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Discussion Starter · #1 ·
Most of us by now have some experience with multi-channel surround sound systems. For myself, after a few years of experience, several glaring issues have developed which compromise the overall sound quality.


The largest issue is not time delay either. Rather it is reproducing the lowest bass properly. Most surround sound processors/receivers have bass management with the noticeable exception of keeping DSD/SACD "pure".


Let’s examine the root cause: small limited bass response of center and surround speakers.


Fixing this limitation in the receiver’s bass management is really a band-aid approach as it redirects the bass away from the small rear or center speakers to any full range speaker (usually to the front and subwoofer).

The result redirected bass can the easily overload the front or subwoofer or at least cause a most unnatural effect.


On the other hand, setting all of the speakers to full range (in the receiver’s bass management) can result in less gross distortions. Over time this is a purer approach is the preferable compromise as there less electronic mixing or summing involved. While the limited range speakers cannot reproduce the lowest bass, or play as loud, at least they preserve the atmosphere that the producer intended.


So are there any practical, affordable, comprehensive real solutions available to solve this most vexing bass management issue?
 

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Thats why I built these.They reproduce the bass from all seven channels (that includes the LFE ) up to about 115db. Thats from 12hz to 100hz. The other seven channels are free to reproduce 100hz and above. It's not the only solution, just mine.


I usually watch movies with the volume around 90db. Peaks here and there up to about 105db. They don't even flinch.


There are subs on the market now that do a great job.You'll read more about SVS here than anywhere.They make a great product. I have heard dual Ultra/2's and they will shake you to your soul.


I like to make mine.You have lots of choices, so read up and stop asking those seven channels to do what they were never meant to do, it's the subs job, and thats a big responsability.

 

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I can't say how each of us would define affordable but Outlaw and M&K both make bass management boxes. Neither correct for time delay. (Which depending on your point of view matters a lot or matters little.)


Outlaw ICBM (pricing on the website.) http://www.outlawaudio.com/products/icbm.html


M&K (pricing also on their website.) http://www.mksound.com/filters-bass_mgmt.php


I own 2 of the Outlaw ICBM's and wouldn't trade them for anything...
 

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Discussion Starter · #4 ·
Quote:
Originally Posted by kgveteran
Thats why I built these.They reproduce the bass from all seven channels (that includes the LFE ) up to about 115db. Thats from 12hz to 100hz. The other seven channels are free to reproduce 100hz and above. It's not the only solution, just mine.


I usually watch movies with the volume around 90db. Peaks here and there up to about 105db. They don't even flinch.


There are subs on the market now that do a great job.You'll read more about SVS here than anywhere.They make a great product. I have heard dual Ultra/2's and they will shake you to your soul.


I like to make mine.You have lots of choices, so read up and stop asking those seven channels to do what they were never meant to do, it's the subs job, and thats a big responsability. :cool:
You are no doubt a committed bass freak! :)

I know that one picture can't tell everything, so I ask for more information.


What kind of amplifiers are those and what type of A/V processor/receiver do you use?


Is that SVS sub in the corner for the LFE?


Is that two enclosers in the front center with each containing two woofers?

In general do separate woofers handle each of the seven channels? Or are some summed/combined electronically?


Thanks!
 

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I use four Adire Tumults in sealed subenclosures.Each cabinet has two drivers.The cabinets are made of two inch MDF and they weigh about 350lbs each. Each Tumult is driven by its own Adcom 555mkII, bridged mono.I use a BFD for room nodes and a Marchand BASSIS to extend the output down to about 12-15hz.Sealed subs roll off gradually quite early.The F3 of each driver is about 30-35hz.


The system is basically mono and fed a single LFE (sub out ) The processor is the Outlaw 990.


Those are basetraps in the corners.


I'll be replacing the Adcoms with pro amps soon.This is just for amp headroom ,not to play louder.The Adcoms do well but were never designed to do 3.6ohms bridged mon down to 15hz.I clipped them once when I was showing off.We must have been well up into 115db.
 

