I have a harmon/kardon satellite speaker system and have some questions
regarding the subwoofer (powered, downfiring, only hookup option is from
single RCA jack).

First off, these are small satellites, so what should I make the crossover
setting on the receiver? (100, 150, and 200 are the options) (the subwoofer
itself has no such option, but I think it reads "60" somewhere on the back).

Also, the woofer has a volume(?) control knob on the back. But I can also
control the subwoofer through the receiver. Is one set of controls better
than the other? Could I just set the woofer's knob to half and adjust the
bass via my receiver remote?

And finally, the woofer has a hollow tube on the back panel. I have the
subwoofer practically against the wall (not the best place, I know, but I'm
cramped for space). Should I just turn the subwoofer around and allow that
tube to face the front rather than against the wall?

Thanks, and sorry for the long post.

"OodlesoFun" wrote in message
.. .
I have a harmon/kardon satellite speaker system and have some questions
regarding the subwoofer (powered, downfiring, only hookup option is from
single RCA jack).

First off, these are small satellites, so what should I make the crossover
setting on the receiver? (100, 150, and 200 are the options) (the
subwoofer
itself has no such option, but I think it reads "60" somewhere on the
back).

Also, the woofer has a volume(?) control knob on the back. But I can also
control the subwoofer through the receiver. Is one set of controls better
than the other? Could I just set the woofer's knob to half and adjust the
bass via my receiver remote?

And finally, the woofer has a hollow tube on the back panel. I have the
subwoofer practically against the wall (not the best place, I know, but
I'm
cramped for space). Should I just turn the subwoofer around and allow
that
tube to face the front rather than against the wall?

Thanks, and sorry for the long post.


The subwoofer crossover issue depends on the speakers. I would have to hear
them to make a solid recommendation, but THX standard is 100hz. Depending
on your receiver model it may have a subwoofer or LFE test tone. Use it to
send a signal to the subwoofer. Adjust the gain with the knob on the back
of the sub up until you begin to hear distortion. Once you do back it down
a bit. From there adjust the level at the amp to your liking. Try to keep
the opening of the sub at least 150% of the diameter of the opening away
from the wall. You will probably get a lot of different opinions on theses
topics. Good luck and have fun!

"OodlesoFun" wrote in message

I have a harmon/kardon satellite speaker system and have some
questions regarding the subwoofer (powered, downfiring, only hookup
option is from single RCA jack).

First off, these are small satellites, so what should I make the
crossover setting on the receiver? (100, 150, and 200 are the
options) (the subwoofer itself has no such option, but I think it
reads "60" somewhere on the back).

The general rule is set the crossover as low as you can without overloading
the satellites with bass. That will depend on your room and the loudness you
prefer to listen at, among other things.

Also, the woofer has a volume(?) control knob on the back. But I can
also control the subwoofer through the receiver. Is one set of
controls better than the other? Could I just set the woofer's knob
to half and adjust the bass via my receiver remote?

Yes, or maybe you could set the volume control on the woofer a little lower
which might reduce any possible noise pickup.

And finally, the woofer has a hollow tube on the back panel. I have
the subwoofer practically against the wall (not the best place, I
know, but I'm cramped for space). Should I just turn the subwoofer
around and allow that tube to face the front rather than against the
wall?

The tube is called a "port" and should not be blocked. If the port is
pointed at the wall, that side of the woofer should be several port
diameters from the wall. If you can't do that, point the port in some other
direction, but preferably not at the listener.

On Wed, 7 Jan 2004 06:56:53 -0600, "Chris"
wrote:

The subwoofer crossover issue depends on the speakers. I would have to hear
them to make a solid recommendation, but THX standard is 100hz.

Actually, it's 80 Hz.

Depending
on your receiver model it may have a subwoofer or LFE test tone. Use it to
send a signal to the subwoofer. Adjust the gain with the knob on the back
of the sub up until you begin to hear distortion. Once you do back it down
a bit. From there adjust the level at the amp to your liking. Try to keep
the opening of the sub at least 150% of the diameter of the opening away
from the wall. You will probably get a lot of different opinions on theses
topics. Good luck and have fun!

Yep, that all sounds fine.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

"OodlesoFun" wrote in message
.. .
I have a harmon/kardon satellite speaker system and have some
questions
regarding the subwoofer (powered, downfiring, only hookup
option is from
single RCA jack).

First off, these are small satellites, so what should I make
the crossover
setting on the receiver? (100, 150, and 200 are the options)
(the subwoofer
itself has no such option, but I think it reads "60" somewhere
on the back).

First read my other post and the two linked articles.

If they are really small satellites you may have integration
issues. What you want is a smooth frequency response from where
the sub drops out to where the mains pick up. With small
satellites at high volumes their low frequency ability is
reduced. You can end up with a dip in the response because the
satellites loose output near the crossover frequency.

One way to combat this with small speakers is to set crossover at
a relatively high frequency. However, you'll have to have a
really good sub that doesn't throw harmonic distortion into
higher audible frequency region...otherwise you'll easily be able
to pinpoint the sub location.

If your really serious about getting a good match I recommend
upgrading to more full range speakers and/or adding midbass
drivers to pick up the slack.

Also, the woofer has a volume(?) control knob on the back. But
I can also
control the subwoofer through the receiver. Is one set of
controls better
than the other? Could I just set the woofer's knob to half and
adjust the
bass via my receiver remote?

I recommend setting the receiver to 0dB and adjusting the sub amp
until the level is as close as you can get. Then use the
receiver to fine tune if necessary.

And finally, the woofer has a hollow tube on the back panel. I
have the
subwoofer practically against the wall (not the best place, I
know, but I'm
cramped for space). Should I just turn the subwoofer around
and allow that
tube to face the front rather than against the wall?

Keep obstructions away from port. A distance equal to several
port diameters is usually sufficient. Make sure at high volume
you can't hear port noise from the listening position.

"Arny Krueger" wrote in message
...
The general rule is set the crossover as low as you can without
overloading
the satellites with bass. That will depend on your room and the
loudness you
prefer to listen at, among other things.

For audio (stereo) this is good advice. For movie soundtracks
with speakers set to 'small' you will loose LFE content above the
crossover frequency. See my other post and links.

