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Speaker impedance compatibility

post #1 of 11
Thread Starter 
Would it be ok to use 4-8 Ohm speakers with an amplifier of 8-16 Ohm?

Also, the two speakers are bi-wire (2 plus and 2 minus connections) but the amplifier is not. If yes to my first question, can I still connect the two?

Thanks.
post #2 of 11
No, the total impedance will be 2.67 ohm, which is way too low

Some speaker impedance calculator you can use here,here and here
post #3 of 11
Thread Starter 
Thanks for the links, Apocalysee.
I see there is serial and parallel wiring....in my case the amp has 2 terminals (one for the left and one for the right speaker).....so not sure how this applies here?

Wrt the bi-wire on the speakers I found four bridges which convert their terminals to standard wiring.
post #4 of 11
Quote:
Originally Posted by suba3333 View Post
Thanks for the links, Apocalysee.
I see there is serial and parallel wiring....in my case the amp has 2 terminals (one for the left and one for the right speaker).....so not sure how this applies here?

Wrt the bi-wire on the speakers I found four bridges which convert their terminals to standard wiring.
The serial and parallel connection occur inside the speaker itself (normally within the crossover) Most speaker uses parallel wiring AFAIK, unless you DIY it

I never looked at bi-amped speaker before, but I believe if you use it separately, you can mixed any sort of impedance without any problem (because woofer and tweeter uses different amp/channel to drive them, unless you connect them together because you don't have bi-amped amp).

Even though your amplifier isn't capable of bi-amped, you can use it. But the combined impedance is too low (2.67ohm) so you can' use it because it's too low for your amp. Read speaker/amplifier FAQ here
post #5 of 11
Bi-wire or Bi-amp?, because they are two completely different things.

Bi-wiring is basically useless, since you still using one amp to drive both the high frequency drivers and low frequency (this is the same as using the bridges you mentioned). Bi-amping on the other hand splits the load between to amps making the work load on the amps might lighter, which will get you better sound.

The speakers would be either 4 or 8ohm not 4-8. No home audio speaker would never go significantly below 4 ohms so I think some clarification is in order. What amp and speakers are dealing with?
post #6 of 11
Depending upon the type of speaker, it is possible for the impedance to be either 4 or 8 ohms, depending upon the connections. Various types of transformers can be placed on the crossover to change the impedance depending upon how they are connected. This was a fairly common practice with apogee speakers. Many people use autoformers (basically a transformer) to bring the 1 ohm apogee's up to 4 ohm or higher.

The crossover may separate the frequencies, but in some cases transformers are used so that all drivers have matched impedance.

To answer the question, you will have to know the design that is used. It may be very to connect your speakers to operate as 4, 8 or 16 ohm. This is very common when designing a car audio system.
post #7 of 11
Quote:
Originally Posted by bhostinsky View Post
Depending upon the type of speaker, it is possible for the impedance to be either 4 or 8 ohms, depending upon the connections. Various types of transformers can be placed on the crossover to change the impedance depending upon how they are connected. This was a fairly common practice with apogee speakers. Many people use autoformers (basically a transformer) to bring the 1 ohm apogee's up to 4 ohm or higher.
Crossovers consist of inductors, capacitors, and resistors. Speakers can have transformers (ceiling or in wall speakers usually) but they wouldn't be part of the crossover.
post #8 of 11
Thread Starter 
The stereo is my sister's, so I don't have too much additional info handy. It's a TEAC mini/midi system consisting of amp, CD, cassette. In the manual it says to use 8-16 Ohm rated speakers. The speakers that came with the stereo are not TEAC speakers (though they look quite hi-quality and are bi-wire) and sizewise seem to fit the stereo, it says on the back that they are 4-8 Ohm. As there is a minimal overlap in these 2 ratings I was wondering if the speakers can still be used, considering that the previous owner seems to have used this configuration without problems?
post #9 of 11
4 Ohm speakers present a difficult-to-drive load in terms of currents. Depending on your speakers' nominal impedance (which I'm guessing hovers in the 6-8 Ohm range), the amp should cope. A high sensitivity will help too. You certainly don't want to hook them up with speakers whose impedance is known to dip in the 2-4 Ohm region (ATC SCM12 is one such speaker IIRC).

Cheers!
post #10 of 11
the impedance of a speker will vary through the audio range and
generally dips down lower at around 100hz and lower speaker
graphs will show this and some speaker mfg's will give the lowest
besides the nominal impedance.
post #11 of 11
Quote:
Originally Posted by ozz View Post
the impedance of a speker will vary through the audio range and
generally dips down lower at around 100hz and lower speaker
graphs will show this and some speaker mfg's will give the lowest
besides the nominal impedance.
Yeah, the 4ohm must represent the minimum impedance, most speakers just list the nominal. I would say those speakers should be fine with the amp. If it doesn't work the worst thing would happen is the amp would just shut down if drive it too hard (loud).
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