Merryfield wrote:
Just thinking about what I had wrote and remembered
the semantics used here...
http://www.maxim-ic.com/app-notes/index.mvp/id/3503
And how would this cause the issue?
One more hint: card X is a very high end one. It
should
be 'perfect', or at least much better than card A.
... which might suggest that Card X is not performing well. Since it has been stated the
card x is not USB, it is possible that this card has it's audio clock derived from the
PC clock which is likely dithered - they call it spread spectrum to help reduce radiated
noise in testing.
9:14 p.m.
Ralf Mardorf wrote:
Veronica Merryfield wrote:
Ok this would cause jitter because of the slew rate? But is there a
distance of (around or exactly) 100 Hz? Will the card itself split the
clock from 1000 Hz to 100 Hz? I guess the standard clock by RT kernels
will be 1000 Hz. Right?
Just thinking about what I had wrote and
remembered the semantics
used here...
http://www.maxim-ic.com/app-notes/index.mvp/id/3503
And how would this cause the issue? One more hint: card X is a very high end one. It
should
be 'perfect', or at least much better than card A.
... which might suggest that Card X is not performing well. Since it
has been stated the card x is not USB, it is possible that this card
has it's audio clock derived from the PC clock which is likely
dithered - they call it spread spectrum to help reduce radiated noise
in testing.
9:15 p.m.
On Fri, 2010-05-28 at 11:54 -0700, Veronica Merryfield wrote:
Just thinking about what I had wrote and remembered
the semantics used here...
I blame Gremlins.
Do I win?
Ricardus...
One more hint: card X is a very high end one. It
should
be 'perfect', or at least much better than card A.
... which might suggest that Card X is not performing well. Since it has been stated the
card x is not USB, it is possible that this card has it's audio clock derived from the
PC clock which is likely dithered - they call it spread spectrum to help reduce radiated
noise in testing.
9:20 p.m.
Ricardus Vincente wrote:
On Fri, 2010-05-28 at 11:54 -0700, Veronica Merryfield
wrote:
I blame laws of nature and I'm right with this, but I guess it's a
little bit to abstract, not the complete wanted answer.
Just thinking about what I had wrote and
remembered the semantics used here...
I blame Gremlins.
Do I win?
Ricardus...
One more hint: card X is a very high end one. It
should
be 'perfect', or at least much better than card A.
... which might suggest that Card X is not performing well. Since it has
been stated the card x is not USB, it is possible that this card has it's audio clock
derived from the PC clock which is likely dithered - they call it spread spectrum to help
reduce radiated noise in testing.
5:39 p.m.
On 05/28/2010 05:05 PM, Robin Gareus wrote:
On 05/28/2010 02:31 PM, fons(a)kokkinizita.net wrote:
on 2nd thought (just been on the toilet) those could be in the order of
-75db but they would not yield a symmetric spectrum as you presented.
Sorry for the noise :)
robin
Hello all,
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
(Free beer at the next LAC for the best analysis)
Ciao,
Well, interpreting an 'experiment' that one has not conducted
him/herself without knowing _all_ parameters of the setup is not
something to encourage doing..
Did you use symmetric (XLR) connections? Are the sample-rate settings of
both cards identical? what was the physical distance between the devices
(cross-talk)? Was there any ground-lift equipment (built-in?) in place
or maybe you simply forgot to switch off phantom-power?
Anyway, good that you've labeled it 'quiz'; so here's my guess:
You're encountering reflections (or even standing-waves) in the cable.
(did you uncoil it? or was it a very short one?) Did you repeat the measurement? using different cables
for example.
Cheers!
robin
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev(a)lists.linuxaudio.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev
7 p.m.
On 05/28/2010 02:31 PM, fons(a)kokkinizita.net wrote:
Hello all,
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
(Free beer at the next LAC for the best analysis)
Ciao,
You can't trust a loop back test.
Any instability or dither on the reference clock of card A (fifo clocking say) is not
going to show in a loop back test.
Vrnc
7:21 p.m.
Veronica Merryfield wrote:
On 05/28/2010 02:31 PM, fons(a)kokkinizita.net wrote:
Is Veronica Merryfield the winner?
Hello all,
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
(Free beer at the next LAC for the best analysis)
Ciao,
You can't trust a loop back test.
Any instability or dither on the reference clock of card A (fifo clocking say) is not
going to show in a loop back test.
Vrnc 
7:26 p.m.
On Fri, 28 May 2010 19:20:54 +0200
Ralf Mardorf <ralf.mardorf(a)alice-dsl.net> wrote:
Veronica Merryfield wrote:
I'm highly suspicious of the USB link, but can't quite put my finger
on why.
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
On 05/28/2010 02:31 PM, fons(a)kokkinizita.net
wrote:
Is Veronica Merryfield the winner? Hello all,
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
(Free beer at the next LAC for the best analysis)
Ciao,
You can't trust a loop back test.
Any instability or dither on the reference clock of card A (fifo clocking say) is not
going to show in a loop back test.
Vrnc
7:37 p.m.
Folderol wrote:
On Fri, 28 May 2010 19:20:54 +0200
Ralf Mardorf <ralf.mardorf(a)alice-dsl.net> wrote:
Card A is the USB card. For USB there could be several issues, but I
don't have knowledge about buffering etc., but I guess it's card A and
that there's a "instability" = jitter. I don't know what dither for CLK
is. I guess the winner is Veronica Merryfield.
Veronica Merryfield wrote:
I'm highly suspicious of the USB link, but can't quite put my finger
on why.
On 05/28/2010 02:31 PM, fons(a)kokkinizita.net
wrote:
Is Veronica Merryfield the winner?
Hello all,
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
(Free beer at the next LAC for the best analysis)
Ciao,
You can't trust a loop back test.
Any instability or dither on the reference clock of card A (fifo clocking say) is not
going to show in a loop back test.
Vrnc
5:24 p.m.
fons(a)kokkinizita.net wrote:
Hello all,
This week I had to perform measurements on a audio
interface, and this resulted in some quite interesting
results. Before revealing what happened, I'll let you
have a look at some of the data and come up with your
own conclusions, see
<http://www.kokkinizita.net/linuxaudio/quiz.html>
(Free beer at the next LAC for the best analysis)
Ciao,
Coupling by drop ground leakage? (Kopplung durch Spannungsabfall an
Masseleitungen?)
5:30 p.m.
This experiment was done in Europe with 50Hz AC line current.
