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StephenM

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Posts posted by StephenM

  1. Trying to get not enough power to reach the spl you want can damage the speakers. The amp goes into more of a solid DC pattern in the wave form due to clipping of the signal, DC through the speaker coils cause them to get hot, very hot and they burn out.

    I'd recommend reading the above link regarding that topic.


    DC in Clipping

    One of the most famous myths
    regarding clipping is that it produces DC. The assumption is made
    because of the flat tops and bottoms to a square wave. It's incorrect to
    think of a squarewave as made up of positive and negative dc
    components. The only way for a it to be DC would be if there was a
    non-zero average value over long periods of time. If the polarity
    changes at all within the time frame that you are looking at, it is
    simply not DC. What are these flat portions of the signal? It is simply a
    combination of the fundamental frequency and all of it's higher order
    harmonics in sine wave form. For example, if you were to play a 20hz
    tone while clipping, there would be the fundamental frequency (ie. 20hz)
    and the second (40hz), third (80hz), and 4th (160hz) order harmonics.
    The sum of these frequencies creates what appears as a squarewave. There
    are two ways to test this for yourself; one is quite easy, the other is
    a little more advanced. The first way is simple if you have a variable
    crossover and an oscilloscope handy. Pass a low frequency square wave.
    You will notice the square shape on the oscilloscope. Now turn your
    crossover's low pass filter on. Slowly lower the setting as you approach
    the fundamental frequency. You will notice the waveform on your
    oscilloscope slowly rounding off into a typical sinewave. Once you have
    reached the fundamental frequency, your oscilloscope will show a perfect
    sinewave. The second way is for your math guys (or for those who like
    to use Matlab). If you look in the frequency domain using a Fast Fourier
    Transform, you will see the fundamental frequency and its higher order
    harmonics only. There will be absolutely no DC present.

  2. If an explosion happens that requires 140 watts and you only have 125 available, your amp will "clip" the signal so as not to hurt itself.

    Of course in that case, you could also just turn the volume down by 1dB (a barely perceptible amount) and also not clip. Conversely, if you turn up the volume another 3dB, you'll even clip a 200wpc amp.

    The result of the clipping actually can damage yor speaker.

    FWIW: http://billfitzmaurice.info/forum/viewtopic.php?t=1886

  3. a friend was saying I could damage my speaker if I put that much power into it.

    You can damage a speaker by putting too much power into it; however, just because an amplifier is rated for 5000 watts doesn't mean it's actually going to be pumping 5000 watts into your speakers all the time. The actual power flowing from the amplifier will be dependant upon the control volume, the variance of volume within the source signal, and how efficient your speakers are.

    Also no one has been able to tell me specifically what the advantages are and if I will notice a difference with my current speakers.

    The most pertinent differences are the additional power will allow you to turn up the volume a bit more without the amplifier distorting, and the ability to drive more difficult electrical loads. If you don't have reason to believe that you're pushing your current receiver hard, ie you've not noticed any significant audible distortion out of your system, it's unlikely that you will see a great difference simply from moving to an external amplifier.

    The key questions in discussing this topic are how sensitive are your speakers, how difficult are they to drive, how far do you sit from your speakers, and how loud do you like to listen.

    Your current (and your future upgrade) speakers are all reasonably sensitive. I do not know with certainly how difficult your current speakers are to drive, although if you've got no major complaints about current performance, then they probably aren't overly difficult. The RF-7II and RC-64II are likely to be fairly difficult to drive. The last two items make a huge difference. If you're sitting 16 feet from your speakers, you will need 4X the power as if you were sitting 8 feet from them. If you listen at reference level (105dB peaks, 85dB average from satellite channels) you need 10X the power than if you listen at -10dB from reference, and 100X the power than if you listen at -20dB from reference. As you might guess from these figures, there isn't a great difference in terms of volume between 100 watts and 200 watts. It's a grand total of 3dB, which is noticable, but not overly significant.

