Simple question. Total speaker impedence.

[JoeBob]

Ok, this may seem silly, but I couldn't find this info anywhere on the net. If woofers are wired up for impedence x, mids are wired up for impedence y and tweeters are wired up for impedence z, what is the total impedence of the speaker? Please help me out...

[Edited by JoeBob on 11-05-2001 at 12:13 AM]

[AudioFreak]

Well JoeBob,

Strickly speaking if everything is done properly, the impedance will be as follows
bass frequencies will see the impedance of the bass drivers, mids will see the impedance of the mid drivers and highs will see the impedance of the tweeters.

In all cases, impedance for any frequency is output impedance of the amp + impedance of the crossover + impedance of the driver at a given frequency.

Of coarse if all drivers are nominal 6ohms for instance, the speakers will 'nominally' be a little higher than this. but this is rarely ever the case because of the crossovers and the non linear nature of the impedance curve of the drivers.

Hope this kinda helps.

[Æ]

Typically one uses a crossover to divide the low, mid and high frequencies. So, your impedance can and will change from low to mid to high. For example: If you have a 4 ohm woofer and an 8 ohm midrange and a 6 ohm tweeter, then your impedance is 4 ohms in the bass frequencies, it would be 8 ohms in the midrange frequencies and 6 ohms in the treble frequencies. So if you have two 4 ohm woofers in series, then your impedance will be 8 ohms, but only 8 ohms through the bass frequencies, because the crossover does not let it go any farther than that.

[JoeBob]

Ah, I get it. One simple question now, if woofers at 4ohm, should the tweeters be 4ohm or 16ohm (two 8ohm horns, parallel or series). I'm gathering it's 4 so that it's pretty much even across the board, but I'm just making sure.

[AudioFreak]

Well depending on the rating of the tweeters............

If they carry a decent power rating, then use them in parallel, you'll get more power and it will make speaker impedance calculations easier.

[JoeBob]

They're piezo horns, so I was wondering if a higher impedence would be better so that they don't have an overpowering treble. But then again, I'm rather new to this, that's why I'm asking.

[Æ]

Of the nature of the driving element.

It has nothing to do whether they are horns or not.
However any horn is always likely to be much more efficient (louder) than a cone or dome. If the tweeter is too loud you need to attenuate (pad) it down. You can do that several ways with PIEZO tweeters. Take a look at the "Using Piezo Tweeters", in the Speakers forum. Adding a PIEZO tweeter to a loudspeaker system will hardly have any impact on the overall impedance, because a piezo tweeter has a very, very high impedance to begin with.