"Rusty Boudreaux" wrote in message


"Arny Krueger" wrote in message
...

The general rule is set the crossover as low as you can without
overloading the satellites with bass. That will depend on your room
and the loudness you prefer to listen at, among other things.

For audio (stereo) this is good advice.

Thanks.

For movie soundtracks
with speakers set to 'small' you will loose LFE content above the
crossover frequency.

That's an interesting claim. I'd like to see it supported.

I've seen two general ways that the LFE channel is handled"

(1) The LFE channel is sent to the subwoofer without actually being changed
by any bass management. If any other speakers are set for "small", their
bass content below the crossover frequency may be added to the LFE info in
the subwoofer feed. This is pretty crude especially the ones where there is
really no bass management. Approaches like these show up in some low-end
implementations, including mid-end consumer PC sound cards. Basically, if
you have no subwoofer, you hear no LFE information. If your LF & RF speakers
lack bass, the LFE speaker may or may not be able to help you.

(2) The LFE channel is distributed among all speakers depending on their
properties and the crossover point settings. In no case is the LFE channel
above the crossover setting sent anyplace but the subwoofer except of course
if there is no subwoofer. If there is no subwoofer, the proper assignment
for LFE channel signal above the crosover point would appear to be the
center channel, subject to the settings for that speaker. However, below
the crossover setting, the LFE channel's content is pooled and divided
between the subwoofer (if present) and all other speakers that were
identified as being "large*. This is a pretty high-quality implementation,
and typical of mid fi consumer audio, and up.

Let me elaborate. My main system which is used for both HT and music, has no
subwoofer at all from the standpoint of surround processor bass management.
My surround processor's subwoofer output receives no signal. A subwoofer is
present, but it is part of the LF & RF subsystem. The RF & LF speakers are
defined to the surround processor as being "large". An outboard 24 dB/octave
crossover splits the subwoofer signal from the feed to the LF & RF speakers.

By all accounts and tests, the LFE channel is well-represented in the sound
field in the listening room even though this system effectively has no LFE
speaker. I note that my surround processor has no level controls for the
subwoofer, but it does have a level control for the LFE channel. The LFE
channel is obviously virtualized.

I arrived at this setup experimentally, because my surround processor has
only a single crossover frequency, and it is inappropriate for the speakers
and the room.

I think this indirectly contradicts the claim that: "For movie soundtracks
with speakers set to 'small' you will loose LFE content above the crossover
frequency." My system has no LFE speaker whatsoever, and yet the LFE channel
is well-represented in the room. Not only is the LFE represesented, but it
is also clearly and logically imaged.

See my other post and links.

OK, let's do it.

"Rusty Boudreaux" wrote in message


"If they are really small satellites you may have integration
issues. What you want is a smooth frequency response from where
the sub drops out to where the mains pick up. With small
satellites at high volumes their low frequency ability is
reduced. You can end up with a dip in the response because the
satellites loose output near the crossover frequency."

This is one of those "depends on" statements without some unstated
dependencies. These days we have subwoofers with 10, 8 and even 6 inch
drivers. These speakers can easily have relatively smooth response up to say
300 Hz, which is the highest "subwoofer" crossover frequency I can conceive
of in a system with pretensions to sound quality. My point is that with a
driver like this pointed at the listener and a decently-designed crossover,
a dip due to the acoustic properties of the sub and satellite is unlikely
for any reasonable crossover setting.

More likely, the bass and perhaps even the mid-bass imaging will be upset.
We can argue all day as to whether the ear hears directionality at 60 Hz,
but by 150 Hz there's very little doubt. For example, the intention of the
recordist might be that the bass come from either the LF or RF, but if the
crossover is at 150 Hz and the subwoofer and LF & RF speakers aren't
positioned very close to each other or if they are close but you are sitting
close to them, you're going to hear a lot of that bass coming from the
center. I call that bass imaging failure.

"One way to combat this with small speakers is to set crossover at
a relatively high frequency. However, you'll have to have a
really good sub that doesn't throw harmonic distortion into
higher audible frequency region...otherwise you'll easily be able
to pinpoint the sub location."

It's true that a sub that is distorting will generate output above the
crossover frequency and therefore be easier to locate. However, you don't
need to presume substandard equipment to explain why a high crossover
frequency will simply allow the listener to localize sounds to the subwoofer
because the crossover point is too high for the application. The ear
localizes the sound source better and better as the signal frequency goes up
from 60 to 80 Hz. One way to partially circumvent this is to put the
subwoofer very close to the satellites and to put the satellites closer to
each other. However, this approach to reducing bass imaging failure causes
some bass imaging to be lost.

"If your really serious about getting a good match I recommend
upgrading to more full range speakers and/or adding midbass
drivers to pick up the slack."

Good advice. I've seen this work many times.

"I recommend setting the receiver to 0dB and adjusting the sub amp
until the level is as close as you can get. Then use the
receiver to fine tune if necessary."

Generally speaking, more good advice. However, it's non-specific about what
the receiver's LFE channel control is called and what it actually controls.
I frequently see a LFE control, not a subwoofer control. There's a big
difference because the LFE is effectively an input to the bass management
subsystem, while the subwoofer is an output from the bass management
subsystem.

No need to comment much on the remaining comment where we agree.

For a counterpoint, I consider the following which showed up in my research:

http://www.abluesky.com/m/p/bs10011b.pdf page 10:

"The LFE Channel was originally designed for film applications as a way to
extend the low frequency "head-room" (not frequency response) of the
playback system. This additional headroom was created by adding
+10dB of in-band gain to the LFE channel. This channel should only be
used when no additional headroom is available in the other channels for
low frequency effects. As an example, you may use the LFE channel to
increase the dynamic low frequency content of a movie that has many
large explosions. This is rarely the case in music, although there may be
some creative reasons to use the LFE from time to time. It is important to
note that no "significant" audio should be sent exclusively to the LFE
channel. The reason for this is that if a Dolby Digital audio track is
folded
down to 2-channels, which can happen if a consumer doesn't have a
surround system, the LFE channel will not be added to the fold-down mix
(all other channels will be added to the fold-down)."

