For an up and coming gig my band are hoping to connect six speakers
through one powered mixer. Two of these will act as monitors and the
other four will face the crowd.

The problem is that we have no idea how to set up such a system and
whether it would even be safe.

I know the specifcation of one set of speakers and the powered
mixer...

MIXER - 80watts/channel in to 4 ohms (18V RMS), 50watts/channel into 8
ohms (20V RMS), 4 0r 8 ohm load (4 ohms min. load), two speaker output
channels.

EACH SPEAKER OF A PAIR - nominal impedance: 8 ohms power capacity:
200watts

Spec. of other speakers - accept as the same as above but would also
appreciate advice for the system setup if these other four speakers
varied in any way

I would greatly appreciate any advice on setting up such a system as
frankly we have no idea.

Cheers,
Mike.

In article writes:

For an up and coming gig my band are hoping to connect six speakers
through one powered mixer. Two of these will act as monitors and the
other four will face the crowd.

The problem is that we have no idea how to set up such a system and
whether it would even be safe.

The first safety issue is whether the speakers will fall on anyone.
Can you get that far?

I know the specifcation of one set of speakers and the powered
mixer...

MIXER - 80watts/channel in to 4 ohms (18V RMS), 50watts/channel into 8
ohms (20V RMS), 4 0r 8 ohm load (4 ohms min. load), two speaker output
channels.

EACH SPEAKER OF A PAIR - nominal impedance: 8 ohms power capacity:
200watts

Does the mixer have two power amplifier channels or three? It might be
configured for left and right plus monitor, or left and right (no
monitor) or mono plus monitor. This makes a difference. You should
know that not specifying the make and model of the mixer means we
can't answer that question for you. Now that you know what information
is needed in order to fully answer your question, dig it up and save
us the trouble.

If you have a mixer with three power amplifiers, it's no problem. Two
8-ohm speakers in parallel on each of the two main channels makes a
4-ohm load, which it will happily accommodate - one pair on each
channel. Then you can connect the two other speakers to the monitor
channel.

If your mixer has only two power amplifiers, you could be at risk.
It's not likely that you'll blow anything up by connecting lower than
a 4 ohm load to the amplifier, but you'll find that it will start to
distort sooner than you want, and if you leave it in that state, you
are quite likely to damage something - the power amplifier or the
speakers.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Michael Henson wrote
For an up and coming gig my band are hoping to connect six speakers
through one powered mixer. Two of these will act as monitors and the
other four will face the crowd.

The monitor speakers will typically require at least a separately
adjustable volume, and possibly a different mix, from the audience
speakers.

I know the specifcation of one set of speakers and the powered
mixer...
MIXER - 80watts/channel in to 4 ohms (18V RMS), 50watts/channel into 8
ohms (20V RMS), 4 0r 8 ohm load (4 ohms min. load), two speaker output
channels.
EACH SPEAKER OF A PAIR - nominal impedance: 8 ohms power capacity:
200watts

If you keep it to 4 speakers in total, it's straightforward. Two 8ohm
speakers in parallel is 4ohms, so you can put two speakers in parallel
on each channel. Each speaker will have the same volume (assuming the
speakers are of the same type).

If you have 4ohm speakers and parallel them the result is 2ohm. Many
amps will be unhappy with that load especially if driven hard.

For 6 speakers it's a bit more complicated. Possibly best doing 4
speakers on one channel, and 2 speakers on the second channel.

The 4 speakers on one channel is wired in series/parallel as:


+ ---------|----------|
| |
+ +
SPKR SPKR
| |
| |
+ +
SPKR SPRK
| |
| |
- ---------|----------|

You need to get the speakers in phase (ie the + and - terminals the
right way round).

If you want to calculate the impedances, speakers in series are added
and for speakers in parallel the reciprocals are added. So for the
series/parallel mix shown, we have two sets of speakers in series,
wired parallel:

Series: 8ohm + 8phm = 16ohm.

Parallel: 1/16 + 1/16 = 2/16 = 1/8 = (undo the reciprocal) 8/1 = 8ohm.

Owain