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Tell me about the subwoofer in a 5.1 setup!

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Anonymous
September 9, 2004 12:45:31 AM

Archived from groups: rec.audio.tech (More info?)

I have some very basic questions for you:

1. When listening to 2 channel music in a 5.1 system, are the 2 (or 5)
channels high pass filtered?
2. Is it any differnt when viewing films in surround?
3. Is the sub woofer output line or speaker level?

I'm about to buy one of those cheap HT receivers and wants to know, in
order not embarrass myself too much in front of the typical 18 yo
salesboy... :-)

(I have tried to look this up, but it's like drinking from a fire
hose!)

Per.

More about : subwoofer setup

Anonymous
September 9, 2004 12:45:32 AM

Archived from groups: rec.audio.tech (More info?)

In article <hbkuj0hfu65iattbqapbk9lvlc7ep1ruu6@4ax.com>, Per Stromgren
<per.stromgren@telia.com> wrote:

> 1. When listening to 2 channel music in a 5.1 system, are the 2 (or 5)
> channels high pass filtered?

Depends on the receiver, amp, pre-amp, or decoder. In general, the
the 5 speakers are full range, and the dot-1 is a sub-woofer. The
dot-1 is not a bass speaker, rather, it is an effects channel.
Some hardware will ask if you have a subwoofer. If you do, they
will route the bass to the effects channel so the main speakers
do not have to reproduce the bass. If you don't have a subwoofer
on the effects channel, some hardware can route the effects to
the main speakers.

The ideal setup is to have full range speakers that can reproduce
deep bass for the main speakers, and still have a hefty subwoofer
for the effects. If you have small speakes for your main right
and left, it would work to have a 2nd subwoofer for these speakers,
and a seperate effects subwoofer.

> 2. Is it any differnt when viewing films in surround?

I find listening to music on my home theatre system to be
annoying. I like my standard stereo system much better for
music. Some people use their 5.1 system for music and like
it very much. It all depends on your systems, your ears,
and how you have it set up.

> 3. Is the sub woofer output line or speaker level?

It can be either or. A receiver will typically have a line
level output for the sub. Some receivers will have a full
range power amp that is switchable between a sub and a 6th
full range channel. It all depends on your hardware. I
prefer the subwoofer amp to be in the subwoofer since they
can be better matched to each other.

-john-

--
====================================================================
John A. Weeks III 952-432-2708 john@johnweeks.com
Newave Communications http://www.johnweeks.com
====================================================================
Anonymous
September 9, 2004 12:45:32 AM

Archived from groups: rec.audio.tech (More info?)

On Wed, 08 Sep 2004 20:45:31 +0200, Per Stromgren
<per.stromgren@telia.com> wrote:

>I have some very basic questions for you:
>
>1. When listening to 2 channel music in a 5.1 system, are the 2 (or 5)
>channels high pass filtered?

That is usually an option in the receiver (or DVD player) and your
choice would depend on the particular speakers. Ideally, you would
want full range speakers all the way around so that HP filtering is
not required.

>2. Is it any differnt when viewing films in surround?

It can be but it does not have to be.

>3. Is the sub woofer output line or speaker level?

Generally, it is at line level since powered subs are assumed today.

Kal
Related resources
Anonymous
September 9, 2004 12:45:32 AM

Archived from groups: rec.audio.tech (More info?)

"Per Stromgren" <per.stromgren@telia.com> wrote in message
news:hbkuj0hfu65iattbqapbk9lvlc7ep1ruu6@4ax.com

> I have some very basic questions for you:

> 1. When listening to 2 channel music in a 5.1 system, are the 2 (or 5)
> channels high pass filtered?

Generally, but not always. It is possible to have and use 5 full-range
speakers.

> 2. Is it any different when viewing films in surround?

Generally not.

> 3. Is the sub woofer output line or speaker level?

A receiver's subwoofer output is almost always line level. After all, why up
the price of the receiver further by putting in a subwoofer amp that might
not even be used.
Anonymous
September 9, 2004 1:26:58 AM

Archived from groups: rec.audio.tech (More info?)

On Wed, 08 Sep 2004 14:15:24 -0500, "John A. Weeks III"
<john@johnweeks.com> wrote:

>In article <hbkuj0hfu65iattbqapbk9lvlc7ep1ruu6@4ax.com>, Per Stromgren
><per.stromgren@telia.com> wrote:
>
>> 1. When listening to 2 channel music in a 5.1 system, are the 2 (or 5)
>> channels high pass filtered?
>
>Depends on the receiver, amp, pre-amp, or decoder. In general, the
>the 5 speakers are full range, and the dot-1 is a sub-woofer. The
>dot-1 is not a bass speaker, rather, it is an effects channel.