The document I quoted relates to a dedicated bass management product for use
in audio production. The manual seems to make interesting reading.

Other similar tools:

http://www.smr-home-theatre.org/surr...image_13.shtml

http://pdf.outlawaudio.com/outlaw/docs/icbm_manual.pdf

Also, various online audio-related discussion groups where various
controversies related to these products have been logged. Google seemed to
find a good selection of these with the search words: bass management
controller .

"Rusty Boudreaux" wrote in message


"Arny Krueger" wrote in message
...

The general rule is set the crossover as low as you can without
overloading the satellites with bass. That will depend on your room
and the loudness you prefer to listen at, among other things.

For audio (stereo) this is good advice.

Thanks.

For movie soundtracks
with speakers set to 'small' you will loose LFE content above the
crossover frequency.

That's an interesting claim. I'd like to see it supported.

I've seen two general ways that the LFE channel is handled"

(1) The LFE channel is sent to the subwoofer without actually being changed
by any bass management. If any other speakers are set for "small", their
bass content below the crossover frequency may be added to the LFE info in
the subwoofer feed. This is pretty crude especially the ones where there is
really no bass management. Approaches like these show up in some low-end
implementations, including mid-end consumer PC sound cards. Basically, if
you have no subwoofer, you hear no LFE information. If your LF & RF speakers
lack bass, the LFE speaker may or may not be able to help you.

(2) The LFE channel is distributed among all speakers depending on their
properties and the crossover point settings. In no case is the LFE channel
above the crossover setting sent anyplace but the subwoofer except of course
if there is no subwoofer. If there is no subwoofer, the proper assignment
for LFE channel signal above the crosover point would appear to be the
center channel, subject to the settings for that speaker. However, below
the crossover setting, the LFE channel's content is pooled and divided
between the subwoofer (if present) and all other speakers that were
identified as being "large*. This is a pretty high-quality implementation,
and typical of mid fi consumer audio, and up.

Let me elaborate. My main system which is used for both HT and music, has no
subwoofer at all from the standpoint of surround processor bass management.
My surround processor's subwoofer output receives no signal. A subwoofer is
present, but it is part of the LF & RF subsystem. The RF & LF speakers are
defined to the surround processor as being "large". An outboard 24 dB/octave
crossover splits the subwoofer signal from the feed to the LF & RF speakers.

By all accounts and tests, the LFE channel is well-represented in the sound
field in the listening room even though this system effectively has no LFE
speaker. I note that my surround processor has no level controls for the
subwoofer, but it does have a level control for the LFE channel. The LFE
channel is obviously virtualized.

I arrived at this setup experimentally, because my surround processor has
only a single crossover frequency, and it is inappropriate for the speakers
and the room.

I think this indirectly contradicts the claim that: "For movie soundtracks
with speakers set to 'small' you will loose LFE content above the crossover
frequency." My system has no LFE speaker whatsoever, and yet the LFE channel
is well-represented in the room. Not only is the LFE represesented, but it
is also clearly and logically imaged.

See my other post and links.

OK, let's do it.

"Rusty Boudreaux" wrote in message


"If they are really small satellites you may have integration
issues. What you want is a smooth frequency response from where
the sub drops out to where the mains pick up. With small
satellites at high volumes their low frequency ability is
reduced. You can end up with a dip in the response because the
satellites loose output near the crossover frequency."

This is one of those "depends on" statements without some unstated
dependencies. These days we have subwoofers with 10, 8 and even 6 inch
drivers. These speakers can easily have relatively smooth response up to say
300 Hz, which is the highest "subwoofer" crossover frequency I can conceive
of in a system with pretensions to sound quality. My point is that with a
driver like this pointed at the listener and a decently-designed crossover,
a dip due to the acoustic properties of the sub and satellite is unlikely
for any reasonable crossover setting.

More likely, the bass and perhaps even the mid-bass imaging will be upset.
We can argue all day as to whether the ear hears directionality at 60 Hz,
but by 150 Hz there's very little doubt. For example, the intention of the
recordist might be that the bass come from either the LF or RF, but if the
crossover is at 150 Hz and the subwoofer and LF & RF speakers aren't
positioned very close to each other or if they are close but you are sitting
close to them, you're going to hear a lot of that bass coming from the
center. I call that bass imaging failure.

"One way to combat this with small speakers is to set crossover at
a relatively high frequency. However, you'll have to have a
really good sub that doesn't throw harmonic distortion into
higher audible frequency region...otherwise you'll easily be able
to pinpoint the sub location."

It's true that a sub that is distorting will generate output above the
crossover frequency and therefore be easier to locate. However, you don't
need to presume substandard equipment to explain why a high crossover
frequency will simply allow the listener to localize sounds to the subwoofer
because the crossover point is too high for the application. The ear
localizes the sound source better and better as the signal frequency goes up
from 60 to 80 Hz. One way to partially circumvent this is to put the
subwoofer very close to the satellites and to put the satellites closer to
each other. However, this approach to reducing bass imaging failure causes
some bass imaging to be lost.

"If your really serious about getting a good match I recommend
upgrading to more full range speakers and/or adding midbass
drivers to pick up the slack."

Good advice. I've seen this work many times.

"I recommend setting the receiver to 0dB and adjusting the sub amp
until the level is as close as you can get. Then use the
receiver to fine tune if necessary."

Generally speaking, more good advice. However, it's non-specific about what
the receiver's LFE channel control is called and what it actually controls.
I frequently see a LFE control, not a subwoofer control. There's a big
difference because the LFE is effectively an input to the bass management
subsystem, while the subwoofer is an output from the bass management
subsystem.

No need to comment much on the remaining comment where we agree.

For a counterpoint, I consider the following which showed up in my research:

http://www.abluesky.com/m/p/bs10011b.pdf page 10:

"The LFE Channel was originally designed for film applications as a way to
extend the low frequency "head-room" (not frequency response) of the
playback system. This additional headroom was created by adding
+10dB of in-band gain to the LFE channel. This channel should only be
used when no additional headroom is available in the other channels for
low frequency effects. As an example, you may use the LFE channel to
increase the dynamic low frequency content of a movie that has many
large explosions. This is rarely the case in music, although there may be
some creative reasons to use the LFE from time to time. It is important to
note that no "significant" audio should be sent exclusively to the LFE
channel. The reason for this is that if a Dolby Digital audio track is
folded
down to 2-channels, which can happen if a consumer doesn't have a
surround system, the LFE channel will not be added to the fold-down mix
(all other channels will be added to the fold-down)."

