9 Nov
2006
9 Nov
'06
10:28 p.m.
There are a lot of hums that are very friendly and encouraging, but the
hum that comes out of my speaker when I start up Jack is way more than
that. It's sharp pitched and I believe it penetrates deep into the soul
and causes unrest there.
It comes about when I use jack at low latencies. I experimented with
ground loops and found it is the same hum (or a similar hum) and simply
gets softer when I use my homebrew ground prong removal cable (it's just
a small extension cord with a three prong socket and a two prong plug. I
must be violating every safety standard in the Universe, and I probably
wouldn't be the first desperate musician to die in an unfortunate
accident caused by valuing artistic purity higher than corporal safety.)
It actually also comes about when I use a pure Alsa program realtime and
at low latencies, but I'm still calling the thing 'Jack Hum' because I
like you jack people so much. That's what you get for being so friendly!
I also don't know any good low latency alsa programs any more.
So... I wonder if someone's looking into this. It's preventing me from
recording stuff. And I've got some insanely good music coming up and
people are actually responding well to my newsletter, which is quite
flabbergasting to me. I'm not used to people responding well to what I do.
I should also mention that I have a firewire audio interface with
included microphone pre-amp, and that the hum gets REALLY lound on the
Mic channels when phantom power is turned on.
So please, please, please help me! I'm desparate. I've been working on
linux audio for over four years and my music's starting to get good
enough to be published and I can't record because of some dumb analogue
engineering problem. Are any smart analogue engineers reading this?
Heck, i'll go for the dumb ones too if it will make my problem go away.
Help!
Carlo
9 Nov
9 Nov
10:49 p.m.
New subject: [linux-audio-user] The famous "Jack Hum" (Can't record and desparate)
Carlo Capocasa wrote:
I should also mention that I have a firewire audio
interface with
included microphone pre-amp, and that the hum gets REALLY lound on the
Mic channels when phantom power is turned on.
So please, please, please help me! I'm desparate. I've been working on
linux audio for over four years and my music's starting to get good
enough to be published and I can't record because of some dumb analogue
engineering problem. Are any smart analogue engineers reading this?
Methinks there is Somewheres (note the forced plural!) in your hardware
setup one or more pieces with bad shielding and/or bad grounding. The
problems might not be limited to cabling - they could be something
inside your hardware.
A possible candidate - your fireware audio interface w/ microphone
pre-amp. It may be originating the hum in the first place, and the mic
pre-amp makes it really loud.
--
David
gnome(a)hawaii.rr.com
authenticity, honesty, community
10 Nov
10 Nov
2:11 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
Methinks there is Somewheres (note the forced plural!)
in your hardware
setup one or more pieces with bad shielding and/or bad grounding. The
problems might not be limited to cabling - they could be something
inside your hardware.
Me thinksesss this beesss precioussss advicessssss.
A possible candidate - your fireware audio interface
w/ microphone
pre-amp. It may be originating the hum in the first place, and the mic
pre-amp makes it really loud.
I have the same problem going over the internal sound card, and it is
more intense there. The odd part is, the lower the latency, the more
intense the hum; and even weirder, I CAN EVEN HEAR THE HUM WHEN THE
COMPUTER IS HOOKED UP TO SPEAKERS THAT ARE TURNED OFF. So you can
actually hear the hum; it's just that whatever sound adapter is hooked
up, firewire or interal, amplifies it.
First I thought it was hard drive noise; but I tried putting Jack's
tempfiles on a ram disk and that had no effect.
Could it actually be that the CPU itself is causing electromagnetic
effects because it has to work so hard?
Curious.
Carlo
2:21 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
Carlo Capocasa wrote:
I think it could be the cpu fan. If you've an AMD with Cool 'n Quiet (or
something similar) the fan adjust its speed according to the cpu usage.
Have you tried to experiment with the pc chassis opened?
Hope this helps.
c.
Methinks there
is Somewheres (note the forced plural!) in your hardware
setup one or more pieces with bad shielding and/or bad grounding. The
problems might not be limited to cabling - they could be something
inside your hardware.
Me thinksesss this beesss precioussss advicessssss.
A possible candidate - your fireware audio
interface w/ microphone
pre-amp. It may be originating the hum in the first place, and the mic
pre-amp makes it really loud.
I have the same problem going over the internal sound card, and it is
more intense there. The odd part is, the lower the latency, the more
intense the hum; and even weirder, I CAN EVEN HEAR THE HUM WHEN THE
COMPUTER IS HOOKED UP TO SPEAKERS THAT ARE TURNED OFF. So you can
actually hear the hum; it's just that whatever sound adapter is hooked
up, firewire or interal, amplifies it.