But not when playing stereo, surely?

>
>The ideal setup is to have full range speakers that can reproduce
>deep bass for the main speakers, and still have a hefty subwoofer
>for the effects. If you have small speakes for your main right
>and left, it would work to have a 2nd subwoofer for these speakers,
>and a seperate effects subwoofer.

Hm... This system is mainly for watching TV, and the current set-up is
a plain old 2 channel reciever plus book shelf speakers and a powered
sub-woofer. We have very humble requirements for SPL and fidelity,
would you think we could use the sub on the dot-1 output and shelf
speakers as fronts?

>
>> 2. Is it any differnt when viewing films in surround?
>
>I find listening to music on my home theatre system to be
>annoying.

Well, I won't, most often. I have better stuff for that. But with a
5.1 system in the house, I guess it will be tempting to listeing
Donald Fagen in a new format!


>> 3. Is the sub woofer output line or speaker level?
>
>It can be either or. A receiver will typically have a line
>level output for the sub. Some receivers will have a full
>range power amp that is switchable between a sub and a 6th
>full range channel. It all depends on your hardware.

Thanks for information, it was most helpful! Any hints on further
reading?

Per.
Anonymous
September 9, 2004 1:26:59 AM

Archived from groups: rec.audio.tech (More info?)

"Per Stromgren" <per.stromgren@telia.com> wrote in message
news:jpmuj0tcunn6ftik1lgpmmik8egvvrpbdu@4ax.com
> On Wed, 08 Sep 2004 14:15:24 -0500, "John A. Weeks III"
> <john@johnweeks.com> wrote:
>
>> In article <hbkuj0hfu65iattbqapbk9lvlc7ep1ruu6@4ax.com>, Per
>> Stromgren <per.stromgren@telia.com> wrote:
>>
>>> 1. When listening to 2 channel music in a 5.1 system, are the 2 (or
>>> 5) channels high pass filtered?
>>
>> Depends on the receiver, amp, pre-amp, or decoder. In general, the
>> the 5 speakers are full range, and the dot-1 is a sub-woofer.

The more likely general case that the 5 speakers have limited bass response
and are best described as satellite speakers for use with a subwoofer. Since
the front-center speaker is roughly coincident with the viewing screen, it
is particularly difficult to make full-range.

> The > dot-1 is not a bass speaker, rather, it is an effects channel.

Typically, it is called upon for both duties - bass, and bass effects.

> But not when playing stereo, surely?

If the subwoofer is also active, why not?
Anonymous
September 9, 2004 12:32:46 PM

Archived from groups: rec.audio.tech (More info?)

On Wed, 8 Sep 2004 16:42:07 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>
>> The > dot-1 is not a bass speaker, rather, it is an effects channel.
>
>Typically, it is called upon for both duties - bass, and bass effects.
>
>> But not when playing stereo, surely?
>
>If the subwoofer is also active, why not?

I was referring to the "effects" function, which is not a part of
stereo. I would of course like it to be used in its
woof-support-of-the-side-speakers function.

Perhaphs I don't make myself very clear. Today I run my stereo
speakers throgh a passive filter (100 Hz) in the subwoofer and want
them to have a HP filter even with a 5.1 gizmo. What you are saying,
Arny, is that this probably will be the case with the typical low end
HT receiver.

Per.
Anonymous
September 9, 2004 12:32:47 PM

Archived from groups: rec.audio.tech (More info?)

"Per Stromgren" <per.stromgren@telia.com> wrote in message
news:sttvj0dqnfccgsl782po6t7l6prtrtl76f@4ax.com
> On Wed, 8 Sep 2004 16:42:07 -0400, "Arny Krueger" <arnyk@hotpop.com>
> wrote:
>
>>
>>> The > dot-1 is not a bass speaker, rather, it is an effects channel.
>>
>> Typically, it is called upon for both duties - bass, and bass
>> effects.
>>
>>> But not when playing stereo, surely?
>>
>> If the subwoofer is also active, why not?

> I was referring to the "effects" function, which is not a part of stereo.

The effects part of LFE refers to content recorded in the 0.1 channel of a
surround-sound recording. The contents of the 0.1 channel of the recording
is up to the producer. It can be nothing, it can be gratuitous, or it can be
musically-related.

When you play a stereo recording there is by definition no explicit content
in the 0.1 channel. However, this does not mean that the LFE speaker goes
dead. Instead, reproduce-side bass management features of the system use the
LFE speaker as a true subwoofer. IOW the subwoofer reproduces sounds that
might be reproduced by the L & R speaker, were they capable of handling deep
bass.

