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Discussion Starter · #1 ·
does the high cut LFE need to be set at the highest cutoff frequency of my speakers. I have been playing around with the multiple cut offs I have the mains at 60 the rest at 80, but I don't know what this high cut is all about, it was default at 150hz please help me figure this out quick thanks. Should it be at 80? What is its purpose
 

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For any speakers set to high-pass (SMALL) in your system, frequencies above the crossover point are sent to the main speaker. Frequencies below the crossover point are redirected to the powered subwoofer.


I virtually every receiver-based system with a powered subwoofer, all of the main speakers should be set to SMALL because the powered subwoofer is better at reproducing low bass and because it provides huge benefits in terms of amplifier power and clean dynamic range.


Some receivers allow you to set different crossover frequencies for each group of speakers. However, in most cases, you will be better off setting one single crossover point for the entire system.


This crossover point should generally be set to a frequency that is appropriate for the speakers with the smallest woofers. If the smallest woofers in the system are 6 inch drivers, then an 80 hz - 100 Hz crossover would be a good choice. If the smallest drivers are 5.25 inch woofers, then a crossover of 100 - 125 Hz would be a good choice. If the smallest woofers are 4 inches, a crossover of 125 hz to 150 Hz would be a good choice. If the smallest woofers are 3.5 inch drivers, then a 200 Hz crossover would be the best bet.


There are some systems where deviating from this normal setup might make sense, but not unless there is some very good reason to do so.


Where I've given a range of crossover frequencies, the lower number will probably provide better subwoofer integration. The higher number will increase the power handling of the system at high volume levels.
 

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Discussion Starter · #3 ·
I do have all the speakers set to small but its this seperate thing that says high cut LFE and then 150hz or whatever, so I set this high cut to the smallest speaker (200hz) and then the other crossovers to the other speakers probably 200hz for surrounds (I still have my old HTIB ones for now) 80hz for center, 60 or 80 hz for monitor 7 mains (I haven't decided yet. The sony da4es has seperate crossovers for each speaker set, fronts, center, surrounds. Is it ok to have them different or do things get more complicated.
 

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Quote:
For any speakers set to high-pass (SMALL) in your system, frequencies above the crossover point are sent to the main speaker. Frequencies below the crossover point are redirected to the powered subwoofer.
Very correct, of course, but KingofOld was asking about the LFE high-cut filter, not the crossover fiilters.


The LFE high cut on Sony gear can be used to limit the frequency response of the LFE channel itself. It is not related to the crossover frequency, which is used for redirecting bass from the five main speakers and into the sub. If you use a subwoofer in your system, then the LFE channel is sent exclusively to the subwoofer. If your subwoofer is not able to reproduce higher frequencies properly, then you may want to apply a high-cut filter to the LFE channel so that the subwoofer is not asked to do so. For example, some very large subwoofers may have boomy or poorly controlled response above, say, 80 or 90 Hz, so you can set the LFE high cut to 80 or 90 Hz (or whatever). In addition, loud bass at frequencies above about 100 Hz can be more easily localised (so you will notice that it comes from the sub's location), so using the filter can help to prevent this effect. The THX specifications dictate that a 80 Hz low-pass filter be applied to the LFE channel.


As a general rule, DD and dts both limit the LFE to 120 Hz anyway. For dts, this is 'set in stone', but for DD, it is the responsibility if the recording engineer to limit the response.


In most cases, it is not necessary to change the setting of the LFE high cut.

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Some receivers allow you to set different crossover frequencies for each group of speakers. However, in most cases, you will be better off setting one single crossover point for the entire system.
True. Most receivers will simply sum all the channels together then apply a low pass filter at a certain (often user-defined) frequency, then add the LFE channel to that, to get the subwoofer signal. The LFE is sometimes optionally filtered before-hand as described above.


In the newer Sony's (4ES, 7ES), there is no longer a subwoofer crossover frequency setting like there used to be. Now, the individual channels are low-pass-filtered at the same frequency as the high-pass filter for the respective channel, then summed, then added to the (optionally filtered) LFE channel, to get the overall subwoofer output signal. So now, there is no reason to use the same crossover frequency for all channels.
 

