Speakers

[TekNoir]

I have recently had about one-hundred small speakers donated to me. The speakers have 64 ohms stamped onto their backs and I assume that this is their impedance. Nearly every schematic that I have ever seen referenced using either a 4 or 8 ohm speaker.

I have to admit that I only have a general working knowledge of impedance and most discussions about impedance only mentioned matching between either high-Z or low-Z. The differences mentioned were what I would consider somewhat extreme, perhaps 8 ohm for low impedance, versus 1k ohm for high impedance or thereabouts.

What I am asking is whether or not I would be able to use these 64 ohm speakers with virtually any amplifier circuit with a low output impedance or is 64 ohms high enough that I will need to do some sort of high impedance matching? What general design changes should I be considering when trying to use a 64 ohm speaker in a circuit that originally called for an 8 ohm?

Thanks in advance...

Edit: As another non-related question, I have noticed that whenever anyone uses the word "ohm" in a post, it turns into an invalid hyperlink. Is there a particular reason for this?"

 

[monkeytree]

there should be no problem
but if you want then you can connect them in parrell 4 connected in parrell
would be 8ohm

 

[David Bridgen]

That's correct, there is no problem.

The most significant result of using a higher impedance load will be a reduction in power.
For a given voltage across the load, the power developoed in 64 ohms will be 8 times less than that developed in 8. (It's directly proportional to the change in impedance.)

Sounds a lot doesn't it? However, it takes a difference of 10 times for the difference to be perceived as a change in volume of 50% (or 2, depending upon whether it's a decrease or an increase.)



8 x 64 ohms in parallel (not 4) would result in 8.

 

[Dr.EM]

We have 64ohm ones at college, I think they are intended to test things, as the high impedance means they can be driven from low power sources like op-amps without causing too much damage.

You could always make a wall of speakers :lol:

 

[zachtheterrible]

Edit: As another non-related question, I have noticed that whenever anyone uses the word "ohm" in a post, it turns into an invalid hyperlink. Is there a particular reason for this?"

click on it: ohm

it is a basic tutorial in the "theory article" section of this forum.