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Discussion Starter · #6 ·
Quote:
Originally Posted by HAN
I can't say how each of us would define affordable but Outlaw and M&K both make bass management boxes. Neither correct for time delay. (Which depending on your point of view matters a lot or matters little.)


Outlaw ICBM (pricing on the website.) http://www.outlawaudio.com/products/icbm.html


M&K (pricing also on their website.) http://www.mksound.com/filters-bass_mgmt.php


I own 2 of the Outlaw ICBM's and wouldn't trade them for anything...
The M&K Bass Management System with the balanced connectors looks nice, but the crossover slopes are not even specified, the crossover frequency is fixed and is priced at a cool $1000.


M&K quote:

The BMC 5.1-MINI, LFE-4, and LFE-5 Bass Management systems are similar in concept and function. The BMC 5.1-MINI is the unbalanced (bad) version using RCA connectors and the LFE-4 and 5 are Balanced versions using balanced 3-pin type (sometimes called XLR or A3) connectors. The LFE-5 has it sown Volume Control; the LFE-4 does not. Depending upon your connection scheme, either is suitable for the finest audiophile home system OR professional or semi-professional critical monitoring situations. If you want to hear it at home the way the professionals hear it in the studio, you have virtually no other choice!

Agreed, this is the desired result!


So you guys are offering excellent advice, but here are a few questions: Are unbalanced signals, separate crossovers, separate bass amplifiers and the many required cables all necessary or practical? I've been down this complicated path myself. Ultimately A/C ground loop hum limited the performance.
 

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reincarnate,


What DVD A/SACD player are you using? Many have some form of bass management available.


On another note, just to share my personal experience, I have a Denon 2900 that I used to run to my MC12 using analog pass through as I prefered that sound to digitizing. However after getting V4 with Room Correction, the digitized and corrected signal sounds way better that the straight pure signal.
 

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Discussion Starter · #9 ·
Quote:
Originally Posted by kgveteran
Reincarnate,

What are you running now ? Why the basemanagement search ?
I will answer all of these questions, but in due time. The goal is practical, affordable, comprehensive solution so that the center and surround sound channels are not limited in the bass or dynamic range. (I only buy full range speakers for the front left and right speakers, so these channels are not an issue here). The has been identified as the new weakest link in my system. The industry as a whole offers no solutions, except redirecting the bass to the full range front speakers (and if that fails then to the subwoofer). This goal of this thread is to offer choices to correct this stupidity. So put forth your ideas and lets discuss them.
 

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Quote:
Originally Posted by reincarnate
Let’s examine the root cause: small limited bass response of center and surround speakers.
Why is this the root cause of any problem? No one is stopping you from using full range centre and/or surround speakers (though there are good reasons for re-directing the bass away from these locations).
Quote:
Fixing this limitation in the receiver’s bass management is really a band-aid approach as it redirects the bass away from the small rear or center speakers to any full range speaker (usually to the front and subwoofer).
This is a helpful option since the best locations for bass reproduction are rarely at the exact same locations where the centre and surrounds are placed.
Quote:
The result redirected bass can the easily overload the front or subwoofer or at least cause a most unnatural effect.
If low frequencies are overloading your front speakers, re-direct some of the bass to the subwoofer. If the subwoofer is being overloaded, get a more competent sub.
Quote:
On the other hand, setting all of the speakers to full range (in the receiver’s bass management) can result in less gross distortions.
Other way round: setting all the speakers to Large in the receiver's bass management can result in more distortion as speakers strain attempting to reproduce frequencies beyond their capabilities.
Quote:
While the limited range speakers cannot reproduce the lowest bass, or play as loud, at least they preserve the atmosphere that the producer intended.
Huh? What "atmosphere that the producer intended" are you talking about? Please explain.


