Why is Centre Speaker lower wattage than Left or right Speakers?

rec.video

16 Apr 2007 9:49 AM

cinemad

I was helping a friend connect up his 5.1 Digital Home Theatre system
last week, I noticed the Centre Front speaker was rated at 50 Watts
rms whereas the Left Front and Right Front were rated at 115 Watts rms
output.
Using "Gladiator" DVD the Centre Speaker(Mainly Dialogue) was drowned
out by the Left and Right front speakers. I had to increase the centre
speaker by 6db to get an anywhere near acceptable balance.
Why is the Centre Front speaker rated at less than half the left front
and right front speakers.It is a SONY system.

Regards,
Peter Mason

16 Apr 2007 12:02 PM

Stuart

<cine***@hotmail.com> wrote in message
Show quoteHide quote

news:1176716956.599466.163200@p77g2000hsh.googlegroups.com...
>I was helping a friend connect up his 5.1 Digital Home Theatre system
> last week, I noticed the Centre Front speaker was rated at 50 Watts
> rms whereas the Left Front and Right Front were rated at 115 Watts rms
> output.
> Using "Gladiator" DVD the Centre Speaker(Mainly Dialogue) was drowned
> out by the Left and Right front speakers. I had to increase the centre
> speaker by 6db to get an anywhere near acceptable balance.
> Why is the Centre Front speaker rated at less than half the left front
> and right front speakers.It is a SONY system.
>
> Regards,
> Peter Mason
>

Why not reduce the level of the left / right by 3db and increase the centre
by 3db to achieve spatial balance that way you are putting less stress on
the centre channel amp. Most normal systems for 5.1 have equal power for the
important LCR channels and slightly lower for the surrounds. The Centre
channel is probably more important as it is the channel that carries
principal dialog. I really don't understand manufactures who produces this
type of stuff. I suspect this is an economy model in the Sony range.

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16 Apr 2007 2:04 PM

Scott Dorsey

<cine***@hotmail.com> wrote:

>I was helping a friend connect up his 5.1 Digital Home Theatre system
>last week, I noticed the Centre Front speaker was rated at 50 Watts
>rms whereas the Left Front and Right Front were rated at 115 Watts rms
>output.

Speaker power ratings for the most part are made up by people in the
marketing department. But in general, the center speaker is going to
carry dialogue primary and in the case of the Sony it's not even full-range
so it won't be needing as much power.

>Using "Gladiator" DVD the Centre Speaker(Mainly Dialogue) was drowned
>out by the Left and Right front speakers. I had to increase the centre
>speaker by 6db to get an anywhere near acceptable balance.

This has nothing to do with the power ratings. The power ratings on the
speaker have to do with the maximum power you can apply to them before
they are damaged, and as I said they are basically made up by the marketing
people.

What reference point did you use? Did you use the basic B-chain calibration
procedure to make sure the levels were all correct in the first place before
you ran the video? If the center channel is different than the right and
left (as it is in this system) it will almost certainly have different
efficiency and require the gain to be set differently. That is what alignment
is all about and it's why your receiver or decoder has gain controls.

>Why is the Centre Front speaker rated at less than half the left front
>and right front speakers.It is a SONY system.

That's how the roulette wheel in the marketing department fell that day.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

17 Apr 2007 9:49 AM

cinemad

On Apr 17, 12:04 am, klu***@panix.com (Scott Dorsey) wrote:

> <cine***@hotmail.com> wrote:
> >I was helping a friend connect up his 5.1 Digital Home Theatre system
> >last week, I noticed the Centre Front speaker was rated at 50 Watts
> >rms whereas the Left Front and Right Front were rated at 115 Watts rms
> >output.
>
> Speaker power ratings for the most part are made up by people in the
> marketing department. But in general, the center speaker is going to
> carry dialogue primary and in the case of the Sony it's not even full-range
> so it won't be needing as much power.

If it's not full range what would the frquency response be
approximately?

>
> >Using "Gladiator" DVD the Centre Speaker(Mainly Dialogue) was drowned
> >out by the Left and Right front speakers. I had to increase the centre
> >speaker by 6db to get an anywhere near acceptable balance.
>
> This has nothing to do with the power ratings. The power ratings on the
> speaker have to do with the maximum power you can apply to them before
> they are damaged, and as I said they are basically made up by the marketing
> people.
>
> What reference point did you use? Did you use the basic B-chain calibration
> procedure to make sure the levels were all correct in the first place before
> you ran the video?

No I didn't, I set the levels entirely by "ear". According to the
instruction book the levels are set at the default
position for a distance of 3 metres(10 ft) this can be varied by 0
metres to 7 metres(24ft).All the levels were set at 00db.
Could you elaborate further on the B-chain procedure please?

