Bass management that we can all use?

Discussion in 'Archived Threads 2001-2004' started by Chris PC, Nov 10, 2001.

  1. Chris PC

    Chris PC Producer

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    Just a suggestion to most people for what bass management might be useful. I noticed that the Outlaw ICBM and the Outlaw 950 have bass management of 40, 60, 80, 100 hz and higher crossover settings. Although this seems nice, it skips the most desirable frequencies. Now before you say I am nit-picking, here is what I mean:
    Most receivers have either a 100 hz or 80 hz crossover and many have said this is too high and they would prefer a lower crossover. Well giving you a 60hz and 40 hz crossover is not good enough. Most peoples front tower speakers, even the most ambitious and full range speakers, generally go down to around 30 or 40 hz. So using the rule that the crossover should be double the -3dB frequency of your front speakers, then I propose bass management utilize more settings between 50 and 80 hz, say a 50,55,60,65,70,and 75 hz set of crossover frequencies as options IN ADDITION to the the 40, 80 and 100 hz settings.
    See, we already have the 80 and 100 hz settings, so lets keep those, as they are useful for those who have small front speakers. But for those of us who want lower, we are not talking about 40 hz. Most of our front speakers don't go down to 20 hz, so 60hz is the only crossover point that is useful to someone who wants to go lower than 80hz. By filling in the gap between 40hz and 80 hz, you then have REAL flexibility. So settings at 5 or 10 hz increments between 40 and 80 hz would be all we would need.
     
  2. Pete Mazz

    Pete Mazz Supporting Actor

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    What about the center and surrounds? They need base management, and usually don't go too low.
    Pete
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  3. Chris PC

    Chris PC Producer

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    That is true. I just figured that I'd start with the front, particularly for use during stereo listening too. I think that many people would agree that a selectable crossover from 50-80 hz in 5 hz increments would be ideal for all channels.
     
  4. Kevin C Brown

    Kevin C Brown Producer

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    I would say that you need that flexibility for all channels.
    The Sony TA-E9000ES pre/pro, which is 3 years old by the way, has crossover settings from 40 to 200 Hz, by 10 Hz increments, for all channels.
    Maybe slightly ahead of their time for that feature. (Of course, it took them a year to get the remote right though...)
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  5. Mal P

    Mal P Stunt Coordinator

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    Hi there,
    Don't forget though... there is a crossover slope involved here. What is it on the Outlaw? If it's the standard 12dB/Octave, then the 40hz cross over might be too low!
    Cheers,
    Mal
     
  6. Doug_B

    Doug_B Screenwriter

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    You could spend a lot of time tweaking your system with this level of flexibility [​IMG] .
    ------------------
    "Today is a good day to die." ...Old Lodge Skins
     
  7. Chris PC

    Chris PC Producer

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    The Sony bass management is probably the closest to perfection I have seen. I truely think that the 40 hz crossover is too low for any front speaker, but then again, room frequency responses are different in each space, so I guess it may work for someone somewhere.
    That is a lot of flexibility, but it would not be too hard to make. Why not ask Sony how expensive it is to implement their crossover? I can't imagine its costly.
    Say settings like this:
    40,45,50,55,60,65,70,75,80,85,90,95,100,120,150 & 200 hz
    That would be all anyone would ever need. Or a continuously variable crossover from 40 to 200 hz?
    I just think that if you measured the frequency response of your speakers and knew what it was, and then measured the frequency response of your subwoofer, all from the listening position(s), then you would be able to choose the most ideal crossover from the above settings.
    [Edited last by Chris PC on November 11, 2001 at 09:37 AM]
     
  8. BruceD

    BruceD Screenwriter

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    The problem with most THX bass management systems (IMO) is that they assume a speaker rolloff of 12dB per octave (main, center, and surround). This means a bass management filter of 12dB per octave (plus the 12dB rolloff is supposed to equal 24dB high-pass) and a low-pass for the sub-out of 24dB per octave.
    My problem with this is two-fold:
    1) Large phase differences with 12dB and 18dB filters.
    2) The 12dB speaker rolloff THX assumes is for a sealed speaker. How many of us use sealed? Not as many as use ported I bet.
    This means most of us will not get a true 24dB high-pass filter, but instead will probably get something much worse. This makes it very difficult to get good subwoofer integration.
    I much prefer a symmetrical 24dB Linkwitz-Riley crossover with zero (0) degree phase offset. IMO these make it much easier to blend a sub with other speakers.
    I wish all the manufacturers would just dump THX bass management and go to symmetrical 24dB Linkwitz-Riley, or at least offer it as an alternative (and let THX bass management die by itself).
    BruceD
    [Edited last by BruceD on November 11, 2001 at 01:02 PM]
    [Edited last by BruceD on November 11, 2001 at 01:03 PM]
    [Edited last by BruceD on November 11, 2001 at 01:04 PM]
    [Edited last by BruceD on November 11, 2001 at 08:32 PM]
     
