Bass management question

[Grador]

I think two things need rehashed here: If you're using the bass management on the receiver DO NOT use the LPF built into the subwoofer. If you're unsure what a setting does or how it works, experiment Download a tone generator for a computer or smartphone, plug it in, see where the tone ends up.

 

[Goliath]

So now I'm probably more confused than when I started. So if all speakers Large mean no crossover and I've chosen the 40 Hz low-pass on the subwoofer in the subwoofer menu then either that means nothing, it's not actually applying any low pass filter or it IS applying a low pass filter on the LFE. That would be crazy.

This manual is very poorly written so I'm not entire sure how this all works. I would IMAGINE that if all speakers were Large that the sub should ONLY handle LFE. Low-passing 40 Hz means signal is truncated above to 120 Hz, so you would be chucking away information. That doesn't make sense to me and I don't understand why it would even be option. Since when do manufacturers give you LPF of LFE at 40 Hz? It's usually user adjustable between 80 Hz-120 Hz, so I'm really confused right now as to what this subwoofer low-pass actually is supposed to do, assuming all speakers are Large.

 

[twoeyedbob]

You really are making this far more complicated that it needs to be...are you just reading the manual,or have you
Played with the processor itself yet ?
I have only read 2 pages of my own pdf ...(and even they were
Pretty poorly written)
Once you've played about with the menu's/submenus
Half this stuff becomes obvious....
Most of the time you have 2 or 3 choices...and the auto eq does most of the work....
If i tried to make sense of mine thru the pdf alone,
I'd of gone mad by now.


Sent from my HTC Vision using Tapatalk 2

 

[Pyrrho]

Yes but the LFE has information up to 120 Hz. I would imagine if you set the sub low-pass to 70 Hz that you would be throwing information from 70-120 Hz. Wouldn't that be the case?

Yes, if you mean that you are adjusting the setting on the subwoofer (NOT in the processor, but on the subwoofer itself) for a crossover at 70 Hz. That is one reason why, with modern surround processors (anything with Dolby Digital and newer), it is a good idea to bypass the crossover on the subwoofer itself. And if that cannot be done, it should be set at the highest frequency possible for it. As I stated earlier in this thread, the way you describe your friend's settings, he is throwing away bass in the LFE channel above 70 Hz.

And, unless his main speakers are as good as his subwoofer at reproducing bass, he is also throwing away the bass below what the main speakers can do that the subwoofer can do.

For a hypothetical example, imagine that the main speakers are capable of 35-20,000Hz +/-3dB, and the subwoofer is capable of 25-150Hz +/-3dB. In such a case, by setting the main speakers to "large", he is throwing away bass between 25-35 Hz, which, if he set his speakers to "small" (and selected a crossover frequency higher than those frequencies), would be going to the subwoofer that is capable of reproducing those frequencies. This is why it is virtually always a good idea to set all channels to "small". [For the pedantic reading this, I know that this is oversimplified, as being lower than 3dB down does not mean that one gets no sound at those frequencies, but it is less than it should be, and so what I am stating is correct; it is throwing away some of the bass that should be there.]

 

[Pyrrho]

I read that LFE has a upper limit at 120 Hz. So if you set 80 H for the low-pass on the LFE channel then you ARE chucking away bass in the LFE from 80-120 Hz. Does that not make sense?

The selectable crossover applies to when the non-subwoofer speakers are set to "small." The frequency selected is the cutoff point for those channels, and so it is the bass from the non-LFE channels that are redirected to the subwoofer output. The LFE channel should still all go to the subwoofer output regardless of whatever crossover point is selected for those other channels to be redirected to the subwoofer (unless one has selected "no subwoofer" for the processor, in which case one would get no sound from that output).

You might want to read page 35 of the manual:

• Five LARGE speakers and sub-
woofer: This system requires no bass re-
direction. All five speakers play the nor-
mal bass recorded in their respective chan-
nels. The subwoofer plays only the LFE
channel bass. Depending on the
soundtrack, there may be minimal use of
the LFE channel, so the subwoofer would
be under utilized. Meanwhile the normal
bass places higher demands on the capa-
bilities of the other speakers and the am-
plifiers driving them.​

...

• All SMALL speakers and subwoofer.
The normal bass from all channels is redi-
rected to the subwoofer, which also plays
the LFE channel. The subwoofer handles
ALL of the bass in the system. This configu-
ration provides several benefits: deep bass
is played by the speaker most suited to do
so, the main speakers may play louder with
less distortion, and the need for amplifier
power is reduced. This configuration should
be used with bookshelf-size or smaller main
speakers. It should also be considered in
some cases with floorstanding front speak-
ers. This configuration is advantageous
when driving the system with moderate
power amplifiers.

