Dual speakers on each channel

[Guest dogmeninreno]

From an electrical point of view, I would connect dual speakers (2 on each channel) in parallel to the power amp. Any advice from experience? Thanks, Dale in Reno.....

[r_laski]

>>From an electrical point of view, I would connect dual speakers (2 on each channel) in parallel to the power amp. Any advice from experience? Thanks, Dale in Reno.....<<

Depends on the Impedance of the speakers and your amp(s). If you equate the impedance of a speaker to resistance:

For each channel-

Rt (Ohms) = Total resistance(impedance);

R1=speaker 1 resistance;

R2=speaker 2 resistance

Parallel Resistance(Ohms): Rt= R1xR2/(R1+R2)

If all four speakers are identical with 8 Ohm impedance. Connecting them in parallel would look like a 4 Ohm load on each channel of the amp. Rt= 8x8/(8+8) Rt=4

I’ve done this before. For many amps, rated power into 4 Ohms is double the power into 8 Ohms. You will draw twice the power out of the amp. Most amps can handle this, even though we know speaker impedance does vary somewhat and will dip below 4 Ohms while it is being driven by the amp.

However, if all four speakers were 4 Ohm impedance, connecting them in parallel would look like a 2 Ohm load to the amp. Rt= 4x4/(4+4) Rt=2

Most amps are not designed or rated to continuously drive a 2 Ohm load. I’ve never owned an amp rated for a 2 Ohm load so I’ve never tried this.

Connecting the 4 Ohm speakers in series would look like an 8 Ohm load to the amp. Rt=R1+R2. Obviously safe load for the amp.

Rich Laski

[Guest Brian_D]

I concurr with the math, and the pure electrical outlay of it all is good.

Most amplifiers have an "a b" selector switch that will allow you to run either of two sets of speakers attached to the amplifiers outputs. Some amps will even allow for both to be selected at the same time. The amplifier will either parallell them or series them, I've seen both and you would have to check your manual to know which your amp does. Very spiffy amps will even do some resistance mojo and allow you to hook two pair of 4 ohm speakers and still keep the resistance at 4 ohms, but you would need to know that your amp does this; usualy it just series the output.

[soundminded]

I can't agree. If the speakers are wired in series, not only is the available power likely to be substantially less for solid state amplifiers but the effective amplifier damping factor will decrease to less than one possibly changing the sound by allowing a resonant peak in the bass. Wired in parallel, the load which will be less than 2 ohms at some frequencies for 12 inch units could result in severe damage to the output stage of many amplifiers unless there is a series resistance element which will again reduce the amplifier's damping factor and waste power. There are some solid state amplifiers such as Crown DC 300 which can handle one or two ohms but they are the exception, not the rule. Some tube amplifiers may have 2 ohm transformer taps, possibly a McIntosh MC 240 or MC 275 but they are also the exception.

IMO, the best way is to have separate amplfiers for each pair. While this is more expensive, it overcomes or avoids other problems.

[Guest dogmeninreno]

>I can't agree. If the speakers are wired in series, not only

>is the available power likely to be substantially less for

>solid state amplifiers but the effective amplifier damping

>factor will decrease to less than one possibly changing the

>sound by allowing a resonant peak in the bass. Wired in

>parallel, the load which will be less than 2 ohms at some

>frequencies for 12 inch units could result in severe damage to

>the output stage of many amplifiers unless there is a series

>resistance element which will again reduce the amplifier's

>damping factor and waste power. There are some solid state

>amplifiers such as Crown DC 300 which can handle one or two

>ohms but they are the exception, not the rule. Some tube

>amplifiers may have 2 ohm transformer taps, possibly a

>McIntosh MC 240 or MC 275 but they are also the exception.

>

>IMO, the best way is to have separate amplfiers for each pair.

> While this is more expensive, it overcomes or avoids other

>problems.

Two amps it is! Thanks all, Dale