4 replies to this topic

[seanie]

I'm curious to know what happens when you link two monitors.Are they linked in parallel or series? What happens to the power ie do you need more power to drive them? What happens to impedence? Does pairing change the sound of wedges(assuming they are identical).

Cheers

[Spectrum]

seanie, on 18 November 2010 - 01:50 AM, said:

I'm curious to know what happens when you link two monitors.Are they linked in parallel or series? What happens to the power ie do you need more power to drive them? What happens to impedence? Does pairing change the sound of wedges(assuming they are identical).

Cheers

Hey Seanie, and welcome to SP!

Can you describe a time when you'd see two pairs of monitors (speakers) linked?

Generally, in multi-monitor (speaker) set-ups, one chooses to listen to Monitors A or Monitors B, but not A and B simultaneously. That is, they're use for comparative purposes.

Wait, just read your reference to 'wedges', so you're referring to foldback monitors on stage, rather than reference monitors in a studio control room, yeah? Ah, got you now.

Ok, so in this case, yes, parallel is generally the way it's done. And by making it twice as easy for the power to jump between the amplifier's + and - terminals, the amplifier will see only half the resistance. For example, 2 x 8 Ohm speakers will appear as 1 x 4 Ohm speaker when the two are wired together in parallel.

Is more power required? Nope, in most cases, the amplifier simply spits out more power (generally double) as it becomes twice as easy to pass from + to - and vice versa. But it ain't always a free lunch. Just gotta read the specification on the amp. While 2 x 8 Ohm becomes 4 Ohms, and most PA amps will cope, some won't. Then consider if 2 x 4 Ohm speakers are paralleled, the resulting 2 Ohm load might exceed the limits of the amplifier, its power supply not being able to maintain the power, overheating, thermal cutouts, though to possibly even permanent damage to the amplifier. So check your speaker Ohms and your amplifier's load limits, and keep within the specification and you'll be fine.

Does the sound change when pairing / running speakers parallel? Essentially no, however, while the amplifier appears to output up to double its power, its ability to control the speaker cone is compromised. Known as 'damping factor', the low end frequencies may become less focused or sloppy as the amplifier struggles to maintain the movement of the speaker cone in line with the input signal.

Trust that helps answers your questions.

[Jester_Fu]

You link in parallel. The issue with series connections is attenuation (the speakers get softer further away from the amp) and impedance issues between the speakers creating phase issues and cancelling the sound out.

Spectrum, on 14 June 2011 - 11:15 PM, said:

Does the sound change when pairing / running speakers parallel? Essentially no, however, while the amplifier appears to output up to double its power, its ability to control the speaker cone is compromised. Known as 'damping factor', the low end frequencies may become less focused or sloppy as the amplifier struggles to maintain the movement of the speaker cone in line with the input signal.Trust that helps answers your questions.

Now you're opening a can of worms...

Amps have this thing called Slew rate. Basically it's how quick the capacitors (or switchmode stage in D type amps) can recover from a burst of current being sucked out - like a bass kick. The better the slew rate, the more solid and less distorted your bass is, in particular. With weak amps and bad slew rates, even mids and high can be effected. So, it's not only the damping qualities of an amplifier that effect the sound.

You'll also increase load on the amplifier in parallel. This means you get more heat, more heat soak and again effect the performance of the amp so higher levels of distortion.

Then of course there's the impedance issues which can create mis-matches between the amp and speakers resulting in again more distortion. To reduce impedance issues, it's important to use speakers of the same impedance characteristics if you're running in parallel. That's more than matching the nominal impedance - it means using the same type and brand of speaker.

The key thing to remember is that sound is a current based thing. Making speakers move requires current - the more you have, generally the clearer and more controlled the sound is. Cheap amps can gain power by producing higher voltages across the rails but don;t have the same current... making them sound weak and distorted in comparison to better amplifiers. It also means they're more likely to saturate and clip. The electronic components in the amp have certain operating limits and while the amp may not pass the voltage limits, they quickly pass current capacity. That's why, as Spec said, it's important to make sure your amp can handle lower impedance like having speakers in parallel.

In general there's no issue with what you're talking about if you're not after the best sound quality or you're operating on a budget. Confirm the amp will run the lower impedance and then just make sure you have your limits set down a bit. Keep in mind when you set up and tune the system that the performance of the speakers will degrade as the show goes on and the amps get hotter. If you allow for that by slightly oversizing your amps then you'll be sweet.

[ryanedward85]

Aren't most amps 6-8 Ohm rated?

[Spectrum]

^^^ Yeah, I can't think of an amplifier on the planet that wouldn't cope with a 8 Ohm load (and would likely cope with a 6 Ohm load as bit of a safety net - and the fact that speakers don't typically present a perfect resistance rating across the entire frequency range). And for whatever reason, 4 Ohms is the de facto standard for car audio.