• LARGE front speakers, SMALL cen-
ter and surround speakers, and a
subwoofer. The normal bass from the
SMALL center and surround speakers is re-
directed to the LARGE front speakers and
the subwoofer. The LARGE front speakers
play their own normal bass plus the redi-
rected bass from the SMALL speakers and
LFE bass. The subwoofer plays the LFE bass
plus the redirected bass from all of the other
channels. This might be an appropriate con-
figuration with a pair of very capable front
speakers driven by a large power ampli-
fier. A potential disadvantage with mixed
LARGE and SMALL configurations is that
the bass response may not be as consis-
tent from channel to channel as it might
be with the all SMALL configuration.​

​

http://www.rotel.com/content/manuals/rsp1068.pdf

 

[Goliath]

The selectable crossover applies to when the non-subwoofer speakers are set to "small." The frequency selected is the cutoff point for those channels, and so it is the bass from the non-LFE channels that are redirected to the subwoofer output.

Okay, I read that portion of the manual. He has set all speakers to Large so there is no crossover. So the subwoofer should only be handling LFE. But what is the 40 Hz low-pass then in the advanced menu about??? What does that do if speakers are all set to Large?

If you turn your subwoofer LPF to maximum then you bypass the subwoofer LPF. Understand that. But if you select 40 Hz in the advanced subwoofer menu then what is the subwoofer low-pass filtering? Since the LFE contains bass from 3 Hz-120 Hz, it would SEEM to roll-off bass above 40 Hz by. So you would be chucking that away from 40-120 or from 40-70 or whatever.

Please clarify this for me.

 

[Goliath]

I mentioned to my friend that if you use both processor LPF and subwoofer LPF that they will cascade. But he tells me that speakers have passive crossovers so any crossover you setup on a receiver or a processor is in effect still/also cascading and that in some cases you will effectively be creating a bandpass xover of x+y order..

Is that true?

 

[Goliath]

Apologies for being such a nuisance, I ask too many questions. I want to say thank you to everyone who has contributed. I hope this thread can continue for a little while longer to answer my remaining questions. I just hate it when I don't understand something or when I don't have the answer for something. It bugs me to no end.

 

[twoeyedbob]

I'm losing the will to live

Sent from my HTC Vision using Tapatalk 2

 

[Goliath]

I take that to mean you can't answer my QUESTIONS.

 

[Goliath]

This is supposed to be a place where I can find answers and up until now no one has effectively put this to rest. Just answer the questions already - making me ask the same questions and then repeat myself until I get an answer is not productive. Come to think of it, just forget it. I've wasted a LOT of time trying with this back and forth and I STILL don't have an answer to my question. It's just so ffing frustrating when I can't ask a question without someone trying to be sarcastic or rude or put me under the gun and I'm NO better than when I started. What a waste of time.

 

[Grador]

I mentioned to my friend that if you use both processor LPF and subwoofer LPF that they will cascade. But he tells me that speakers have passive crossovers so any crossover you setup on a receiver or a processor is in effect still/also cascading and that in some cases you will effectively be creating a bandpass xover of x+y order..

Is that true?

Since this is actually a new question I'll tackle it. Almost no speakers have a high pass for the woofer, so this is not true at all. The first crossover in the speaker will be the one from the woofer to tweeter [or mid] well above the sub crossover point.

 

[PENG]

So now I'm probably more confused than when I started. So if all speakers Large mean no crossover and I've chosen the 40 Hz low-pass on the subwoofer in the subwoofer menu then either that means nothing, it's not actually applying any low pass filter or it IS applying a low pass filter on the LFE. That would be crazy.

It is applying low pass on the LFE. Yes it is crazy if you chose 40 Hz. I chose 150 Hz. When you set the L/R/C/Surrs to large, they play full band, but the LPF is for the subwoofer, that does not play full band unless you set it to OFF, and you should only do that if the other speakers are set to small.

This manual is very poorly written so I'm not entire sure how this all works.

I agree, but if you read page 35 through 36 you can still get most of your questions answered.

I would IMAGINE that if all speakers were Large that the sub should ONLY handle LFE.

That is correct if you set the subwoofer to "yes" but if you set it to "max", then the subwoofer will also handle the redirected bass even if all other speakers are set to "large". See page 36.

ow-passing 40 Hz means signal is truncated above to 120 Hz, so you would be chucking away information.

Agree, that's way I set it to 150 Hz. Again, why would you set it to 40 Hz?

That doesn't make sense to me and I don't understand why it would even be option. Since when do manufacturers give you LPF of LFE at 40 Hz? It's usually user adjustable between 80 Hz-120 Hz,

Again, I agree with you, my Denon and Marantz allow for 40 to 250 Hz. I do think Rotel does it that way because their "large" setting allows the other (not subwoofers) speakers to play not only full band but also the LFE signal, so there is a case for the lower LPF (such as the example of 40 Hz you cited) for the subwoofer to avoid the potentially possible interaction of the bass signals between so many speakers. The manual sort of advise against using those advanced settings.

so I'm really confused right now as to what this subwoofer low-pass actually is supposed to do, assuming all speakers are Large.