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I have a denon 1803 and I have my fronts set to large. Would I notice better audio performance by setting these to small?


My front speakers are floor standing JBL N38IIs which have 8' woofers

My surround speakers are book shelf N26IIs which have 6' woofers
 

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Quote:
I have a denon 1803 and I have my fronts set to large. Would I notice better audio performance by setting these to small?
Jules,


Are you using a subwoofer with the system? If so, it most likely will sound better. It will clean up your midrange by relieving your mains of the low end duty. This also will reduce the strain on your amplifier which will allow for better dynamics as hwc already stated.
 

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Quote:
I have a denon 1803 and I have my fronts set to large. Would I notice better audio performance by setting these to small?
Do not ask this question in this thread... it is completely off-topic. Start a new thread.
 

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Quote:
Originally posted by macboy
In the newer Sony's (4ES, 7ES), there is no longer a subwoofer crossover frequency setting like there used to be. Now, the individual channels are low-pass-filtered at the same frequency as the high-pass filter for the respective channel, then summed, then added to the (optionally filtered) LFE channel, to get the overall subwoofer output signal. So now, there is no reason to use the same crossover frequency for all channels.
I have not been able to get my hands on the latest Cirrus tech papers for the newest generation chipsets with this feature. But, I have my doubts that the independently variable crossover feature really works as you describe.


The low pass filter part of a Dolby Digital crossover takes place in what as referred to as the "bass summing module" and takes place after all of the redirected channels are summed. The high-pass filter part of the crossover takes place in a "bass management processing module" for each channel.


My strong suspicion, based on spending several hours looking at this very issue, is that the separate crossover points are JUST for the high-pass portion of the crossover and that you then have to set the low-pass portion of the filter to the highest of the crossover points you've set.


As I say, I'm not absolutely positive about this and can't be until I get the application tech papers on the new generation chips. But, I believe there is still just one low-pass filter for all channels.


BTW, the terminology and descriptions that appear in owners manuals are typically useless for understanding what is really happening with the bass management.
 

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Discussion Starter · #9 ·
Any ideas on how to test where I should put the high cut, like unplug all the other speakers and listen to the sub alone to see if it sounds boomy at certain frequencies. Should this be done with music or movies/does it matter. Honestly as far as technical stuff goes I am pretty inexperienced so I don't follow exactly what you guys are saying but I get the idea. I have the avia test disk, and a pretty good variety of music/movies, and an spl meter. Knowing this could I get some advice on how to go about figuring this out. Sub is towards a corner, its a midq tempest DIY sub (I had it built for me) Thanks for the help.
 

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The odds of getting the right setting by "ear" are slim and none.


If I were you, I would set all of your speakers to SMALL. Set the high-pass crossover to 80 Hz for everything. Set the "LFE high cut filter" (a very bad name for this, IMO) to 80 Hz.


Most likely, your HTIB surrounds have a blocking cap lo-cut filter to keep from blowing them up. Live with a hole in the response of the surround speakers until you can upgrade the surrounds.


BTW, you conundrum is exactly why I recommend spending the price of a pair of Monitor 7s on four Mini-Monitors instead. Having identical speakers all around makes system configuration so easy. I don't think there really is a "good' configuration for your system right now.


Here's another possibility. If you have the old passive HTIB subwoofer in the garage and it has a passive crossover, maybe you should wire it up to the surround channels with your HTIB satellites. Then, an 80 Hz crossover would be fine for the surrounds, too.
 

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Quote:
Originally posted by hwc
I have not been able to get my hands on the latest Cirrus tech papers for the newest generation chipsets with this feature. But, I have my doubts that the independently variable crossover feature really works as you describe.


The low pass filter part of a Dolby Digital crossover takes place in what as referred to as the "bass summing module" and takes place after all of the redirected channels are summed. The high-pass filter part of the crossover takes place in a "bass management processing module" for each channel.


