loudspeakers & nominal impedance

gyaala

I`m going to buy a new audio system and I need some answers to my questions.

Could anyone describe please what`s the nominal impedance and how do I have to choose loudspeakers to amplifier depending on nominal impedance. What differences are there between 4, 6 or 8 Ohm loudspeakers. I moved to Ireland recently and I don`t know a lot about loudspeakers that are available here. Are these all widely spread in Ireland (4,6,8 ohm) ?

thanks,

gyaala

Sparky

most speakers are 8 ohms and many amps take 4 to 8 ohms, but if i remember correctly and i can be corrected, less than 8 ohms makes more power available to the speakers.
but its all about matching your speakers to your amp, and dont buy say a 4 ohm speaker and an 8 ohm speaker because you will have an imbalance in power.

ie 4ohm +8 ohm =12ohms total

amp=100watts power
speaker 1 gets 33 watts power
speaker 2 gets 66 watts power

but im sure you know this already.
just make sure your speakers can handle the power aswell of the output of the amplifier.

Red Alert

Sparky i presume you mean 12 ohms in series, as opposed to parallel!

4 ohm will give you the most output as long as it's a SINGLE speaker per channel of the amp. Most floor-standers are 4ohm minimum nominal impedance - the impedance of many speakers is actually frequency dependent.

Sparky

yeah in series, forgot to mention that

Michael Collins

Just make sure not to use 4 Ohm speakers on an amp meant for 8 Ohms, that could damage the amp. Higher ones are OK but the sound won't be as loud.

ZENER

Red Alert wrote:

Sparky i presume you mean 12 ohms in series, as opposed to parallel!

4 ohm will give you the most output as long as it's a SINGLE speaker per channel of the amp. Most floor-standers are 4ohm minimum nominal impedance - the impedance of many speakers is actually frequency dependent.

Actually the impedance of ALL speakers is frequency dependent that's why they are quoted as "nominal" impedances. Impedance is the opposition a load presents to an alternating current where the load is either capacitive or inductive or both (both types may contain some resistance).

Measuring into the speaker with an ohmeter doesn't give the "impedance" of the speaker only the DC resistance of the crossover and voice-coil so don't do this.

The effect of using the incorrect speaker on a given amp will be distorted lower frequencies. A low(er) impedance speaker on a high(er) impedance amp will result in poor low frequency reproduction and vise-versa. This is the reason some speaker/amp combinations work better - better impedance matching among other factors of course.

*/ Zips up anorak and leaves . . . :rolleyes:

ZEN

Stoner

Very well put ZENER, enough to earn my first ever "well done" post, but that post is worth calling everyone back in to read again. All this fluting about resistors in series and parallel and then bang straight into impedance matching

ZENER

*/ Bows Cautiously !! Awaits Sarcastic Comeback.

ZEN