I don't know about his receiver, but many receivers now switch B the
speakers into series with the A speakers. With no B speakers connected,
switching the A and B speakers on together will cause no sound as the series
circuit is open. Less commonly found is a 8-4 ohm switch on the back. I
believe this switch selects a lower voltage tap for 4 ohm speaker use on the
transformer that supplies the power to the output stage to reduce power for
less heat and stress.
John


"Jerry G." wrote in message
...
If you add a second set of speakers and they are 8 ohms, and connected in
parallel, the impedance will be 4 ohms to the amplifier. This is going to
make the output stage run very hot, if the amplifier is not rated for 4
ohms. We see many amplifiers damaged from users adding on extra speakers
like this.

You can put them in series, but you will loose a lot of efficiency, and
also
loose a lot of the damping factor.

What you really need is an amplifier that is rated to take a 4 ohm speaker
load for its operation. This will do the job for you.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Henrik Johannisson" henrik[.]johannisson[@]telia[.]com wrote in message
...
Hi all!

I'm a owner of a Pioneer VSX-609RDS receiver and on the front speaker
system A
I have a pair of Pioneer S-H510V speakers (8 ohm, 90 dB/W).

Now I want to connect one more pair of speakers. These will then be
connected to
fron speaker system B. My purpose is to have both system A and B activated
at the
same time i.e. I want to hear sound from both A and B at the same time.

If I had understood everything correctly, the speaker pair A and speaker
pair B shall
have the same rating on BOTH impedance and sensivity in order for them to
sound
equally "loud".
But my big question is what ohm ratings the speakers must have in order to
avoid
overload the amplifier. Unfortunately the manual isnt good help : "Please
use
speakers rated between 8 ohm - 16 ohm".

What does that means? If only using system A it is obvious, the speakers
must be rated
between 8 and 16 ohm. But if I add another speaker pair on the system B? I
mean,
shall I see the speaker system A and B in serial or in parallel?!?! I
think
I have seen
in some NAD manual that A and B seems to be in parallel.

Example 1:
Assume both A and B speakers are rated as 8 ohm. If A and B is in serial,
the total
will be 8+8=16 and it is within the range.

Example 2:
Assume both A and B speakers are rated as 8 ohm. If A and B is in
parallel,
the total
will be 1 / (1/8+1/8) = 4 ohm and we are out of range!

So what should my ohm ratings be!?!?

Please help me!

/Henrik