GE SmartCom Audio Question - Contractor Talk - Professional Construction and Remodeling Forum

ABLE1 · 06-11-2009, 04:10 PM

Hello all,

I have a friend that is installing a GE SmartCom in a new home for a customer. Long story short customer wanted 4 speakers in a room. The speakers are 8 ohms each. The specs on the SmartCom is that each connection is to be 8 ohms or one speaker for left and one for right.

In conversation with GE my friend finds out that there is some modification that needs to be made to the controller in order to connect four 8 ohm speakers. He was told that he needs to send the controller to a third party that will make the modification and return. Which is his plan to do.

So I was wondering what detrimental effect would happen if a 8ohm 10watt load resistor was placed at each speaker and then two on the left were wired in series and two on the right were wired in series giving the equivalent load of 8ohms per each speaker input.

I am not a audio person but I know that electrically a 8 ohm load is a 8 ohm load. However do not know what will happen with sound quality if this is done in this way on this system.

Anyone here able to put an answer to this question??

Thanks in advance.

Les

Tinstaafl · 06-11-2009, 05:44 PM

Quote:

Originally Posted by ABLE1

I am not a audio person but I know that electrically a 8 ohm load is a 8 ohm load. However do not know what will happen with sound quality if this is done in this way on this system.

Technically, amps are built to drive an 8 ohm impedance, as opposed to resistance. Proper snobtronic theory would have to account for the inductance and capacitance in the circuit as well.

Having said that, in practical terms there's not much wrong with your idea. As long as each channel is looking at an 8 ohm load, you're not going to hurt the amp. What will happen though, is that your volume won't go nearly as high, because half of the energy will be passing through the resistors. Any actual distortion of the audio should be so minimal you'd never be able to hear the difference.

If there's no need to crank it, I see no reason not to do it that way.

Tinstaafl · 06-11-2009, 05:49 PM

Afterthought: If the intercom feature uses the speakers as audio pickups, this might not be such a good idea. The minimal signal output from a speaker used that way would be way down in the mud with resistors across the terminals.

Inner10 · 06-11-2009, 06:17 PM

Quote:

So I was wondering what detrimental effect would happen if a 8ohm 10watt load resistor was placed at each speaker and then two on the left were wired in series and two on the right were wired in series giving the equivalent load of 8ohms per each speaker input.

Ok, 8 ohms wired in series makes 16 I don't see where your resistors come into play? Maby I don't understand but here's the skinny:

The GE Smart Comm is a more an intercomm then an audio distribution system, frankly they make a poor sound system at best. The tiny little amps they use get pretty stressed when you wire the speakers in parallel...therefor reducing them to 4ohms a side. Less resistance demands more current from the wussy little amp, causing them to click into protection if played loud. If you series them they will play quieter since your at 16ohms but reduce stress on the amp. Either way you are sacrificing a tad of performance (not like it matters on a GE).

Now, a speaker is not an 8ohm load, put your meter on it and it will read near 8ohms...but get it playing and it will constantly change.

No company will ever recommend paralleling speakers since its hard on amps. Chances are if you did you would never have a problem if it was used at a reasonable volume. When I spec systems with more then 2 speakers on one zone I always insist on an additional power amp (really only occurs in backyards etc.)

Les, if the system doesn't have a separate line level out for an additional amp then you can get a pair of line-taps (converts speaker to line level by channeling it through a resistor) and then hook up a nice beefy amp.

Is that what you meant or am I way off base?

ABLE1 · 06-11-2009, 07:17 PM

Quote:

Originally Posted by Inner10

Ok, 8 ohms wired in series makes 16 I don't see where your resistors come into play? Maby I don't understand but here's the skinny:

The GE Smart Comm is a more an intercomm then an audio distribution system, frankly they make a poor sound system at best. The tiny little amps they use get pretty stressed when you wire the speakers in parallel...therefor reducing them to 4ohms a side. Less resistance demands more current from the wussy little amp, causing them to click into protection if played loud. If you series them they will play quieter since your at 16ohms but reduce stress on the amp. Either way you are sacrificing a tad of performance (not like it matters on a GE).

Now, a speaker is not an 8ohm load, put your meter on it and it will read near 8ohms...but get it playing and it will constantly change.

No company will ever recommend paralleling speakers since its hard on amps. Chances are if you did you would never have a problem if it was used at a reasonable volume. When I spec systems with more then 2 speakers on one zone I always insist on an additional power amp (really only occurs in backyards etc.)

Les, if the system doesn't have a separate line level out for an additional amp then you can get a pair of line-taps (converts speaker to line level by channeling it through a resistor) and then hook up a nice beefy amp.

Is that what you meant or am I way off base?

Close but no cigar............................ Maybe I was not REAL clear.

What I was suggesting was placing a 8ohm 10watt resistor at each speaker in parallel with the speaker which will produce a 4ohm load. Then wiring two speakers in series thus getting a total of 8ohms.

Thanks for the extra input. I will pass it on.

Les

ABLE1 · 06-11-2009, 08:38 PM

Quote:

Originally Posted by Inner10

Les, if the system doesn't have a separate line level out for an additional amp then you can get a pair of line-taps (converts speaker to line level by channeling it through a resistor) and then hook up a nice beefy amp.

Hi again,

Any chance you would have a mfg. and or part number for the line-taps you describe??

TIA

Les

Inner10 · 06-12-2009, 10:09 AM

http://www.russound.com/adp1.2.htm

or make it yourself for cheap!

ABLE1 · 06-12-2009, 01:27 PM

Quote:

Originally Posted by Inner10

or make it yourself for cheap!

Would you mind expanding that thought???

Inner10 · 06-12-2009, 02:40 PM

I had a feeling they were just a combination of resistors, most amps take a line level signal which is about 200mv. May not be worth your time considering the ADP1.2 is rather cheap to begin with.

In car audio they use these all the time on factory units that don't have line level out.