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LFE frequency range

Discussion in 'Home Cinema Speakers' started by Dr.Rock, Jul 27, 2002.

  1. Dr.Rock

    Dr.Rock
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    My old B&W "Solid range" PowerBass Subwoofer goes down to 38Hz at -3dB.

    I was wondering whether to keep it or go for a new one. What sort of frequency range should we aim for, to get all the LFE for films?

    Thanks.
     
  2. Jase

    Jase
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    Hi

    The LFE channel has bass from 0 - 120Hz. I would have thought a sub that goes to at least 20/25hz +/- 3db should do the trick. Of course there are others that go lower but you´re starting to talk about a lot of money.
     
  3. Ian J

    Ian J
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    I agree with Jase but bear in mind that some manufacturers are a little economical with the truth on their statistics.

    My Storm goes down to 25Hz which gives a satisfying bass without endangering the windows or ornaments.
     
  4. Dr.Rock

    Dr.Rock
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    Thanks for the infos.

    What frequency Is 20dB what the LFE channel in films usually go down to, or are they known to go down even lower than that?
     
  5. Jase

    Jase
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    Some films have bass that is very low (U571 has it down to 5hz!). The Phantom Menace also has some very low bass as well.

    Have a look HERE for some films with great bass.:)
     
  6. Stuart Wright

    Stuart Wright
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    Jase - you're wrong - the official specification is 20Hz to 120Hz.
    In any case a subwoofer which only goes down to 38 Hz is seriously lacking IMO.
    You want something which easily goes down reasonably flat to 20Hz.
    Problem is that this usually means serious money.
     
  7. Charlie Whitehouse

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    Sorry to quibble Spectre, but Dolby's own document 5.1-Channel Production Guidelines, Section 1.2 states "Dolby Digital bitstreams deliver full frequency bandwidth main channels, from 3Hz to 20kHz, and a limited frequency bandwidth LFE channel, from 3Hz to 120Hz." What it doesn't state is whether these are the -3dB down points or whether it's flat between these limits.

    Also, of note, according to the tests I did last year on frequency response of DD & DTS, U571 does indeed have bass going down to 5Hz on both DD & DTS versions (and actually a bit lower!), but interestingly much of this is not in the LFE channel, it is present in the main channels and gets routed to the sub via bass management. Another reason for not setting all your speakers to large ! But that's a different argument ! ;)
     
  8. Dr.Rock

    Dr.Rock
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    I looked at the Yamaha site and read the specs for the YSTW320 subwoofer, which What HiFi and other reviewers highly recommend. This sub goes down to 40Hz, according to the specs. Does that mean that this sub isn't necessarily as good as the old one I already have, if I'm considering a change? Or is the sub still capable of outputting bass at 20Hz?

    Thanks.
     
  9. Ian J

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    If the sub only goes down to 40Hz it won't be much better (if at all) than the one you already have.

    The difference between 20Hz and 40Hz is the difference between a slight raising of the corner of the mouth and a big grin when listening to films with a lot of LFE content.

    Listening to U571 on my old Q Bass bought a smile to my face. Listening again on my Storm brings a big grin whilst listening to the same piece on Uncle Eric's twin Q100s brought a mixture of grin and fright. I understand that listening to his new big monster necessitates a change of underwear.

    It is all a combination of depth and power and the more deeper and powerful the sub goes, the more money it will cost.

    Getting back to the real world, have you looked at the Velodynes offered at £325 in the Power Buyers Forum.
     
  10. Stuart Wright

    Stuart Wright
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    Charlie and all - in that case Dolby have 'upgraded' their specifications since I last read them. And I stand corrected.

    Ian and Dr Rock, the Yamaha 'could' be better depending on what your definition of 'better' is. It could have a much better driver and amp in there.
    But at the end of the day, you should look for a subwoofer which has it's lowest frequency quoted in the ower 20s.
     
