Speakers, ohms, confused !

[blast05]

One for the techies.....

I have bought a cinema system which has 3 ohm satellite speakers. I am not going to use 4 of the satellite speakers and am instead going to get 4 ceiling recess speakers which are already wired for. My problem is i can only seem to find 4, 6 or 8 ohm ceiling speakers online. As i understand it, the wattage of the ceiling speakers does not have to exactly match the ones i will not use from the cinema system but the different impedance (ohms) could result in me blowing the in-built amplifier that comes with the cinema system. Can anybody confirm  re this ? I couldn't get a definitive answer from the sony centre i visited.

2nd problem/question .....  i am using the 4 satellite speakers from the cinema system as standalone speakers in a high ceiling living area. These are going to connect back to a 2 way stereo amplifier (thus the speakers can only be controlled in pairs) to which i will connect a small radio/CD player. Given that the satellite speakers are 3 ohm, does this mean each channel of the stereo amplifier which will be each supporting 2 speakers would have to be 6 ohm ?

Finally, i am presuming the wiring that is done on the house will not in anyway change the impedance / ohms and thus the 2 scenarios above are the only 2 i need worry about ?

[Fear ón Srath Bán]

I have bought a cinema system which has 3 ohm satellite speakers. I am not going to use 4 of the satellite speakers and am instead going to get 4 ceiling recess speakers which are already wired for. My problem is i can only seem to find 4, 6 or 8 ohm ceiling speakers online. As i understand it, the wattage of the ceiling speakers does not have to exactly match the ones i will not use from the cinema system but the different impedance (ohms) could result in me blowing the in-built amplifier that comes with the cinema system. Can anybody confirm  re this ? I couldn't get a definitive answer from the sony centre i visited.

If speakers have a higher impedance than spec'ed for, the power output will suffer (downwards), and the higher frequencies might take a hit. (Only if the ohm rating were lower would you risk blowing the amp, ohm = electrical resistance, which become impedance in an A/C set-up, which speakers are).

2nd problem/question .....  i am using the 4 satellite speakers from the cinema system as standalone speakers in a high ceiling living area. These are going to connect back to a 2 way stereo amplifier (thus the speakers can only be controlled in pairs) to which i will connect a small radio/CD player. Given that the satellite speakers are 3 ohm, does this mean each channel of the stereo amplifier which will be each supporting 2 speakers would have to be 6 ohm ?

It seems like each speaker will be connected in parallel from each channel (not one wire going from one speaker to the next, but two coming from the channel), therefore  3 ohms is all that will be 'seen' on each channel.

Finally, i am presuming the wiring that is done on the house will not in anyway change the impedance / ohms and thus the 2 scenarios above are the only 2 i need worry about ?

Correct, and good luck with it!

[blast05]

Cheers F an SB.
So based on replacing ~120 watt cinema system 3 ohm satellite speakers with ~80 watt 4 ohm recess ceiling speakers, you reckon i should chance going with it ?

For my second scenario, i have it wired both ways, i.e.: i can have each speaker independently controlled (4 separate cables) this requiring a dearer 4 way amp or the way i am going to go - 2 speakers to the front of the living area (cable going from amplifier location to the first speaker and then on to the second) going through 1 of the stereo channels and the other 2 speakers to the rear going through the other stereo channel.

I am sure i am mixing up all the lingo here 

[Fear ón Srath Bán]

Welcome Blast.

Cheers F an SB.
So based on replacing ~120 watt cinema system 3 ohm satellite speakers with ~80 watt 4 ohm recess ceiling speakers, you reckon i should chance going with it ?

I'd be a little nervous here -- the power rating of your replacement speakers is lower than the original speakers (assuming both are a measurement of 'RMS' or 'Average' power?), therefore the power that's being fed into the 80W speakers could be too powerful. I wouldn't chance it.

