Hi Fi Speaker ohm

[mike mills]

Rather than go to more expense I wonder if I can change the impedance of my old Theatre system speakers from 3 to 4 ohms or lift the impedance to 8ohms then run two speakers either side bringing the impedance down to 4 ohms. If it is possible what resistor would I need. At the moment the speakers are 3ohm and the min on the amp is 4ohm I dont play them loudly just that I find boosting the tv sound via hi fi amp better than using my ridiculous 1000watt theatre system that Comet ripped me off for. Thanks for any assistance

 

[telectrix]

if you wire 2 8 ohm speakers in parallel, that would give a combined impedance of 4 ohms.

 

[mike mills]

if you wire 2 8 ohm speakers in parallel, that would give a combined impedance of 4 ohms.

Yep get that used to do it all the time in band situations this problem I have is a little different I need to raise the Impedance using a resistor but dont know the right rating of resistor to take speaker from 3 to 4 ohm or from three to 8 ohm

 

[jackhammerJIM]

Does the amp have 2 channels . connect a speaker to each channel . Don't run them hard they will be fine .


If you have 2 speakers per channel connect them in series . 6 ohms per channel .

 

[Lucien Nunes]

The difference between 3 and 4 ohm speakers is actually fairly trivial. The impedance is only correct at one frequency, usually around 1kHz. At other frequencies a '4 ohm' speaker can be anywhere between maybe 3 and 30 ohms, do a Google image search for 'speaker impedance curve' for examples. If you don't run your amp at full power, a 3-ohm speaker will usually be OK on a 4-ohm min output, although technically the amp can be overloaded at full welly.

If you have two identical speakers each side, why not wire them in series for a total of 6 ohms? That will be safe for your amp and will be able to uitilise most of its available power.

Don't add resistors, they will muck up your damping factor and frequency response - the speaker is designed to see a low impedance, maybe 0.1 ohms, looking back into the amplifier. Incidentally, a 4 ohm speaker will measure around 3 ohms to a multimeter. That is because the rated impedance (4 ohms) must always be higher than the DC resistance, and most commercial speakers achieve a resistance / impedance ratio of about 3/4.

 

[mike mills]

Thank you all for straight forward replies you have all answered the question I posted and can now move forward to solving the issue, I'm on say half a dozen musician sites and this is the only one that has given me a straight forward intelligent reply,my faith in people has been restored

 

[UKMeterman]

Hi,
What power is the amp, and what cables are you currently using to connect them up, however for most sensible domestic purposes some 1.5mm2 2core flex would do fine, you can get this at most independent electrical and household appliance shops.