"unitron" wrote in message
m...
"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


If the manual says use speakers that are at least 8 Ohms and doesn't
say anything about not using both the A and the B set at the same time
then you should be alright if all 4 speakers are at least 8 Ohms.
There should be a section of the manual with the specifications for
the receiver--it'll have a section with something about the
sensitivity of the FM tuner part and input impedences or levels (in
Volts or miilivolts or microvolts) and stuff like that--and among all
of this should be a section that says that the output of the power amp
part has so many Watts of power per channel and such and it should
list the output or load impedence of the amp per channel. If that
figure is 4 Ohms or lower then you can hook up two 8 Ohm apeakers per
channel with no worries.
It's almost as sure as the sun rising in the east and setting in the
west that setting the receiver to run both the A and the B set of
speakers puts the A speaker and the B speaker for each channel in
parallel, not series.

Hi!
Really appreciate all answers I got already!
Following your suggestion, I have copied exactly the text as it appears
in the manual, see at bottom.
But I'm still a bit confused, what does 80+80 means!?!
Is this the common way of telling that left channel can handle up to
80 W (at 8 ohm) and right channel can also handle 80 W (at 8 ohm)
or am I totally lost? Is anyone able to translate this into what the
rules are for what ohm rating I should follow? (I get all the other
technical stuff, but this one seems very hard to get, I dont know
why they managed to complicate this piece this much....)

By the way, there is an interesting note which might give a clue
in the chapter "Connecting You Equipment" under the section
called "Speakers".

"The receiver has two speaker systems, A & B. A is the main system
supporting the full complement of surround sound speakers. If you
switch on both A & B speaker systems, only the front speakers and
the sub woofer will be audible. No sound will come from the center
or surround speakers but multi channel sources will be down-mixed
to the active speakers so no sound will be lost. Similarly, if you choose
just the B system you'll only hear the speakers connected to the B system,
and multi channel sources will be down-mixed to these two speakers.
Please use speakers rated between 8 ohm and 16 ohm".

/Henrik



=== Specifications ===

::: Amplifier Section :::

Continuous Power Output (STEREO MODE)
FRONT ..... 80 W + 80 W (DIN 1kHz, THD 0.9 %, 8 ohm)

Continuous Power Output (SURROUND MODE)
FRONT ............ 80 W/ch (1 kHz, THD 0.9 %, 8 ohm)
CENTER .......... 80 W (1 kHz, THD 0.9 %, 8 ohm)
SURROUND .... 80 W/ch (1 kHz, THD 0.9 %, 8 ohm)

Above specifications are applicable when the power supply is 230V.