Voltage or current?

[Brianrzr]

I’m trying to understand the effects of Ohm’s Law regarding on audio systems. When adding a 4 ohm speaker in parallel to another, voltage drops, but current increases. Does current have more effect on the sound produced than voltage? So when an amplifier is 2 Ohm stable, that means it can handle the additional heat generated by the additional current?

[Bamer]

I’m trying to understand the effects of Ohm’s Law regarding on audio systems. When adding a 4 ohm speaker in parallel to another, voltage drops, but current increases. Does current have more effect on the sound produced than voltage? So when an amplifier is 2 Ohm stable, that means it can handle the additional heat generated by the additional current?

Wow, this is a pretty deep question. Let’s start with a speaker. A speaker makes sound by moving back and forth in which air pressure is increased and then decreased at the surface or the speaker. Then the change in air pressure travels through the air at the speed of sound creating sound waves. Now, what makes the speaker move? The answer is a coil (aka inductor)surrounded by a magnet. The coil is a very long and small diameter wire in the shape of a coil, spiral or helix. It looks like a coil spring, but with a lot more turns. When current passes through the coil, a magnetic field is produced. The direction of the current determines the direction of the magnetic field produced by the coil. The magnetic fields of the coil and magnetic either attract or repel just like 2 magnets which causes the speaker to move. Long answer short, more current = more mechanical speaker movement = more sound.

Voltage does not drop(assuming the amp has an ideal output impedance)........if 2 12V batteries are in parallel the equivalent voltage is still 12V. 2 speakers in parallel will have the same voltage. The power consumed by the each speaker is determined by the impedance of each speaker based on : Power=Voltage^2 / Impedance.




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[Bamer]

When an amp is said to be 2 ohm stable, it just means that the amp was designed to operate with a 2 ohm load. There are infinite number of speaker combinations to get to 2 ohm equivalent as seen by the amp. If you connect a 2 ohm load to an amp that is only rated to be 4ohm stable, then you could get degraded performance from the amp in the form of clipping/distortion, excessive heat, premature amp failure, frequency dependent oscillations, or it could work just fine in some cases. Not a good idea to use the amp outside of what it was designed for. Kinda like towing a 10k lbs boat with a truck only designed and rated at 5k lbs. bad things can happen.

[JohnnieMo]

Great answers here! I’ve nothing to add as it’s been said.

[chpthril]

When adding a 4 ohm speaker in parallel to another, voltage drops, but current increases.

When wiring a 2nd 4 ohm speaker to another, in parallel, the impedance (ohm) drops by half. However, the output of the amplifier in wattage, may go up, may not change, depends on amplifier.

2 ohm stable means only that the amp can handle a load as low as 2 ohm per chnl.

[Brianrzr]

So does a 2 ohm load produce improved audio performance over a 4 ohm load?

[chpthril]

In a controlled environment, there can be a decrease in audio quality as the load goes up (impedance goes down), but in the open environment of a boat, most will never detect it. So basically, one 4 ohm speaker per chnl on an 8 chnl amp will sound better then then the same eight 4 ohm speakers on a 4 chnl amp with each chnl seeing a 4 ohm load. The best was to combat this, is headroom wattage wise. More wattage available then the speakers need.