My strong suspicion, based on spending several hours looking at this very issue, is that the separate crossover points are JUST for the high-pass portion of the crossover and that you then have to set the low-pass portion of the filter to the highest of the crossover points you've set.


As I say, I'm not absolutely positive about this and can't be until I get the application tech papers on the new generation chips. But, I believe there is still just one low-pass filter for all channels.


BTW, the terminology and descriptions that appear in owners manuals are typically useless for understanding what is really happening with the bass management.
When U set the high pass filter for a specific set of speakers, this also sets the low pass filter as well. Any other way U could lose certain frequencies. For example if U set the High pass @ 120Hz and the Low pass @ 80Hz, U have just created hole between 80-120Hz as these frequencies will be filtered out. Once U set the crossover points for each set of speakers then the low pass output from each set of speakers is summed and added along with the LFE (.1) channel and sent out the Sub/LFE output. If a speaker is set to Large then NO low or high pass filters are applied to that respective set of speakers as it is passing full range frequencies with NO bass redirection.


Note that these are very complex calculations as the total gain of the DSP capability must be addressed. If not possible DSP clipping may happen due to the very significant dynamic headroom for the LFE channel... :cool:
 

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Quote:
Originally posted by Sinitro
When U set the high pass filter for a specific set of speakers, this also sets the low pass filter as well. Any other way U could lose certain frequencies. For example if U set the High pass @ 120Hz and the Low pass @ 80Hz, U have just created hole between 80-120Hz as these frequencies will be filtered out.
I understand the potential for a huge hole or significant overlap in the crossover frequencies. But, I have not seen any evidence that these bass management modules have separate low-pass filters for each channel. Quite the contrary, the specific DSP software I've been playing with has an advanced speaker setup menu that allows you to set an individual crossover point for each group of speakers. But, the same menu also has an option for selecting ONE low-pass filter frequency.


My best guess is that this new "custom" crossover feature that is sprouting like weeds on the latest generation stuff may very well result in holes or overlaps if you use it.


The first thing you learn when you start digging into the implementation of these DSP processors is that the rush to add features doesn't necessarily pause long enough to figure out if it's a good feature.


For example, the "PLUS" or "DOUBLE-BASS" setting that sprouted a couple of years back is a demonstrably horrible feature that will almost guarantee not being able to properly calibrate a system. But, every Dolby Digital receiver and pre-pro has it.


I hope I'm wrong. And, if someone can show me a table of register settings and or bass management/bass summer module block diagrams from one of the chip manufacturers that proves me wrong I'd love it. But, as I say, I've studied the tech documentation for Dolby Digital chipsets pretty closely and, so far, I have seen no mechanism for independent lo-pass filtering on each channel.
 

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It is all based upon software coefficients and there are multiple possibilities, but these more complex configurations are basically straight forward but require a great deal of debugging and testing as it is extremely difficult to balance all of the proper levels for each DSP mode.


U have mentioned Cirrus Logic, they have 2 basic audio DSPs the CS 49326 and CS 49400, the CS 49326 is found in about 70% of the AVRs built today. The CS 49400 is a new part which is a CS 49326 front DSP and then a 2nd DSP for post processing. In the application notes for the CS 49326, there are many options such as:

1. Low Pass Filter Frequencies

The standard frequencies for Dolby is 80Hz-120Hz, and THX is 80Hz. DTS basically follows the Dolby requirements. For the Dolby standard frequencies Cirrus Logic provides the config files, for other frequencies these are programmable by the brand.

2. Slope of Low Pass Filter

This can be programmed as 2nd order (12dB/Octave), 3rd order (18dB/Octave) or 4th order (24dB/Octave). Most brands use the 4th order option.

3. High Pass Filter Frequencies

Same frequencies as the low pass filters, however here a separate software instruction can be given to make this setting independent of the Low Pass.

4. Slope of High Pass Filter

This too like the low pass is programmable but the majority of applications leave this as a 2nd order (12dB/Octave).


So Yes..

