[vlad]

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

[Kalman Rubinson[_3_]]

On Wed, 26 Nov 2008 12:48:19 -0800 (PST), 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?

Mebbe but, in general, there will be mention of this in the user's
manuals. I would advise you to buy a receiver that is supposed to be
able to handle 4ohm speakers. Many do.

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

They need not be 4 ohms.

Kal

[Richard Crowley]

"Kalman Rubinson" wrote ...
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?

Mebbe but, in general, there will be mention of this in the user's
manuals. I would advise you to buy a receiver that is supposed to be
able to handle 4ohm speakers. Many do.

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

They need not be 4 ohms.

Although impedance *MAY* be part of the "sensitivity" factor
and that may be important if you don't have independent balance
control of each channel.

So you really "need" 7.1? I'm feeling guilty now with my 2.0 :-)
I'll have to think about 2.1 someday.

[Kalman Rubinson[_3_]]

On Wed, 26 Nov 2008 14:47:04 -0800, "Richard Crowley"
wrote:

"Kalman Rubinson" wrote ...
vlad wrote:
2. I need to buy new pair of surrounds. Should they be too 4ohms. Can
I mix 4ohms and 8 ohms?

They need not be 4 ohms.

Although impedance *MAY* be part of the "sensitivity" factor
and that may be important if you don't have independent balance
control of each channel.

All modern AVRs have independent control, at least by pairs. So, if
the new surrounds are more/less sensitive than the others,
compensation is available.

So you really "need" 7.1? I'm feeling guilty now with my 2.0 :-)
I'll have to think about 2.1 someday.

Yeah. There is so little real 7.1 source material, I, too, question
the motivation. And most non-dedicated rooms require even more
compromises in setup for 7.1 than for 5.1 (or, even, 2.0)!

Kal

[Mr.T]

"vlad" wrote in message
...
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?

It's usually safe to assume that if they don't mention 4 ohm speakers, then
the amp is designed for 8 ohm speakers only.
IF you keep well below maximum power output, you can probably get away with
4 ohm, however it is far better to buy an amp rated for the purpose, or buy
8 ohm speakers.

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

If the amp is rated for 4 ohm speakers, it will have no trouble using 8 ohm
speakers on some channels.

MrT.

[Mark D. Zacharias[_3_]]

"vlad" wrote in message
...
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

Any given receiver will run cooler with 8-ohm (or "6-ohm") speakers than
with 4-ohm. This can be important in terms of the longevity and reliability
of the receiver.

Mark Z.

[vlad]

On Nov 26, 5:39*pm, "Mark D. Zacharias" wrote:
"vlad" wrote in message

...



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

Any given receiver will run cooler with 8-ohm (or "6-ohm") speakers than
with 4-ohm. This can be important in terms of the longevity and reliability
of the receiver.

Mark Z.

Thanks to all of you who replied to my questions.

Answering to your comments:

- almost every Blu-Ray disk has either Dolby or DTS 7.1 sound track.
This addresses issue of 7.1 source.

- I already have 5.1 HT setup at home. So upgrading to 7.1 should not
be difficult with new AV receiver and additional pair of speakers.

From now on I will be looking AV receiver that exp[lisitely made
for 4ohm speakers.

Thanks again to everybody.

vova

[Kalman Rubinson[_3_]]

On Wed, 26 Nov 2008 20:43:03 -0800 (PST), vlad
wrote:

Answering to your comments:

- almost every Blu-Ray disk has either Dolby or DTS 7.1 sound track.
This addresses issue of 7.1 source.

Not true. Most have 5.1.

- I already have 5.1 HT setup at home. So upgrading to 7.1 should not
be difficult with new AV receiver and additional pair of speakers.

Assuming your room layout permits.

From now on I will be looking AV receiver that exp[lisitely made
for 4ohm speakers.

None are. All are made for 8ohms but many will accommodate 4ohm
speakers as well.

Kal

[Chris Hornbeck]

On Thu, 27 Nov 2008 09:56:58 -0500, Kalman Rubinson
wrote:

On Wed, 26 Nov 2008 20:43:03 -0800 (PST), vlad
wrote:

From now on I will be looking AV receiver that exp[lisitely made
for 4ohm speakers.

None are. All are made for 8ohms but many will accommodate 4ohm
speakers as well.

And really, this just isn't something to get excited about. Speakers
aren't really "4 Ohms" or "8 Ohms" or whatever, but are a very, very
complicated load, and an amplifier must to designed to deal with the
real world of real loudspeakers with complex impedances and some
motor characteristics. But folks have had many decades to get a
handle on this, and competance doesn't cost much these days.

Don't worry about this (totally BS, anyway) number. Worry about
HDMI compliance, or something else really interesting.