If the center channel is different than the right and
Show quoteHide quote

> left (as it is in this system) it will almost certainly have different
> efficiency and require the gain to be set differently. That is what alignment
> is all about and it's why your receiver or decoder has gain controls.
>
> >Why is the Centre Front speaker rated at less than half the left front
> >and right front speakers.It is a SONY system.
>
> That's how the roulette wheel in the marketing department fell that day.
> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

17 Apr 2007 2:51 PM

Scott Dorsey

<cine***@hotmail.com> wrote:
Show quoteHide quote

>On Apr 17, 12:04 am, klu***@panix.com (Scott Dorsey) wrote:
>> <cine***@hotmail.com> wrote:
>> >I was helping a friend connect up his 5.1 Digital Home Theatre system
>> >last week, I noticed the Centre Front speaker was rated at 50 Watts
>> >rms whereas the Left Front and Right Front were rated at 115 Watts rms
>> >output.
>>
>> Speaker power ratings for the most part are made up by people in the
>> marketing department. But in general, the center speaker is going to
>> carry dialogue primary and in the case of the Sony it's not even full-range
>> so it won't be needing as much power.
>
>If it's not full range what would the frquency response be
>approximately?

I dunno, look at the data sheet with the thing (but take it with a big grain
of salt). Don't expect much response below 100 Hz on the center channel
of one of those things, though. And expect a big honking presence peak
and lots of cheap dome tweeter spittiness too.

>> What reference point did you use? Did you use the basic B-chain calibration
>> procedure to make sure the levels were all correct in the first place before
>> you ran the video?
>
>No I didn't, I set the levels entirely by "ear". According to the
>instruction book the levels are set at the default
>position for a distance of 3 metres(10 ft) this can be varied by 0
>metres to 7 metres(24ft).All the levels were set at 00db.
>Could you elaborate further on the B-chain procedure please?

You run a standard test video with various tones. Then you adjust the
levels as measured at the listening position so they are all correct.

I am note sure what you mean by "the levels were set at 00dB." Do
you mean the level control was set to 0 dB attenuation, or something
else? If you don't say that the reference point is, "decibel" is
meaningless.

In a theatre you will also tend to use an RTA to equalize the room, but
in smaller rooms this is apt to do more damage than good.

Take a look at the manual for any of the Dolby decoders. They should
all be up on http://www.film-tech.com.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

17 Apr 2007 3:46 PM

Scott Norwood

In article <f02mtf$j8***@panix2.panix.com>,
Scott Dorsey <klu***@panix.com> wrote:

>
>In a theatre you will also tend to use an RTA to equalize the room, but
>in smaller rooms this is apt to do more damage than good.

Out of curiousity, why? Is this because smaller rooms tend to have fewer
issues than bigger rooms? What about compensating for different types of
screen perforations and such? Wouldn't there still be some benefit for
room EQ in a small venue?

--
Scott Norwood: snorw***@nyx.net, snorw***@redballoon.net
Cool Home Page: http://www.redballoon.net/
Lame Quote: Penguins? In Snack Canyon?

24 Apr 2007 2:14 PM

Scott Dorsey

Scott Norwood <snorw***@redballoon.net> wrote:

>In article <f02mtf$j8***@panix2.panix.com>,
>Scott Dorsey <klu***@panix.com> wrote:
>>
>>In a theatre you will also tend to use an RTA to equalize the room, but
>>in smaller rooms this is apt to do more damage than good.
>
>Out of curiousity, why? Is this because smaller rooms tend to have fewer
>issues than bigger rooms? What about compensating for different types of
>screen perforations and such? Wouldn't there still be some benefit for
>room EQ in a small venue?

Room problems are different at different places in the room. That is, if
you have a standing wave at 50 Hz in the room, there will be one spot in
the room where there is a huge buildup at 50 Hz, and then another spot
where there is no 50 Hz at all. So you cannot equalize for all places in
the room at once.

With a large room, first of all the standing wave problems all will move
down to lower frequencies, and secondly it's more expensive to fix the
higher frequency problems so people are less likely to do it. EQ can help
hide those higher frequency problems.

That said, the major problem with too many large rooms used for cinema
is that they are too live at all frequencies, usually because they were
designed for live theatre and music and other applications where a longer
room reverb time is appropriate. And EQ can't fix that.

When it all comes down to it, all EQ can really do is fix one class of
response problems with the speaker. But it CAN help hide some kinds of
room problems. Smaller rooms, though, tend to have the kinds of problems
that EQ can't help. And EQ is never any substitute for proper room design
with proper acoustical treatment.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

17 Apr 2007 4:35 PM

Bill Vermillion

In article <f02mtf$j8***@panix2.panix.com>,
Scott Dorsey <klu***@panix.com> wrote:
Show quoteHide quote