The document I quoted relates to a dedicated bass management product for use
in audio production. The manual seems to make interesting reading.

Other similar tools:

http://www.smr-home-theatre.org/surr...image_13.shtml

http://pdf.outlawaudio.com/outlaw/docs/icbm_manual.pdf

Also, various online audio-related discussion groups where various
controversies related to these products have been logged. Google seemed to
find a good selection of these with the search words: bass management
controller .

"Arny Krueger" writes:

An outboard 24 dB/octave crossover splits the subwoofer signal from
the feed to the LF & RF speakers.

Can you be more specific about this crossover product? Who makes it?
Are there any negative effects of using it?

--
Steven E. Harris ::
Raytheon :: http://www.raytheon.com

"Steven E. Harris" wrote in message


"Arny Krueger" writes:

An outboard 24 dB/octave crossover splits the subwoofer signal from
the feed to the LF & RF speakers.

Can you be more specific about this crossover product? Who makes it?

It's a Rane MX-22 modified to drop its frequency adjustment range from
about 100 Hz to 3.2 KHz, to 50 Hz to 1.6 Khz (add 6 small
capacitors-schematic and pictorals available from the www.rane.com web
site.).

The MX-22's actual frequency adjustment limits are more like 80 to 3.5 KHz,
so the mod would not be needed by most people. because of how my subwoofer
is positioned and the robustness of my satellites, I need to, and am
reasonably able to use a crossover in the 50-60 Hz range. Not everybody
needs to or should go that low.

Are there any negative effects of using it?

IME, nothing audible. The MX-22 is a component that was designed for an
audio production environment, so its inputs and outputs are all balanced XLR
connectors. At the point where it is inserted into my system, the other
components are balanced, so it fits in nicely. See a thread from a week or
so ago about using so-called DJ amps (actually, amps designed for
professional use) in home audio systems for more details.

Other than the connector issues, which is addressed with connecting cables,
the MX-22 could fit in a purely consumer-oriented system quite nicely. It
has a L+R output with back-panel level control for the low frequency side of
the crossover.

The major advantage of the MX-22 for me is that has just one knob for
setting the crossover frequency for both channels. This means that I can
easily check out the audible effects of changing the crossover frequency.

IMO, a properly-executed crossover should sound pretty much the same over a
reasonable range of frequencies. This indicates to me that a frequency
chosen in this range is relatively non-critical. This in turn suggests that
the relevant choices are nicely centered in their optimal ranges.

On Thu, 08 Jan 2004 08:10:20 -0800, "Steven E. Harris"
wrote:

"Arny Krueger" writes:

An outboard 24 dB/octave crossover splits the subwoofer signal from
the feed to the LF & RF speakers.

Can you be more specific about this crossover product? Who makes it?
Are there any negative effects of using it?

Take your pick:

http://www.zzounds.com/prodsearch?fo...& submit.y=13

http://www.starlight-online.com/audio/dbx/223.htm

http://ecoustics.consumerreview.com/...4_1590crx.aspx

http://www.dynamicprecision.no/Pages_UK/205UK_PA.html

Here's a fairly simplified discussion about crossovers:

http://ccs.exl.info/crossovr.html

This didn't seem to make it the first time around, so, here goes
again. Sorry if it ends up being a double posting...

On Thu, 08 Jan 2004 08:10:20 -0800, "Steven E. Harris"
wrote:

"Arny Krueger" writes:

An outboard 24 dB/octave crossover splits the subwoofer signal from
the feed to the LF & RF speakers.

Can you be more specific about this crossover product? Who makes it?
Are there any negative effects of using it?

Take your pick:

http://www.zzounds.com/prodsearch?fo...& submit.y=13

http://www.starlight-online.com/audio/dbx/223.htm

http://ecoustics.consumerreview.com/...4_1590crx.aspx

http://www.dynamicprecision.no/Pages_UK/205UK_PA.html

Here's a fairly simplified discussion about crossovers:

http://ccs.exl.info/crossovr.html

check these sites for info on excellent crossovers from inexpensive
DIY to exotic tube L/R crossovers
http://sound.westhost.com/index.html

http://www.marchandelec.com/

Louis



On Thu, 08 Jan 2004 08:10:20 -0800, "Steven E. Harris"
wrote:

"Arny Krueger" writes:

An outboard 24 dB/octave crossover splits the subwoofer signal from
the feed to the LF & RF speakers.

Can you be more specific about this crossover product? Who makes it?
Are there any negative effects of using it?

"Arny Krueger" wrote in message
...
"Rusty Boudreaux" wrote in message


"Arny Krueger" wrote in message
...

The general rule is set the crossover as low as you can
without
overloading the satellites with bass. That will depend on
your room
and the loudness you prefer to listen at, among other
things.

For audio (stereo) this is good advice.

Thanks.

For movie soundtracks
with speakers set to 'small' you will loose LFE content above
the
crossover frequency.

That's an interesting claim. I'd like to see it supported.

For a preamp/receiver to sport the Dolby Digital or THX logos it
is required the processing be done this way. This is detailed in
their "confidential" design papers. I couldn't find a good
description on their public site. However, it is briefly
discussed in this document:

5.1-Channel Production Guidelines Issue 1 (page 31 of 83)
http://www.dolby.com/tech/L.mn.0002.5.1Guide.s.pdf

"Consumer decoders take the LFE signal and add any channels in
need of bass management, as determined either by product design
or user selection. The five main channels are then high-pass
filtered at either a fixed frequency of 80 Hz or a selectable
frequency of 80, 100, or 120 Hz. The summation of the LFE and any
other channels is low-pass filtered at the same frequency. If the
crossover frequency is fixed at 80 Hz, as is standard in lower
priced decoders, information in the LFE channel between 80 Hz and
120 Hz will be reproduced at a lower level than it is recorded"

The design guidelines spell out in no uncertain terms that the
LFE channel must be summed with the full range channels first and
then LPF. Therefore, any content in the LFE channel above the
crossover frequency will be attenuated in the subwoofer output.