When rectified by a non-switching power supply, that ends up being 100hz "hum".
Alternately, it's 50 hz ground loop noise that is being rectified or
has cross-over distortion resulting in 100Hz noise.
This "rectification" could take place through a number of unexpected
means, including oxidized contacts that act as semiconductors (
http://en.wikipedia.org/wiki/Rusty_bolt_effect ) , low-quality
electrolytic capacitors being used for Ac-coupling, and output
transformer hysteresis. (
http://en.wikipedia.org/wiki/Intermodulation#Passive_intermodulation
)
The 100hz signal due to it's regularity, could also be caused by
"periodic jitter"... i think more info is needed to determine whether
the situation you're seeing is caused by jitter or modulation by
external hum (like testing at a bunch of difft freqs and mixing two
sine waves to see the IMD behavior). Perhaps this periodic jitter is
the effect of AC line hum interfering with the sampling clock??
http://wolfsonmicro.com/uploads/documents/en/Specifying%20Jitter%20Performa…
....
Audio ADCs and DACs have three important inputs;
the signal input, the voltage reference, and the clock.
Noise and interference on the voltage reference causes
amplitude modulation, and jitter on the clock causes
phase modulation. The resulting modulation products
look very similar in the frequency domain. One of the
authors once spent several days trying to track down a
low-frequency jitter problem, only to find that it was
in fact a problem of LF noise on the voltage reference.
....
Niels
http://nielsmayer.com
5:42 p.m.
On Fri, May 28, 2010 at 08:30:54AM -0700, Niels Mayer wrote:
Audio ADCs and DACs have three important inputs;
the signal input, the voltage reference, and the clock.
Noise and interference on the voltage reference causes
amplitude modulation, and jitter on the clock causes
phase modulation. The resulting modulation products
look very similar in the frequency domain. One of the
authors once spent several days trying to track down a
low-frequency jitter problem, only to find that it was
in fact a problem of LF noise on the voltage reference.
You're close. See the extra hint in a previous post.
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !
6:25 p.m.
On Fri, May 28, 2010 at 05:37:47PM +0200, fons(a)kokkinizita.net wrote:
On Fri, May 28, 2010 at 08:30:54AM -0700, Niels Mayer
wrote:
is that an USB card ?
there is a "small" peak at 1000Hz which looks like a usb power drain at
isochronous packet frequency.
maybe its the packets voltage lifting the local ground a bit.
Audio ADCs and DACs have three important inputs;
the signal input, the voltage reference, and the clock.
Noise and interference on the voltage reference causes
amplitude modulation, and jitter on the clock causes
phase modulation. The resulting modulation products
look very similar in the frequency domain. One of the
authors once spent several days trying to track down a
low-frequency jitter problem, only to find that it was
in fact a problem of LF noise on the voltage reference.
You're close. See the extra hint in a previous post.
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev(a)lists.linuxaudio.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev
--
torben Hohn
6:39 p.m.
torbenh wrote:
Does not explain that what is seen is a modulation effect.
Ciao,
lifting the local ground a bit.
Is there a difference if the ground leakage is dropped or lifted? It's a
difference anyway.
Fons wrote:
On Fri, May 28, 2010 at 05:24:25PM +0200, Ralf Mardorf wrote:
Coupling by
drop ground leakage? (Kopplung durch Spannungsabfall an
Masseleitungen?)
6:33 p.m.
fons(a)kokkinizita.net wrote:
On Fri, May 28, 2010 at 08:30:54AM -0700, Niels Mayer
wrote:
AM could be caused by residual ripple from the DC source, but the signal
was clearly separated from any 50 Hz harmonics. So it wasn't LF noise on
the voltage reference?
Audio ADCs and DACs have three important inputs;
the signal input, the voltage reference, and the clock.
Noise and interference on the voltage reference causes
amplitude modulation, and jitter on the clock causes
phase modulation. The resulting modulation products
look very similar in the frequency domain. One of the
authors once spent several days trying to track down a
low-frequency jitter problem, only to find that it was
in fact a problem of LF noise on the voltage reference.
You're close. See the extra hint in a previous post.
Ciao,
7:24 p.m.
Hi,
nice quiz. Can't wait for the solution!
On Friday 28 May 2010 17:37:47 fons(a)kokkinizita.net wrote:
On Fri, May 28, 2010 at 08:30:54AM -0700, Niels Mayer
wrote:
I would say it is an effect of the power-supply. As others stated, 50Hz
switching power supplies produce distortions of 100Hz (and of much higher
harmonics).
Here I think these affect the op-amp of the input by modulating the supply
voltage and/or the reference-voltage. This could probably be fixed by more or
better capacitors stabilizing the +5V (or +12V).
My guess why the development engineers didn't catch it:
a) They used a high-quality lab-power supply during development which is
stabilized far better then the consumer psu that is shipped.
b) Someone swapped the high-quality capacitors for lower-spec ones at the end
of the development cycle to cut costs.
c) The capacitors in your special device just broke their smoke-seal. Better
refill them soon:-)
BTW: The graphs would be better to interpret if both had the same x-axis-
scaling.
Have fun,
Arnold
Audio ADCs and DACs have three important inputs;
the signal input, the voltage reference, and the clock.
Noise and interference on the voltage reference causes
amplitude modulation, and jitter on the clock causes
phase modulation. The resulting modulation products
look very similar in the frequency domain. One of the
authors once spent several days trying to track down a
low-frequency jitter problem, only to find that it was
in fact a problem of LF noise on the voltage reference.
You're close. See the
extra hint in a previous post. 
7:40 p.m.
Dammit, Fons! I'm trying to get some work done today and go
off and nerd snipe me.....
On Fri, 28 May 2010, fons(a)kokkinizita.net wrote:
OK, here's my guess (standing on the shoulders of guys
like Neil)...
The signal is being amplitude-modulated by a 100 Hz
saw-tooth signal. This signal by itself produces a
tight frequency series in multiples of the fundamental
(i.e. 100, 200, 300, 400 Hz...) and constant
amplitude. When used to modulate the amplitude of the
input signal, it results in a peak at the input
singal's frequency... with symmetric, attenuated peaks
@ 100 Hz spacing (like the ones that you show).
If you change the frequency of the input signal, the
surrounding peaks will move with it to maintain a 100 Hz
spacing.
The 100 Hz (being 2x 50Hz, the power freq. in Italy)
suggests that it is probably related to some manner of
power supply. However, I have no theory why we're
getting 2x 50Hz (and I think I need one :-)).