Sanjay
 

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Quote:
Originally Posted by reincarnate
Let’s examine the root cause: small limited bass response of center and surround speakers.
Why is this the root cause of any problem? No one is stopping you from using full range centre and/or surround speakers (though there are good reasons for re-directing the bass away from these locations).
Quote:
Fixing this limitation in the receiver’s bass management is really a band-aid approach as it redirects the bass away from the small rear or center speakers to any full range speaker (usually to the front and subwoofer).
This is a helpful option since the best locations for bass reproduction are rarely at the exact same locations where the centre and surrounds are placed.
Quote:
The result redirected bass can the easily overload the front or subwoofer or at least cause a most unnatural effect.
If low frequencies are overloading your front speakers, re-direct some of the bass to the subwoofer. If the subwoofer is being overloaded, get a more competent sub.
Quote:
On the other hand, setting all of the speakers to full range (in the receiver’s bass management) can result in less gross distortions.
Other way round: setting all the speakers to Large in the receiver's bass management can result in more distortion as speakers strain attempting to reproduce frequencies beyond their capabilities.
Quote:
While the limited range speakers cannot reproduce the lowest bass, or play as loud, at least they preserve the atmosphere that the producer intended.
Huh? What "atmosphere that the producer intended" are you talking about? Please explain.
Quote:
The M&K Bass Management System with the balanced connectors looks nice, but the crossover slopes are not even specified
Yes they are: second order.
Quote:
M&K quote:
If you want to hear it at home the way the professionals hear it in the studio, you have virtually no other choice!

Agreed, this is the desired result!
But to get this "desired result" M&K recommends doing the opposite of what you were saying.


From the instruction manual of their bass management system:

Due to unavoidable room modes, five or more correctly placed full range speakers, (in even the most perfectly designed studio) will produce dramatically different low frequency characteristics at the mix position. This is especially true for the very crucial center channel speaker. Variations of 10 to 20 dB may be measured at frequencies below 80 Hz.


When the bass from all the channels is redirected into a single, PROPERLY placed subwoofer, then each and all of the multiple channels exhibits the identical bass response at the listening position, and gives surprisingly even coverage in virtually every control room.

Quote:
Are unbalanced signals, separate crossovers, separate bass amplifiers and the many required cables all necessary or practical?
Of course not. Just use the bass management in your receiver.


Sanjay
 

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Quote:
Originally Posted by reincarnate
Let’s examine the root cause: small limited bass response of center and surround speakers.
Why is this the root cause of any problem? No one is stopping you from using full range centre and/or surround speakers (though there are good reasons for re-directing the bass away from these locations).
Quote:
Fixing this limitation in the receiver’s bass management is really a band-aid approach as it redirects the bass away from the small rear or center speakers to any full range speaker (usually to the front and subwoofer).
This is a helpful option since the best locations for bass reproduction are rarely at the exact same locations where the centre and surrounds are placed.
Quote:
The result redirected bass can the easily overload the front or subwoofer or at least cause a most unnatural effect.
If low frequencies are overloading your front speakers, re-direct some of the bass to the subwoofer. If the subwoofer is being overloaded, get a more competent sub.


BTW, what do you mean by "most unnatural effect"? What does it sound like?
Quote:
On the other hand, setting all of the speakers to full range (in the receiver’s bass management) can result in less gross distortions.
Other way round: setting all the speakers to Large in the receiver's bass management can result in more distortion as speakers strain attempting to reproduce frequencies beyond their capabilities.
Quote:
While the limited range speakers cannot reproduce the lowest bass, or play as loud, at least they preserve the atmosphere that the producer intended.
Huh? What "atmosphere that the producer intended" are you talking about? Please explain.
Quote:
The M&K Bass Management System with the balanced connectors looks nice, but the crossover slopes are not even specified
Yes they are: second order.
Quote:
M&K quote:
If you want to hear it at home the way the professionals hear it in the studio, you have virtually no other choice!

Agreed, this is the desired result!
But to get this "desired result" M&K recommends doing the opposite of what you were saying.


