Distribution of audio from receiver

Posted by Alan L. Maier [SysOp] [IP: 129.37.205.20] on December 31, 1998 at 20:55:18:

In Reply to: Distribution of audio from receiver posted by Nate Nelson on December 31, 1998 at 04:27:28:

Nate,

I am glad to help! Let's take your questions one at a time...

: What spec on the receiver determines how many speakers I can drive? Watts?

Personally I am not worried about watts here. You might be very surprized at how little power you really need for most music playback - especially for background music. I would look for a receiver that can handle a 4 ohm load safely. Due to the 4/8 ohm switch in the rear of your receiver (which adjusts amplifier power capability to prolong the life of the receiver) you are set.

: Don't understand the concept of impedance; Why is it bad to have a low impedance load? Why will a long run help?

Imdepance is the resistance of the speaker when driven with a AC voltage (audio is AC). The lower the impedance, the more current (amperage) the speaker requires from the amplifier. It's like adding cars behind the locomotive on a train... the more and heavier you add, the more the locomotive has to strain. Normally just 1 8 ohm speaker is what the receiver likes to drive. When you add another 8ohm speaker the receiver has to really strain. Unfortunately with the receiver, it's ability to drive speakers is limited and asking too much will result in damage to the output transistors. The impedance switch (4-8 ohm switch on the rear)helps by reducing the output power in effort to prolong the life of the receiver when pressed hard. Adding resistance to a speaker (due to a long wire run) will actually help here as it takes a bit of this load off the receiver.

: ...my speakers are rated at 6. What does this measurement mean and should I attempt to match ohms on all of the speakers I purchase?

The impedance of the speaker is the amount of load - in my locomotive example it would be the weight of the cars it is pulling. A 4 ohm speaker places twice the demand on the receiver than a 8 ohm one will (like a fully loaded tank car vs. and empty one). With your multi-speaker setup you definitely should stick with 8 ohm speakers as your remotes.

: You also mention protection options- What exactly needs to be protected? Can the amp short out with too many speakers? How do the speaker selectors prevent this?

Many of the speaker selectors give you the option of engaging a "protection" button, which will either insert a resistor into the output or manipulate the speaker connection method to keep the impedance from dropping too low. Your output transistors of the receiver are at risk of overheating and in time, shorting out due to excessive demand being placed on them. I restore older audio equipment as a hobby, and I have a room full of recevier, most with "blown" amplifiers due to the previous onwers attempt to drive too many speakers. They are mine now as the cost to have a repair shop fix them is quite high.

: And in connecting the speaker selector controller would I leave my primary speakers connected to output A and plug the controller into output B or do I plug the controller into A and the primary speakers into the controller. Th first option seems to give me a little more flexibility and might distribute the load better, but....???

And what a big but that is! Don't use both the A and B outputs!!! Only use the A outputs and operate everything via the selector switch unit. Go a step farther - take duct tape (or whatever) and tape across the B terminals.. and write "do not use!" on it. This is very important!

: Finally, an integrated amp. What exactly is it and where does this fit into the scheme of things?

A second amplifier would allow you to do the following setup... 2 speaker pairs driven by the receiver and 2 more speaker pairs driven by a second amplifier. For people who are wanting to install a pair of good speakers in the living room and family room... then a small pair in the den and the garage/outside, this setup will work well.

However if you wish to have a good pair in the living room, a second pair in the family room, a pair in the den, a pair in the garage, a pair outside, inwalls in the kitchen and dining room - well I see a 6 pair switcher in your future!

When you buy the speaker switcher unit, there will be instructions in the box. Read them very carefully. Also by all means feel free to drop me a note whenever you have a question. When you post a message here, I receive an e-mail automatically to let me know you've posted a question for me so I'll catch it.

Best wishes for the new year!

Alan

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