  11. uncle eric

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    Charlie,
    For this and other reasons, I use a BMC 5.1

    www.mkprofessional.com/bass_mgmt2.html

    Eric
     
  12. Charlie Whitehouse

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    Looks good Eric! I'm fortunate that I can do most of this already (and maybe some more!) in the Casablanca, but for those with more mainstream amps and receivers, it could be a good solution, particularly for those that have models that have been shown recently to struggle combining BM & LFE without distortion.

    Does this go between DVD player and amp 5.1 input only? Or does it have enough output to drive active speakers / power amplifiers? Does it operate in digital or analogue domain?

    Anyway, I've got the 'ump at the moment! I was quite happy with my REL Stentor II until you lot started singing the virtues of servo control. That HGS18 is starting to sound tempting. :( :D
     
  13. Jase

    Jase
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    :blush: oops! Only 3hz out!;) :D
     
  14. Brox

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    If I loved in a detached house i'd be looking for a sub that goes down to 20 htz, however I don't so i'll make do with my Kef 20b that goes down to 36htz without any boundary reinforcemnt.

    I did listen to a Rel 150 as I wanted a sub that goes deeper - but i felt it was a bit fatigueing as it didn't integrate very well with the other speakers, and I felt the neighbours would hear too much.

    To be honest though all I ever hear about with subwoofers is outright depth as if that all there is - it seems to me its the AV equivalent of saying your hi fi goes loudest, or has nore flashing lights on it!
     
  15. Ian J

    Ian J
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    :D :) :D
     
  16. MikeK

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    True, but in the spirit of high fidelity sound reproduction, if a soundtrack has 20Hz (or lower) components in it, then ideally it would be nice if a hifi/AV system reproduced that.

    With subwoofers though, it's not especially easy to do.
    I certainly wouldn't rely too much on manufacturers figures.
    Manufacturers have been known to "cook" the figures a little bit (and that's being kind in some cases). They sometimes quote f6 or even f10 figures (without qualification), and they sometimes quote "typical in room response" - if the figures for different models aren't all measured the same way under the same conditions, then they become a bit meaningless. You've no way to know if one manufacturer's typical room is the same as another.
    Also, they know that some people will buy based on these figures - so as well as the tricks above, they actually design the product to look good on a spec sheet, which often leads to very significant design compromises in the system as a whole.
    You can design a "very cheap to produce" subwoofer with a very low f10 figure - doesn't mean that it will sound good in action though!

    There seems to be a preconception that a sub quoted at say 20Hz will be better than one quoted at 30Hz. It may be, but there's a lot more to it than that, and "may be" doesn't always translate into "will be".

    Think about what the figure is actually telling you!
    In reality, in many cases, it's not much!

    The ideal sub would have a flat response from it's upper level (usually 80-120Hz for AV systems) down to 20Hz or lower, but this isn't as easy to achieve as it sounds, especially with the enclosure sizes many people want. It requires very careful design, using good quality components and it will also most likely require the application of EQ at the lower frequencies, and this is not easy to do properly either. The smaller the enclosure, the harder it gets - eventually as you get smaller it simply becomes almost impossible. In that case, you'd be far better designing for flat response to say 30Hz or even 35Hz and just accepting that the bottom half octave or so isn't realistically possible in such a small enclosure (which usually means a small driver as well).

    One thing is certain - the cheap little subs with 70W amps and 8" drivers, in enclosures less than 1cuft, simply won't do it, no matter what the manufacturer claims. Doesn't necessarily mean they are crap, but you just have to have realistic expectations.
     
  17. Reiner

    Reiner
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    To be honest though all I ever hear about with subwoofers is outright depth as if that all there is - it seems to me its the AV equivalent of saying your hi fi goes loudest, or has nore flashing lights on it!

    Not the same me thinks: we are talking about a value and level corresponding to the frequency response and thus a sub which cannot fullfil the requirements is either unsuitable or a compromise (depending on the budget for example).
    Naturally you want a sub to cover the entire frequency range - or would you buy a hifi speaker which goes up to e.g. 12kHz only?

    Besides, nobody here is bragging about his sub, we are just trying to answer the questions accurately and trying to give you the best and correct advise.
     

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