>I would of course like it to be used in its
> woof-support-of-the-side-speakers function.

That is what happens in a well-designed surround system. There are many
paths to true knowledge, and so there are many ways to accomplish effective
bass management.

> Perhaps I don't make myself very clear. Today I run my stereo
> speakers through a passive filter (100 Hz) in the subwoofer and want
> them to have a HP filter even with a 5.1 gizmo.

You have many options. One is to carry your existing scheme forward. Just
add 3 other speakers - center and surround. Set the bass management in your
surround processor (receiver, etc) in a straight-forward way, which includes
setting the surround processor so that the composite of your front main L &
R speakers are "large" speakers. This means that they can handle serious
bass Your existing passive crossover will continue to work as it does right
now.

> What you are saying, Arny, is that this probably will be the case with
> the typical low end
> HT receiver.

That, and the mid and high end ones as well.

BTW, are you unclear about how bass management is set up and works?
Anonymous
September 9, 2004 11:58:32 PM

Archived from groups: rec.audio.tech (More info?)

On Thu, 9 Sep 2004 07:13:43 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>> Perhaps I don't make myself very clear. Today I run my stereo
>> speakers through a passive filter (100 Hz) in the subwoofer and want
>> them to have a HP filter even with a 5.1 gizmo.
>
>You have many options. One is to carry your existing scheme forward. Just
>add 3 other speakers - center and surround. Set the bass management in your
>surround processor (receiver, etc) in a straight-forward way, which includes
>setting the surround processor so that the composite of your front main L &
>R speakers are "large" speakers. This means that they can handle serious
>bass Your existing passive crossover will continue to work as it does right
>now.

Aha, that easy!

>
>BTW, are you unclear about how bass management is set up and works?

Yes (*), but that can wait until I actually buy one of those HT
receivers. I guess even cheap ones comes with a manual. :-)

Now I know enough to have the guts to step into a shop and buy one!

Thanks!

Per.

*) But, if I am curious, what would be good words to google for? As I
said, many of these HT terms will get you flooded, and most is ad copy
for products.
Anonymous
September 10, 2004 6:58:25 AM

Archived from groups: rec.audio.tech (More info?)

Per Stromgren wrote:
>
> >
> >BTW, are you unclear about how bass management is set up and works?
>
> Yes (*), but that can wait until I actually buy one of those HT
> receivers. I guess even cheap ones comes with a manual. :-)
>
> Now I know enough to have the guts to step into a shop and buy one!
>
> Thanks!
>
> Per.
>
> *) But, if I am curious, what would be good words to google for? As I
> said, many of these HT terms will get you flooded, and most is ad copy
> for products.


As I recall, Yamaha used to put soft copies of their HT receivers
online on their home site:

http://www.yamaha.com/yec/index1.htm

Download one and read up on how the bass management works for
their receivers. It might help answer some of your questions.

- Jeff
Anonymous
September 11, 2004 1:34:20 PM

Archived from groups: rec.audio.tech (More info?)

On Fri, 10 Sep 2004 02:58:25 GMT, Jeff Wiseman
<wisemanja@earthlink.net> wrote:

>
>
>As I recall, Yamaha used to put soft copies of their HT receivers
>online on their home site:
>
>http://www.yamaha.com/yec/index1.htm

Yes! That was a good one. But, my goodness, they seem awfully complex
beasts, these HT receivers, even to a EE engineer like myself. Did
they put all these features in there because they can, rather than
customers asking for them? Couldn't be, could it? :-)

>
>Download one and read up on how the bass management works for
>their receivers. It might help answer some of your questions.

It did. Thank you!

Per.
Anonymous
September 11, 2004 1:42:04 PM

Archived from groups: rec.audio.tech (More info?)

On Fri, 10 Sep 2004 16:09:11 +0000 (UTC), Steven Sullivan
<ssully@panix.com> wrote:

>
>You can even download a manual for many receivers as .pdf files
>before you buy it,
>from manufacterer;s websites -- usually in the 'support' or
>'dowbnlaods' area.

Yes, Jeff gave me that advice too. Yamaha have rather good manuals, I
must say.

"Home theater faq" was the key search, silly of me not think about
that one myself.

Thanks for all the good advive. The salesboys can't fool me now!

Per.
Anonymous
September 12, 2004 12:22:35 AM

Archived from groups: rec.audio.tech (More info?)