I don't know why you say that, it seems to me you understand what the manual is saying for the most part, just that you don't seem to see the merits of some of the flexibilities provided by this product.

 

[PENG]

This is supposed to be a place where I can find answers and up until now no one has effectively put this to rest. Just answer the questions already - making me ask the same questions and then repeat myself until I get an answer is not productive. Come to think of it, just forget it. I've wasted a LOT of time trying with this back and forth and I STILL don't have an answer to my question. It's just so ffing frustrating when I can't ask a question without someone trying to be sarcastic or rude or put me under the gun and I'm NO better than when I started. What a waste of time.

I read through this thread quickly so I might have missed something but I do get the impression that people are trying to answer your questions. You asked quite a few questions in multiple posts so you are going to have to be a little more patient with us. I tried responding to the points your raised in your more recent post. You may want to post one more time to recap all of the points that you think has not been addressed. That way some of us can all refer to, with quotes, just one single post. Again, be patient though, as I guess most of us do not own a Rotel processor, and I can tell you after reading through the manual you link, their bass management scheme is not quite the same as the more popular (around here I assume) Denon, Yamaha, Onkyo models.

 

[Pyrrho]

Okay, I read that portion of the manual. He has set all speakers to Large so there is no crossover. So the subwoofer should only be handling LFE. But what is the 40 Hz low-pass then in the advanced menu about??? What does that do if speakers are all set to Large?

If you turn your subwoofer LPF to maximum then you bypass the subwoofer LPF. Understand that. But if you select 40 Hz in the advanced subwoofer menu then what is the subwoofer low-pass filtering? Since the LFE contains bass from 3 Hz-120 Hz, it would SEEM to roll-off bass above 40 Hz by. So you would be chucking that away from 40-120 or from 40-70 or whatever.

Please clarify this for me.

Pages 36-37 (with emphasis added):

CROSSOVER (40Hz/60Hz/80Hz/
100Hz/120Hz/150Hz/200Hz): Typi-
cally, the RSP-1068 uses a single master set-
ting for the high-pass and low-pass crossover
point between all SMALL speakers and the
subwoofer. This master crossover point is set
on the SUBWOOFER SETUP menu described
in the following section. When you first ac-
cess the ADVANCED SPEAKER SETUP menu,
the current master crossover point will be shown
on this line. Change the value of this line only
if you want the current speaker to have a dif-
ferent crossover point. For example, if your
master crossover is set to 80Hz, but you want
your front speakers to crossover to the sub-
woofer at 60 Hz, you would select 60Hz for
the front speakers on this line. This setting ONLY
affects redirected bass and does not affect the
LFE channel in any way. The OFF setting (avail-
able only for the subwoofer) sends a full-range
signal to your subwoofer so that you can use
its built-in low-pass filter.​

​

http://www.rotel.com/content/manuals/rsp1068.pdf

Basically, the settings you are concerned about within the processor affect the non-LFE channels and where the bass goes from those non-LFE channels. The LFE goes to the subwoofer output, unless no subwoofer is selected.

 

[Pyrrho]

I mentioned to my friend that if you use both processor LPF and subwoofer LPF that they will cascade. But he tells me that speakers have passive crossovers so any crossover you setup on a receiver or a processor is in effect still/also cascading and that in some cases you will effectively be creating a bandpass xover of x+y order..

Is that true?

Since this is actually a new question I'll tackle it. Almost no speakers have a high pass for the woofer, so this is not true at all. The first crossover in the speaker will be the one from the woofer to tweeter [or mid] well above the sub crossover point.

Grador is correct.

The crossover for the subwoofer, if set at the same frequency on both the subwoofer itself and the processor, will cause the high end of the subwoofer's frequency reproduction to drop off faster than it would if only using the processor's crossover. Thus, if the processor was not designed by an idiot who got it completely wrong, there will be a dip in the frequency response at the crossover point if someone uses both crossovers at the same point. With a competently designed processor, using just its crossover (and also properly setting the levels of the various channels) will result in a proper bass response (insofar as the speakers and room effects allow). Thus, using both results in improper frequency response and inferior sound. Of course, some people like things set improperly, and they are free to do that if they so desire. But if one wishes to have as accurate reproduction of the sound as possible, one should set things properly.

 

[PENG]

The LFE goes to the subwoofer output, unless no subwoofer is selected.

I thought so too until I read the manual, then I realize this thing actually allows the front L/R to play the LFE signal if set to large, strange but that may be the reason why it allows the subwoofer LPF to be set as low as 40 Hz. That seems going a little too far though, even in terms of maximizing flexibility.