That the signal is (or is approximately) a sawtooth wave
suggests a capacitor somewhere... either corrupting the
ground signal or creating a ripple in the DC power supply
(rectifier circuit or a broken voltage regulator). I would
probably start by checking the MOBO power supply.
-gabriel
p.s. Nerd Sniping... http://xkcd.com/356/
Noise and
interference on the voltage reference causes
amplitude modulation, and jitter on the clock causes
You're close. See the extra hint in a previous post.
7:50 p.m.
On Fri, May 28, 2010 at 12:39 PM, Gabriel M. Beddingfield
<gabrbedd(a)gmail.com> wrote:
The 100 Hz (being 2x 50Hz, the power freq. in Italy)
suggests that it is probably related to some manner of
power supply. However, I have no theory why we're
getting 2x 50Hz (and I think I need one :-)).
Doh! When the AC wave is rectified, it results in a signal that is 2x
the freq. because the negative part gets inverted. That's why we see
100 Hz instead of 50 Hz.
-gabriel
7:57 p.m.
Gabriel Beddingfield wrote:
On Fri, May 28, 2010 at 12:39 PM, Gabriel M.
Beddingfield
<gabrbedd(a)gmail.com> wrote:
On card A or X?
Why AM and not additive signals?
The 100 Hz (being 2x 50Hz, the power freq. in
Italy)
suggests that it is probably related to some manner of
power supply. However, I have no theory why we're
getting 2x 50Hz (and I think I need one :-)).
Doh! When the AC wave is rectified, it results in a signal that is 2x
the freq. because the negative part gets inverted. That's why we see
100 Hz instead of 50 Hz.
-gabriel
8:07 p.m.
On Fri, 28 May 2010, Ralf Mardorf wrote:
On card A or X?
X. A has already been "proven" -- unless it's a trick
question that we can't trust that "proof."
The 100 Hz (being 2x 50Hz, the power freq. in Italy)
suggests that it is probably related to some manner of
power supply. However, I have no theory why we're
getting 2x 50Hz (and I think I need one :-)).
Doh! When the AC wave is rectified, it results in a signal that is 2x
the freq. because the negative part gets inverted. That's why we see
100 Hz instead of 50 Hz.
-gabriel
Why AM and not additive signals?
Because the peaks shift with the input signal. If the
signals were just added (mixed) then the peaks would always
be at 100Hz, 200Hz, 300Hz... etc. and have the same
amplitude.
Try modelling it up with AMS (that's what I did).
-gabriel
8:18 p.m.
Gabriel M. Beddingfield wrote:
Try modelling it up with AMS (that's what I did).
-gabriel
:D
Not now, because ...
Gabriel M. Beddingfield wrote:
Dammit, Fons! I'm trying to get some work done today and go off and
nerd snipe me.....
[snip]
p.s. Nerd Sniping... http://xkcd.com/356/
... I now need to do some transactions and I never used AMS before.
$ ams started with a 'demo synth' or a preset, so it seems to work on my
machine, anyway, I don't have time to test it now.
Good luck!
Ralf
8:15 p.m.
The 100 Hz (being 2x 50Hz, the power freq. in Italy)
suggests that it is probably related to some manner of
power supply. However, I have no theory why we're
getting 2x 50Hz (and I think I need one :-)).
The implication has been that the USB audio device is a cheaper device. It is therefore
more likely that the device runs from the USB 5 volt line than have a separate power
supply, and that 5v line is regulated and therefore less likely to have a power line
ripple on it.
8:22 p.m.
Veronica Merryfield wrote:
USB power source very often breaks down and regulation isn't filtering.
The 100 Hz
(being 2x 50Hz, the power freq. in Italy)
suggests that it is probably related to some manner of
power supply. However, I have no theory why we're
getting 2x 50Hz (and I think I need one :-)).
The implication has been that the USB audio device is a cheaper device. It is therefore
more likely that the device runs from the USB 5 volt line than have a separate power
supply, and that 5v line is regulated and therefore less likely to have a power line
ripple on it.
8:23 p.m.
On Fri, 28 May 2010, Veronica Merryfield wrote:
Yes, as I go back and read that A was proven by A... it
could be the power source for either device -- and most
likely the "cheaper" card A.
-gabriel
The 100 Hz (being 2x 50Hz, the power freq. in
Italy)
suggests that it is probably related to some manner of
power supply. However, I have no theory why we're
getting 2x 50Hz (and I think I need one :-)).
The implication has been that the USB audio device is a
cheaper device. It is therefore more likely that the
device runs from the USB 5 volt line than have a separate
power supply, and that 5v line is regulated and therefore
less likely to have a power line ripple on it.
8:26 p.m.
Gabriel M. Beddingfield wrote:
On Fri, 28 May 2010, Veronica Merryfield wrote:
But it's more likely ;)!
and therefore less likely to have a power line
ripple on it.
Yes, as I go back and read that A was proven by A... it could be the
power source for either device -- and most likely the "cheaper" card A.
8:34 p.m.
On Fri, 28 May 2010 13:23:21 -0500 (CDT)
"Gabriel M. Beddingfield" <gabrbedd(a)gmail.com> wrote:
On Fri, 28 May 2010, Veronica Merryfield wrote:
Yes, as I go back and read that A was proven by A... it
could be the power source for either device -- and most
likely the "cheaper" card A.
-gabriel
OK, had a bit more of a think.
Once you connect the analogue side of the the USB device to the
installed (high quality card) you have an earth loop that traverses
both the analogue and digital domains. You also have an +5V loop (unless
the USB device is externally powered) This loop does not exist when the
USB card is self testing. I still can't think exactly how, but I
believe this is likely to be a significant part of the problem.
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
The 100 Hz (being 2x 50Hz, the power freq. in
Italy)
suggests that it is probably related to some manner of
power supply. However, I have no theory why we're
getting 2x 50Hz (and I think I need one :-)).
The implication has been that the USB audio device is a
cheaper device. It is therefore more likely that the
device runs from the USB 5 volt line than have a separate
power supply, and that 5v line is regulated and therefore
less likely to have a power line ripple on it.
8:40 p.m.
On Fri, 28 May 2010, Folderol wrote:
Once you connect the analogue side of the the USB device to the
installed (high quality card) you have an earth loop that traverses
both the analogue and digital domains. You also have an +5V loop (unless
the USB device is externally powered) This loop does not exist when the
USB card is self testing. I still can't think exactly how, but I
believe this is likely to be a significant part of the problem.