All the best fortune,
Chris Hornbeck

[Arny Krueger]

"Chris Hornbeck" wrote in
message
On Thu, 27 Nov 2008 09:56:58 -0500, Kalman Rubinson
wrote:

On Wed, 26 Nov 2008 20:43:03 -0800 (PST), vlad
wrote:

From now on I will be looking AV receiver that
exp[lisitely made for 4ohm speakers.

None are. All are made for 8ohms but many will
accommodate 4ohm speakers as well.

And really, this just isn't something to get excited
about. Speakers aren't really "4 Ohms" or "8 Ohms" or
whatever, but are a very, very complicated load,

The usual convention is that a speaker's rated impedance is actually its
minimum at any frequency.

Often the frequencies associated with the minimum impedance are in a few or
as little as 1 narrow band.

Music is composed of multiple concurrent tones, often at harmonic intervals.
The thermal load on the amplifier will be more like a weighted average of
the speakers impedance curve. The weighting constants are based on the
music. Therefore, the odds that the entire output of the amplifier will fall
into just these few narrow band(s) is very small.

and an
amplifier must to designed to deal with the real world of
real loudspeakers with complex impedances and some motor
characteristics.

The power supply and heatsinks are designed based on a single frequency that
drives a the minimum rated impedance. They are therefore likely to be
overbuilt for use with real-world music and real-world speakers. In a modern
duel between amplifiers and speakers, the speakers usually lose out first.

But folks have had many decades to get a
handle on this, and competence doesn't cost much these days.

Not only that, but the cost of capacious power transformers, heat sinks and
transistors has fallen quite a bit.

[Mr.T]

"Chris Hornbeck" wrote in message
...
And really, this just isn't something to get excited about. Speakers
aren't really "4 Ohms" or "8 Ohms" or whatever, but are a very, very
complicated load, and an amplifier must to designed to deal with the
real world of real loudspeakers with complex impedances and some
motor characteristics.

True, and some amps handle difficult loads far better than others.

But folks have had many decades to get a
handle on this, and competance doesn't cost much these days.

Which is such a shame that many manufacturers skimp on this issue
particulary, since savings can be made to power supply, and output
transistors.

Don't worry about this (totally BS, anyway) number. Worry about
HDMI compliance, or something else really interesting.

Or perhaps speaker sensitivity and good overload protection.

MrT.

[Mr.T]

"Arny Krueger" wrote in message
...
Not only that, but the cost of capacious power transformers, heat sinks
and
transistors has fallen quite a bit.

And yet many manufacturers will continue to cut costs on those items, to
reduce their selling price, and increase their profit margin.
Whilst I don't buy those bottom feeder electronics, many people do, so it is
silly to think everything has improved when in fact many of the cheaper amps
are now worse than 20 years ago. Unfortunately some people expect 7 channels
with more power than a two channel amp of similar price, and refuse to
believe there might be a trade off somewhere.
Whilst Chinese manufacture has reduced the price, so has the quality IMO.

MrT.

[vlad]

On Nov 27, 6:56*am, Kalman Rubinson wrote:
On Wed, 26 Nov 2008 20:43:03 -0800 (PST), vlad

wrote:
Answering to your comments:

- almost every Blu-Ray disk has either Dolby or DTS 7.1 sound track.
This addresses issue of 7.1 source.

Not true. *Most have 5.1.

- I already have 5.1 HT setup at home. So upgrading to 7.1 should not
be difficult with new AV receiver and additional pair of speakers.

Assuming your room layout permits.

* From now on I will be looking AV receiver that exp[lisitely made
for 4ohm speakers.

None are. *All are made for 8ohms but many will accommodate 4ohm
speakers as well.

Kal

Kal,

what do you mean by phrase "Assuming your room layout permits"?

What is the minimal requirement for putting 7.1 setup in a room?

Thanks in advance.

vlad

[Eeyore]

vlad wrote:

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?

Absolutely NOT.

Never assume anything. It's another word for 'guess'.

Graham

[Eeyore]

"Mark D. Zacharias" wrote:

Any given receiver will run cooler with 8-ohm (or "6-ohm") speakers than
with 4-ohm.

Or maybe even avoid burning out or sounding lousy because it triggers internal
protection.

Graham

[ChrisCoaster]

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
_____________________________
The only intent of consumer-grade 6.1 & 7.1 digital surround is to
MAKE MONEY selling MORE SPEAKERS. Period.
5.1 is more than sufficient for most residential home theatre/surround
setups, unless your theater/viewing room is at least 20' wide by at
least 30' deep!

As for the ohms/resistance thing, manufacturers design their receivers/
amps to produce a given output at a given range of resistance(load).
That may be either 4~8ohms or 8~16ohms. I haven't seen a model that
can drive 4~16ohms - yet - but I'm sure there are a couple out
there.