 

[Pyrrho]

Pages 36-37 (with emphasis added):

CROSSOVER (40Hz/60Hz/80Hz/
100Hz/120Hz/150Hz/200Hz): Typi-
cally, the RSP-1068 uses a single master set-
ting for the high-pass and low-pass crossover
point between all SMALL speakers and the
subwoofer. This master crossover point is set
on the SUBWOOFER SETUP menu described
in the following section. When you first ac-
cess the ADVANCED SPEAKER SETUP menu,
the current master crossover point will be shown
on this line. Change the value of this line only
if you want the current speaker to have a dif-
ferent crossover point. For example, if your
master crossover is set to 80Hz, but you want
your front speakers to crossover to the sub-
woofer at 60 Hz, you would select 60Hz for
the front speakers on this line. This setting ONLY
affects redirected bass and does not affect the
LFE channel in any way. The OFF setting (avail-
able only for the subwoofer) sends a full-range
signal to your subwoofer so that you can use
its built-in low-pass filter.​

​

http://www.rotel.com/content/manuals/rsp1068.pdf

Basically, the settings you are concerned about within the processor affect the non-LFE channels and where the bass goes from those non-LFE channels. The LFE goes to the subwoofer output, unless no subwoofer is selected.

I thought so too until I read the manual, then I realize this thing actually allows the front L/R to play the LFE signal if set to large, strange but that may be the reason why it allows the subwoofer LPF to be set as low as 40 Hz. That seems going a little too far though, even in terms of maximizing flexibility.

Where does it say that in the manual?

I mean, of course, when there is a subwoofer; like most processors, it will redirect the LFE to the main speakers if no subwoofer is selected (as per p. 35: "LARGE front, center, surround speakers, no subwoofer.")

 

[PENG]

Where does it say that in the manual?

I mean, of course, when there is a subwoofer; like most processors, it will redirect the LFE to the main speakers if no subwoofer is selected (as per p. 35: "LARGE front, center, surround speakers, no subwoofer.")

Page 35, under the heading LARGE front speakers, SMALL center
and surround speakers, and a
subwoofer.

"The normal bass from the
SMALL center and surround speakers is redirected
to the LARGE front speakers and
the subwoofer. The LARGE front speakers
play their own normal bass plus the redirected
bass from the SMALL speakers and
LFE bass. The subwoofer plays the LFE bass
plus the redirected bass from all of the other
channels."

I forced myself to read it twice to make sure I wasn't seeing things too. I have had quite a few AVR and one processor so far, none has such feature.

 

[Pyrrho]

Page 35, under the heading LARGE front speakers, SMALL center
and surround speakers, and a
subwoofer.

"The normal bass from the
SMALL center and surround speakers is redirected
to the LARGE front speakers and
the subwoofer. The LARGE front speakers
play their own normal bass plus the redirected
bass from the SMALL speakers and
LFE bass. The subwoofer plays the LFE bass
plus the redirected bass from all of the other
channels."

I forced myself to read it twice to make sure I wasn't seeing things too. I have had quite a few AVR and one processor so far, none has such feature.

If I owned that processor, I would contact Rotel to find out if that is a misprint. That would be a weird (and stupid) way for them to deal with such settings.

That does not say that the crossover applies to the LFE channel. It only states that the LFE is sent to both the front speakers and the subwoofer (which I suspect may be a misprint; if it is not a misprint, that setting should never be selected).

Also, that is not the setting that the person has selected:

I'm trying to help my friend out, but I'm having difficulty understanding how he has set up his system. He has a Rotel RSP-1065 processor and has run all speakers as large apparently.

He told me that the subwoofer lpf has been set to 40 Hz with all speakers set to Large. At the back of his subwoofer he is using the lowest lpf available, which is 70 Hz. But I looked in the RSP-1068 manual and I can't find any user adjustable lpf for a subwoofer unless speakers are selected as Small.

Either he is confused, or I can't find this user adjustable lpf. He is happy with his sound, but I'm trying to help him get better sound out of his system. Can someone help me out?

Thus, the relevant part of the manual would be:

• Five LARGE speakers and sub-
woofer: This system requires no bass re-
direction. All five speakers play the nor-
mal bass recorded in their respective chan-
nels. The subwoofer plays only the LFE
channel bass. Depending on the
soundtrack, there may be minimal use of
the LFE channel, so the subwoofer would
be under utilized. Meanwhile the normal
bass places higher demands on the capa-
bilities of the other speakers and the am-
plifiers driving them.

​

Page 35:
http://www.rotel.com/content/manuals/rsp1068.pdf

So as set, even if the processor were designed perversely as stated for large fronts and small center and surround speakers with subwoofer, the crossover frequency selected would be irrelevant in this case as the crossover only applies when something is set to "small".