First I thought it was hard drive noise; but I tried putting Jack's
tempfiles on a ram disk and that had no effect.
Could it actually be that the CPU itself is causing electromagnetic
effects because it has to work so hard?
Curious.
Carlo
--
www.cesaremarilungo.com
On the Internet, no one knows you're using Windows NT
-- Submitted by Ramiro Estrugo, restrugo(a)fateware.com
12 Nov
12 Nov
4:35 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
I think it could be the cpu fan. If you've an AMD
with Cool 'n Quiet (or
something similar) the fan adjust its speed according to the cpu usage.
Have you tried to experiment with the pc chassis opened?
Thanks for caring, Cesare. It's a notebook, but I'll just do it anyway.
I already did a little while back to put some thermal paste on the CPU
when I was having the Dell Heatwaves a little while back.
I also found a CPU cooling management tool for dell books a while bac
(i8k), but that won't wrestle thermal control out of the Dell Bios' evil
hands. It will only argue (IE Bios will turn fans on, a millisecond
later the tool will turn it off, etc.)
I'll probably also look into the Open Source bios project to see if I
can flash my notebook bios with something new, possibly
custom-developed. I'm so desperate to get a working solution out of my
old book I'll do just about ANYTHING.
Carlo
10 Nov
10 Nov
2:22 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
On Fri, Nov 10, 2006 at 07:10:03PM +0100, Carlo Capocasa wrote:
I CAN EVEN HEAR THE HUM WHEN THE
COMPUTER IS HOOKED UP TO SPEAKERS THAT ARE TURNED OFF.
And where is it coming from then, if not from the speakers ?
--
FA
Lascia la spina, cogli la rosa.
3:22 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
On Fri, Nov 10, 2006 at 07:10:03PM +0100, Carlo Capocasa wrote:
I CAN EVEN HEAR THE HUM WHEN THE
COMPUTER IS HOOKED UP TO SPEAKERS THAT ARE TURNED OFF.
My computer had a barely audible whine when KDE started, but when I
started JACK, it would quit. As soon as I stopped JACK, the whine
came back. I finally discovered that if I disabled KDE's normal sound
daemon, the whine went away.
I still have no clue what was whining, since it would do this even
with no speakers connected.
-TimH
8:54 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
On Friday, 10. November 2006 19:10, Carlo Capocasa wrote:
I have the same problem going over the internal sound
card, and it is
more intense there. The odd part is, the lower the latency, the more
intense the hum; and even weirder, I CAN EVEN HEAR THE HUM WHEN THE
COMPUTER IS HOOKED UP TO SPEAKERS THAT ARE TURNED OFF. So you can
actually hear the hum; it's just that whatever sound adapter is hooked
up, firewire or interal, amplifies it.
A while ago I had a very similar problem, on an Athlon XP desktop machine.
Whenever I ran jack at low latency, there was a high pitched noise coming
from somewhere inside the case. I was unable to pinpoint where exactly it
came from, but I'm pretty sure it originated somewhere on the mainboard,
maybe the CPU or the PCI cards.
But it didn't just come from the case, it was also audible on headphones,
on both my PCI sound cards!
At 256 frames/second, the noise was barely audible... At 128 it was quite
easily noticable, and at 64 it became downright annoying. At 32 or 16
frames/second it was even worse...
But the most intriguing part of the whole story: Not only did the noise
get louder at a lower latency, it also seemed to precisely double its
frequency when running at halve the number of frames. I even tried to
measure the frequency of the noise. As far as I remember, when running
jack for instance at 44100Hz, periodsize 32, the noise was at exactly
44100/32 = 1378Hz!
Anyway, this whole issue went away after I disabled athcool (a utility to
reduce heat and power consumption on Athlon CPUs) while running jack. But
still all of this remains a mystery to me...
Dominic
11 Nov
11 Nov
8:48 a.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
But the most intriguing part of the whole story: Not
only did the noise
get louder at a lower latency, it also seemed to precisely double its
frequency when running at halve the number of frames. I even tried to
measure the frequency of the noise. As far as I remember, when running
jack for instance at 44100Hz, periodsize 32, the noise was at exactly
44100/32 = 1378Hz!
Is an interrupt fired at each period? If so the cpu will use more power
(or woken if it was asleep); a small power 'surge' which can of course
have an influence on any analog hardware near by.
daniel
3:43 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
On Sat, 2006-11-11 at 13:51 +0100, Daniel Wagner wrote:
Really sounds like the power supply, the high frequency transformers can
"sing" with changes in load if the windings are a bit loose. I think
capacitors can also do that.