From the instruction manual of their bass management system:

Due to unavoidable room modes, five or more correctly placed full range speakers, (in even the most perfectly designed studio) will produce dramatically different low frequency characteristics at the mix position. This is especially true for the very crucial center channel speaker. Variations of 10 to 20 dB may be measured at frequencies below 80 Hz.


When the bass from all the channels is redirected into a single, PROPERLY placed subwoofer, then each and all of the multiple channels exhibits the identical bass response at the listening position, and gives surprisingly even coverage in virtually every control room.



So M&K is recommending re-directing the bass from all the channels to a single subwoofer rather than running them as full range.
Quote:
Are unbalanced signals, separate crossovers, separate bass amplifiers and the many required cables all necessary or practical?
Of course not. Just use the bass management in your receiver.


Sanjay
 

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Quote:
Originally Posted by reincarnate
Let’s examine the root cause: small limited bass response of center and surround speakers.
Why is this the root cause of any problem? No one is stopping you from using full range centre and/or surround speakers (though there are good reasons for re-directing the bass away from these locations).
Quote:
Fixing this limitation in the receiver’s bass management is really a band-aid approach as it redirects the bass away from the small rear or center speakers to any full range speaker (usually to the front and subwoofer).
This is a helpful option since the best locations for bass reproduction are rarely at the exact same locations where the centre and surrounds are placed.
Quote:
The result redirected bass can the easily overload the front or subwoofer or at least cause a most unnatural effect.
If low frequencies are overloading your front speakers, re-direct some of the bass to the subwoofer. If the subwoofer is being overloaded, get a more competent sub.


BTW, what do you mean by "most unnatural effect"? What does it sound like?
Quote:
On the other hand, setting all of the speakers to full range (in the receiver’s bass management) can result in less gross distortions.
Other way round: setting all the speakers to Large in the receiver's bass management can result in more distortion as speakers strain attempting to reproduce frequencies beyond their capabilities.
Quote:
While the limited range speakers cannot reproduce the lowest bass, or play as loud, at least they preserve the atmosphere that the producer intended.
Huh? What "atmosphere that the producer intended" are you talking about? Please explain.
Quote:
The M&K Bass Management System with the balanced connectors looks nice, but the crossover slopes are not even specified
Yes they are: second order.
Quote:
M&K quote:
If you want to hear it at home the way the professionals hear it in the studio, you have virtually no other choice!

Agreed, this is the desired result!
But to get this "desired result" M&K recommends doing the opposite of what you were saying.


From the instruction manual of their bass management system:

Due to unavoidable room modes, five or more correctly placed full range speakers, (in even the most perfectly designed studio) will produce dramatically different low frequency characteristics at the mix position. This is especially true for the very crucial center channel speaker. Variations of 10 to 20 dB may be measured at frequencies below 80 Hz.


When the bass from all the channels is redirected into a single, PROPERLY placed subwoofer, then each and all of the multiple channels exhibits the identical bass response at the listening position, and gives surprisingly even coverage in virtually every control room.



So M&K is recommending re-directing all the bass to a single subwoofer rather than running any channel as full range.
Quote:
Are unbalanced signals, separate crossovers, separate bass amplifiers and the many required cables all necessary or practical?
Of course not. Just use the bass management in your receiver.


Sanjay
 

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Discussion Starter · #15 ·
Why is this the root cause of any problem? No one is stopping

you from using full range centre and/or surround speakers (though there are good reasons for re-directing the bass away from these locations).


As you already know, almost all rooms and budgets prevent the use of identical full range speakers for all channels. The point of this thread is to explore a different philosophy or approach to overcome the lack of full bass response in the center and surround channels.


