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DC power vs AC power

DonH56 said:
A motor is a known source of RFI. I am not surprised the noise is louder when you approach it with your guitar, but I would not expect a significant change if you bring the laptop closer unless the laptop's audio interface is poorly shielded. If the only connection to the laptop is via USB and power cord then a USB isolator should help. I have no experience with USB isolators. USB has a long history of poor implementations that inject noise into audio interfaces, but I would have expected most interfaces and laptops to have solved that by now. But again not something I am very familiar with.
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When I approach the laptop the noise is really awful :(
 
WIth your knowledge, refrigerator, two prong outlets and noisy laptop there is a very simple solution: Get an acoustic guitar.
Do not amplify it. All those troubles gone!
Pure, clean, unamplified, ear friendly sound will fill the room and make you happy.
Probaply the rest of your house, too.

PS Did you ever play the "Troll Song"? It's nice, just don't play it for too long.
 
Wolf11Man said:
WIth your knowledge, refrigerator, two prong outlets and noisy laptop there is a very simple solution: Get an acoustic guitar.
Do not amplify it. All those troubles gone!
Pure, clean, unamplified, ear friendly sound will fill the room and make you happy.
Probaply the rest of your house, too.

PS Did you ever play the "Troll Song"? It's nice, just don't play it for too long.
Click to expand...

OMG, are you Einstein's grandson? I never thought of that
 
You do not need to be an Einstein to tell a troll when the fun is over. Consider me to be more of a Heisenberg.
 
Wolf11Man said:
You do not need to be an Einstein to tell a troll when the fun is over. Consider me to be more of a Heisenberg.
Click to expand...


What does "troll" mean to you? I don't know your culture, but to us a troll is someone who makes fun of people.
 
Icarus88 said:
Friends that's true?
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Umm, no, unless I am really missing something in or about the quotation you shared.

wavelength (of sound) = frequency / velocity (of sound)

Hum (of the United States AC carrier frequency kind, still the most pervasive kind in our environment in most places -- I think) is 60 Hz.
in that case:
frequency = 60 sec^-1
velocity = (ca.) 1125.3 feet/sec = (ca.) 343 m/sec
When rectified, amplified, and reproduced by a loudspeaker, the wavelength of a 60 Hz tone is about 18.8 feet (i.e., about 5.72 meters) at 68 degrees Fahrenheit (20 degrees Celsius).
 
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Another thing I'm wondering is, is there a need to put ferrite beads on Jack cables and USB cables?
 
DVDdoug said:
The ground is a safety ground and it's required depending on the design. If the case is metal, the case is earth grounded in case of a fault that puts lethal voltage on the case. It gets grounded-out and blows the breaker before anyone can get hurt. It doesn't serve any purpose if nothing goes wrong. If a product is double insulated it can be sold with a 2-prong plug.

Some older equipment (like maybe a vintage tube guitar amp) has a polarized 2-prong plug with the neutral connected to the chassis. The neutral is connected to earth ground at the electrical box, so again it's safe as long as nothing goes wrong. But if the wiring (or extension cord) gets reversed you get voltage on the chassis, and with a guitar voltage on the guitar's "ground". If you've heard of stories about musicians getting electrocuted on stage, that's a safety-ground problem.
Click to expand...
There's no safety ground in his country.
 
Icarus88 said:
1/4. inch
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OK. On a USB line and for b+ lines leading to digital processors and other digital ICs the inductor (Can be a ferrite bead arrangement.) inline on a PCB prevents digital switching noise from polluting the B+ line coming from the power supply. With a USB cable the inductor will smooth out any irregularities in the frequency bandwidth that the USB cable is conducting. It may block noise going to and coming from the source and destination.

For RCA, 1/4" and 3.5mm a ferrite bead is not required and may cause a unwanted response in my opinion.
 
Doodski said:
OK. On a USB line and for b+ lines leading to digital processors and other digital ICs the inductor (Can be a ferrite bead arrangement.) inline on a PCB prevents digital switching noise from polluting the B+ line coming from the power supply. With a USB cable the inductor will smooth out any irregularities in the frequency bandwidth that the USB cable is conducting. It may block noise going to and coming from the source and destination.

For RCA, 1/4" and 3.5mm a ferrite bead is not required and may cause a unwanted response in my opinion.
[/QUO
Doodski said:
OK. On a USB line and for b+ lines leading to digital processors and other digital ICs the inductor (Can be a ferrite bead arrangement.) inline on a PCB prevents digital switching noise from polluting the B+ line coming from the power supply. With a USB cable the inductor will smooth out any irregularities in the frequency bandwidth that the USB cable is conducting. It may block noise going to and coming from the source and destination.

For RCA, 1/4" and 3.5mm a ferrite bead is not required and may cause a unwanted response in my opinion.
Click to expand...
..
Click to expand...

So then it might be good to put a ferrite bead on the USB cable that I use between the interface and computer, then there is no need for a guitar Jack cable
 
Icarus88 said:
So then it might be good to put a ferrite bead on the USB cable that I use between the interface and computer, then there is no need for a guitar Jack cable
Click to expand...
If there is no issue/digital noise on the USB line then don't bother putting/trying a ferrite bead on it. The beads have a value of inductance and so guessing of what bead/value to apply is not the best way to go about this. Leave it to the engineer to calculate the value and place the bead on the cable if one is used at all.
 
Another question, cover the laptop charger adapter with aluminum foil
 
If u have noise problem when using laptop with AC power brick,
and no/less noise problem when using laptop in battery mode,
the simplest solution is just use the laptop in battery mode during your session.

U can charge the laptop in-between sessions.

Some laptops have those extender/bigger battery option which can extend the laptop runtime while on battery.

Also, have you tried with a different laptop to see if the problem remains or goes away...
 
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