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Thread: Sierras, thumbs up up up up up!!!!

  1. #11

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    Unknowledgeable Person Warning (i.e. go easy on me):

    I thought (quality) speakers had built-in protections against frequencies that are too low (or high). I assumed this was part of the job of the cross-over circuitry.
    So, is there really a danger at running a speaker like the Sierra as full range?


    Mitch

  2. #12
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    It is not so much running the speaker fullrange, you can do that with any speaker.

    The problem occurs with turning up the volume high and the speaker receiving signals that push the drivers to over excursion. Also, having an amp/receiver that is not up to par, can cause it to clip at high volumes, and thus damaging the speaker.
    -curtis

  3. #13
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    I emailed the local A/V shop owner and asked him what his favorite bookshelves were, price no factor, and that mziegler and I wanted to compare.

    He came back with this:

    have a few that i really like:

    the dali helicon 300 (but you have to have enough space to let the tweeter breath)
    the kef reference 201/2 (havent heard it yet, but i expect it to be fantastic)
    usher is releasing a bookshelve with the beryllium tweeter. i have this on order.

    you may borrow any, or spend time in the store listening.
    So when time permits, we are going to try and set this up.
    -curtis

  4. #14

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    Curtis' answer is exactly right, and just to add to what he said, with movie soundtracks playing at their full dynamic range, you'd have to turn the volume up high enough to hear the dialogue when characters are whispering, and that's when the mighty LFE channel can potentially damage your speakers while running full-range (the main channels are also quite dynamic--much more than you'd get from an audio CD, depending on the movie). I don't mean to be an alarmist, but amid the excitement over what the Sierra-1 can do, I don't want people to blow out their new speakers by playing bass-heavy movie DVDs at full range and volume. More likely than not, it would be the amps that would fail first, sending a highly clipped signal or a huge DC current that could fry any speaker.

    The choice of the frequency at which to cross over to your sub is not based only on what frequency range your speakers can handle (which is important), but also the total amount of bass that it can reproduce with adequate volume and safety. Obviously, as this frequency goes up, more of the bass will be diverted away from the speakers and to the subwoofer. At the same time, the lower the crossover frequency your speakers can handle, the better the quality of the resulting bass will be, albeit only to a point. Dave himself had suggested a 60 Hz crossover frequency for music (if you need a sub at all, like for organ music), and I've been suggesting that people at least try out slightly higher frequencies for movies that have wicked levels of bass (although 60 Hz may be perfect given the Sierra-1's considerable capabilities--there's only one way to find out and that is to experiment).

  5. #15
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    Actually, that brings up a question or two.

    If you have no sub in your system....ie. sub=no, does the LFE(.1) channel get directed to the mains?

    If you do have a sub....ie. sub=yes, speakers set to large, what does the spec say in terms of the recording....what is the frequency range sent to the mains, and for the sub?

    I had thought the FR for the sub was 120hz and below, but I have never read anything about the guidelines for the mains.
    -curtis

  6. #16
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    yeh... whenever all this talk of blowing out speakers with bass-heavy movie soundtracks comes up i get really scared. since i don't own a sub yet, i have my speakers set to large all around with the low frequencies being sent to the front speakers (just the mains, according to the on-screen display of my receiver). i haven't had any problems yet, but these threads always make me worried i am screwing up my speakers...
    CMT-340SE Mains & Center, CBM-170SE Surrounds, Rythmik F15, Yamaha RX-V2400, Emotiva XPA-5, Samsung LN52A650, Sony CDP-CA70ES, Numark TT-200, JVC TD-W103, XBox 360, PS3, Wii

  7. #17
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    Bottom line.......if you like to watch bass heavy movies at high SPL's do your Ascends a favor and run them "small", get a decent sub and cross at 60, 80 or 100hz (whatever floats your boat).
    L/R - Sierra Towers
    Center - Sierra Horizon Tower
    Surrounds - 200SE
    SW - Dual PSA XV15's
    TV - Panasonic TC-P65VT60
    A/V Receiver - Denon AVR-4311CI
    Blu-ray/DVD - Sony BDP-S5100
    DVR STB - Motorola Arris X1

  8. #18

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    Quote Originally Posted by curtis
    If you have no sub in your system....ie. sub=no, does the LFE(.1) channel get directed to the mains?
    That's a good question, and the broadest answer is that the standard is flexible with regard to bass management (typical ), and that most AVRs (certainly the ones with which I'm familiar) will mix at least some of the LFE into either the front left and right speakers or possibly divide it up amongst all speakers set to Large. Here is what the ATSC A/52 (Dolby Digital) standard actually says:

    Downmixing of the lfe channel is optional. An ideal downmix would have the lfe channel reproduce at an acoustic level of +10 dB with respect to the left and right channels. Since the inclusion of this channel is optional, any downmix coefficient may be used in practice. Care should be taken to assure that loudspeakers are not overdriven by the full scale low frequency content of the lfe channel.

    That's probably not a very satisfying answer, but it is what it is. To take one example, my Denon receiver, like many others, allows the user to set the LFE mix level (-10 to 0 dB plus the standard +10), which also affects how much LFE makes it into the front left and right speakers in the absence of an externally powered subwoofer. I'm not absolutely sure whether the LFE signal is automatically attenuated by some amount in order to prevent overload when downmixing to 5.0, but it sure seemed to all be there when I've played with that configuration. This may not be true for all receivers, by the way.