  4. I am guessing he meant the inconsistant, skewed, misleading wattage specs that the mass market AVR companies publish.

    Unfortunately, that's one of the realities of a market where consumers expect 100 watts per channel, even if it only represents a relatively insignificant 3dB over 50 watts per channel. Still though, not sure why he changed his mind over that. The only things that should matter are if it gets loud enough for your purposes and if it sounds good. Sounded like SQ wasn't an issue, although perhaps he wanted to really crank his system.

  5. Having been on this board more than a week now, I've seen the regular suggestions of horn loaded subs. To satisfy my curiosity, I did peruse some measurements of a couple models, one DIY, and the other the vaunted Danley DTS-10. While the output was most impressive for both models, I did note an interesting anomaly:

    The DIY horn sub:

    http://www.data-bass.com/images/measurements/42/E%20gjallerhorn%20waterfall.jpg

    The Danley DTS-10

    http://www.data-bass.com/images/measurements/29/E%20dts10%20waterfall.jpg

    That's some pretty significant resonant activity. Here's a couple more conventional subs for reference:

    SVS PB13U, 20Hz mode

    http://www.data-bass.com/images/measurements/53/B%20svs%20pb13%20ultra%2020hz%20waterfall.jpg

    SVS PB13U, Sealed mode

    http://www.data-bass.com/images/measurements/57/B%20pb13%20sealed%20waterfall.jpg

    Velo DD18+

    http://www.data-bass.com/images/measurements/68/B%20dd18%2B%20servo%20gain%208%20waterfall.jpg

    Is this a recognized drawback of horn loaded subs? What causes this behavior?

  6. From what I've read, the Captivator is supposed to be a beast, but I've not seen any measurements on it to confirm. I would assume given that it is a fairly large ported subwoofer, it should outperform the two sealed models at the 20Hz mark.

    Anything you want to know about the Empire is right here:

    http://www.data-bass.com/data?page=system&id=50&mset=48

    Don't have much objective data on the Craigsub either, though if we take their specs at face value, it would appear to be on par with the Empire.

    Another option I'd throw out there:

    http://www.data-bass.com/data?page=system&id=51

    It would expect it would have no trouble meeting your requirements as well, with a good bit more output than the Empire can muster down low.

  7. They must feel that spending more on the Heresy would not yield them a reasonable return.

    Well I figured that much. But I'm questioning if they feel it is a matter of "too much money" (which I find hard to believe at this price point) or just that there simply isn't much to improve upon.

    If you truly want to appreciate the manufacturing side of things start a company of your own and find out for yourself.

    Nah, I'm satisfied with the products Klipsch puts out. That's why I keep buying em!

  8. Like I said you can't scratch your back for a few bucks in manufacturing. Seemingly small changes can and often do end up costing a lot more than you would imagine.

    Do tell. I've seen some pictures of the production process of a Cornwall and I'd expect that of the Heresy isn't much different. Given that we're not really talking about retooling a mechanized assembly line so much as adding another step in the hand crafted production process, how much do you figure it'd add to the price tag of a Heresy to add some basic bracing?

  9. It is the human ear which should make the final design decission not the measurement device.

    In this regard, I leave you with one last thought: "You can't make what you can't measure because you don't know when you've got it made."

    Hollow square (ish) boxes make bad speaker cabinets. To say otherwise is wrong.

    They are not necessarily ideal, but as you say:

    it did a reasonable job then and it still does today

    So out of curiosity, why do you suppose Klipsch wouldn't include some bracing in the Heresy III. In a review at Audioholics a little while back, even a $300 bookshelf model, the RB-15, had a shelf brace and foam lining. I find it hard to believe that Klipsch is penny pinching on a model selling for 5x more.
  10. Measurements do not tell the whole story.

    They may not tell the whole story, but they do tell quite a bit. They're also considerably more accurate and less biased than human ears.

    you seem to be expecting me to believe that this is a mechanically sound engineering design.

    It doesn't matter whether you believe it or not. The Heresy is a decades old speaker that remains fairly popular to this day. That alone is a testament to the quality of sound it produces and correspondingly, the engineering behind the speaker itself.

