From: John Williamson on
wardy wrote:
> Hi,
> Advice needed please from all you experts out there.
> I have a decent background in sound engineering and live mic/desk
> setups, however I am no expert.
> I want to find the best way of installing a particular system in a
> public venue.
> I am installing a Technics amp with normal Stereo output (+- L and +-
> R)
> I have to send the audio thru the amp to 12 separate speakers across a
> sprawling venue.
> I have purchased a mono splitter and a stereo splitter.
> Firstly i tried the mono splitter so that each speaker would be mono.
> I tried to convert this stereo output from the amp to mono by
> combining the cables. firstly i tried to wire both the + outputs from
> the amp into the + of 1 speaker cable and both the - into the - of
> the cable. this however simply forced the amp to "click" off after a
> few seconds of sound so i presume it wasnt happy with the level of
> impedance of whatever.
> So a mono splitter is out.
Protection circuit doing what it's supposed to do. <Grin>

If you want mono, combine the channels at the input. Connecting the
outputs of a stereo amp together is likely to cause damage.

> I am going to try the 6 way skytronic Stereo splitter next.
> I am going to run 2 cables from the amp to the splitter (for L & R)
> Then use the L and R channel from each of the 6 "rooms" on the
> splitter as a separate L or R speaker on either side of the room thus
> giving 12 speakers (6 L and 6 R).
An easy/ cheap way is to just set up the speakers in series and parallel
connection so the impedance matches what the amp wants to see. In this
case, four series chains of three speakers each *should* be OK.

Impedance shown to amp = (Number of speakers in chain * impedance of
each speaker)/ Number of chains. In this case, two chains of three 8 ohm
speakers per channel would show 12 ohms (nominal) to the amp. Three
chains of two per channel would show a fraction over 5 ohms, which may
or may not be safe.

The easiest way would probably be to go for a 70 or 100 volt line
system. This also gives you the opportunity to easily individually
control the volume from each speaker. You can even turn speakers off
locally if desired without causing problems.

You'd need to buy the right amp, then just parallel the speaker
transformers, up to the available power.

Tciao for Now!