As a side note, all THX certified speakers are designed to be set
to small.

I've seen two general ways that the LFE channel is handled"

(1) The LFE channel is sent to the subwoofer without actually
being changed
by any bass management. If any other speakers are set for
"small", their
bass content below the crossover frequency may be added to the
LFE info in
the subwoofer feed. This is pretty crude especially the ones
where there is
really no bass management. Approaches like these show up in
some low-end
implementations, including mid-end consumer PC sound cards.
Basically, if
you have no subwoofer, you hear no LFE information. If your LF
& RF speakers
lack bass, the LFE speaker may or may not be able to help you.

This certainly violates the Dolby Digital licensing agreement.

(2) The LFE channel is distributed among all speakers depending
on their
properties and the crossover point settings.

Dolby/THX licensing allows redirection of the LFE to all channels
only if no subwoofer. If subwoofer exists then LFE can only be
routed to the main left/right. However, some decoders have a
"super" mode that combines LFE and bass from small channels and
redirects to all large speakers. THX does not recommend this and
if done THX requires all THX processing to be disabled.
Compliance is tested during THX certification.

In no case is the LFE channel
above the crossover setting sent anyplace but the subwoofer
except of course
if there is no subwoofer.

Further, the LFE content above the crossover frequency is being
filtered for the subwoofer output and content is lost.

If there is no subwoofer, the proper assignment
for LFE channel signal above the crosover point would appear to
be the
center channel, subject to the settings for that speaker.

see above for dolby/thx certification.

However, below
the crossover setting, the LFE channel's content is pooled and
divided
between the subwoofer (if present) and all other speakers that
were
identified as being "large*. This is a pretty high-quality
implementation,
and typical of mid fi consumer audio, and up.

Again, see above for dolby/thx certification.

Let me elaborate. My main system which is used for both HT and
music, has no
subwoofer at all from the standpoint of surround processor bass
management.
My surround processor's subwoofer output receives no signal. A
subwoofer is
present, but it is part of the LF & RF subsystem. The RF & LF
speakers are
defined to the surround processor as being "large". An outboard
24 dB/octave
crossover splits the subwoofer signal from the feed to the LF &
RF speakers.

This is one of the best ways to implement LFE and low bass from
the full range channels. Although, I'm not doing it now I intend
to shortly.

By all accounts and tests, the LFE channel is well-represented
in the sound
field in the listening room even though this system effectively
has no LFE
speaker. I note that my surround processor has no level
controls for the
subwoofer, but it does have a level control for the LFE
channel. The LFE
channel is obviously virtualized.

I arrived at this setup experimentally, because my surround
processor has
only a single crossover frequency, and it is inappropriate for
the speakers
and the room.

It also preserves all LFE content regardless of crossover
frequency...which is why I'm gonna do it soon

I think this indirectly contradicts the claim that: "For movie
soundtracks
with speakers set to 'small' you will loose LFE content above
the crossover
frequency." My system has no LFE speaker whatsoever, and yet
the LFE channel
is well-represented in the room. Not only is the LFE
represesented, but it
is also clearly and logically imaged.

My comments were intended for the sub output on a pre/pro in
which there is loss. With an outboard crossover as you have done
it's not an issue.

"Rusty Boudreaux" wrote in message


"If they are really small satellites you may have integration
issues. What you want is a smooth frequency response from
where
the sub drops out to where the mains pick up. With small
satellites at high volumes their low frequency ability is
reduced. You can end up with a dip in the response because the
satellites loose output near the crossover frequency."

This is one of those "depends on" statements without some
unstated
dependencies. These days we have subwoofers with 10, 8 and even
6 inch
drivers. These speakers can easily have relatively smooth
response up to say
300 Hz, which is the highest "subwoofer" crossover frequency I
can conceive
of in a system with pretensions to sound quality. My point is
that with a
driver like this pointed at the listener and a
decently-designed crossover,
a dip due to the acoustic properties of the sub and satellite
is unlikely
for any reasonable crossover setting.

The point I was trying to make is small satellites will be
excursion limited in their lowest octaves. In my case, I have a
massive IB subwoofer that has 15 liters of displacement at Xmax.
With my original satellite speakers I adjusted levels to achieve
a flat response at low and moderate SPL. However, when cranked
to high SPL the satellites couldn't keep up on their low end and
a dip in the response appeared. Even with the crossover at 160Hz
the dip would appear at the highest SPLs. I upgraded to mains
with better bass capability and no dip even at 110dB at 80Hz.

More likely, the bass and perhaps even the mid-bass imaging
will be upset.
We can argue all day as to whether the ear hears directionality
at 60 Hz,
but by 150 Hz there's very little doubt. For example, the
intention of the
recordist might be that the bass come from either the LF or RF,
but if the
crossover is at 150 Hz and the subwoofer and LF & RF speakers
aren't
positioned very close to each other or if they are close but
you are sitting
close to them, you're going to hear a lot of that bass coming
from the
center. I call that bass imaging failure.

Agreed.

"One way to combat this with small speakers is to set crossover
at
a relatively high frequency. However, you'll have to have a
really good sub that doesn't throw harmonic distortion into
higher audible frequency region...otherwise you'll easily be
able
to pinpoint the sub location."

It's true that a sub that is distorting will generate output
above the
crossover frequency and therefore be easier to locate. However,
you don't
need to presume substandard equipment to explain why a high
crossover
frequency will simply allow the listener to localize sounds to
the subwoofer
because the crossover point is too high for the application.
The ear
localizes the sound source better and better as the signal
frequency goes up
from 60 to 80 Hz. One way to partially circumvent this is to
put the
subwoofer very close to the satellites and to put the
satellites closer to
each other. However, this approach to reducing bass imaging
failure causes
some bass imaging to be lost.

Good point.

"If your really serious about getting a good match I recommend
upgrading to more full range speakers and/or adding midbass
drivers to pick up the slack."