Somebody I know had a fanless computer in his room (a very old machine
that really did not need fans if the case was left wide open) and the
only remaining sound was some component singing with the network
traffic...
-- Fernando
But the most
intriguing part of the whole story: Not only did the noise
get louder at a lower latency, it also seemed to precisely double its
frequency when running at halve the number of frames. I even tried to
measure the frequency of the noise. As far as I remember, when running
jack for instance at 44100Hz, periodsize 32, the noise was at exactly
44100/32 = 1378Hz!
Is an interrupt fired at each period? If so the cpu will use more power
(or woken if it was asleep); a small power 'surge' which can of course
have an influence on any analog hardware near by. 
12 Nov
12 Nov
10:42 a.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
Fernando Lopez-Lezcano wrote:
On Sat, 2006-11-11 at 13:51 +0100, Daniel Wagner
wrote:
Really sounds like the power supply, the high frequency transformers can
"sing" with changes in load if the windings are a bit loose. I think
capacitors can also do that.
Somebody I know had a fanless computer in his room (a very old machine
that really did not need fans if the case was left wide open) and the
only remaining sound was some component singing with the network
traffic...
A simple test to see if the load is causing the hum:
Open a PDF in acroread (if you have it installed). I noticed that I can
make some computer sing by dragging the view (hand tool) in acrobat
reader. acroread seems to contignously redraw when you use the hand tool.
The solution: get a high quality power supply & possibly a high quality
mainboard too. But as you are experiencing this with a laptop there's
not much you can do.
Pieter
PS: Maybe this is the one good reason to choose Apple over Dell... ?
But the
most intriguing part of the whole story: Not only did the noise
get louder at a lower latency, it also seemed to precisely double its
frequency when running at halve the number of frames. I even tried to
measure the frequency of the noise. As far as I remember, when running
jack for instance at 44100Hz, periodsize 32, the noise was at exactly
44100/32 = 1378Hz!
Is an interrupt fired at each period? If so the cpu will use more power
(or woken if it was asleep); a small power 'surge' which can of course
have an influence on any analog hardware near by.
2:09 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
On Sun, 2006-11-12 at 15:42 +0100, Pieter Palmers wrote:
PS: Maybe this is the one good reason to choose Apple
over Dell... ?
Apple's quality control is as bad as the PC guys these days (google
"Macbook random shutdown").
Lee
4:30 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
A while ago I had a very similar problem, on an Athlon
XP desktop machine.
Whenever I ran jack at low latency, there was a high pitched noise coming
from somewhere inside the case. I was unable to pinpoint where exactly it
came from, but I'm pretty sure it originated somewhere on the mainboard,
maybe the CPU or the PCI cards.
But it didn't just come from the case, it was also audible on headphones,
on both my PCI sound cards!
This is EXACTLY the problem I faced, and EXACTLY the response I had to
it. Where the hell is that faint hum coming from?
What was especially confusing is that it was audible both without
headphones, very slightly, and with headphones, amplified.
At 256 frames/second, the noise was barely audible...
At 128 it was quite
easily noticable, and at 64 it became downright annoying. At 32 or 16
frames/second it was even worse...
This is exactly the behavior I experienced. Very slight at higher
latencies; however, I tried it at my friend's club and over the
high-powered amps it is still a clear annoyance, not to mention not
being able to sing and run effects over it at low latency.
But the most intriguing part of the whole story: Not
only did the noise
get louder at a lower latency, it also seemed to precisely double its
frequency when running at halve the number of frames. I even tried to
measure the frequency of the noise. As far as I remember, when running
jack for instance at 44100Hz, periodsize 32, the noise was at exactly
44100/32 = 1378Hz!
That is absolutely fascinating. I WILL investigate this; if it
coincides, we have a VERY strong case that this is the same problem.
Anyway, this whole issue went away after I disabled
athcool (a utility to
reduce heat and power consumption on Athlon CPUs) while running jack. But
still all of this remains a mystery to me...
What would be the corresponding utility for a Pentium 4 mobile (used
before centrinos, slightly modified for notebook assemblage but still a
full Pentium 4) be? How could I completely de-activate power management
and open the case and put some ice cubes in? (IE manage power myself,
with a room fan, or liquid cooling, or whatever...)
Carlo
8:29 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
On Sun, 2006-11-12 at 21:29 +0100, Carlo Capocasa wrote:
Really sounds like you have a singing capacitor. IOW your problem is
cheap hardware. If this is the case, you won't be able to fix it.
Lee
But the most
intriguing part of the whole story: Not only did the noise
get louder at a lower latency, it also seemed to precisely double its
frequency when running at halve the number of frames. I even tried to
measure the frequency of the noise. As far as I remember, when running
jack for instance at 44100Hz, periodsize 32, the noise was at exactly
44100/32 = 1378Hz!