    Including the LFE in 2.0 downmixes, as opposed to 5.0, is likewise considered optional, but in practice it is virtually always left out entirely (I have yet to see an exception to this rule in consumer electronics).

    Quote Originally Posted by curtis
    If you do have a sub....ie. sub=yes, speakers set to large, what does the spec say in terms of the recording....what is the frequency range sent to the mains, and for the sub?
    The spec makes a lot of sensible, logical suggestions but dictates very little with regard to reproduction. The receiver is free to send pretty much whatever it wants to the mains, within reason, and the meanings of the settings vary among different makes and models; some even allow you to send the combined signal intended for the sub to the mains in addition to their own full-range DD channels.

    Regarding the encoded soundtrack itself, all of the channels should be high-pass filtered at 3 Hz, and the LFE channel should be low-pass filtered (eighth-order elliptic) at 120 Hz. In practice, Dolby's encoder will also low-pass filter the five main channels at 20 kHz when the bitrate is 448 kb/s (DVD), 18 kHz when it's 384 kb/s (DVD and LD), and 15 kHz when it's 320 kb/s (commercial theaters); additionally, mixers avoid using the frequency range 80-120 Hz in the LFE channel because most receivers will low-pass filter the subwoofer output at the crossover frequency, potentially throwing out this information anyway.

    Quote Originally Posted by curtis
    I had thought the FR for the sub was 120hz and below, but I have never read anything about the guidelines for the mains.
    The main channels are all full range: from 3 Hz to 20 kHz. However, the LFE channel, as noted earlier, ideally (according to Dolby) has twice the power of all of them combined from 3 Hz to 120 Hz (80 Hz in practice).

    Quote Originally Posted by drewface
    yeh... whenever all this talk of blowing out speakers with bass-heavy movie soundtracks comes up i get really scared.
    Note that I'm trying really hard not to spread disinformation and undue paranoia here. We don't hear about people blowing up their speakers constantly, so it's not likely to happen under most circumstances (although it can and does occasionally). I just want everyone to be careful and use some common sense instead of getting carried away with pushing the limits of their new speakers. For example, if the speakers begin distorting or the amps begin clipping just as a scene is about to get even louder, then for God's sake, reduce the volume right away!

    Quote Originally Posted by drewface
    since i don't own a sub yet, i have my speakers set to large all around with the low frequencies being sent to the front speakers (just the mains, according to the on-screen display of my receiver). i haven't had any problems yet, but these threads always make me worried i am screwing up my speakers...
    Some people have even damaged their subwoofers by driving them too hard, and unfortunately it's difficult to offer any concrete guidelines because there is so much variation between movies, preferred listening levels, bass management schemes, and so forth. Don't worry so much that you can't enjoy your speakers--just pick the "bassiest" scene you know of, replay it repeatedly as you gradually increase the volume each time to determine what the limits (if any) are, make some adjustments on your receiver (e.g. LFE level, dynamic range compression) if necessary, and let fate take care of the rest.

    Quote Originally Posted by Gov
    Bottom line.......if you like to watch bass heavy movies at high SPL's do your Ascends a favor and run them "small", get a decent sub and cross at 60, 80 or 100hz (whatever floats your boat).
    Great advice, Gov, although I just remembered another reason I like to cross over at 80 Hz for movies (alluded to above): most AVRs stupidly low-pass filter the subwoofer pre-out at the crossover frequency, which means that you could lose some of the LFE signal from the crossover frequency to 80 Hz.

    The bottom-bottom line is that if you want accurate and complete reproduction of movie soundtracks, you must have a full 5.1 (or 6.1 or 7.1) system, a bass management crossover frequency of 80 Hz or higher (80 Hz is best), speakers that are all capable of being crossed over at this frequency, and a subwoofer that digs down to 10 Hz if possible (20 Hz is a more practical goal to shoot for in most cases). Anything else would leave you at the whim of many variable, uncontrollable, often unknowable factors from many different sources.

    Geez, if ignorance is bliss, then it seems that all I ever do is spread misery.

  9. #19
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    Curtis,

    I am really interested in your opinion crossing the Sierra's at 80hz (small) with a sub for music and movies. I am wondering just how much better (if at all) they are compared to the 340SE's in that roll.
    L/R - Sierra Towers
    Center - Sierra Horizon Tower
    Surrounds - 200SE
    SW - Dual PSA XV15's
    TV - Panasonic TC-P65VT60
    A/V Receiver - Denon AVR-4311CI
    Blu-ray/DVD - Sony BDP-S5100
    DVR STB - Motorola Arris X1

  10. #20

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    Quote Originally Posted by Dread Pirate Robert
    most AVRs stupidly low-pass filter the subwoofer pre-out at the crossover frequency, which means that you could lose some of the LFE signal from the crossover frequency to 80 Hz.
    Note that I said "most AVRs"--some do this right, and if yours has independent crossover settings for each speaker or type of speaker, then it's a pretty safe bet that you can set your crossover lower than 80 Hz without missing out on any of the LFE signal.

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