Two Speakers in Parallel with Uneven Wattage

[dgame]

Speakers in Parallel with Uneven Wattage

There are two speakers wired in a parallel in my Smash TV cabinet.

One 6” round speaker is 20W and the 4” Piezo speaker is 50W.

I measured the resistance across the parallel circuit and it read 8 ohms on the DC voltmeter.

From reading around the net to total power draw is 70W, but I haven found how this is distributed between two speakers of different Wattage wired in parallel.

How much power can I put on the circuit?
Will anything more than 20W want to fry to 20W speaker?
Can I safely put 40W on the circuit?

I am using a mono amp.

Thanks

[AussieJuke]

You will be limited to the 20W capability of the 6" speaker.

[mountain]

A lot of people worry too much about the wattage of a speaker. A speaker's wattage rating is not at all related to the amount of power the amp will deliver,  the impedance of the speaker is more related to that.

Do they have a crossover? A poorly designed crossover, or even worse, no crossover at all, will give your amp uneven loads that will fluctuate drastically depending on what frequency is being played. Since you have two drivers designed to play at different frequencies, I would be more concerned on dividing the frequency range with a crossover. Very experienced crossover builders are so good that they can equalize an entire audio system by changing out components in the crossover to raise and lower the impedance at certain frequencies.

Distortion is generally what blows a speaker, not too much power. So hooking your 20 watt speaker to a 40 watt amp will be fine, just turn it down a notch when it starts sounding like crap.

Hope this helps.

[dgame]

Thanks,

I talked to my audiophile friend and he said the same thing. Distortion is the real problem. So I will use the 40W amp and turn it down.

[digitaldj]

Actually, if both speakers are the same resistance power gets divided between them. You put 40watts into the circuit and you get 20w to each speaker(ohms laws). Now the problem is if both speakers are 8 ohms that makes the circuit 4 ohms and can drive the output power of the amp up, if the amp will allow it without overheating and being destroyed. Since you are measuring with a ohm meter that is not a correct way to measure the resistance. Typically you have to times that reading by 1.4. This actually only gives a reference and as Mountain mentioned frequency has alot to do with resistance(load) on the amp. I always have my speaker ratings twice the amp output!

[Blanka]

If they are supposed to deliver different parts of the spectrum, use a cross-over filter. As they both respond different to the same tone, the generated current from the speaker (yes, when it moves back to neutral in generates current) will influence the other. It will sound poop. If they should produce the same sound, just use one. Better one good driven speaker, than 2 bad driven ones. Or the amplifier must have an A+B speaker mode with seperate clamps for each.

[AussieJuke]

Guys, you're missing what he said: "One 6” round speaker is 20W and the 4” Piezo speaker is 50W." A piezo speaker does not behave the same way as a coiled speaker. You can quite happily parallel a woofer and a piezo and still have practically the same impedance as the woofer alone.

Now, that said, there will be some mid-upper frequencies that they will both reproduce so it will sound a little peaky. You can get around that by either installing a crossover or just putting a 0.47uF polyester capacitor in series with the piezo to act as a hi-pass filter. Try values from 0.22uF - 1.0uF and see what sounds best in your case.

No matter what you do (crossover, no crossover or just the capacitor), the rating of the whole thing will be 20 Watts. Not 40W, not 30W, but 20W!

Yes, you can kill a 20W speaker with a 10W amplifier driven into hideous clipping. You can also kill that 20W speaker with a 40W amplifier if you let it go into gross distortion for any length of time. Just turn it down when it sounds bad. It's that simple. Really.