We need to make progress in our compromised multi-channel systems, which means overcoming the shortcomings of redirected bass. Redirected bass seriously degrades the imaging, soundstage and atmosphere which the mixing engineer intended. In my opinion bass electronic bass redirection was implemented chiefly to reach the largest target audience. The design obviously focused on cost, weight and space (speaker size) reductions. The loser/orphan is the low bass response in the following channels:


Center Channel

-------------------

The optimum center channels characteristics would be identical to the front left and right. However this is NOT practical for several reasons.

a) cost

b) the center speaker cannot physically block the view of the projectors screen

c) appearance

d) if located on top of projector must be small and light weight

e) if located below projector must be short not to much volume


These attributes are simple observations of the surround sound systems which manufactured today. The point of this thread is to find ways to overcome each of these attributes which limit the bass response and dynamic range of the center channel.


Surround Channels

-----------------------

The optimum surround channels characteristics would be identical to the front left and right speakers. However this is not practical for several reasons as the typical home theater multi-channel system has the small light-weight surround speaker mounted on the side walls (and even to the rear wall).


a) cost

c) appearance - must be small

c) cannot be heavy


Again, these attributes are simply observations of surround sound systems which manufactures are producing. The point of this thread is to find ways to overcome each of these attributes which limit the bass response and dynamic range of the surround channels.

This is a helpful option since the best locations for bass reproduction are rarely at the exact same locations where the centre and surrounds are placed.

Agreed.

Other way round: setting all the speakers to Large in the receiver's bass management can result in more distortion as speakers strain attempting to reproduce frequencies beyond their capabilities.

Agreed.

Huh? What "atmosphere that the producer intended" are you talking about?

Accurately recreating the intended atmosphere which was mixed at the studio.

Huh? Subsequent questions like this will be ignored

When the bass from all the channels is redirected into a single, PROPERLY placed subwoofer, then each and all of the multiple channels exhibits the identical bass response at the listening position, and gives surprisingly even coverage in virtually every control room.[/i]

Following this logic all full range speakers with adequate low bass response should be discarded. (There goes high-end audio!):)

The LFE subwoofer is most essential to any multi-channel surround sound system.

Its design needs no discussion and can effectively be used as is.


Sanjay, my goals in surround sound are rather different than common industry accepted philosophy. (I don’t accept it at all!)

Please give those of us who are interested an opportunity to explore ways to achieve the accurate reproduction of in each channel without resorting to the redirection or mixing of the bass.


Thanks!
 

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Quote:
Originally Posted by reincarnate
We need to make progress in our compromised multi-channel systems, which means overcoming the shortcomings of redirected bass.
Bass re-direction is not some sort of limitation or compromise to overcome. In fact, quite the oppsite: it is a useful tool that can allow significant improvements to a system's ability to reproduce sound.
Quote:
Redirected bass seriously degrades the imaging, soundstage and atmosphere which the mixing engineer intended.
You keep repeating this without explaining how re-directed bass degrades anything, let alone what those degradations are. And there's that 'intended atmosphere' phrase again. Like I asked you before, what atmosphere are you talking about? Can you please describe it?
Quote:
The loser/orphan is the low bass response in the following channels:
The opposite is true: by redirecting the low frequencies away, the bass from the centre and surround channels can be better reproduced because: a) it is being sent to transducers that are designed specifically for bass playback, and b) it is being sent to locations that can help improve frequency response. Subsequent questions like this will be ignored
Quote:
Following this logic all full range speakers with adequate low bass response should be discarded.
That's M&K's logic, which the company's product line is consistent with (note they make no full range speakers - none).
Quote:
(There goes high-end audio!):)
Are we discussing the preservation of "high-end audio" (whatever that may mean) or how best to reproduce low frequencies in your system?
Quote:
Please give those of us who are interested an opportunity to explore ways to achieve the accurate reproduction of in each channel without resorting to the redirection or mixing of the bass.
I'm not standing in the way of anyone's opportunity to explore anything. In fact, I'm taking the time to address many of your points individually.


However, if your goal is to improve low frequency playback BY eliminating bass management, then you're starting from a false premise.


