Adding A Speaker

[Roger Bielen]

I have an A-B-A set that I've converted to TMCC with a TAS SAW board and sound. Don't you just love all those acronyms? I have the board in the B unit and the speaker in one of the A's. I'd like to add another speaker into the other A unit.

Has anyone done this? If so do I use an identical speaker wired in parrallel to the existing or do I need to replace both speakers?

[Buckeye Riveter]

Roger, I have read or heard of a speaker being added as you described. In fact, I may have read it in some old TAS brochure. I remember something about the speakers being identical.

Just call TAS, they should be able to help you.

[Anonymous]

Check the impedance of the speakers. You need to ballance the impedance to not overload the amp by lowering the resistance too much or provide so much impedance neither unit makes much noise. Audio amps are set up to see a specific load, usually 4, 8 or sometimes 16 ohms. Most of the earlier sound systems expected 8 ohms. I believe that the newer PS-2 systems use a 4 ohm speaker. The ballance act gets a little weird in that hooking up speakers in series means you add the resistance. Two 8 ohm speakers wired in series results in a 16 ohm load. If you wire them in parallel, the resistance will drop to 4 ohms. If he amp is ballanced for 8 ohms neither situation is desireable. You would need to wire up the speakers in a series parallel bridge to get back to 8 ohms. If you add a second speaker you also want to check the polarity of the speaker to make sure both cones push and pull air in same way. If they are wired opposite the sound waves produced will be out of phase and tend to cancel each other out. Some of the earlier two speaker Lionel SD-90's had the second speaker wired out of phase at the factory and the sound was pretty muddy. Swap the wire leads and the loco sounded great..

This is from a car stereo site but the basic principals are the same.

http://www.bcae1.com/spkrmlti.htm

chuck

[Roger Bielen]

Thanks guys.