DC power vs AC power

[Icarus88]

Most of the single-line replies you've received have been 100% unhelpful. I'm afraid this is often a feature of this particular forum.

However let's first ask why you are thinking of using DC and where you will get this DC from?

Vinnie Rossi's Red Wine Audio used to use batteries to power their highly regarded kit (including power amps) about 20 years ago, but they have now moved away from batteries, I believe. There is very little gear (apart from automotive) at any price level that uses DC via batteries. I often wonder why, but explanations about capacitance or whatever else, may be part of the reason. AC just seems a lot easier provided your kit has excellent power supplies and good ways of rejecting RFI, etc. There should be no need for costly "mains conditioners", "regenerators", etc but I understand the quality of AC in the US is often pretty poor and this encourages dealers to flog the notion that these are essential for good music in the home - and of course ridiculously costly power cables! None should be necessary with well-designed kit.

DC cannot easily be changed from one voltage to another and the battery voltage will vary quite a bit between fully-charged and in need of recharge. Good AC power supplies will maintain a steady DC output over a very wide variation in AC supply.

I did own a Red Wine Signature 30 Mk II amp, but I never got along with it powering my Avantgarde horn speakers, despite mods by RW to match the amp's gain for my speakers and install a new type of battery. I sold it after a couple of years and have been AC since then.

the background noise disappears when i use only laptop battery as power source in my system, this is due to ground loop, system is bass guitar+ EQ pedal+ audio interface+ headphones, i thought a battery system would be good

 

[DonH56]

the background noise disappears when i use only laptop battery as power source in my system, this is due to ground loop, system is bass guitar+ EQ pedal+ audio interface+ headphones, i thought a battery system would be good

I would purchase a Hum-X for the laptop's power cord and see if that's enough to fix the problem.

For guitars, the usual noise source is the pickup, and even humbucker pickups will not always fix the problem. That is not the problem here.

That's two lines, hopefully helpful.

 

[DonH56]

Friends that's true?

He's talking about EMI and wavelengths for audio signals are very, very long. True'ish but irrelevant, because EMI/RFI is usually RF signal being converted to audio by circuits inside the component, not directly perceived, and that is not (highly probably) related to the problem you are having.

 

[Icarus88]

I would purchase a Hum-X for the laptop's power cord and see if that's enough to fix the problem.

For guitars, the usual noise source is the pickup, and even humbucker pickups will not always fix the problem. That is not the problem here.

That's two lines, hopefully helpful.

Hum x is not available in my country, we use two-prong plugs

I don't know the difference in guitar pickup effect between two-prong plugs and three-prong plugs.

 

[Icarus88]

He's talking about EMI and wavelengths for audio signals are very, very long. True'ish but irrelevant, because EMI/RFI is usually RF signal being converted to audio by circuits inside the component, not directly perceived, and that is not (highly probably) related to the problem you are having.

For example, will Faraday shielding on the guitar pickup circuit prevent the EMI noise coming from the refrigerator motor?

My refrigerator motor is noisy

 

[Hear Here]

the background noise disappears when i use only laptop battery as power source in my system, this is due to ground loop, system is bass guitar+ EQ pedal+ audio interface+ headphones, i thought a battery system would be good

In the past, I've used batteries very successfully with video recording in places where mains power wasn't readily available - supermarkets, etc. I needed power for 2 x VCRs (DVCAM and VHS at the time), monitor, radio remote controllers (transmitters and receivers) and microphone. All powered by 12 V rechargeable YUASA batteries that were each good for 3+ hours. There's no reason you shouldn't use batteries, although a guitar amp will need a lot of juice unless Class D.

As long as the equipment is happy with DC and you won't need to use DC with inverter to provide power for the equipment, I'd go for it.

 

[Icarus88]

In the past, I've used batteries very successfully with video recording in places where mains power wasn't readily available - supermarkets, etc. I needed power for 2 x VCRs (DVCAM and VHS at the time), monitor, radio remote controllers (transmitters and receivers) and microphone. All powered by 12 V rechargeable YUASA batteries that were each good for 3+ hours. There's no reason you shouldn't use batteries, although a guitar amp will need a lot of juice unless Class D.

