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Thread: sound quality varies with carpet or hardwood?

  1. #31
    Administrator Robh3606's Avatar
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    Compared to concrete it might as well be cardboard. However it doesn't matter, yours is still an apples to oranges comparison. Strange your not grasping it.
    There is nothing to grasp the primary excitation of resonances is through the air not the cabinet. You should take a couple of minutes and look at a couple of speaker reviews and see just how much energy is being radiated by the cabinets by looking at the accelerometer plots from the cabinets. If there is anything it is typically high Q and no where near the energy from the drivers.
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  2. #32
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    Quote Originally Posted by Robh3606 View Post
    There is nothing to grasp the primary excitation of resonances is through the air not the cabinet. You should take a couple of minutes and look at a couple of speaker reviews and see just how much energy is being radiated by the cabinets by looking at the accelerometer plots from the cabinets. If there is anything it is typically high Q and no where near the energy from the drivers.
    I do not refute your position, however you have not yet addressed the issue I brought up. You're still talking apples and oranges. You've missed something while reading. I suggest you reread the thread. At least my interaction

  3. #33
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    Quote Originally Posted by gasfan View Post
    Post#22

    The point of contention is what percentage of over all resonance is influenced by this parameter. IMO it's large.
    Okay. On concrete floors (no carpet) a small percentage compared to the radiation from the cone and port (air movement). But that is a general statement. On a timber floor see below:

    But this is the thing. I think the apples and oranges is about the loudspeaker in question and the timber floor under discussion.

    For example a tall tower loudspeaker (which l own) with the woofer(s) near the top of the enclosure and a small foot print is going to benefit from the stabilising influence of spikes particularly on carpet as opposed to decoupling from a floor.

    On the other hand a heavy lowboy enclosure with a much larger foot print with the large woofer closer to the floor is going to react differently with direct contact with the floor. It’s like bolting large panel of timber to the bottom side of the enclosure so it becomes an extension of the enclosure. Depending on the density and stiffness of the panel (the floor) it’s going move independently of the enclosure at certain frequencies and transmit other frequencies already absorbed by the enclosure walls.

    That said not all loudspeakers are constructed equally. The actual mass of the loudspeaker, the stiffness and density of the enclosure walls is also a key factor concerning actual vibration of the enclosure down into the floor as in the explanation above. The term boom box comes to mind where thin unbraced particle board enclosure walls are used.

    But not all timber floors are the same. Timber floors were once hardwood. These days they are tongue and groove particle board. Hardwood is iikely a stiffer floor. If you ever jumped up and down on a particle board floor it makes a like a boom. In comparison a concrete floor typically a waffle slab you don’t hear or feel anything

  4. #34
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    Quote Originally Posted by Ian Mackenzie View Post
    Okay. On concrete floors (no carpet) a small percentage compared to the radiation from the cone and port (air movement). But that is a general statement. On a timber floor see below:

    But this is the thing. I think the apples and oranges is about the loudspeaker in question and the timber floor under discussion.

    For example a tall tower loudspeaker (which l own) with the woofer(s) near the top of the enclosure and a small foot print is going to benefit from the stabilising influence of spikes particularly on carpet as opposed to decoupling from a floor.

    On the other hand a heavy lowboy enclosure with a much larger foot print with the large woofer closer to the floor is going to react differently with direct contact with the floor. It’s like bolting large panel of timber to the bottom side of the enclosure so it becomes an extension of the enclosure. Depending on the density and stiffness of the panel (the floor) it’s going move independently of the enclosure at certain frequencies and transmit other frequencies already absorbed by the enclosure walls.

    That said not all loudspeakers are constructed equally. The actual mass of the loudspeaker, the stiffness and density of the enclosure walls is also a key factor concerning actual vibration of the enclosure down into the floor as in the explanation above. The term boom box comes to mind where thin unbraced particle board enclosure walls are used.

    But not all timber floors are the same. Timber floors were once hardwood. These days they are tongue and groove particle board. Hardwood is iikely a stiffer floor. If you ever jumped up and down on a particle board floor it makes a like a boom. In comparison a concrete floor typically a waffle slab you don’t hear or feel anything
    The gist of my argument is that decoupling/isolation is a benefit to sq over and above attaching the speaker to the room, period, regardless to how well the speaker is attached. Fully isolated yields the best most coherent accurate transparent sq. Achieving it fully is a different topic, albeit possible. We know attaching the speaker is no problem. The undisputed fact that there is an influence to sq in coupling the speaker to the floor affirms my position.

    It's the notion that there is an incidental benefit to transient performance that gives strength to the argument of coupling in some respect. I say that's bullshit. Even Greg Timbers made it clear spiking was about the issue of uneven substrate causing rocking to occurr. He stopped short of declaring cab movement caused by the drivers alone would compromise performance. How fast does a cone move? How fast is a 30hz tone? How fast is a 30hz transient? All said and done by the time the cab knows what happened. At most, speaker sensitivity is what is affected. How much is measurable for any given system.

  5. #35
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    Can you provide your explanation or reasoning on your argument to de coupling benefits?

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    Quote Originally Posted by Ian Mackenzie View Post
    Can you provide your explanation or reasoning on your argument to de coupling benefits?
    My post #6 pretty well explains my experience. Instead of mostly feeling the subs, I now mostly hear them. I now only feel resonance in my feet when they're at concert hall level even though I've turned them way up. I "hear" every note. Spikes fool you into thinking transients are better when "boom" begins. It won't be expensive to prove me wrong in any case if you do the experiment.

