crossovers and speakers

[tnjfitzy]

Hello,

Don't know if this is the appropriate area to post this sorry if it is not.

I have inherited some OLD speakers and amp from a friend. The amp is 8ohm per channel (so it says on the back) The speakers consist of 1 x 12" sub (8ohm), 1 x 4" Mid (8ohm) 1 x tweeter (8ohm) all connected to a 3-way crossover then to the amp. This is where I get confused, If all the speakers are 8ohm would that make them like a total impedance load of 24 or does the crossover change that. If it is an 8ohm 3-way crossover, do all the speakers connected up to it have to be 8ohm (unless in series or parallel) and will the crossover make it a total load of 8ohm anywayz and if a crossover is 150watt in put does that mean all the speakers have to come close to 150watts

I am getting a new amp this week (kenwood krfv6400d) which is 6ohm per channel in surround or stereo, will those speakers work with it.. I am new to building speakers and stuff like that, soall the help and patience is much appreciated.


Thank you

[planet10]

The question usually is, why isn't the total impedance 8/3 ohm

1/ a driver's impedance is rarely a straight line. 8 ohm or 4 ohm are nominal impedances.
2/ the CO causes the impedance to rise dramatically out of band.

8 ohms in parallel with a really large impedance is 8 ohms.

dave

[tnjfitzy]

Thanks for the reply.
I am still confused about the total impedance of the speakers are and how it works fine with the amp. And if it will work fine with a 6ohm amp

[wintermute]

ok basically what Dave was saying was that overall it will still be nominally 8 ohms even though you have three 8 ohm drivers in parallel (ohms law would suggest the impedance be 2.666 ohms), this is because the crossover makes the load appear much higher than 8 ohms outside of each speakers range so where they overlap the impedance is high and you don't get the 8/3).

the rating of the amp is the minimum speaker impedance it will drive safely, so driving an 8 ohm speaker with an amp rated to 6 ohms is no problem at all...

Tony.

[tnjfitzy]

Thanks for all the replies so far... very very much appreciated.

So that is good to hear that my amp wont die..
will the speakers blow because of the output from the new amp because from what i could see the Sub was like 20w I am not sure about the mid and tweeter..

Thanks again

[DougL]

Most amplifiers are capable of destroying most speakers. However, the speakers should sound very bad long before that.

Doug

[tnjfitzy]

Originally Posted by DougL

Most amplifiers are capable of destroying most speakers. However, the speakers should sound very bad long before that.

Doug

So is that a yes or no ?

[wintermute]

If you don't turn it up too far it will be fine... even if you had a 20W amp you could still blow your 20W speakers if the amp is over-driven into clipping (where the tops of the waveforms are cut off because the amplifier doesn't have enough voltage left to properly form them).

When an amplifier clips the amount of current going to the speakers increases dramatically causing them to overheat and die.

You are more likely to clip a low powered amp than you are a high powered amp. The risk with a high powered amp is that you can blow the speakers without clipping,, simply by over-powering them with a clean music signal.

You would be surprised how loud 10W is (even 1W)! to get twice as loud again you need 100W. I don't think you will have any issue provided you are sensible

Tony.