Need advice on hooking 2 speakers to 1 output

Wayne Carver · Post by **Wayne Carver** » 28 Apr 2004 7:33 am

I have two 8 ohm speakers that i want to hook up to a Mono pa amp. Should I wire them in parallel to the 8 ohm tap or wire them in series to the 4 ohm tap? I have them wired in parallel to the 8 ohm and it sounds ok. The amp is powerful enough and the speakers are small so I could only turn the volume up about halfway as it is. Just wondered what the advantages of either hookup would be.

C Dixon · Post by **C Dixon** » 28 Apr 2004 10:12 am

Wire the speakers in parallel. This will match perfectly your PA's 4 ohm output and the transfer of power will be maximum.

As far as a listening test, few (if any) would ever know the difference. A missmatch causes a fall off in power directly proportional to the amount of missmatch in either direction. But remember, the human ear cannot detect a power increase or decrease by a factor of 2 until the power has changed by a factor of 10!

Thus, missmatches rarely are noticed, unless one compares in an A/B test. Also, unless the amp is running full power, it makes little difference anyway, because a slight adjustment of the gain control will make up for any loss in power. Noticable fidelity changes is rarely ever a factor in missmatches.

carl

Roger Kelly · Post by **Roger Kelly** » 28 Apr 2004 10:14 am

I believe I would hook the two 8 ohm speakers in parallel to the 4 ohm tap.
Have you tried that? The Amp should "See" a 4 ohm load that way.

Wayne Carver · Post by **Wayne Carver** » 28 Apr 2004 10:46 am

Thanks for the tips. I never can remember the formula. So: two 8ohm speakers(parallel)equals 4ohms
two 8ohm speakers(series)equals 16ohms
Any advantage to wiring them in series to the 16ohm? I guess it would be better on the amp wiring them in parallel to the 4ohm taps?

Roger Kelly · Post by **Roger Kelly** » 28 Apr 2004 12:44 pm

If you have a 16 Ohm Tap, you can hook two 8 Ohm Speakers wired in series to it and the Amp will like it.....but you said you only had a 8 Ohm and a 4 Ohm Tap. If you hook a 16 Ohm load to an 8 Ohm Tap, it will cut your power down to about half, but otherwise shouldn't cause any problems to the Amp.

C Dixon · Post by **C Dixon** » 28 Apr 2004 1:09 pm

Wayne, here is the formula:

If the two speakers are not equal, use...

"product over the sum".

Example: a 16 ohm speaker in parallel with an 8 ohm speaker, is (16 times

divided by (16 plus

; or 5.34 ohms.

If the speakers are equal, simply divide one of them by two if parallel; or add them together if in series. Thus two 8 ohms in parallel is 4 ohms. In series it is 16 ohms.

carl

jeff reynolds · Post by **jeff reynolds** » 4 May 2004 7:57 am

does any of the different wiring i see hear change the tone?

C Dixon · Post by **C Dixon** » 4 May 2004 8:12 am

For all practical purposes no.

Of course if you changed it on a given person's guitar, and they knew it, in all likelyhood, "the tone has changed". If they did not know it, few (if any) would ever detect a power or tone change at all.

I must add the following story I have told before on this forum. I was at a dear friend's house one time and was talking about cabinet drop. Whereupon he said, "my guitar does not have it". I said, "may I try it?" He said, "sure, go ahead"

So when I put a tuner on it and pressed the A pedal, the 6th string dropped. When I showed him the tuner, he said,

"well, it never did that before you messed with it!"

He was NOT kidding.

carl