OK... but ground loops usually produce noise or a DC offset,
right? What could be causing the ground loop to oscillate?
-gabriel
8:50 p.m.
Gabriel M. Beddingfield wrote:
On Fri, 28 May 2010, Folderol wrote:
Somebody ask for ground lift before, this is regarding to your thoughts.
I was thinking about differences for ground leakage.
No, it isn't ground.
Once you connect the analogue side of the the USB device to the
installed (high quality card) you have an earth loop that traverses
both the analogue and digital domains. You also have an +5V loop (unless
the USB device is externally powered) This loop does not exist when the
USB card is self testing. I still can't think exactly how, but I
believe this is likely to be a significant part of the problem.
OK... but ground loops usually produce noise or a DC offset, right?
What could be causing the ground loop to oscillate?
-gabriel
8:52 p.m.
Ralf Mardorf wrote:
Gabriel M. Beddingfield wrote:
The switch, for totally cutting or decoupling by a capacitor.
On Fri, 28 May 2010, Folderol wrote:
Somebody ask for ground lift
Once you connect the analogue side of the the USB device to the
installed (high quality card) you have an earth loop that traverses
both the analogue and digital domains. You also have an +5V loop
(unless
the USB device is externally powered) This loop does not exist when the
USB card is self testing. I still can't think exactly how, but I
believe this is likely to be a significant part of the problem.
OK... but ground loops usually produce noise or a DC offset, right?
What could be causing the ground loop to oscillate?
-gabriel 
8:28 p.m.
On Fri, May 28, 2010 18:39, Gabriel M. Beddingfield wrote:
Dammit, Fons! I'm trying to get some work done today and go
off and nerd snipe me.....
[...]
-gabriel
p.s. Nerd Sniping... http://xkcd.com/356/
Well nerd sniped... I went to the xkcd blag, and what did I find there?
http://blog.xkcd.com/2010/05/15/miscellaneous/
"Also, Jacob Rus nerd sniped me with this, which is not related to the
color survey but I’m sharing it anyway."
I don't know about the colour survey, and even though I'm no engineer or
electrician or physicist, the article linked to in that paragraph on the
xkcd blog is a xrxaxtxhxexrx xixnxtxexrxexsxtxixnxgx xrxexaxdx enough to
get me interested in engineering/electrician/physics - if i could spare
the time that is.
james
8:27 p.m.
On Fri, May 28, 2010 at 8:37 AM, <fons(a)kokkinizita.net> wrote:
On Fri, May 28, 2010 at 08:30:54AM -0700, Niels Mayer
wrote:
It the "close" has to do with jitter:
* Something on the USB bus is causing a "periodic jitter" with a cycle of
100Hz?
* Something is causing a buffer to become empty every 0.01 seconds and
causing a periodic desync?
If the "close" has to do with induced or actual 50hz hum, perhaps
frequency-doubled via rectification:
* something in the USB power supply, as well as how that power supply
floats w/r/t ground (ground noise) is the source.
Which would agree with the Wolfson experts from
http://wolfsonmicro.com/uploads/documents/en/Specifying%20Jitter%20Performa…
stating "One of the authors once spent several days trying to track
down a low-frequency jitter problem, only to find that it was in fact
a problem of LF noise on the voltage reference."
Niels
http://nielsmayer.com
[...]
You're close. See the extra hint
in a previous post.
8:30 p.m.
Niels Mayer wrote:
On Fri, May 28, 2010 at 8:37 AM,
<fons(a)kokkinizita.net> wrote:
Don't forget to argue for what card. A or X?
On Fri, May 28, 2010 at 08:30:54AM -0700, Niels
Mayer wrote:
It the "close" has to do with jitter:
* Something on the USB bus is causing a "periodic jitter" with a cycle of
100Hz?
* Something is causing a buffer to become empty every 0.01 seconds and
causing a periodic desync?
If the "close" has to do with induced or actual 50hz hum, perhaps
frequency-doubled via rectification:
* something in the USB power supply, as well as how that power supply
floats w/r/t ground (ground noise) is the source.
Which would agree with the Wolfson experts from
http://wolfsonmicro.com/uploads/documents/en/Specifying%20Jitter%20Performa…
stating "One of the authors once spent several days trying to track
down a low-frequency jitter problem, only to find that it was in fact
a problem of LF noise on the voltage reference."
Niels
http://nielsmayer.com
[...]
You're close. See the extra hint in a previous post.
8:39 p.m.
Niels Mayer wrote:
If the "close" has to do with induced or
actual 50hz hum, perhaps
frequency-doubled via rectification:
It's the residual ripple for the DC that comes with 100 Hz. 50 Hz hum is
'send' by the transformer and could be heard as additive analog audio
signal, because of the 'electric smog'.
9:14 p.m.
On 2010-05-28, at 11:39 AM, Ralf Mardorf wrote:
Niels Mayer wrote:
The times I have measured the power line frequency to check it's effect or otherwise,
I have not measured it as exactly 50.0hz (when I lived in the UK).
Vrnc
If the "close" has to do with induced
or actual 50hz hum, perhaps
frequency-doubled via rectification:
It's the residual ripple for the DC that comes with 100 Hz. 50 Hz hum is
'send' by the transformer and could be heard as additive analog audio signal,
because of the 'electric smog'.
9:17 p.m.
Veronica Merryfield wrote:
On 2010-05-28, at 11:39 AM, Ralf Mardorf wrote:
I do agree, unfortunately I can't watch my meter right now, anyway, the
graphic might have distances of around 100 Hz.
Niels Mayer wrote:
The times I have measured the power line frequency to check it's effect or otherwise,
I have not measured it as exactly 50.0hz (when I lived in the UK).
Vrnc If the "close" has to do with induced
or actual 50hz hum, perhaps
frequency-doubled via rectification:
It's the residual ripple for the DC that comes with 100 Hz. 50 Hz hum
is 'send' by the transformer and could be heard as additive analog audio signal,
because of the 'electric smog'.
11:24 p.m.
-------- Original Message --------
Subject: Re: [LAD] A little quiz about audio measurements...