Good advice. I've seen this work many times.

"I recommend setting the receiver to 0dB and adjusting the sub
amp
until the level is as close as you can get. Then use the
receiver to fine tune if necessary."

Generally speaking, more good advice. However, it's
non-specific about what
the receiver's LFE channel control is called and what it
actually controls.
I frequently see a LFE control, not a subwoofer control.
There's a big
difference because the LFE is effectively an input to the bass
management
subsystem, while the subwoofer is an output from the bass
management
subsystem.

Yep. You're right.

No need to comment much on the remaining comment where we
agree.

For a counterpoint, I consider the following which showed up in
my research:

http://www.abluesky.com/m/p/bs10011b.pdf page 10:

"The LFE Channel was originally designed for film applications
as a way to
extend the low frequency "head-room" (not frequency response)
of the
playback system. This additional headroom was created by adding
+10dB of in-band gain to the LFE channel. This channel should
only be
used when no additional headroom is available in the other
channels for
low frequency effects. As an example, you may use the LFE
channel to
increase the dynamic low frequency content of a movie that has
many
large explosions. This is rarely the case in music, although
there may be
some creative reasons to use the LFE from time to time. It is
important to
note that no "significant" audio should be sent exclusively to
the LFE
channel. The reason for this is that if a Dolby Digital audio
track is
folded
down to 2-channels, which can happen if a consumer doesn't have
a
surround system, the LFE channel will not be added to the
fold-down mix
(all other channels will be added to the fold-down)."

Yes, this is verbatim from the Dolby manual.

Rusty Boudreaux wrote:


"Consumer decoders take the LFE signal and add any channels in
need of bass management, as determined either by product design
or user selection. The five main channels are then high-pass
filtered at either a fixed frequency of 80 Hz or a selectable
frequency of 80, 100, or 120 Hz. The summation of the LFE and any
other channels is low-pass filtered at the same frequency. If the
crossover frequency is fixed at 80 Hz, as is standard in lower
priced decoders, information in the LFE channel between 80 Hz and
120 Hz will be reproduced at a lower level than it is recorded"

If one wanted the receiver to NOT do this "effect", what would they
look for? A better higher-end model, or some specific mode/technology?

"Joseph Oberlander" wrote in
message
ink.net...
"Consumer decoders take the LFE signal and add any channels
in
need of bass management, as determined either by product
design
or user selection. The five main channels are then high-pass
filtered at either a fixed frequency of 80 Hz or a selectable
frequency of 80, 100, or 120 Hz. The summation of the LFE and
any
other channels is low-pass filtered at the same frequency. If
the
crossover frequency is fixed at 80 Hz, as is standard in
lower
priced decoders, information in the LFE channel between 80 Hz
and
120 Hz will be reproduced at a lower level than it is
recorded"

If one wanted the receiver to NOT do this "effect", what would
they
look for? A better higher-end model, or some specific
mode/technology?

If it properly decodes DD it will do this. It's a part of the
Dolby/THX licensing and there are technical reasons why it's
done. Some higher end preamps allow all sorts of interesting
configurations but I'm leery of their practicality.

In reality it's not that big a deal. Most content creators
understand this and don't put any significant content above 80 Hz
or so in the LFE track.

I've found for my system 100Hz works best in minimizing lost
content, sub/main integration, and non localization of the sub.

You can do as Arny suggested and connect an external crossover to
your mains for the sub and set the receiver to no sub.

"Rusty Boudreaux" wrote in message

"Arny Krueger" wrote in message
...
"Rusty Boudreaux" wrote in message


"Arny Krueger" wrote in message
...

The general rule is set the crossover as low as you can without
overloading the satellites with bass. That will depend on
your room
and the loudness you prefer to listen at, among other
things.

For audio (stereo) this is good advice.

Thanks.

For movie soundtracks
with speakers set to 'small' you will loose LFE content above the
crossover frequency.

That's an interesting claim. I'd like to see it supported.

For a preamp/receiver to sport the Dolby Digital or THX logos it
is required the processing be done this way. This is detailed in
their "confidential" design papers. I couldn't find a good
description on their public site. However, it is briefly
discussed in this document:

5.1-Channel Production Guidelines Issue 1 (page 31 of 83)
http://www.dolby.com/tech/L.mn.0002.5.1Guide.s.pdf

"Consumer decoders take the LFE signal and add any channels in
need of bass management, as determined either by product design
or user selection. The five main channels are then high-pass
filtered at either a fixed frequency of 80 Hz or a selectable
frequency of 80, 100, or 120 Hz. The summation of the LFE and any
other channels is low-pass filtered at the same frequency. If the
crossover frequency is fixed at 80 Hz, as is standard in lower
priced decoders, information in the LFE channel between 80 Hz and
120 Hz will be reproduced at a lower level than it is recorded"

I guess you lost me when you say that LFE content is lost. In fact, its just
reproduced at a lower level than recorded.

The design guidelines spell out in no uncertain terms that the
LFE channel must be summed with the full range channels first and
then LPF. Therefore, any content in the LFE channel above the
crossover frequency will be attenuated in the subwoofer output.

I don't read "attenuated" as "lost". I guess that's a matter of personal
interpretation.

As a side note, all THX certified speakers are designed to be set
to small.

I've seen two general ways that the LFE channel is handled"

(1) The LFE channel is sent to the subwoofer without actually being
changed by any bass management. If any other speakers are set for
"small", their bass content below the crossover frequency may be
added to the LFE info in the subwoofer feed. This is pretty crude
especially the ones where there is really no bass management.
Approaches like these show up in some low-end
implementations, including mid-end consumer PC sound cards.
Basically, if you have no subwoofer, you hear no LFE information. If
your LF & RF speakers
lack bass, the LFE speaker may or may not be able to help you.

This certainly violates the Dolby Digital licensing agreement.

Stuff happens!

(2) The LFE channel is distributed among all speakers depending on
their properties and the crossover point settings.

Dolby/THX licensing allows redirection of the LFE to all channels
only if no subwoofer. If subwoofer exists then LFE can only be
routed to the main left/right. However, some decoders have a
"super" mode that combines LFE and bass from small channels and
redirects to all large speakers. THX does not recommend this and
if done THX requires all THX processing to be disabled.
Compliance is tested during THX certification.