    Can we simply agree to diagree here?

    Not a problem. Looks like the OP is setting upon his quest one way or another.

  11. At various times, I've had my system hooked up to a standard point of service surge protector, an APC UPS, and currently to an APC C10 surge protector/line conditioner I picked up for a whopping $30 when they were getting blown out by Tiger Direct.

    Aside from looking nifty, I've noticed no tangible improvements.

  12. If you want you can go on line and use a free box response simulation program and see for yourself.

    Surprisingly, simulations and reality do on occasion differ...

    They just cannot throw a few extra dollars at products.

    Come on, we're not talking about Insignia speakers here. If the engineers at Klipsch felt the Heresy could have significantly benefited from bracing, they'd be braced, and they could tack on an extra $50 a pair. They'd still be a bargain compared to the next expensive Heritage product.

  13. If the Op reads and asks questions and follows his ear there is no reason that he cannot end up with a fine sounding set of speakers and quite possibly a better set than what he started with.

    A. The OP already has a pair of fine sounding speakers. He has expressed no dissatisfaction with the sound, only that the internal parts do not appear to be fancy.

    B. How much money should he sink to "possibly" get a better set than what he started with?

    I don't have to measure a thing to know this.

    If you haven't measured, then you don't actually KNOW anything.

    If I install brace work which stops or reduces my cabinet distortion and as a result of the slight cabinet volume reduction my 2 db down point shifts up lets say 5 Hz. so what?

    You have no idea how much cabinet distortion there was in the first place because you never measured it. You have no idea how far your 2dB down point shifts because you didn't measure it. You don't know how changing the volume impacts other distortion because you didn't measure it.

    Are you actually measuring the internal volume and the wood used for the brace work to know its only a 10% change or less, or are you just winging it?

    I don't see why you seem to think that making physical changes to a cabinet is some sort of insult to Klipsch or that Klipsch are the only competitent people capable of building a box.

    I don't think the engineers at Klipsch are the only folks capable of designing a speaker. But there is no doubt in my mind that they have far greater resources at their disposal than you or I do for designing and actually testing their work.

  14. I would like to see flex measurements, but the measurement equipment to see the flex of the cabinet walls would be rather expensive, involving mirrors, lasers, a nice lab, etc.

    While I won't claim to be an expert on the subject, afaik, the tool needed to measure the pertinent cabinet resonance would be something like the plastic-tape accelerometer that Stereophile uses.

    http://search.digikey.com/us/en/products/1-1001220-0/MSP1001-ND/279641

    Of course, I presume it isn't just as simple as plugging it in and getting a nice graph like Stereophile gets either.

  15. I don't see any reason for anybody not to build an upgraded crossover.

    It's no sweat off my back either way. I just think its a waste of time if he has little or no idea what he's doing. I'd trust the results of a competent engineer working with inexpensive but effective parts over a guy who doesn't have a clue picking parts at random off a shelf based on cost and shininess.

    A shift of 10% cabinet volume for brace material is no big deal.

    Considering that you haven't measured anything you've done, I have to take this with a big grain of salt. You might like the results, but if you're not measuring anything, you don't really know what is happening and how big of a deal it may or may not be to someone else.

    It's not tinkering it's finishing the job that did not get finished for what ever reason.

    Of course its tinkering. Klipsch isn't some halfassed outfit selling junk, and the Heresy is hardly a poorly engineered bargain basement speaker.The Heresy III is a well engineered and finely crafted $1700 speaker from what is indisputably one of the greatest speaker manufacturers in the world. If a couple dollars of extra bracing would have resulted in a great improvement in sound, there is little doubt in my mind they would have included it.

    One other question for you moray: what is your experience with the Heresy III?

  16. That said these are by no stretch of the imagination SOTA parts so there is no reason not to upgrade and expect improvements in performance.

    I'd have to disagree. You may well get different, but there is no guarantee different will be better, especially when one considers that Heresy III is (reasonably well) engineered to work around the parts that are in it, versus this guy potentially selecting parts because they cost a lot and look fancy.
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