  7. #37
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    Quote Originally Posted by gasfan View Post
    Coupling the speakers to the floor just causes the building to add it's own response to the spectrum excited by the speakers. There is no advantage to transient performance by doing so. The speed of the cones renders the issue moot. What happens is some frequencies are boosted, muddying others with the net result being just boom. The best way to place speakers is to do the opposite and decouple them. Now you get the flattest performance with good bottom end definition. Directly flat on the carpet doesn't work because they're now using the floor as a sound board which is even worse. There are expensive devices/products that are designed to decouple. I just use soft 1" thick 12"X18" fiber pads used for floor polishers from Home Depot with a 1/4" rubber mat between it and the speaker. They absorb virtually everything, the floor does not vibrate at all. The large 12X18 pad takes a lot of weight spread evenly over it. A stiff board placed on top might be needed if your speakers have a small foot print. I currently have my two Velodyne subs on this set up. The difference is quite dramatic. This is at least a very cheap experiment I would encourage all to try. You may be pleasantly surprised.

    This set up is also very beneficial under your tube gear.Attachment 82588
    Okay

    Looking at your image in post 6 what you seen to have is the sub sitting on the pad which is raised over the floor by a support of some kind.

    Can you post a wider angle image?

    What you have done appears to involve more than what you have described?

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    Perhaps it’s also useful to clarify when we are just referring to a sub and when referring to a full range loudspeaker.

    I full range loudspeaker by virtue of radiating mid range frequencies may have more clarity without direct surface contact with a timber floor where vibration courts between the surface of the enclosure and the floor.

    I don’t own a Velodyn sub so l cannot comment on your assertion.

  9. #39
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    Quote Originally Posted by Ian Mackenzie View Post
    Perhaps it’s also useful to clarify when we are just referring to a sub and when referring to a full range loudspeaker.

    I full range loudspeaker by virtue of radiating mid range frequencies may have more clarity without direct surface contact with a timber floor where vibration courts between the surface of the enclosure and the floor.

    I don’t own a Velodyn sub so l cannot comment on your assertion.
    Sure, one confirms the other incrementally. Remove the subs and it's anybody's guess. When they're playing they may as well be attached to the mains.

  10. #40
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    Assuming what you say is true the possible explanations lies in the case of your Velodye Sub exhibiting enough low frequency energy to vibrate against your floor regardless of using spikes or feet of some sort.

    Being the case where a small low mass enclosure is radiating enough bass energy then that is to be expected.

    In comparison a heavy JBL like a 4645 the significant mass on the enclosure on the floor via feet or spikes may acts to damp spurious vibrations caused be the acoustic output of the 2245 driver and ports.

    What this means is it’s most likely a case by case situation rather than one observation applying to all loudspeakers and floors.

    I am surprised that your Velodyne sub shakes and rattles to the point you need to put pads under it!(Lol)

    As an experiment you could try mass loading the sub with a few concrete slabs on top of it and evaluate any change?

  11. #41
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    Quote Originally Posted by Ian Mackenzie View Post
    Assuming what you say is true the possible explanations lies in the case of your Velodye Sub exhibiting enough low frequency energy to vibrate against your floor regardless of using spikes or feet of some sort.

    Being the case where a small low mass enclosure is radiating enough bass energy then that is to be expected.

    In comparison a heavy JBL like a 4645 the significant mass on the enclosure on the floor via feet or spikes may acts to damp spurious vibrations caused be the acoustic output of the 2245 driver and ports.

    What this means is it’s most likely a case by case situation rather than one observation applying to all loudspeakers and floors.

    I am surprised that your Velodyne sub shakes and rattles to the point you need to put pads under it!(Lol)

    As an experiment you could try mass loading the sub with a few concrete slabs on top of it and evaluate any change?
    Well okay, in that case I'll get my ass in gear and build those 2269 subs to integrate with my Acoustat Monitor 3 and see what happens. The Velodynes are actually quite rigid. But with an 18X14.5 foot print, they couple to the floor well. The way I have them set up, they work.

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    Please take my posts not too seriously but more as light entertainment to relieve an otherwise boring uneventful day.

    Some trivia.
    My writing style has been compared to this American writer. https://en.m.wikipedia.org/wiki/William_T._Vollmann
    I take this as a compliment but draw the distinction at not being a cross dresser as noted in the above link.

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    Quote Originally Posted by gasfan View Post
    Well okay, in that case I'll get my ass in gear and build those 2269 subs to integrate with my Acoustat Monitor 3 and see what happens. The Velodynes are actually quite rigid. But with an 18X14.5 foot print, they couple to the floor well. The way I have them set up, they work.
    That is all that counts.
    Please keep us informed on your future plans.

  14. #44
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    Quote Originally Posted by Ian Mackenzie View Post
    Please take my posts not too seriously but more as light entertainment to relieve an otherwise boring uneventful day.
    Some trivia.
    My writing style has been compared to this American writer. https://en.m.wikipedia.org/wiki/William_T._Vollmann
    I take this as a compliment but draw the distinction at not being a cross dresser as noted in the above link.
    I respect your knowledge Ian, and therefore your opinions.

  15. #45
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    Quote Originally Posted by Mannermusic View Post
    There is a reason folks like Greg Timbers get degrees in both electronics AND acoustics.
    Add education and experience in music, and you have won a triple crown event.
    "Why don't you Mine your own Bismuth, so you won't be mining mine?"

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