DC power vs AC power

[Icarus88]

When I ran my laptop on battery only, the ground loop noise that went away completely caused such a thunderclap in my head. ://

 

[DVDdoug]

ALL audio & video electronics run on DC internally. The power supply converts AC to DC at whatever DC voltages are needed. Frequently, there are multiple-different DC voltages and power amplifiers usually have positive and negative voltages.

The DC-side of the power supply is sometimes completely isolated from the AC/earth ground. In fact it's "naturally" isolated by the transformer (the "main" part of the power supply). But for safety reasons the case (if metal) is usually connected to earth ground and the designer may choose to connect the audio ground to the case and/or earth ground.

There are amplifiers (and other audio equipment) like this that use an external power supply. You could use a battery if you can find an appropriate one.

High-power car amplifiers have a built-in DC-DC voltage booster. It converts 12VDC to high-frequency pulses that are boosted through a transformer, and then converted back to DC at a higher voltage. Again, there might be positive and negative internal voltages.

 

[JeffS7444]

Years ago, I had fun installing a couple of photovoltaic panels on the roof, which charged a pair of deep-cycle lead acid batteries. But ended up using DC only as far as to power an inverter, because as soon as you go beyond low voltage, low current loads, things start to get complicated: Proper DC-rated fuses, circuit breakers and switches can be kind of pricey, assuming that you can find them at all.

 

[egellings]

My hypothesis (I don't know if you know better or if it has already been proven) is the sound quality better with DC power than with AC power? Because DC does not need ground as much as AC. I want to run the system with only DC power.

I want to run my system completely DC power is it wrong?

If your eguipment has 50/60 Hz power transformers, the transformers will go up in smoke when powered by DC. If you have switch mode supplies instead, they may work well with DC.

 

[Icarus88]

If your eguipment has 50/60 Hz power transformers, the transformers will go up in smoke when powered by DC. If you have switch mode supplies instead, they may work well with DC.

With laptop battery I didn't get any smoke

 

[JeffS7444]

With laptop battery there is no smoke

But non-standardized DC voltages present another challenge! Your laptop likely requires ~19 volts, but a Class D power amplifier may work best at 48 volts, and so on.

 

[Icarus88]

But non-standardized DC voltages present another challenge! Your laptop likely requires ~19 volts, but a Class D power amplifier may work best at 48 volts, and so on.

That's true, a laptop battery can't power an amplifier, my system is, guitar -} a battery powered EQ pedal-} one interface-} one 40 watt amp or headphones-)one laptop simple

 

[DonH56]

My hypothesis (I don't know if you know better or if it has already been proven) is the sound quality better with DC power than with AC power? Because DC does not need ground as much as AC. I want to run the system with only DC power.

On the extremely off chance this is serious, all components convert from AC wall power to DC internally (or through an external power brick), so technically all of your system is already run by "DC power".

Current conduction is a loop, so there must always be a return, ground or otherwise, whether the incoming source is AC or DC. Ground loops can occur whatever the power source; do a search and you'll see all sorts of ground loop problems in cars which use "DC power". They may be less obvious using battery (DC) power since there won't be a 50/60 Hz signal from the power line, but the loop could still be there given different components powered by the same DC supply. I have an article about ground loops (see link in my sig to a list) with some pictures showing multiple loops that exist no matter the power source.

I want to run my system completely DC power is it wrong?

You already are, so, no. But it is unlikely to benefit the sound and be challenging (and costly) to implement.

There are a lot of drawbacks to using batteries to power systems. Batteries need recharging and have limited lifetime, have limited energy density, generally have higher impedance (are a poorer power source) compared to AC (wall) powered DC supplies, and there are concerns with leaking, exploding, and disposal.

A laptop running on its battery breaks the safety ground connection thus no loop. There are plenty of other means for isolating the ground in that situation, using either power line or signal line isolators, but if that is the only issue you can either run the laptop on battery when you use it or purchase a power line isolator for the power brick (e.g. https://www.amazon.com/Ebtech-Hum-Ground-Voltage-Filter/dp/B0002E4YI8). Or figure out the root cause of the loop and fix it.

 

[Icarus88]

On the extremely off chance this is serious, all components convert from AC wall power to DC internally (or through an external power brick), so technically all of your system is already run by "DC power".

Current conduction is a loop, so there must always be a return, ground or otherwise, whether the incoming source is AC or DC. Ground loops can occur whatever the power source; do a search and you'll see all sorts of ground loop problems in cars which use "DC power". They may be less obvious using battery (DC) power since there won't be a 50/60 Hz signal from the power line, but the loop could still be there given different components powered by the same DC supply. I have an article about ground loops (see link in my sig to a list) with some pictures showing multiple loops that exist no matter the power source.


You already are, so, no. But it is unlikely to benefit the sound and be challenging (and costly) to implement.

There are a lot of drawbacks to using batteries to power systems. Batteries need recharging and have limited lifetime, have limited energy density, generally have higher impedance (are a poorer power source) compared to AC (wall) powered DC supplies, and there are concerns with leaking, exploding, and disposal.