> <cine***@hotmail.com> wrote:
>>On Apr 17, 12:04 am, klu***@panix.com (Scott Dorsey) wrote:
>>> <cine***@hotmail.com> wrote:
>>> >I was helping a friend connect up his 5.1 Digital Home Theatre system
>>> >last week, I noticed the Centre Front speaker was rated at 50 Watts
>>> >rms whereas the Left Front and Right Front were rated at 115 Watts rms
>>> >output.
>>>
>>> Speaker power ratings for the most part are made up by people in the
>>> marketing department. But in general, the center speaker is going to
>>> carry dialogue primary and in the case of the Sony it's not even full-range
>>> so it won't be needing as much power.
>>
>>If it's not full range what would the frquency response be
>>approximately?
>
>I dunno, look at the data sheet with the thing (but take it with a big grain
>of salt). Don't expect much response below 100 Hz on the center channel
>of one of those things, though. And expect a big honking presence peak
>and lots of cheap dome tweeter spittiness too.
>
>>> What reference point did you use? Did you use the basic B-chain calibration
>>> procedure to make sure the levels were all correct in the first place before
>>> you ran the video?
>>
>>No I didn't, I set the levels entirely by "ear". According to the
>>instruction book the levels are set at the default
>>position for a distance of 3 metres(10 ft) this can be varied by 0
>>metres to 7 metres(24ft).All the levels were set at 00db.
>>Could you elaborate further on the B-chain procedure please?
>
>You run a standard test video with various tones. Then you adjust the
>levels as measured at the listening position so they are all correct.
>
>I am note sure what you mean by "the levels were set at 00dB." Do
>you mean the level control was set to 0 dB attenuation, or something
>else? If you don't say that the reference point is, "decibel" is
>meaningless.

>In a theatre you will also tend to use an RTA to equalize the room, but
>in smaller rooms this is apt to do more damage than good.

And actually any RTA or room any type analysis and equalization
- done by people who don't know >what< they should be doing and

>why< they should be doing that can royally screw up a system.

A smooth curve is far better than flat as can be. The latter
quite often sound very bad.

>Take a look at the manual for any of the Dolby decoders. They should
>all be up on http://www.film-tech.com.
>--scott
>
>--
>"C'est un Nagra. C'est suisse, et tres, tres precis."

Bill

--
Bill Vermillion - bv @ wjv . com

18 Apr 2007 10:18 AM

cinemad

On Apr 18, 12:51 am, klu***@panix.com (Scott Dorsey) wrote:
Show quoteHide quote

> <cine***@hotmail.com> wrote:
> >On Apr 17, 12:04 am, klu***@panix.com (Scott Dorsey) wrote:
> >> <cine***@hotmail.com> wrote:
> >> >I was helping a friend connect up his 5.1 Digital Home Theatre system
> >> >last week, I noticed the Centre Front speaker was rated at 50 Watts
> >> >rms whereas the Left Front and Right Front were rated at 115 Watts rms
> >> >output.
>
> >> Speaker power ratings for the most part are made up by people in the
> >> marketing department. But in general, the center speaker is going to
> >> carry dialogue primary and in the case of the Sony it's not even full-range
> >> so it won't be needing as much power.
>
> >If it's not full range what would the frquency response be
> >approximately?
>
> I dunno, look at the data sheet with the thing (but take it with a big grain
> of salt). Don't expect much response below 100 Hz on the center channel
> of one of those things, though. And expect a big honking presence peak
> and lots of cheap dome tweeter spittiness too.
>
> >> What reference point did you use? Did you use the basic B-chain calibration
> >> procedure to make sure the levels were all correct in the first place before
> >> you ran the video?
>
> >No I didn't, I set the levels entirely by "ear". According to the
> >instruction book the levels are set at the default
> >position for a distance of 3 metres(10 ft) this can be varied by 0
> >metres to 7 metres(24ft).All the levels were set at 00db.
> >Could you elaborate further on the B-chain procedure please?
>
> You run a standard test video with various tones. Then you adjust the
> levels as measured at the listening position so they are all correct.
>
> I am note sure what you mean by "the levels were set at 00dB." Do
> you mean the level control was set to 0 dB attenuation, or something
> else? If you don't say that the reference point is, "decibel" is
> meaningless.

When you go into the MENU the SONY has each speaker position set at 0
db
and you can adjust it up or down 6db. There is no mention in the
Instruction book of
what the default level is.

Regards,
Peter Mason

Show quoteHide quote

>
> In a theatre you will also tend to use an RTA to equalize the room, but
> in smaller rooms this is apt to do more damage than good.
>
> Take a look at the manual for any of the Dolby decoders. They should
> all be up onhttp://www.film-tech.com.
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

18 Apr 2007 12:48 PM

Scott Dorsey

<cine***@hotmail.com> wrote:

>
>When you go into the MENU the SONY has each speaker position set at 0
>db
>and you can adjust it up or down 6db. There is no mention in the
>Instruction book of
>what the default level is.

Okay, that's basically a meaningless number, then, until you actually
calibrate it with a reference. That's saying you are increasing the
level by so many dB over an arbitrary unknown reference. This is enough
to set the balances but you will still need to set the standard listening
level with the main volume control and these numbers are with respect
to that.

When you do the B-chain alignment you set the levels of _everything_ so
that when the volume control is set to a nominal standard level, the
actual measured sound pressure in the hall is correct for the tones on
the test medium. So you know that -20dBFS on the disc gives you 85 dBSPL
in the room for the center channel, etc.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."