U can program separate instructions for the low pass and high pass filters but in the hands of a less knowledgeable user he can definitely screw up the overall sound balance by misusing the available settings. As many user think that the bass manager is a form of tone controls. Additionally since satellite speaker sizes continue to be smaller, this requires a more flexible bass manager as typically they need a higher X-over frequency. In the future we will continue to see even more advanced bass manager schemes for new AVRs as we go into the Fall season... :cool:


Regarding the double bass feature, I think U are referring to ability of rerouting some of the LFE channel (.1) back into the Left/Right fronts if set in the Large mode. Here too it is easy to screw things up by having too much LFE sent to the L/R fronts.
 

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Discussion Starter · #14 ·
Well I have come to learn that going with the Monitor 7 was a bit of a mistake (not as much as one might think because I did get them for a pretty good price, still not as cheap as mini-monitors). I am a bit confused why there really is no "good" configuration unless you were talking about how I am still using the HTIB surrounds. I don't hardly pay attention to them because I know they suck, and I'm getting some better surrounds pretty soon. From my understanding the minis and the 7's are basically the same, I get the advantage is slim to none for the 7's but I don't see how they could be worse. I'll probably just set everything to 80 and try to forget about it. Sorry for my lack of understanding but hey I'm only 20 and started into all this about 4 monthes ago. One thing I can say though is that for the past two weeks I left the High cut alone at 150hz and had everything at 80. you guys said that could create a hole but there isnt' one really on the Avia frequency sweep. Thanks for all the help though guys, any more will be appreciated.
 

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Quote:
Originally posted by Sinitro
U can program separate instructions for the low pass and high pass filters but in the hands of a less knowledgeable user he can definitely screw up the overall sound balance by misusing the available settings.
That's not really the issue. There is no question that the designer of the A/V receiver can tailor both the crossover point and slopes of the low-pass filters and high-pass filters.


The issue we are talking about here is a new feature: the ability for the user to set different crossover points for the front speakers, center speaker, and surround speaker. That function is available because there is a seperate high-pass filter for each channel in the chipset. No debate about that.


The question is whether you can set a different LOW-PASS filter for each each channel. If I set the crossover to my surrounds at 150 Hz, then I want all bass from the surround channels below 150 Hz to be sent to the subwoofer. Then, if I set my fronts to 80 Hz, I want all bass from the front channels below 80 Hz to be redirected to the subwoofer. This requires a separate lo-pass filter for each channel, with the low-pass filtering to be done before the bass summing module.


What I'm suggesting is that these chipsets have traditionally only had ONE low-pass filter bank and that the low-pass filtering for redirected bass come AFTER the summing module. The corner frequency of this one filter bank can be changed, but no matter where it is set, it is the low-pass filter for all redirected bass from all channels. Unless this has changed, then setting different crossover points for each speaker is going to result in at least one set of channels being wrong. You can't use the same low-pass filter frequency to match both an 80 Hz and a 150 Hz high pass filter. Some channel is either going to have unwanted overlap or an unwanted hole.


Given that the low-pass filter setting in these new pre-pro's is still a global setting, I do not believe that this has changed. I could be wrong, but based on what I know so far, that's the way I see it.


This has never been a problem before because the crossover setting as been global. Set a new crossover frequency in the user menus, and the low-pass filter and all of the high pass filters change accordingly in unison.


Until I am able to determine otherwise, my recommendation remains the same: use five (or six or whatever) identical speakers, set one high-pass filter frequency and a matching lo-pass filter frequency for the entire system.


BTW: the "double-bass" I refer to is option that allows the front channel "LARGE" speakers to play their own bass PLUS redirecting that bass to the subwoofer. It is a horrid configuration.
 

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Quote:
Originally posted by KingofOld
I am a bit confused why there really is no "good" configuration unless you were talking about how I am still using the HTIB surrounds.
Yes. That's the only thing I was talking about. You would prefer to be able to use an 80 Hz or 100 Hz crossover point for all of the speakers in the system and have the bass performance remain constant as signals pan from front to back or vice versa.


The Monitor 7s are fine.
 
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