[Cyberserf]

On Nov 26, 3:48*pm, vlad wrote:
I have a surround 5.1 setup consisting of 4ohm speakers. Now I need to
upgrade to 7.1. So I am on the market for new 7.1 AV receiver with
full alphabet soup of sound protocols.
I pretty much narrowed on Denon, Marantz and Integra brands.

In relations with this I have two questions:

1. Looking in specs of new receivers I noticed that they quote their
power ratings for 8ohms without mentioning 4ohms without mention if I
can plug in 4ohms speakers. So is it safe to assume that modern AV
solid state receiver can handle 4ohm?

2. I need to buy new pair of surrounds. Should they be too 4ohms. Can
I mix 4ohms and 8 ohms?

I would appreciate any technical advise on this matter. You can send
responses directly to my e-mail address.

Thx

vova

IIRC, Impedance should be equal or greater if you're going to drive
the system. Presumably an 8 ohm 7.1 system will be wanting at least
that much per channel...you can always add a 4 ohm resistor to each 4
ohm speaker to match the requisite resistance...or double the number
of speakers (chain them) on each channel...assuming you buy two new 8
ohms, you'll need 5 more 4 ohm speakers and one more 4 ohm sub to
double up...uhm...I think that'll make you a 12.2 system...ready for
the future ;-)

-CS

[[email protected]]

On Dec 1, 8:07 am, Cyberserf wrote:
IIRC, Impedance should be equal or greater if you're going to drive
the system. Presumably an 8 ohm 7.1 system will be wanting at least
that much per channel...you can always add a 4 ohm resistor to each 4
ohm speaker to match the requisite resistance

While that MIGHT make the amplifier happy,
it's pretty much a bad idea for several reasons,
among them:

1. Assuming nominal 4-ohm impedance, you're
essentially doubling the amount of power dissipated
as pure heat: it's a waste of power.

2. Along with the above, you're looking at a substantial
reduction in system sensitivity and efficiency,

3. Your already non-flat response is now going to get
worse because the fact that you've now connected
a frequency-dependent attenuator due to the
frequency-dependent impedance variations of the speaker.

4. And how big a resistor do you think you might
need? Assume a measely 50 watts per channel,
25 watt resistors would be the absolute minimum
recommended. These are easily available, where?

...or double the number of speakers
(chain them) on each channel...

It's called "series connection" and, if the speakers
are identical, is a FAR better solution than your resistor
proposal.

assuming you buy two new 8 ohms, you'll need 5 more
4 ohm speakers and one more 4 ohm sub to
double up...uhm...I think that'll make you a 12.2 system

Uhm, no it won't.

[Cyberserf]

On Dec 1, 11:22*am, wrote:
On Dec 1, 8:07 am, Cyberserf wrote:

IIRC, Impedance should be equal or greater if you're going to drive
the system. Presumably an 8 ohm 7.1 system will be wanting at least
that much per channel...you can always add a 4 ohm resistor to each 4
ohm speaker to match the requisite resistance

While that MIGHT make the amplifier happy,
it's pretty much a bad idea for several reasons,
among them:

1. Assuming nominal 4-ohm impedance, you're
* *essentially doubling the amount of power dissipated
* *as pure heat: it's a waste of power.

2. Along with the above, you're looking at a substantial
* *reduction in system sensitivity and efficiency,

3. Your already non-flat response is now going to get
* * worse because the fact that you've now connected
* * a frequency-dependent attenuator due to the
* * frequency-dependent impedance variations of the speaker.

4. And how big a resistor do you think you might
* * need? Assume a measely 50 watts per channel,
* * 25 watt resistors would be the absolute minimum
* * recommended. These are easily available, where?

...or double the number of speakers
(chain them) on each channel...

It's called "series connection" and, if the speakers
are identical, is a FAR better solution than your resistor
proposal.

assuming you buy two new 8 ohms, you'll need 5 more
4 ohm speakers and one more 4 ohm sub to
double up...uhm...I think that'll make you a 12.2 system

Uhm, no it won't.

LOL...you're a funny guy. Stay Well.

-CS