4ohm Ceiling Speakers

Hi Guys,

We are currently installing a 7 zone multi room audio system for a client who has requested that we split 1 zone between 2 rooms. That is 1 remote amp in the lounge powering 2 speakers in the lounge room and 2 in the dining room.

When we attended the MRA demonstration in Melbourne we were advised that in order to do this properly we needed to use 4 ohm speakers not the normal Clipsal 8 ohm ones.

I have now sourced 4 ohm speakers, but before I purchase these, can someone confirm that the advice given to us at the demo is in fact correct? If so how come Clipsal can not supply 4 ohm speakers?

Also can I purchase additional Clipsal speaker grills in case I need to match up the speakers in all the rooms?

Your advice will be greatly appreciated.

 

I have just read the manual regarding the remote amps, and what it basically says is that each speaker output is rated to run speakers from 4 to 8 ohms, at 6 watts per channel without an external power supply, or 25 watts per channel WITH an external power supply (both of these numbers are using a 4 ohm load).

Therefore, running 2 speakers on each channel that were 4 ohms (assuming they are wired in parallel) would mean that they would be presenting a 2 ohm load on the amp, and I doubt that it would like it very much. So theoretically, you should be using 2 x 8 ohm speakers wired in parallel, to present a total of 4 ohms per amp channel. You could also use 2 x 4 ohm speakers, but this would mean you would need to wire them in series, which is more complicated than the parallel option.

Wiring 2 x 8 ohm speakers per channel in parallel is the wiser choice, as the lower the ohms, the more power the amp can provide per channel. There are alot of standard ceiling speakers out there that are 8 ohm 10W speakers, and considering that the remote amps are rated to supply 25W into 4 ohms per channel with an external Power Supply, these would do the job just fine. But if you are not using an external power supply, they are only rated to run 6 watts worth of speakers at 4 ohms per channel. (I'm thinking you should definately use an external PSU).

With the standard Clipsal In-Ceiling speakers having an impedance of 8 ohms, you can use 2 of these wired in parallel quite happily with the remote amps.

Hope these sheds some light on your question,
Regards,

Darpa

 

Darpa is quite right.

In my day I was taught about a chap called Ohm. Being pretty good at physics and maths he came up with the theory that for three or more resistances in parallel calculate the reciprocals - one over.

For two resistance values it is easier, R = (R1xR2) over (R1+R2).

For two resistances of the same value in parallel it is dead easy, half the resistance value. 8 ohms and 8 ohms in parallel = a 4 ohm load. (Less ohms = more load )

Who steered you towards 4 ohm speakers

PS. Have used C-Bus multi room audio amps with 8 ohm speakers in parallel (2 of) and it works fine. I have never heard of anyone wiring speakers in series.

 

Just to add to the history lesson Sir Joseph Ohm Law (or Joe as we used to call him) is in fact the great grand father of Australian AM radio's golden Tonsils - John Law's.

Just a bit of trivia...

 

Yeah Right I wish I was playing against you at a Trivia Night.

For the record his name was Georg and we used to call him "The G Man"

 

Thanks Guys this makes sense, ans I may just stick with the Clipsal 8 ohm speakers, my only question is why did the Clipsal folk recommend 4 ohm in parallel?

 

Sorry guys,

I may actually have misunderstoond the Clipsal folk here, I take that back.

 

Just remember the MARPA Mantra...

OHM... OHHHHHMMMMM...

 

I always thought his name was Georg, we always used to call him "Georgie Boy". He was far more interesting than that Pythagoras clown with his square of the Hypotenuse.

 

Yeah, I know what you mean. Did you ever meet "The big E"? Einstein was his name I think....... now that guy needed help. E=MC2 what the hell was that all about?

 

Phil,

Series wiring of speakers is commonly done when installing multiple subwoofers in a car, easpecially when the subwoofers have Dual voice coils.

Thats why I have experience on the topic, lol


Darpa