Date: Fri, 28 May 2010 21:17:38 +0200
From: Ralf Mardorf <ralf.mardorf(a)alice-dsl.net>
To: Veronica Merryfield <veronica.merryfield(a)tesco.net>
CC: Linux Audio Developers <linux-audio-dev(a)lists.linuxaudio.org>
References: <20100528123116.GA4058@zita2>
<AANLkTimYc_TFtVixHNTCRXvj3n_LtCJQzOsyKFnXiXTh(a)mail.gmail.com>
<20100528153747.GF4042@zita2>
<AANLkTim-FH9FRjAxxL9fwZ1nSG5K2yv3AXTYmpX9_BHN(a)mail.gmail.com>
<4C000DC7.1030709(a)alice-dsl.net>
<719832DC-9545-4B5A-8D5E-EE5F7F962867(a)tesco.net>
[snip]
OT followup:
Oberhausen, Rheinland, Germany; power line frequency right now is at 49
Hz, measured with a low cost energy consumption costs meter. Those low
cost meters shouldn't be able to do correct measurements ;). The best
test at home might be to compare the sound of a transformer with a 50 Hz
sine wave.
The times I have measured the power line
frequency to check it's effect or otherwise, I have not measured it as exactly 50.0hz
(when I lived in the UK).
Vrnc
[snip]
29 May
29 May
12:31 a.m.
On Fri, May 28, 2010 at 11:24:29PM +0200, Ralf Mardorf wrote:
Oberhausen, Rheinland, Germany; power line frequency
right now is at
49 Hz, measured with a low cost energy consumption costs meter.
Those low cost meters shouldn't be able to do correct measurements
;). The best test at home might be to compare the sound of a
transformer with a 50 Hz sine wave.
49 Hz is impossible. It would mean that a clock using this
frequency would be slow by more than a minute per hour.
Long-term accuracy is extremely high, precisely because clocks
depend on it. And since almost all of Europe is interconnected,
adjusting the frequency must be a _very_ slow process. So errors
of 2 percent really can't be tolerated.
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !
12:42 a.m.
fons(a)kokkinizita.net wrote:
On Fri, May 28, 2010 at 11:24:29PM +0200, Ralf Mardorf
wrote:
The meter is bad. As I've written before (I fetched your mail), you're
right, the tolerance is < 0.2 Hz (< 0,4%), but 1 Hz (2%) ;).
Oberhausen, Rheinland, Germany; power line
frequency right now is at
49 Hz, measured with a low cost energy consumption costs meter.
Those low cost meters shouldn't be able to do correct measurements
;). The best test at home might be to compare the sound of a
transformer with a 50 Hz sine wave.
49 Hz is impossible. It would mean that a clock using this
frequency would be slow by more than a minute per hour.
Long-term accuracy is extremely high, precisely because clocks
depend on it. And since almost all of Europe is interconnected,
adjusting the frequency must be a _very_ slow process. So errors
of 2 percent really can't be tolerated.
Ciao,
1:56 a.m.
On Friday 28 May 2010, fons(a)kokkinizita.net wrote:
On Fri, May 28, 2010 at 11:24:29PM +0200, Ralf Mardorf
wrote:
I beg to differ a bit. But this is also OT, sorry.
I can recall an instance while I was C.E.ing at KIVA-tv in Farminfton NM, in
the later 70's that was certainly odd to say the least. We had come off the
network into kiddie hour in the afternoon, with my operator on duty fussing
because the network ran over, way over, only to discover that no tv made
could sync to the video coming out of our Sony 2800, 3/4" U-Matic vcr's, and
moving the tape to another machine made no diff.
Since our power was from the W.A.P.A. grid, which is most of the US west of
the river, I glanced at the wall clock, which was then still a wall powered
synch motor clock, and found it was about 13 minutes ahead of my watch, an
early digital one.
So I called the local power company who had no clue what it was that I was
talking about, so they gave me another number to call. Shortening the
story here, 3 numbers & 15 minutes later I am talking to the engineer in
charge in the W.A.P.A. control room (I think in Bonneville Utah), and when I
said they were running fast, he laughed, so I asked him what time it was,
and got a quote that matched our wall clock to a second or so. I said, no,
its not, its such and such a time right now, and the whole grid is running
at what my counter says is 71HZ, I had by that time measured it. So he
walked over to his vibrating reed meter and of course it was so far off it
was silent. He came back to the phone and asked if I could hear anything,
at which point I could hear the air conditioner blowers almost coasting back
down to their usual speed, and it was back to about 59.6 HZ, which my vcr's
with their synch motors and eddy current brakes which made the belts slip
ever so slightly so that the drum speed was once again 1800 rpms (actually
1,798.2 rpms, NTSC of course), and we were back on the air. The wall clock
was finally right again about 22:00 that night.
The point being that he had the controls that allowed the whole grid west of
the river (Miss. River) to be dropped about 11 hertz in slightly over a
minute. And that is an area larger than Europe I believe.
Pull that today and they would probably send the black helicopters to check
your bodies DNA. After the fact.
Yup, broadcast engineering can be a "but that can't happen (but it just
did)" scenario at least once a week. I stuck around for 45 years just to
see what happened next. And it was quite a ride. ;-)
Now, back to your regularly scheduled puzzles. Your turn again Fons. ;-)
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
I still miss Windows, but my aim is getting better.
Oberhausen, Rheinland, Germany; power line
frequency right now is at
49 Hz, measured with a low cost energy consumption costs meter.
Those low cost meters shouldn't be able to do correct measurements
;). The best test at home might be to compare the sound of a
transformer with a 50 Hz sine wave.
49 Hz is impossible. It would mean that a clock using this
frequency would be slow by more than a minute per hour.
Long-term accuracy is extremely high, precisely because clocks
depend on it. And since almost all of Europe is interconnected,
adjusting the frequency must be a _very_ slow process. So errors
of 2 percent really can't be tolerated.
Ciao,
8:30 a.m.
Gene Heskett wrote:
On Friday 28 May 2010, fons(a)kokkinizita.net wrote:
Full ACK :D. I once repaired a mic cable. The so called 'audio engineer'
who 'repaired' it before I did it, didn't know what a 'balanced'
connection is, he thought 2 cords and 1 shield must be a stereo cable
for a stereo mic. What he wanted was a connection that fit the mono
microphone to a 6.3 mm stereo jack for a consumer cassette recorder.
O'Toole's Corollary of Finagle's Law: 'The perversity of the Universe
tends towards a maximum.'
Veronica Merryfield wrote:
On Fri, May 28, 2010 at 11:24:29PM +0200, Ralf
Mardorf wrote:
[snip]
Yup, broadcast engineering can be a "but that can't happen (but it just
did)" scenario at least once a week.