As long as the equipment is happy with DC and you won't need to use DC with inverter to provide power for the equipment, I'd go for it.

My fender rumble 40 is running with 40 watt

 

[Icarus88]

hello, my setup is: bass guitar, EQ pedal, interface, laptop and headphones, does the two prong plug have any effect on ground loop or background noise? three prong plugs, they better?

Thanks

 

[earlevel]

No difference, you can have ground loops through either.

Basically, the ground pin is to tie a metal case to ground. Imagine if a power wire comes loose inside the case, and rests against the case. Touching it might kill you, if it's not grounded. With a ground, most of the current will travel directly to ground through the connection, and not you. But if it's a plastic case, there is no need for "equipment ground".

You're having ground loops? Or just planning in case? The easiest way to have ground loop problems is to have power coming in at one outlet through long wire that's minimal thickness (higher resistance), and similar on another, and power different parts of the audio chain from the two. Long cheap extension cords will make that worse. Power everything from one outlet if you can—that's the cheapest way to avoid the issue. I rewired my office/studio decades ago—nothing fancy, just not using junk—went from really bad to no ground loops.

 

[Icarus88]

No difference, you can have ground loops through either.

Basically, the ground pin is to tie a metal case to ground. Imagine if a power wire comes loose inside the case, and rests against the case. Touching it might kill you, if it's not grounded. With a ground, most of the current will travel directly to ground through the connection, and not you. But if it's a plastic case, there is no need for "equipment ground".

You're having ground loops? Or just planning in case? The easiest way to have ground loop problems is to have power coming in at one outlet through long wire that's minimal thickness (higher resistance), and similar on another, and power different parts of the audio chain from the two. Long cheap extension cords will make that worse. Power everything from one outlet if you can—that's the cheapest way to avoid the issue. I rewired my office/studio decades ago—nothing fancy, just not using junk—went from really bad to no ground loops.

yes I have ground loop issues,

 

[Speedskater]

When a power amplifier converts the incoming AC to its DC supply it also creates more noise on the AC power line. So all audio components are designed to deal with this added noise.

 

[AnalogSteph]

So I infer that both of the mains connections are 2-prong? That might explain why you're having issues.

In any setup with unbalanced connections, like yours, you want exactly one device to be grounded by some means. A 3-prong power plug is one way of accomplishing this, but not the only one by far - a piece of wire fitted with the ends to go underneath a screw at the interface and clip onto an outlet ground or something else known to be grounded is another option and probably cheaper than getting another laptop power supply (cheap generic replacement supplies can be of very poor quality, e.g. lacking mains filtering and cable strain reliefs, and are not recommended).

If your system ground is floating in thin air, its potential can be quite different from the environment and generally polluted by power supply mains filters, and any weak point in shielding on the guitar, the pedal or the cable could pick up part of that e.g. by capacitive coupling to yourself or the floor. That's why you want a ground connection somewhere.

This is actually not a ground loop problem, but rather the opposite in a way - you don't have too many ground connections, you have too few.

 

[Icarus88]

So I infer that both of the mains connections are 2-prong? That might explain why you're having issues.

In any setup with unbalanced connections, like yours, you want exactly one device to be grounded by some means. A 3-prong power plug is one way of accomplishing this, but not the only one by far - a piece of wire fitted with the ends to go underneath a screw at the interface and clip onto an outlet ground or something else known to be grounded is another option and probably cheaper than getting another laptop power supply (cheap generic replacement supplies can be of very poor quality, e.g. lacking mains filtering and cable strain reliefs, and are not recommended).

If your system ground is floating in thin air, its potential can be quite different from the environment and generally polluted by power supply mains filters, and any weak point in shielding on the guitar, the pedal or the cable could pick up part of that e.g. by capacitive coupling to yourself or the floor. That's why you want a ground connection somewhere.

This is actually not a ground loop problem, but rather the opposite in a way - you don't have too many ground connections, you have too few.

each plug is two-pronged in my country

 

[DonH56]

Hum x is not available in my country, we use two-prong plugs

Is the guitar and other equipment on the same outlet as the laptop? You cannot really isolate the safety ground if there is no safety ground (see below). I did not know you were in another country.

I don't know the difference in guitar pickup effect between two-prong plugs and three-prong plugs.