  9. Chris PC

    Chris PC Producer

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    Good info. I thought, however, that a ported speaker rolled off even faster than a sealed speaker. Isn't that true? Either way, I believe 0 phase differences would be desirable too.
    Anyways, I think having user selectable crossover points is the only way to go. They have to make their receiver or pre-pro work with all kinds of speakers, subwoofers and rooms. How can one crossover frequency work for all that?
    [Edited last by Chris PC on November 11, 2001 at 04:52 PM]
     
  10. John Kotches

    John Kotches Cinematographer

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    Chris,
    The usual recommendation for setting a crossover frequency is to go one octave above the -3dB to insure linear frequency response through the first octave when dealing with non-THX spec speakers (which are designed for 80Hz L3 (-3dB point). So, in the case of a 30Hz -3dB speaker, the usual recommended crossover frequency is 60Hz. This allows for flat response through the first octave below the crossover. Below that, the contribution is essentially nil. This is especially true of a 12dB/octave crossover, which is the standard high pass crossover for main speakers.
    Rolloff from -3dB is 24dB/octave on a ported speakers, 12dB/octave on sealed speakers -- so you are correct on this point.
    My mains and surrounds have -3dB point of 35Hz, and I crossover with the ICBM @ 60Hz for both of them. My center has a -3dB point of 45Hz and I find 80Hz to be fine for this speaker. Have you worked with the ICBM, because it would seem based on your writing that you have not. The available choices 40,60,80,100 and 120Hz will be perfectly adequate for > 98% of all speakers installed in everyones system. It's a US$250 product, and you want an unrealistic feature set for a US$500 product. To do what you want, would require you to purchase dedicated stereo crossovers, and subwoofers with multiple unfiltered inputs.
    I've worked with (and reviewed) the ICBM and I can tell you that it is more than sufficient for any system which does not have full range speakers all around, for use between any analog output and input, be that preamp to amp, source to preamp or receiver or what have you. Hell, if you wanted to do a stereo crossover on the cheap, without sacrificing quality I wouldn't hesitate to offer this product as a solution.
    Would you mind expounding on your real world experiences with the ICBM which lead you to the statement that it has insufficient flexibility?
    Regards,
    ------------------
    John Kotches
    Contributing Writer
    Secrets of Home Theater and High Fidelity
    [Edited last by John Kotches on November 11, 2001 at 06:16 PM]
     
  11. Vietor

    Vietor Stunt Coordinator

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    Why would anyone need to cross over at something like 150 or 200 Hz?
    Wouldn't that be horribly directional? (fires up tone generator, YUP!)
    I mean if they are spending enough to get all the options, then there is no way they are going to have such crappulent speakers that they have a -3 dB point at 75-100 Hz.?
    It just seems to me like something that would never be used, Everything under the sun lower then 120Hz, yes, that would be great, a wonderful time sink!
     
  12. Chuck Kent

    Chuck Kent Supporting Actor

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    I agree with John.
    While having a large number of crossover points (like every 10 Hz or so) is great, 40, 60, 80, 100, 120 Hz (like that of the ICBM) is more than enough. I do agree that having a choice of different slopes would be a bonus.
    I have an ICBM. It is a wonderful piece of technology that really helps to achieve a good system setup.
    We may disagree that a crossover point every 20 Hz is too little or just right...Can we agree that the key thing here is finally having the ability to set more "appropriate" choices for each type of speaker being used? At long last manufacturers are providing the tools to give us the best bass we've ever had.
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  13. BruceD

    BruceD Screenwriter

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    John,
    Since I have never tried an ICBM, I took the side reference to it out of my response, as I was simply railing on THX bass management in general. I'm still very disatisfied with THX bass management available in many HT receivers and pre-pros. So much so that I use electronic xovers (symmetrical 24dB L-R ).
    Bruce
     