You're also not helping this discussion by evading questions. When asked about your system, you don't answer. When asked what you mean by intended atmosphere, you don't answer.
Quote:
Subsequent questions like this will be ignored
In that case I'll paraphrase kgveteran: I thought you were serious about exploring this. Never mind.


Sanjay
 

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Good reading material.

http://www.grammy.com/pe_wing/5_1_Rec.pdf


"Full range" speakers are defined as 40Hz and or lower at the low end, and 18kHz or higher at the high end.



Your correct choices are either to run a "full range" speaker as large, or you run any speaker as "small" and use bass redirection plus filters (bass management).



You seem to be looking for some other option!!!
 

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I was concerned that my setup couldn't run full range for dvd-Audio and SACD, so I decided to augment all my channels with subs. I run a pair of CSW P-500s and a pair of CSW P-1000s. I've tried all the options, including separate signals for L,C,R,and surrounds, separate signals for front L,C,R, and rear+side surround, and twin LFE, and finally the old standby 4 LFE and all speakers small (Harmon white paper mode). The complexity of separate signals led me to use one P-500 for the front trio of speakers, one for the side and rear surrounds, and the pair of P-1000s for LFE. I switch from full range to small all around plus sub when going from music to movies. It was difficult to blend them all, but the results are pretty good. All in all, though, two subs probably would have been plenty, one front, one rear, all speakers set full range, no bass management. BTW, my subs allow left, right, and center inputs, so I was able to work it all out.
 

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Discussion Starter · #19 ·
Quote:
Originally Posted by floridapoolboy
All in all, though, two subs probably would have been plenty, one front, one rear, all speakers set full range, no bass management. BTW, my subs allow left, right, and center inputs, so I was able to work it all out.
This is exactly the direction I'm thinking of going too. The left and right surrounds bass frequencies can be summed at the second subwoofer. Not a perfect solution but a good compromise.

This second surround subwoofer should be placed towards the back of the room.

This is where we make use of the subwoofers crossover and amplifier. With this configuration surrounds are only sent frequencies from 80 Hz up and this second sub is feed from 80Hz down. How about 24db per octive lowpass slope?


Now the question comes down to the best implementation. What is the best way to get the line level left and right surround signal back to the subwoofers crossover. The choices are:

1) UNbalanced analog

2) balanced analog

3) digital SPDIF


Of the three transmission techniques which is the best technically today? A requirement is is to handle multi-channel SACD and Dvd-Audio playback.
 

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Discussion Starter · #20 ·
Quote:
Originally Posted by J_Palmer_Cass
Good reading material.

http://www.grammy.com/pe_wing/5_1_Rec.pdf


"Full range" speakers are defined as 40Hz and or lower at the low end, and 18kHz or higher at the high end.



Your correct choices are either to run a "full range" speaker as large, or you run any speaker as "small" and use bass redirection plus filters (bass management).



You seem to be looking for some other option!!!
Yes I am. The issue is I can easily hear the bass redirection degrading the sound quality. Remember too that I am not only focusing on Dobly and DTS sound tracks, but also analog SACD and Dvd-audio playback.


Another requirement is that once the system is set up correctly, I don't want to have to fiddle with settings for different sources. I've been through the nightmare of page after page of surround sound settings (especially in Denon and Sony receivers) and the whole issue sinks in its complexity. I mean, I figured it all out, but only us most-dedicated-fools will take the time to get all the settings just right. Almost all of the population could care less. I don't blame them either.


But out of all of the issues, getting the bass to sound just right is the most difficult. The more channels that are summed the more unpredictable the algebraic sum (read output level) becomes. A lot of the bass differences are lost forever in this degrading process. The whole concept is bass summing/redirection is mid-fi at best. Its use should be kept to a minimum in true high-end systems. Of course this is just my opinion based upon years of experience.


The multi-channel audio industry needs to overcome its chronic limitations by getting off the infant formula and start eating some real meat. This does not mean adding more surround channels either. We need to accurately reproduce the channels we already have.
 
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