None for your case. The third connection in the U.S.A. is for a safety ground. It ties to ground in the electrical service panel, along with the neutral (return) wire, and the hot wire goes to the breaker. The safety ground is to provide a secondary ground path in the event of a defective component or user error (like running a hair dryer in the shower).

For example, will Faraday shielding on the guitar pickup circuit prevent the EMI noise coming from the refrigerator motor?

My refrigerator motor is noisy

You can't shield the pickup and the strings entirely and still play the guitar. Do you notice noise in the audio feed when the refrigerator is on? That is a different problem than your laptop.

now there is no clean AC wave and dirty unregulated AC wave phenomenon?
wouldn't this cause a problem with the home system signals especially high empedance electrical instrumens? please enlighten me

You keep adding other things into the picture. Any audio component includes a power supply that will reject a huge amount of noise on the AC line. RFI (radio-frequency interference) could be coupled into the guitar pickup and be rectified (processed) by the preamp but again that is unrelated to the noise you hear when you plug in your laptop.

I would try a power strip with all the equipment plugged into it to see if that helps if you are not already doing that.

Some laptops are better than others for noise but I have little experience with that. Of the last three I have had (two Dell, one MSI), two caused noise when plugged in whilst using an audio interface, and one did not. But in my case a Hum-X fixed them. You might also try asking your laptop manufacturer for advice, and/or look into a different (external) audio interface.

 

[DonH56]

FYI this is a continuation of this thread: https://www.audiosciencereview.com/...c-power-vs-ac-power.57291/page-5#post-2095482

 

[Icarus88]

Is the guitar and other equipment on the same outlet as the laptop? You cannot really isolate the safety ground if there is no safety ground (see below). I did not know you were in another country.


None for your case. The third connection in the U.S.A. is for a safety ground. It ties to ground in the electrical service panel, along with the neutral (return) wire, and the hot wire goes to the breaker. The safety ground is to provide a secondary ground path in the event of a defective component or user error (like running a hair dryer in the shower).


You can't shield the pickup and the strings entirely and still play the guitar. Do you notice noise in the audio feed when the refrigerator is on? That is a different problem than your laptop.


You keep adding other things into the picture. Any audio component includes a power supply that will reject a huge amount of noise on the AC line. RFI (radio-frequency interference) could be coupled into the guitar pickup and be rectified (processed) by the preamp but again that is unrelated to the noise you hear when you plug in your laptop.

I would try a power strip with all the equipment plugged into it to see if that helps if you are not already doing that.

Some laptops are better than others for noise but I have little experience with that. Of the last three I have had (two Dell, one MSI), two caused noise when plugged in whilst using an audio interface, and one did not. But in my case a Hum-X fixed them. You might also try asking your laptop manufacturer for advice, and/or look into a different (external) audio interface.

"Is the guitar and other equipment on the same outlet as the laptop? You cannot really isolate the safety ground if there is no safety ground (see below). I did not know you were in another country."

Yes, on the same outlet


"You keep adding other things into the picture. Any audio component includes a power supply that will reject a huge amount of noise on the AC line. RFI (radio-frequency interference) could be coupled into the guitar pickup and be rectified (processed) by the preamp but again that is unrelated to the noise you hear when you plug in your laptop."

My audio interface has no external power supply, USB power


"Some laptops are better than others for noise but I have little experience with that. Of the last three I have had (two Dell, one MSI), two caused noise when plugged in whilst using an audio interface, and one did not. But in my case a Hum-X fixed them. You might also try asking your laptop manufacturer for advice, and/or look into a different (external) audio interface."


My laptop is bad, maybe USB isolator fix this problem.





The noise gets louder when I approach the refrigerator motor, the refrigerator is two rooms away

 

[boxerfan88]

Maybe one of these can solve the clean AC problem…

S-2500 Quantum MK-II - STROMTANK - German Power Tank

“The new middle class”, if you go by our device hierarchy. Otherwise, the S2500-Quantum is of course absolute top class.

stromtank.com

 

[Icarus88]

This is the wrong place to troll. I have no knowledge of these things, I'm just researching.

 

[DonH56]

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.

 

[DVDdoug]

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.