In no case is the LFE channel
above the crossover setting sent anyplace but the subwoofer except
of course if there is no subwoofer.

Further, the LFE content above the crossover frequency is being
filtered for the subwoofer output and content is lost.

I believe you just said "attenuated", which I interpret as being different
than "lost"

If there is no subwoofer, the proper assignment
for LFE channel signal above the crossover point would appear to be
the center channel, subject to the settings for that speaker.

see above for dolby/thx certification.

However, below
the crossover setting, the LFE channel's content is pooled and
divided between the subwoofer (if present) and all other speakers
that were identified as being "large*. This is a pretty
high-quality implementation, and typical of mid fi consumer audio,
and up.

Again, see above for dolby/thx certification.

Let me elaborate. My main system which is used for both HT and
music, has no subwoofer at all from the standpoint of surround
processor bass management. My surround processor's subwoofer output
receives no signal. A subwoofer is present, but it is part of the LF
& RF subsystem. The RF & LF speakers are defined to the surround
processor as being "large". An outboard 24 dB/octave crossover
splits the subwoofer signal from the feed to the LF & RF speakers.

This is one of the best ways to implement LFE and low bass from
the full range channels. Although, I'm not doing it now I intend
to shortly.

I don't know about "best", but it does seem to work. It also seems to avoid
some fairly widespread problems with reproducing stereo music on the same
system.

By all accounts and tests, the LFE channel is well-represented in
the sound field in the listening room even though this system
effectively has no LFE speaker. I note that my surround processor
has no level controls for the subwoofer, but it does have a level
control for the LFE channel. The LFE channel is obviously virtualized.

I arrived at this setup experimentally, because my surround
processor has only a single crossover frequency, and it is
inappropriate for the speakers and the room.

It also preserves all LFE content regardless of crossover
frequency...which is why I'm gonna do it soon

I guess it does avoid the attenuation effect that is described in the
standard.

I think this indirectly contradicts the claim that: "For movie
soundtracks with speakers set to 'small' you will loose LFE content
above the crossover frequency." My system has no LFE speaker
whatsoever, and yet the LFE channel
is well-represented in the room. Not only is the LFE represesented,
but it is also clearly and logically imaged.

My comments were intended for the sub output on a pre/pro in
which there is loss. With an outboard crossover as you have done
it's not an issue.

Trust me, I blundered into this arrangement.

;-)

Rusty Boudreaux wrote:


If it properly decodes DD it will do this. It's a part of the
Dolby/THX licensing and there are technical reasons why it's
done. Some higher end preamps allow all sorts of interesting
configurations but I'm leery of their practicality.

In reality it's not that big a deal. Most content creators
understand this and don't put any significant content above 80 Hz
or so in the LFE track.

So it doesn't do this in DVDA/SACD?

"Joseph Oberlander" wrote in
message
k.net...
In reality it's not that big a deal. Most content creators
understand this and don't put any significant content above
80 Hz
or so in the LFE track.

So it doesn't do this in DVDA/SACD?

My knowledge of DVDA/SACD is limited. However, I assume they
don't have an LFE channel and wouldn't have this issue.

The LFE channel (when used) on DVD and laserdisk to allow direct
transcription of the *cinema* soundtrack. In today's digital
world the LFE channel is unnecessary but maintains compatibility
with existing cinema infrastructure.

"Arny Krueger" wrote in message
...
The design guidelines spell out in no uncertain terms that
the
LFE channel must be summed with the full range channels first
and
then LPF. Therefore, any content in the LFE channel above
the
crossover frequency will be attenuated in the subwoofer
output.

I don't read "attenuated" as "lost". I guess that's a matter of
personal
interpretation.

"lost" was a poor choice of words on my part.

Of course something ridiculous like setting the preamp crossover
at 30Hz would knock the upper end of the LFE down
by -48dB...which is pretty close to being lost.

"Stewart Pinkerton" wrote in message
...
On Wed, 7 Jan 2004 06:56:53 -0600, "Chris"
wrote:

The subwoofer crossover issue depends on the speakers. I would have to
hear
them to make a solid recommendation, but THX standard is 100hz.

Actually, it's 80 Hz.



Yeah yer right... sorry, it was early.



Depending
on your receiver model it may have a subwoofer or LFE test tone. Use it
to
send a signal to the subwoofer. Adjust the gain with the knob on the
back
of the sub up until you begin to hear distortion. Once you do back it
down
a bit. From there adjust the level at the amp to your liking. Try to
keep
the opening of the sub at least 150% of the diameter of the opening away
from the wall. You will probably get a lot of different opinions on
theses
topics. Good luck and have fun!

Yep, that all sounds fine.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Rusty Boudreaux wrote:

"Joseph Oberlander" wrote in
message
k.net...

In reality it's not that big a deal. Most content creators
understand this and don't put any significant content above

80 Hz

or so in the LFE track.

So it doesn't do this in DVDA/SACD?


My knowledge of DVDA/SACD is limited. However, I assume they
don't have an LFE channel and wouldn't have this issue.

The LFE channel (when used) on DVD and laserdisk to allow direct
transcription of the *cinema* soundtrack. In today's digital
world the LFE channel is unnecessary but maintains compatibility
with existing cinema infrastructure.

What I was asking about wasnn't this os much as the processing - since
this is done by the various surround processing modes.

In any case, you'd have to reset the speaker types, wouldn't you,
for music versus movies to get rid of this artificial limiting?

Rusty Boudreaux wrote:

"Joseph Oberlander" wrote in
message
k.net...

In reality it's not that big a deal. Most content creators
understand this and don't put any significant content above

80 Hz

or so in the LFE track.

So it doesn't do this in DVDA/SACD?


My knowledge of DVDA/SACD is limited. However, I assume they
don't have an LFE channel and wouldn't have this issue.

Oh - one more question:

Let's say you have a 5.1/6/1/etc setup and are listening to movies.

Given that this low-frequency cutoff effect is in place, what is
the point where such response is virtually non existant in the
surround channels? This might be nice to put in the FAQ as if
there is virtually nothing below 50hz, for instance, then buying
large surrounds is a moot point - just shop for 50hz capable bookshelfs
and ther you go.