That is absolutely fascinating. I WILL investigate this; if it
coincides, we have a VERY strong case that this is the same problem. 
10:01 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
Am Montag, 13. November 2006 01:28 schrieb Lee Revell:
On Sun, 2006-11-12 at 21:29 +0100, Carlo Capocasa
wrote:
Really sounds like you have a singing capacitor. IOW your problem is
cheap hardware. If this is the case, you won't be able to fix it.
Guess Lee is right.
Does noise vanish when laptop is running on battery?
Erm, and what exactly is that laptop called?,
so I can avoid to buy one of those ;-)
Karsten
But the
most intriguing part of the whole story: Not only did the noise
get louder at a lower latency, it also seemed to precisely double its
frequency when running at halve the number of frames. I even tried to
measure the frequency of the noise. As far as I remember, when running
jack for instance at 44100Hz, periodsize 32, the noise was at exactly
44100/32 = 1378Hz!
That is absolutely fascinating. I WILL investigate this; if it
coincides, we have a VERY strong case that this is the same problem. 
10:22 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
On Mon, Nov 13, 2006 at 03:01:48AM +0100, Karsten Wiese wrote:
Am Montag, 13. November 2006 01:28 schrieb Lee
Revell:
Oooh yeah, I didn't notice you guys were talking about a laptop.
Try unplugging the power supply.
I found with all three laptops I've had (all Dells) that
the power supply makes a lot of really horrible noise
that leaks into all my audio gear. Only solution I've found is
to use a 3-prong-to-2-prong power adapter and leave the grounding
tab unconnected to anything. Dunno how safe that is :-\
--
Paul Winkler
http://www.slinkp.com
On Sun, 2006-11-12 at 21:29 +0100, Carlo Capocasa
wrote:
Really sounds like you have a singing capacitor. IOW your problem is
cheap hardware. If this is the case, you won't be able to fix it.
Guess Lee is right.
Does noise vanish when laptop is running on battery? But the
most intriguing part of the whole story: Not only did the noise
get louder at a lower latency, it also seemed to precisely double its
frequency when running at halve the number of frames. I even tried to
measure the frequency of the noise. As far as I remember, when running
jack for instance at 44100Hz, periodsize 32, the noise was at exactly
44100/32 = 1378Hz!
That is absolutely fascinating. I WILL investigate this; if it
coincides, we have a VERY strong case that this is the same problem.
10:32 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
Paul Winkler wrote:
I don't trust Dell hardware. I spent 11 years working on a help desk for
a large local corporation. When they switched from IBM hardware to Dell
hardware, our hardware trouble call counts TRIPLED.
I can't find any such noise on my Toshiba laptop.
--
David
gnome(a)hawaii.rr.com
authenticity, honesty, community
Does noise
vanish when laptop is running on battery?
Oooh yeah, I didn't notice you guys were talking about a laptop.
Try unplugging the power supply.
I found with all three laptops I've had (all Dells)
13 Nov
13 Nov
12:16 p.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
tab unconnected to anything. Dunno how safe that is
:-\
I can think of worse ways to die.
Actually I already did that, and it did remove the ground loop.
Apparently I have a singing capacitor as well.
Carlo
10 Nov
10 Nov
6:20 a.m.
New subject: [linux-audio-user] The famous "Jack Hum" (Can't record and desparate)
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Carlo Capocasa schrieb:
There are a lot of hums that are very friendly and
encouraging, but the
hum that comes out of my speaker when I start up Jack is way more than
that. It's sharp pitched and I believe it penetrates deep into the soul
and causes unrest there.
I had a quite similar Problem (that ceased after i stop using a
Lamp-dimmer in the room next door) and i am sure to call it
"network-hum" instead of "jack-hum". Little poor innocent jack is
just
software - has no capabilities to fetch stuff from the real world, that
is not *there* in the first place ;-)
some 20 Years of fightig (unwanted) noise in audioelectronics give me
the strong feel, that your problem is caused by
hardware/cabeling/powersupply. You have mentioned, that you have a
fw-sounddevice and that the hum unfolds, as you start up jackd. Jackd
fetches the stream from the fw-device and if it causes humming jackd
naively thinks, you want everything you precious soundcard generates ;-)
here are some suspects:
power-supply of the device: try changing its connection to the ac-net
(vulgo: connect it to another powerline - preferably the same, you have
your Computer connected to, rule of thumb: all devices should share the
same fuse.)
cabeling of the stuff, that is connected to the device:
Microphone-cables should be hi-class, adapters shall be at the same fuse
(see above) if you need phantom-power, fetch it from a mixer/preamp,
that gets its current from the same etc...