A laptop running on its battery breaks the safety ground connection thus no loop. There are plenty of other means for isolating the ground in that situation, using either power line or signal line isolators, but if that is the only issue you can either run the laptop on battery when you use it or purchase a power line isolator for the power brick (e.g. https://www.amazon.com/Ebtech-Hum-Ground-Voltage-Filter/dp/B0002E4YI8). Or figure out the root cause of the loop and fix it.

Your articles are very interesting but overly technical. I wish there was a more simplified version for us mere mortals. I ordered a signal line isolator (but customer service said not to use it for long periods of time during the day).

 

[egellings]

With laptop battery I didn't get any smoke

The supply for that charger is a switchmode type, as almost all of them are. So no smoke is what you should get when DC Is used to power them.

 

[MaxwellsEq]

Your articles are very interesting but overly technical. I wish there was a more simplified version for us mere mortals. I ordered a signal line isolator (but customer service said not to use it for long periods of time during the day).

Eliminating ground loops can be simple, but often is frustrating (especially if you want to be safe). Studios use balanced / differential working to minimise the issue.

If you find the article by @DonH56 (which is not too challenging - just take your time and go over it a few times), you may find this article helpful: https://www.edn.com/the-g-word-how-to-get-your-audio-off-the-ground/

 

[Icarus88]

Eliminating ground loops can be simple, but often is frustrating (especially if you want to be safe). Studios use balanced / differential working to minimise the issue.

If you find the article by @DonH56 (which is not too challenging - just take your time and go over it a few times), you may find this article helpful: https://www.edn.com/the-g-word-how-to-get-your-audio-off-the-ground/

Thank you very much

 

[Icarus88]

On the extremely off chance this is serious, all components convert from AC wall power to DC internally (or through an external power brick), so technically all of your system is already run by "DC power".

Current conduction is a loop, so there must always be a return, ground or otherwise, whether the incoming source is AC or DC. Ground loops can occur whatever the power source; do a search and you'll see all sorts of ground loop problems in cars which use "DC power". They may be less obvious using battery (DC) power since there won't be a 50/60 Hz signal from the power line, but the loop could still be there given different components powered by the same DC supply. I have an article about ground loops (see link in my sig to a list) with some pictures showing multiple loops that exist no matter the power source.


You already are, so, no. But it is unlikely to benefit the sound and be challenging (and costly) to implement.

There are a lot of drawbacks to using batteries to power systems. Batteries need recharging and have limited lifetime, have limited energy density, generally have higher impedance (are a poorer power source) compared to AC (wall) powered DC supplies, and there are concerns with leaking, exploding, and disposal.

A laptop running on its battery breaks the safety ground connection thus no loop. There are plenty of other means for isolating the ground in that situation, using either power line or signal line isolators, but if that is the only issue you can either run the laptop on battery when you use it or purchase a power line isolator for the power brick (e.g. https://www.amazon.com/Ebtech-Hum-Ground-Voltage-Filter/dp/B0002E4YI8). Or figure out the root cause of the loop and fix it.

What about USB isolators?

 

[Icarus88]

Eliminating ground loops can be simple, but often is frustrating (especially if you want to be safe). Studios use balanced / differential working to minimise the issue.

If you find the article by @DonH56 (which is not too challenging - just take your time and go over it a few times), you may find this article helpful: https://www.edn.com/the-g-word-how-to-get-your-audio-off-the-ground/

What equipment and devices do studios use for such problems?

 

[Wolf11Man]

XLR

 

[DVDdoug]

What equipment and devices do studios use for such problems?

Balanced connections. Virtually all pro equipment used in studios and live has balanced inputs & outputs. Virtually all home equipment has unbalanced connections (RCA or 3.5mm).

In MOST home setups with relatively short cables it's not a problem.

 

[Icarus88]

Balanced connections. Virtually all pro equipment used in studios and live has balanced inputs & outputs.

I also read that they use filtering devices, UPSs, etc.

 

[Philbo King]

When I was designing PLLs and clock generator circuits I would use battery power, working inside a screen room (aka Faraday cage) to get the absolute minimum noise possible.
But using a DC battery to power a stereo system for dubious audio benefits falls into 'tin foil hat' territory, IMHO.

 

[tomtoo]

My hypothesis (I don't know if you know better or if it has already been proven) is the sound quality better with DC power than with AC power? Because DC does not need ground as much as AC. I want to run the system with only DC power.

I want to run my system completely DC power is it wrong?

You could. Would it be realy usefull? No. On ASR you have all the measurements needet to see if there is any bad influence from AC.

 

[Icarus88]

When I was designing PLLs and clock generator circuits I would use battery power, working inside a screen room (aka Faraday cage) to get the absolute minimum noise possible.
But using a DC battery to power a stereo system for dubious audio benefits falls into 'tin foil hat' territory, IMHO.

Haha pseudoscience