  14. Chris PC

    Chris PC Producer

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    No, I have not used the ICBM. I am making the comment that the ICBM and the 950 were at the leading edge of bass management and yet they skip the frequencies from 60 to 80 hz. I am only asking for more fine tuning ability. It seems that many people have front speakers with low frequency -3 dB points of between 30 and 40 hz. That corresponds to 60 and 80 hz. Using myself as an example, my fronts are ported and go to 32 hz -3 dB. I thought if I wanted to choose a crossover, I would want to try 32 x 2 or about 65 hz, or maybe 70 hz or 75 hz. All I'm saying is that some people find 80 hz too high and yet anything below 60 hz is only useful for people with fronts that go below 30 hz. I wanted to fill in the crossover points for the people who find 80 hz too high.
    I guess what you are telling me is that if 80 hz is too high, then 60 hz will work fine. I thought perhaps the more the better in terms of flexibility.
    If it really is too complicated to do 5 hz increments, then maybe to simplify, perhaps a crossover frequency of 70 hz is all you would need to add. Or just cover the same range below 100hz with 10hz increments, like 40,50,60,70,80,90,100 etc.
    I mentioned the 120,150 and 200 as an extreme example of accomodating people who use tiny cube speakers. Those are too high. I think the upper limit would be 120 hz. If you need higher, you need better front speakers.
    I'm not knocking the ICBM, its a solid unit from what I have heard and read. If I ever get an external amp for use in my system, I would seriously consider an ICBM to use between my pre/receiver and the amp. Either that or a crossover of some kind.
    We can all agree that the 950 and the ICBM are definitely showing the other manufacturers (apart from Sony, who already provides good flexible bass management) what they should be doing. Kudo's to Outlaw. I only hope the other manufactures will listen.
    [Edited last by Chris PC on November 11, 2001 at 09:35 PM]
     
  15. Sania M

    Sania M Agent

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    Ok, I am really stupid w/ XO's. Why would you not just set your crossover at 80 or 60 hz giving your receiver does that and send everything for each channel to the sub? Can your sub not handle that? It seems odd that the sub would be kicking in for your center channel below 60 hz, but it wouldn't kick in for your fronts until say 40. Therefore, at say 50 your sub and center would be sharing the bass?!? Correct if my logic is really flawed b/c I don't have that much real world experience w/ this. That just seems like the mixing of that bass would just cause more problems b/c you don't want to waste your fronts. Does this make sense? Is this the reason people have a sub for each speaker?
     
  16. John Kotches

    John Kotches Cinematographer

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    Chris,
    I'll ignore the fact that you have zero experience with either of these products, because if I don't I will be violating the standards of this forum.
    Instead, let's talk about what's between 60 and 80Hz for a minute on a musical basis. This is in what's considered the 2nd octave (40-80Hz).
    Between 60 and 80 Hz are 4 notes (D, Db, C and B). Do you really suppose that crossing over on or about one of these other pitches will make a substantial impact in the sound?
    Remember we are not talking about speaker crossovers here, we are discussing bass management, although the ICBM could easily be used as an active crossover.
    I will also point out to you, that adding additional frequencies increases the complexity of the product, and increases the cost. Making available additional frequencies means not hitting their intended price point. Then the product ceases to be a "high value" product, which defeats Outlaw's marketing objectives.
    Or alternatively, I'll say it like this: It would cost too much!
    I cannot make things simpler than that.
    Regards,
    ------------------
    John Kotches
    Contributing Writer
    Secrets of Home Theater and High Fidelity
     
  17. John Kotches

    John Kotches Cinematographer

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    Sania,
    We are talking about adding on Bass Management for DVD-Audio and Multi-Channel SACD players, neither of which have anything more than the most rudimentary bass management capability.
    Most receivers / processors cannot apply a crossover to these analog only signals either.
    The ICBM allows you to tailor the crossovers to several groupings of speakers.
    I think I cover this pretty thoroughly in my product review at Secrets of Home Theater and High Fidelity, on this page .
    Regards,
    ------------------
    John Kotches
    Contributing Writer
    Secrets of Home Theater and High Fidelity
     
  18. BruceD

    BruceD Screenwriter

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    John,
    I don't have your credentials, but where I tend to disagree with you (IMO) is that, because of different speakers and different rooms, it IS desireable to have as many crossover points as possible to accomodate these differences.
    Because there is so much variability in everyone's HT environment, one-size-fits-all crossovers are typically a very poor solution for accurate reproduction (especially for music).
    I found this to be very true by correlating my listening experience with MLS and FFT analysis of my speaker/crossover/room combinations.
    For me, the capability to smoothly integrate bass with other speakers (especially for music, less for HT) depends on optimizing the crossover points, crossover slopes, and the phase changes of the crossover with the speakers and room modes.
    All is IMHO.
    BruceD
     
  19. John Kotches

    John Kotches Cinematographer

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    Bruce,
    I understand your point, but it's always a tradeoff between features and street price when you're talking about delivering a product built with pricing constraints.
    Honestly, the difference between 80/70/60 and 80/60 is almost nil when dealing with the situation we are discussing, add-on bass management for DVD-A / SACD.
    Lest we forget, we are not trying to replace a loudspeakers crossover, we are trying to get equivalent (or better) bass management out of the ICBM than we are getting in our DVD-A/SACD/preamps/processors/receivers.
    Some fairly expensive products have less crossover options than the ICBM, so I don't really see the logic in this line of thinking, but certainly it is your opinion -- we just don't happen to agree on it [​IMG]
    Regards,
     
  20. Chris PC

    Chris PC Producer

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    Fair enough. Out of curiosity, what problems arise from using an infinitely variable crossover dial, between, say 50 and 100 hz? Cost? Phase problems?
     

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