Neon-lights, dimmers, everything that needs a power-transformator. It
can be the cute lights for the aquarium in the room next door... those
produce electromagnetic waves that can pollute badly grounded/shielded
cables, device-hulls etc etc
If you play Guitars, Synths etc hardwired (eg. with an electric
connection to the network/system), try to use direct-injection-boxes.
network means: everything that has an electrical connection to whatever
device you use, including stuff like modems, ethernet AND ac-plugs,
electronical instruments, Lamps, hair-dryers, chainsaws, peripherals
like printers, scanners, cameras etc. connected via USB, Firewire,
ethernet, guitarcables, ac-adapters - you name it.
good luck
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2:24 p.m.
New subject: [linux-audio-user] Re: The famous "It is not proven that it is because of Jack Hum" (Can't record and desparate)
Thanks, Hartmut!
Actually I was able to get rid of one kind of hum with my forced ground
remover.
Quite possible that there's lamp dimmers somewhere near every single
place I start making music, but I found that the hum originates
somewhere in my computer is a more credible explanation, especially
since I can hear it with bare ears; a soft noise, almost like hard drive
spinup noise, but a bit louder and continuous. Only comes up when using
realtime live audio.
I had a quite similar Problem (that ceased after i
stop using a
Lamp-dimmer in the room next door) and i am sure to call it
"network-hum" instead of "jack-hum". Little poor innocent jack is
just
software - has no capabilities to fetch stuff from the real world, that
is not *there* in the first place ;-)
LOL... agreed on Jack, I guess... Unless, of course, the hum really does
originate inside the computer, in which case 'CPU kernel controlled by
jack hum' would be probably most accurate.
some 20 Years of fightig (unwanted) noise in
audioelectronics give me
the strong feel, that your problem is caused by
hardware/cabeling/powersupply. You have mentioned, that you have a
fw-sounddevice and that the hum unfolds, as you start up jackd. Jackd
fetches the stream from the fw-device and if it causes humming jackd
naively thinks, you want everything you precious soundcard generates ;-)
here are some suspects:
power-supply of the device: try changing its connection to the ac-net
(vulgo: connect it to another powerline - preferably the same, you have
your Computer connected to, rule of thumb: all devices should share the
same fuse.)
Already done... no noticable effect.
cabeling of the stuff, that is connected to the
device:
Microphone-cables should be hi-class, adapters shall be at the same fuse
(see above) if you need phantom-power, fetch it from a mixer/preamp,
that gets its current from the same etc...
Done. The hum is also there when there is no microphone connected.
Neon-lights, dimmers, everything that needs a
power-transformator. It
can be the cute lights for the aquarium in the room next door... those
produce electromagnetic waves that can pollute badly grounded/shielded
cables, device-hulls etc etc
I do suspect the noise originates inside the computer... Since I can
hear it with bare ears and it just gets amplified by whatever sound card
I happen to be using.
If you play Guitars, Synths etc hardwired (eg. with an
electric
connection to the network/system), try to use direct-injection-boxes.
network means: everything that has an electrical connection to whatever
device you use, including stuff like modems, ethernet AND ac-plugs,
electronical instruments, Lamps, hair-dryers, chainsaws, peripherals
like printers, scanners, cameras etc. connected via USB, Firewire,
ethernet, guitarcables, ac-adapters - you name it.
K guess I'll try some more... But I still think jack is making my
computer hum, if only because of the stress the guy is putting on my
museal notebook computer created by the ancient Romans in 200 B.C. The
front plaque reads 'Dellus' and it runs a kernel called 'Linus'. The
vendor assured me the new stone roads would ensure excellent technical
support by the educated greek slave nerds, but they let me know that
ridding hum was 'not among the things they get forced to do.'.
Carlo
16 Nov
16 Nov
12:18 a.m.
New subject: [linux-audio-user] Re: The famous "Jack Hum" (Can't record and desparate)
Thanks to everyone who replied, I couldn't have solved this without you.
Singing capacitor! Load generator workaround! You guys are awesome, each
and every one of you.
Carlo
6585
days inactive
6591
days old
linux-audio-user@lists.linuxaudio.org
20 comments
13 participants
participants (13)
-
Carlo Capocasa -
Cesare Marilungo -
Daniel Wagner -
david -
Dominic Sacré -
Fernando Lopez-Lezcano -
Fons Adriaensen -
Hartmut Noack -
Karsten Wiese -
Lee Revell -
Paul Winkler -
Pieter Palmers -
Tim Howard