[snip]
Oberhausen, Rheinland, Germany; power line
frequency right now is at
49 Hz, measured with a low cost energy consumption costs meter.
Those low cost meters shouldn't be able to do correct measurements
;). The best test at home might be to compare the sound of a
transformer with a 50 Hz sine wave.
49 Hz is impossible. It would mean that a clock using this
frequency would be slow by more than a minute per hour.
Long-term accuracy is extremely high, precisely because clocks
depend on it. And since almost all of Europe is interconnected,
adjusting the frequency must be a _very_ slow process. So errors
of 2 percent really can't be tolerated.
Ciao,
On 2010-05-28, at 3:26 PM, fons(a)kokkinizita.net
wrote:
I don't think that we need to worry too much about the frequency. In the
morning, when all the people turn on all the coffee machines and
toasters, might be a bad time to adjust the H/V deflection for a
television set, because of the voltage that differs, but the frequency
should be stable. But indeed, during a snow storm the frequency will
drop extremely, but if so, we will hear about power blackouts in the
radio news, this happened e.g. in 2006 in Western Europe, there we had
around 49 HZ.
I guess even if it's OT, it's important. We won't a Hammond B3 become
similar to a tuning unstable Minimoog.
Indeed Veronica and Gene, I guess Fons is right. Yesterday evening it
wasn't 49 Hz, but a bad measurement done by my supermarket meter. But
who knows? Maybe the frequency really was down. Regarding to station
clocks I guess they are synced by radio and not by the power line. In
Parma there the clocks might be heritage-protected ;) and stills synced
by the power line frequency.
Cheers!
Ralf
--
Listen to Jasper van't Hof and Achim Jaroschek | Campus inter|national
#39 today in Leipzig
I can't be in Leipzig myself, but I saw some rehearses on video, when I
visited Achim and I'm sure it's worth it to visit their concert.
http://www.achimjaroschek.com/images/mediencampus_jaja.jpg
[snip]
Assume it at your peril. The usual spec is to arrange that over a given 24 hour period,
the total cycle count will result in a mains clock being within 1 second. Often, the power
generators can get much closer and I believe these days they use atomic clocks as the
reference 24 hour time period.
The frequency will drop upon sudden demand. This is often coincident with the start of
adverts in a national sporting event or high ratings soap, end of the news broadcast and
so on. It takes a while to add more power and as a consequence the rotating machines will
slow. Also, things like storm damage removing a significant section from the grid will
result in an increase in frequency.
Vrnc 
8:42 a.m.
Regarding to station clocks I guess they are synced by
radio and not by the power line. In Parma there the clocks might be heritage-protected ;)
and stills synced by the power line frequency.
The ones I have visited have two clocks, one on the power line and one atomical. The
control systems have the same thing, so they say, but when talking through the running of
the station it seemed much of that sort of control is manual.
The significance here, I was surprised to see 100.0hz if it was mains bourn.
Vrnc
9:14 a.m.
Veronica Merryfield wrote:
The Wiki on German:
"Unterfrequenz", droped frequency for Germany:
Stufe 1: 49,8 Hz "Alarmierung des Personals, Einsatz der noch
nicht mobilisierten Kraftwerksleistung."
On the alert
Stufe 2: 49,0 Hz Unverzögerter Lastabwurf von 10 - 15 % der
Netzlast.
First load shedding (disconnect all hospitals
first ;)
Stufe 3: 48,7 Hz Unverzögerter Lastabwurf von weiteren 10 - 15 %
der Netzlast.
Second load shedding
Stufe 4: 48,4 Hz Unverzögerter Lastabwurf von weiteren 15 - 20 %
der Netzlast.
Third load shedding
Stufe 5: 47,5 Hz Alle Kraftwerke müssen sich vom Netz trennen.
Stone Age
"Unterfrequenz" for Austria:
Maßnahmen im Erzeugungsbereich ab 49,8 Hz bis 49,3 Hz
Alarmierung des Personals, Einsatz der noch nicht mobilisierten
Kraftwerksleistung, Automatisches Einleiten von Pumpenabstellprogrammen
(beispielsweise von Pumpspeicherkraftwerken).
On the
alert + turning of pumps
Maßnahmen im Netznutzerbereich ab 49,0 Hz bis 48,2 Hz
Stufenweise Reduktion der Netzwirkleistung auf bis zu ca. 40 % der
Leistung vor Störungseintritt.
Load
shedding (again, I guess hospitals first ;), animal kingdom ;)
Maßnahmen zur Kraftwerksabstellung ab 47,5 Hz bis 45 Hz
Abstellprogramme zur Netzabtrennung von Maschinensätzen des
Kraftwerks-Eigenbedarfes.
The Four
Horsemen of the Apocalypse
Ende der Netzversorgung unterhalb von 45 Hz Trennung
der Kraftwerke vom Netz.
Stone Age
I found no Wiki for "Überferquenz", increased frequency. At what value
was the voltage, when there were 100 Hz?
So if anybody wants to program a virtual Hammond B3, should he take care
about tuning effects caused by the power line?
Btw. is the motors speed for a B3 depending to the voltage or is it
synced by the frequency?
Ralf
Regarding to
station clocks I guess they are synced by radio and not by the power line. In Parma there
the clocks might be heritage-protected ;) and stills synced by the power line frequency.
The ones I have visited have two clocks, one on the power line and one atomical. The
control systems have the same thing, so they say, but when talking through the running of
the station it seemed much of that sort of control is manual.
The significance here, I was surprised to see 100.0hz if it was mains bourn.
Vrnc
6:18 p.m.
On Saturday 29 May 2010, Ralf Mardorf wrote:
[...]
I found no Wiki for "Überferquenz", increased
frequency. At what value
was the voltage, when there were 100 Hz?
The 100 HZ component is what you get by rectifying both halves of the sine
wave, effectively inverting the lower half to become another pulse, with
lots of distortion so there will be harmonics of the 100HZ also displayed on
the spectrum display. In most power generators, the voltage at the output
is regulated by the current through the rotating armature being controlled,
so the voltage, should the armature overspeed, is generally fairly stable.