For my second scenario, i have it wired both ways, i.e.: i can have each speaker independently controlled (4 separate cables) this requiring a dearer 4 way amp or the way i am going to go - 2 speakers to the front of the living area (cable going from amplifier location to the first speaker and then on to the second) going through 1 of the stereo channels and the other 2 speakers to the rear going through the other stereo channel.

I am sure i am mixing up all the lingo here 

Lingo good 

Can you have a look at this link: http://colomar.com/Shavano/spkr_wiring_sp.html, it gives a good pictorial breakdown of serial and parallel amplifier-speaker wiring arrangments, and also how the impedance is calculated (added for in series, split for parallel).

[Armagh4SamAgain]

f**k i dont understand a word of that! 

[Fear ón Srath Bán]

I know nothing about speakers but here's something about Ohm.
This means that the current is equal to voltage (potential difference) divided by the resistance.
I = V/R or V = IR or R = V/I.
This may help you.

You're not wrong there HS, except that this is, strictly speaking, for Direct Current (D/C), not Alternating Current (A/C), which brings in phase considerations (hence the use of impedance instead of resistance), i.e., the voltage won't always peak with the current.

An additional equation is P = VI, where P is power, therefore P = I²R

Edit (just copped this now):

I know nothing about speakers but here's something about Ohm.

http://en.wikipedia.org/wiki/Georg_Ohm

He had a law you know. I can't remember the name of it, it wasn't catchy but....

Yes, it is/was Ohm's Law! 

[Gnevin]

One for the techies.....

I have bought a cinema system which has 3 ohm satellite speakers. I am not going to use 4 of the satellite speakers and am instead going to get 4 ceiling recess speakers which are already wired for. My problem is i can only seem to find 4, 6 or 8 ohm ceiling speakers online. As i understand it, the wattage of the ceiling speakers does not have to exactly match the ones i will not use from the cinema system but the different impedance (ohms) could result in me blowing the in-built amplifier that comes with the cinema system. Can anybody confirm  re this ? I couldn't get a definitive answer from the sony centre i visited.

2nd problem/question .....  i am using the 4 satellite speakers from the cinema system as standalone speakers in a high ceiling living area. These are going to connect back to a 2 way stereo amplifier (thus the speakers can only be controlled in pairs) to which i will connect a small radio/CD player. Given that the satellite speakers are 3 ohm, does this mean each channel of the stereo amplifier which will be each supporting 2 speakers would have to be 6 ohm ?

Finally, i am presuming the wiring that is done on the house will not in anyway change the impedance / ohms and thus the 2 scenarios above are the only 2 i need worry about ?

But a seperate amp them built in things are useless

[blast05]

But a seperate amp them built in things are useless

I know, ideally i would but they are 3 times the price and given the level of use i will knock out of it then i couldn't justify it.
What i am going to do is bring back the cinema system (haven't opened it yet) and get one with 70 watt satellite speakers with 4 ohm resistance (142 watt 3 ohm satellite speakers on the one i am bringing back). I can get similar spec'd ceiling speakers to replace these no problems so all should be grand.

[blast05]

Apologies for bringing this up again but could anyone comment on the following spec of gear for my scenario:

Cinema system: http://www.superfi.co.uk/index.cfm/page/moreinfo.cfm/Product_ID/3431
Ceiling speakers: http://www.cybermarket.co.uk/ishop/923/shopscr162.html  .... is it ok to buy 2 pairs of these as replacements for 4 of the satellite speakers in the cinema system ?
Stereo amp to be used with the 4  satellite speakers from the cinema system: http://www.sony.ie/view/ShowProduct.action?product=TA-FE370&site=odw_en_IE&pageType=Overview&imageType=Main&category=HFC+Amplifier


My latest problem/confusion from reading up about this and only half understanding it all is that satellite speakers from the cinema system that i will be deploying with the sony stereo amp may not have any crossovers built in, with the crossover being provided internally in the DVD/amp in the cinema system. In this scenario, bass would be sent to the satellite speakers and damage them ...or something like that