[linux-audio-user] The famous "Jack Hum" (Can't record and desparate)

[Hartmut Noack]

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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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