In what we call standby power systems here, the throttle of the engine doing
the turning is usually controlled by the output frequency, with a drop in
frequency being assumed to be an increase in the load, and an increase being
a drop in the load, generally achieving about a +- 1 hz tolerance. In much
larger systems, there will be a fixed frequency reference derived from a
master clock, and the phase angles of the power are compared to this
reference, with a very high gain so the phase errors are usually within a
degree. So the system is said to be phase locked. The input energy to turn
the machinery, water gates, whatever, are where the control is actually
exerted. Should any one 'generator' get more than a few degrees out of
lock, it will usually disconnect itself, or reduce its excitation current to
allow it to catch up or increase it if it needs to slow minutely, this may
cause a few millivolts of a voltage change to the whole grid. Somewhere in
here the load shedding also comes into play if it is a controllable item for
that section of the grid.
Where the grid idea fails in places like the US, is when the light speed
propagation delays begin to play with the phase reference. Because of this
the USA is broken into smaller pieces grid wise.
So if anybody wants to program a virtual Hammond B3,
should he take care
about tuning effects caused by the power line?
Btw. is the motors speed for a B3 depending to the voltage or is it
synced by the frequency?
Ralf
They are synch motors Ralf. Its a different motor for me at 60hz on this
side of the pond.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Windows 98 is the most popular virus on the market today.
30 May
30 May
7:29 a.m.
On Sat, 2010-05-29 at 12:18 -0400, Gene Heskett wrote:
On Saturday 29 May 2010, Ralf Mardorf wrote:
...
I've never heard of an out-of-tune Hammond being a problem? Perhaps
because we are not partying yet when the factories close down and all
the switching is done, and on Sundays when we go to church - which we
all do, no? - the factories aren't running at all.
What can be said though, is that in order to mimic the electric sizzling
sound of a melting power-station in America, you will build up your
drone in the key of A# rather than in G - which would have been closer
to the European 50 Hz
There is a switch on the backside of the Hammond to spin it down in
remembrance of those unforgettable brown-out moments.
--
jedes mal wenn du eine quintparallele verwendest
tötet bach ein kätzchen
http://www.youtube.com/watch?v=43RdmmNaGfQ
So if anybody wants to program a virtual Hammond
B3, should he take care
about tuning effects caused by the power line?
Btw. is the motors speed for a B3 depending to the voltage or is it
synced by the frequency?
Ralf
They are synch motors Ralf. Its a different motor for me at 60hz on this
side of the pond.
1:05 p.m.
Jens M Andreasen wrote:
There is a switch on the backside of the Hammond to
spin it down in
remembrance of those unforgettable brown-out moments.
I can't translate 'brown-out' into German. Is this regarding to James
Brown? Not my kind of music, but Bernie Worrell still is alive and he
always did the better funky beats.
Bernie Worrell
http://www.youtube.com/watch?v=MEDB4xJsXVo
Also listen to
http://en.wikipedia.org/wiki/Praxis_(band)
I don't have a killer switch on my guitar and I don't wish to have one,
but I would like to play like Mr. Worrell, unfortunately keys aren't my
gift.
--
'jedes mal wenn du eine quintparallele verwendest tötet bach ein kätzchen'
Zum Glück haben Katzen 7 Leben, denn gelegentlich mache ich Pop-Musik und dabei dann alles
mögliche böse.
'http://www.youtube.com/watch?v=43RdmmNaGfQ'
Among others I do have a bass tromp, playing it can cause toothaches, because this
swinging metal-something sometimes crashes against the tooth.
2:29 p.m.
On Sun, 2010-05-30 at 13:05 +0200, Ralf Mardorf wrote:
Nope, and I think it already is "proper" German. From Wikipedia:
[Stromausfall]
...
1) ...
2) Kurzzeitige Spannungsabsenkung zufolge Überlastung aufgrund
unvorhergesehener Ereignisse. Dieser Zustand wird im Englischen auch
als /Brown-Out/ oder Sag bezeichnet und tritt insbesondere in kleineren
Stromnetzen oder unterdimensionierten Netzen mit zu gering verfügbarer
Regelleistung auf. /Brown-Outs/ sind beispielsweise im Japanischen
Stromversorgungsnetzen relativ häufig, auch aufgrund der gemischten
Netzfrequenz von 50 Hz und 60 Hz, während im europäischen Verbundsystem
überregionale /Brown-Outs/ nur sehr selten vorkommen.
/Brown-Outs/ können auch unmittelbar vor einem Totalausfall auftreten.
--
eins, zwei, drei ... tekno tekno??
http://www.youtube.com/watch?v=ZEgbW1FxR78
There is a
switch on the backside of the Hammond to spin it down in
remembrance of those unforgettable brown-out moments.
I can't translate 'brown-out' into German. Is this regarding to James
Brown? ...
2:35 p.m.
Jens M Andreasen wrote:
On Sun, 2010-05-30 at 13:05 +0200, Ralf Mardorf
wrote:
Nope, and I think it already is "proper" German. From Wikipedia:
[Stromausfall]
...
1) ...
2) Kurzzeitige Spannungsabsenkung zufolge Überlastung aufgrund
unvorhergesehener Ereignisse. Dieser Zustand wird im Englischen auch
als /Brown-Out/ oder Sag bezeichnet und tritt insbesondere in kleineren
Stromnetzen oder unterdimensionierten Netzen mit zu gering verfügbarer
Regelleistung auf. /Brown-Outs/ sind beispielsweise im Japanischen
Stromversorgungsnetzen relativ häufig, auch aufgrund der gemischten
Netzfrequenz von 50 Hz und 60 Hz, während im europäischen Verbundsystem
überregionale /Brown-Outs/ nur sehr selten vorkommen.
/Brown-Outs/ können auch unmittelbar vor einem Totalausfall auftreten.
Hahaha :D
sorry, I had a ...
"Brownout
aus Wikipedia, der freien Enzyklopädie
Wechseln zu: Navigation, Suche
Brownout (zu Deutsch: „Verminderte Lichtstärke“ bzw. „Abdunkelung“) ist
ein aus dem Englischen stammender Begriff und bezeichnet:
* in Stromversorgungsnetzen einen kurzzeitigen Spannungseinbruch und
eine Vorstufe eines Stromausfalls sein kann
* ein Absinken der Versorgungsspannung – primär bei Mikrocontrollern –,
welche einen Reset (Neustart) auslösen kann
* in der Informatik den Ausfall eines Servers, dessen Lasten dann von
anderen Servern getragen werden müssen
* eine Einschränkung der Sichtverhältnisse durch Staub oder Sand beim
Fliegen, die zum vollständigen Verlust der Orientierung führen kann.