Per Stromgren wrote:
>
> Yes! That was a good one. But, my goodness, they seem awfully complex
> beasts, these HT receivers, even to a EE engineer like myself. Did
> they put all these features in there because they can, rather than
> customers asking for them? Couldn't be, could it? :-)


Actually, the complexity is mainly in the function rather than
(as it used to be) in the hardware. To answer your question, it's
likely some of both but a lot of it is just plain necessary. Once
sound exists in the digital domain, there are all SORTS of things
that you can do to it using mathematically based filters and
algorithms. Tone control, bandpass, hi or lo pass filtering is
all a matter of applying the appropriate algorithms in the
processing chips.

On the other hand, just think of the various ways that 5 and 1/2
channels of sound might be configured in someone's home. You need
to be flexible for handling all situations. E.g., starting with
just a stereo and 2 large main speakers? Well let's route the
center channel voices evenly between them. Bring the rear effects
to the front, massage them a bit and blend them with the front.
And don't forget the low frequency effects channel. That will
also need to be sent to the two mains. This can all be configured
by just telling the system that you only have 2 speakers-it'll
figure out the rest.

However, once you add a subwoofer of some sort, your
configuration choices increase and depend on several things. The
typical configuration is that you simply tell (i.e., configure)
the system that you have a sub on the LFE output and that the LFE
channel is to be sent there (the ".1" channel in the "5.1" system
is not a full channel--it only carries frequencies of around
0-250Hz or thereabouts). Now the sub will carry only LF effects
and when the boomy/rumbling effects from that channel aren't
there, the sub is silent. The low bass sounds in the other 5
channels are sent to each of their respective speakers so a bass
drum in the musical score of a DVD movie will still show up on
the main speakers EVEN IF IT WOULD SOUND BETTER IF SENT TO THE SUBWOOFER.

Note that the LFE channel's output must also have it's own level
control so that it can be set up to not over or under power the
sound compared with the rest of the speakers. Note also that this
is not the "subwoofer" volume but rather the LFE channel volume.
There is no practical difference in the above example but there
is in the following.

What if the front speakers on the system are tiny and have really
lousy bass? Well, since you now have a subwoofer on the system,
you can tell the system that your front speakers are inadaquate
for the great bass in the musical soundtracks of the DVDs you are
trying to listen to (i.e., tell the AV receiver that the main
speakers are "small") and the receiver will route the bass away
from the main speakers and into the subwoofer, blending it with
the LFE channel's output. This not only has the advantage of
extending your sound on the front main channels (such as for
musical scores) but if the receiver also engages hi pass
filtering in this configuration, it can offload the small
speakers from large bass currents which can actually help the
small speakers sound a bit better and not overload as easily on
high level sound passages (i.e., the basic satellite/sub arrangement)

Since unlike the original Dolby Surround where the side or rear
speakers only carried effects type sounds and were limited in
bandwidth (sorta like the LFE ".1" channel in 5.1), Dolby 5.1 has
5 FULL RANGE channels. This means that the center and two rear
channels can have the same problem as mentioned in the above
example for the mains if they are small or bass-shy as well.
Again, by stipulating that there is a sub attached to the system
AND the center and/or rear speakers are SMALL, the receiver will
route their bass signal to the subwoofer instead (or if you have
no subwoofer but your main speakers are "Large", it can send them
to the mains instead).

This is the same effect as running the mains, center, or rears
through a physical low pass filter and sending the result to the
sub. It may also be that the 5 non sub speaker channels are run
through a high pass filter to remove the bass from the channel
before hitting the speakers. The filtering is all done in the
digital domain though and doesn't need physical outboard filters.

In this second example the bass being routed to the subwoofer
from the mains (or center or rears) is a different thing from the
LFE channel and so some way of controlling its level to the sub
independant from the LFE level is needed and is usually provided
for in some way.

What if your main speakers are already fairly good for bass but
you have a killer sub that can go down to 15Hz? It you took all
the bass from the mains and sent it to the sub to get the "way
down deep" music from the main channels, there might be a problem
with the crossover region in that the better sounding speakers
have sound now sent to the sub. What you need is the ability to
change the crossover region for the "low pass" filtering going to
the sub so that only the very low frequencies are sent there.
Many receivers (such as the Yamahas) have a setting for speaker
size such as "medium" to handle this. Others have an actual
frequency setting for where you want the low pass filtering to
roll over at.

Anyway, as you can see, all ov these configuration issues are
simply a "forced" result of the fact that there are many ways to
set up speakers to listen to 5.1 sound depending on the number of
speakers, their size/freq. range, placement, etc. so nearly all
of the functions described above need to be supported some way or
another in the configurations of any AV receiver.

Hope this helps answer some in your questions.

- Jeff
!