"Rusty Boudreaux" wrote in message


"Arny Krueger" wrote in message
...

The design guidelines spell out in no uncertain terms that the
LFE channel must be summed with the full range channels first and
then LPF. Therefore, any content in the LFE channel above the
crossover frequency will be attenuated in the subwoofer output.

I don't read "attenuated" as "lost". I guess that's a matter of
personal interpretation.

"lost" was a poor choice of words on my part.

Anyway, thanks for the recital of the THX standard. You may have also
explained why I've never really had the stereo/HT compatibility problems
reported by others.

Of course something ridiculous like setting the preamp crossover
at 30Hz would knock the upper end of the LFE down
by -48dB...which is pretty close to being lost.

Using a 58 Hz subwoofer crossover as I do would have been pretty suboptimal,
except for the somewhat nonstandard way I implemented it.

"Joseph Oberlander" wrote in
message
ink.net...
Rusty Boudreaux wrote:

"Joseph Oberlander" wrote in
message
k.net...

In reality it's not that big a deal. Most content creators
understand this and don't put any significant content above

80 Hz

or so in the LFE track.

So it doesn't do this in DVDA/SACD?


My knowledge of DVDA/SACD is limited. However, I assume they
don't have an LFE channel and wouldn't have this issue.

The LFE channel (when used) on DVD and laserdisk to allow
direct
transcription of the *cinema* soundtrack. In today's digital
world the LFE channel is unnecessary but maintains
compatibility
with existing cinema infrastructure.

What I was asking about wasnn't this os much as the
processing - since
this is done by the various surround processing modes.

In any case, you'd have to reset the speaker types, wouldn't
you,
for music versus movies to get rid of this artificial limiting?

I don't think so since it only applies to how information in the
LFE track is handled.

"Joseph Oberlander" wrote in
message
nk.net...
Rusty Boudreaux wrote:

"Joseph Oberlander" wrote in
message
k.net...

In reality it's not that big a deal. Most content creators
understand this and don't put any significant content above

80 Hz

or so in the LFE track.

So it doesn't do this in DVDA/SACD?


My knowledge of DVDA/SACD is limited. However, I assume they
don't have an LFE channel and wouldn't have this issue.

Oh - one more question:

Let's say you have a 5.1/6/1/etc setup and are listening to
movies.

Given that this low-frequency cutoff effect is in place, what
is
the point where such response is virtually non existant in the
surround channels? This might be nice to put in the FAQ as if
there is virtually nothing below 50hz, for instance, then
buying
large surrounds is a moot point - just shop for 50hz capable
bookshelfs
and ther you go.

I'm not sure I complete understand your question.

There isn't any issues with the surround channels. Surround
output below the crossover frequency is routed to the subwoofer
output.

There are many preferences to the size and types of surrounds
(direct radiating, dipoles, identical speakers all around etc).
For my setup I prefer dipoles. I set surrounds to small so bass
is redirect to the sub. In certain cases you can have issues
with multiple sources of bass. The small setting can also
increase their dynamic range since the speakers don't have to
struggle with the bass.

Rusty Boudreaux wrote:

"Joseph Oberlander" wrote in
message
nk.net...

Rusty Boudreaux wrote:


"Joseph Oberlander" wrote in
message
link.net...


In reality it's not that big a deal. Most content creators
understand this and don't put any significant content above

80 Hz


or so in the LFE track.

So it doesn't do this in DVDA/SACD?


My knowledge of DVDA/SACD is limited. However, I assume they
don't have an LFE channel and wouldn't have this issue.

Oh - one more question:

Let's say you have a 5.1/6/1/etc setup and are listening to

movies.

Given that this low-frequency cutoff effect is in place, what

is

the point where such response is virtually non existant in the
surround channels? This might be nice to put in the FAQ as if
there is virtually nothing below 50hz, for instance, then

buying

large surrounds is a moot point - just shop for 50hz capable

bookshelfs

and ther you go.


I'm not sure I complete understand your question.

There isn't any issues with the surround channels. Surround
output below the crossover frequency is routed to the subwoofer
output.

Right - but you are saying that it falls off rather than a
sharp cutoff. So, say a standard 80hz cutoff - at what point
is more bass moot for surrounds?

"Joseph Oberlander" wrote in
message
ink.net...
There isn't any issues with the surround channels. Surround
output below the crossover frequency is routed to the
subwoofer
output.

Right - but you are saying that it falls off rather than a
sharp cutoff. So, say a standard 80hz cutoff - at what point
is more bass moot for surrounds?

Could you eloborate a little more about what you're asking?

A typical preamp/receiver has a 2nd order 12dB per octave high
pass crossover for speakers set to 'small'. The subwoofer output
has a 4th order 24dB per octave low pass filter.

So, if you set your crossover at 80Hz:

the subwoofer output will be attenuated
24dB at 160Hz
48dB at 320Hz
96dB at 640Hz, etc

the 'small' speaker will be attenuated
12dB at 40Hz
24dB at 20Hz
48dB at 10Hz

Note, this is the attenuation of the speaker electrical input not
the speaker output. The speaker may have additional rolloff of
it's own. For example, a typical surround speaker will have
insignificant output below 20-40Hz even when driven by a full
range signal. So the total attenuation is much higher than just
the crossover.

Rusty Boudreaux wrote:

A typical preamp/receiver has a 2nd order 12dB per octave high
pass crossover for speakers set to 'small'. The subwoofer output
has a 4th order 24dB per octave low pass filter.

So, if you set your crossover at 80Hz:

the subwoofer output will be attenuated
24dB at 160Hz
48dB at 320Hz
96dB at 640Hz, etc

the 'small' speaker will be attenuated
12dB at 40Hz
24dB at 20Hz
48dB at 10Hz

Note, this is the attenuation of the speaker electrical input not
the speaker output. The speaker may have additional rolloff of
it's own. For example, a typical surround speaker will have
insignificant output below 20-40Hz even when driven by a full
range signal. So the total attenuation is much higher than just
the crossover.

Thanks. That's exactly what I needed.