Siehe auch
* Whiteout
* Blackout
* Greyout
* Redout"
... Blackout ;).
It's Sunday 'morning' 13:00 - 14:00 o'clock ;).
Cheers!
Ralf
There is
a switch on the backside of the Hammond to spin it down in
remembrance of those unforgettable brown-out moments.
I can't translate 'brown-out' into German. Is this regarding to
James
Brown? ...
29 May
29 May
5:58 p.m.
On Saturday 29 May 2010, Veronica Merryfield wrote:
That is because the 50hz is full wave rectified, becoming 100hz and
harmonics thereof because that waveform is not a sin wave.
Regarding to
station clocks I guess they are synced by radio and not by
the power line. In Parma there the clocks might be heritage-protected ;)
and stills synced by the power line frequency.
The ones I have visited have two clocks, one on the power line and one
atomical. The control systems have the same thing, so they say, but when
talking through the running of the station it seemed much of that sort of
control is manual.
The significance here, I was surprised to see 100.0hz if it was mains
bourn.
Vrnc
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev(a)lists.linuxaudio.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Windows 98 is the most popular virus on the market today.
3:59 a.m.
On 2010-05-28, at 3:26 PM, fons(a)kokkinizita.net wrote:
49 Hz is impossible. It would mean that a clock using
this
frequency would be slow by more than a minute per hour.
Long-term accuracy is extremely high, precisely because clocks
depend on it. And since almost all of Europe is interconnected,
adjusting the frequency must be a _very_ slow process. So errors
of 2 percent really can't be tolerated.
Assume it at your peril. The usual spec is to arrange that over a given 24 hour period,
the total cycle count will result in a mains clock being within 1 second. Often, the power
generators can get much closer and I believe these days they use atomic clocks as the
reference 24 hour time period.
The frequency will drop upon sudden demand. This is often coincident with the start of
adverts in a national sporting event or high ratings soap, end of the news broadcast and
so on. It takes a while to add more power and as a consequence the rotating machines will
slow. Also, things like storm damage removing a significant section from the grid will
result in an increase in frequency.
Vrnc
12:33 a.m.
Ralf Mardorf wrote:
-------- Original Message --------
Subject: Re: [LAD] A little quiz about audio measurements...
Date: Fri, 28 May 2010 21:17:38 +0200
From: Ralf Mardorf <ralf.mardorf(a)alice-dsl.net>
To: Veronica Merryfield <veronica.merryfield(a)tesco.net>
CC: Linux Audio Developers <linux-audio-dev(a)lists.linuxaudio.org>
References: <20100528123116.GA4058@zita2>
<AANLkTimYc_TFtVixHNTCRXvj3n_LtCJQzOsyKFnXiXTh(a)mail.gmail.com>
<20100528153747.GF4042@zita2>
<AANLkTim-FH9FRjAxxL9fwZ1nSG5K2yv3AXTYmpX9_BHN(a)mail.gmail.com>
<4C000DC7.1030709(a)alice-dsl.net>
<719832DC-9545-4B5A-8D5E-EE5F7F962867(a)tesco.net>
Really OT, but maybe anyway interesting, regarding to a German Wiki,
http://de.wikipedia.org/wiki/Netzfrequenz:
Because of magnetostriction of the ferrite core, the sound of
transformer stations is at 100 Hz. Dunno if this is the same for
transformer in our power supplies too.
The load of the public power supply will change the frequency in Western
Europe < 0,2 Hz. When there was a blackout at 11/04/2006 the frequency
change like this:
http://de.wikipedia.org/w/index.php?title=Datei:Netzfrequenz_20061104_Area_…
Regarding to the German Wiki http://de.wikipedia.org/wiki/Unterfrequenz
all power stations need to disconnect at 47.5 Hz. At 49.8 Hz there is an
alert.
We should assume that the frequency in Western Europe is solid 50.19 to
49.81 ;).
[snip]
OT followup:
Oberhausen, Rheinland, Germany; power line frequency right now is at
49 Hz, measured with a low cost energy consumption costs meter. Those
low cost meters shouldn't be able to do correct measurements ;). The
best test at home might be to compare the sound of a transformer with
a 50 Hz sine wave. The times I have measured the power line
frequency to check it's
effect or otherwise, I have not measured it as exactly
50.0hz (when I
lived in the UK). >
Vrnc
[snip]
30 May
30 May
4:06 p.m.
Am Freitag 28 Mai 2010 schrieb fons(a)kokkinizita.net:
On Fri, May 28, 2010 at 08:30:54AM -0700, Niels Mayer
wrote:
Sound Card A's DAC and ADC share the same voltage reference,
which has a 100 Hz ripple?
Regards,
Karsten
Audio ADCs and DACs have three important inputs;
the signal input, the voltage reference, and the clock.
Noise and interference on the voltage reference causes
amplitude modulation, and jitter on the clock causes
phase modulation. The resulting modulation products
look very similar in the frequency domain. One of the
authors once spent several days trying to track down a
low-frequency jitter problem, only to find that it was
in fact a problem of LF noise on the voltage reference.
You're close. See the extra hint in a previous post.
6:08 p.m.
Am Sonntag 30 Mai 2010 schrieb Karsten Wiese:
Am Freitag 28 Mai 2010 schrieb fons(a)kokkinizita.net:
ah erm, just found "the winners" thread.
On Fri, May 28, 2010 at 08:30:54AM -0700, Niels
Mayer wrote:
Sound Card A's DAC and ADC share the same voltage reference,
which has a 100 Hz ripple? Audio ADCs and DACs have three important inputs;
the signal input, the voltage reference, and the clock.
Noise and interference on the voltage reference causes
amplitude modulation, and jitter on the clock causes
phase modulation. The resulting modulation products
look very similar in the frequency domain. One of the
authors once spent several days trying to track down a
low-frequency jitter problem, only to find that it was
in fact a problem of LF noise on the voltage reference.
You're close. See the extra hint in a previous post.
5319
days inactive
5321
days old
linux-audio-dev@lists.linuxaudio.org
74 comments
17 participants
participants (17)
-
Arnold Krille -
Chris Cannam -
Florian Faber -
Folderol -
fons＠kokkinizita.net -
Gabriel Beddingfield -
Gabriel M. Beddingfield
-
Gene Heskett -
James Morris -
Jens M Andreasen -
Karsten Wiese -
Niels Mayer -
Ralf Mardorf -
Ricardus Vincente -
Robin Gareus -
torbenh -
Veronica Merryfield