A good analogy is if you run 8 or 16 ohm speakers with your 8~16ohm
amp, that is akin to driving your car on a normal road, close to or at
the speed limit, with your self and at least one passenger. OTOH, if
you run 4ohm speakers off that amp, it's like revving your car's
engine while the drive wheels are suspended(as on a rack in a
garage). There's no load(asphalt) for the wheels to spin against and
you could easily overheat the engine/drive-train and even cause a tire
to explode from centrifugal force. Yikes!

-CC

[Kalman Rubinson]

On Sat, 29 Nov 2008 18:38:10 -0800 (PST), ChrisCoaster
wrote:

As for the ohms/resistance thing, manufacturers design their receivers/
amps to produce a given output at a given range of resistance(load).
That may be either 4~8ohms or 8~16ohms. I haven't seen a model that
can drive 4~16ohms - yet - but I'm sure there are a couple out
there.

Actually, once you leave the world of multichannel receivers where as
much as possible is packed on to one small chassis and power supply,
it is common to have amplifiers (not AVRs) which are completely stable
and competent with loads from 4 - 16 ohms.

Kal

[ChrisCoaster]

On Nov 30, 10:35*am, Kalman Rubinson wrote:
On Sat, 29 Nov 2008 18:38:10 -0800 (PST),ChrisCoaster

wrote:
As for the ohms/resistance thing, manufacturers design their receivers/
amps to produce a given output at a given range of resistance(load).
That may be either 4~8ohms or 8~16ohms. *I haven't seen a model that
can drive 4~16ohms - yet - but I'm sure there are a couple out
there.

Actually, once you leave the world of multichannel receivers where as
much as possible is packed on to one small chassis and power supply,
it is common to have amplifiers (not AVRs) which are completely stable
and competent with loads from 4 - 16 ohms.

Kal
_________________

You mean, Kal, that there are actually multichannel AMPLIFIERS for
sale now? Thank heavens. With DVI & HDMI inputs in addition to all
the analogs we've been accustomed to?

I guess I haven't been following the dedicated amp side of this
business as well as I've been immersed in all-in-one receivers(AM-FM-
phono preamp + all the AV inputs). How about digital 5-channel hybrid
(graphic OR para- switchable)EQs with presets? Now we're talkin'
stuff I'd actually like in my rack.

-CC

[Kalman Rubinson[_3_]]

On Sun, 30 Nov 2008 07:52:37 -0800 (PST), ChrisCoaster
wrote:

On Nov 30, 10:35*am, Kalman Rubinson wrote:
On Sat, 29 Nov 2008 18:38:10 -0800 (PST),ChrisCoaster

wrote:
As for the ohms/resistance thing, manufacturers design their receivers/
amps to produce a given output at a given range of resistance(load).
That may be either 4~8ohms or 8~16ohms. *I haven't seen a model that
can drive 4~16ohms - yet - but I'm sure there are a couple out
there.

Actually, once you leave the world of multichannel receivers where as
much as possible is packed on to one small chassis and power supply,
it is common to have amplifiers (not AVRs) which are completely stable
and competent with loads from 4 - 16 ohms.

Kal
_________________

You mean, Kal, that there are actually multichannel AMPLIFIERS for
sale now? Thank heavens. With DVI & HDMI inputs in addition to all
the analogs we've been accustomed to?

No. Audio amplifiers amplify. They do not process or resample or
anything video. There are many such multichannel amplifiers. I use a
Bryston 9B-SST in one of my systems http://bryston.com/9bsst_m.html

I guess I haven't been following the dedicated amp side of this
business as well as I've been immersed in all-in-one receivers(AM-FM-
phono preamp + all the AV inputs). How about digital 5-channel hybrid
(graphic OR para- switchable)EQs with presets? Now we're talkin'
stuff I'd actually like in my rack.

Gack. Old stuff. We use DSP for this today. More powerful, more
flexible and easier, considering almost all signals are digital
already. There are many in the pro arena and a few in the consumer
arena.

Kal

[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

[dizzy]

Eeyore wrote:

"Mark D. Zacharias" wrote:

Any given receiver will run cooler with 8-ohm (or "6-ohm") speakers than
with 4-ohm.

Or maybe even avoid burning out or sounding lousy because it triggers internal
protection.

My receiver, and I assume many others, won't "sound lousy" when the
internal protection triggers - they'll shut-down.

The 5.1 movies, what works for me is to set the receiver (a Pioneer
Elite rated for 6 ohms) for "all speakers are small" (even though they
are not) so all the lows go to the sub. I also had to change the
crossover freq to 100 Hz (80 is normal), and then it works well.

For music, I swap speaker cables to use a "real" amplifier that can
handle the low impedance.