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Author Topic: Quality of Components?  (Read 8791 times)

Brad Weber

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Re: Quality of Components?
« Reply #20 on: February 18, 2011, 10:02:48 am »

A general rule of thumb is if your going to put live kick through it, you'll want 15's.  2 10's is lovely for bass guitar but think "physics". If your total cone area is less than a kick drum head, how is it going to "re-inforce" kick drum?  Good luck.
The monitors don't have subs so you'll probly want at least a 10" there. (again, it can get ugly when you put kick thru an 8". Oh the humanity!)
Directly equating the radiator surface areas might be more valid if one were also using the same kick drum and beater for the subwoofer, but you're probably not meaning that the physics involved is much more complex with multiple factors involved.  It's also not just the 'force' or energy of the driver but could also be things such as how effectively that mechanical energy is converted to acoustical energy.  That's why it is not viable to make absolute statements based solely on cone diameter.

Perhaps a bit ironically, years ago Bag End took a typical 8" ceiling speaker, mounted it in a standard shallow backcan and sealed it very well so that the assembly had a higher natural resonance frequency.  Then they ran it with a custom integrator.  As I recall, the resulting frequency response was almost flat down to below 20Hz but the output was extremely low.  They weren't trying to create a viable product but rather demonstrating their concept and the type of compromises and decisions that speaker designers often have to make or for which they must develop creative solutions.
« Last Edit: February 18, 2011, 10:05:25 am by Brad Weber »
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John Fiorello

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Re: Quality of Components?
« Reply #21 on: February 18, 2011, 02:48:40 pm »

If you want to send me a PM, I'm about an hour north of you and I'd be glad to let you know who we are using for what with our current upgrades.


JF
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Brian Ehlers

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Re: Quality of Components?
« Reply #22 on: February 18, 2011, 05:23:25 pm »

Perhaps a bit ironically, years ago Bag End took a typical 8" ceiling speaker, mounted it in a standard shallow backcan and sealed it very well so that the assembly had a higher natural resonance frequency.  Then they ran it with a custom integrator.  As I recall, the resulting frequency response was almost flat down to below 20Hz but the output was extremely low. 
And therein lies the problem with trying to make a loudspeaker do something it's not good at (such as producing frequencies below resonance).  It may work well under some circumstances (low power), but not under others.

My home loudspeakers used to be a full-size model of sealed-box design which used a manufacturer-provided line-level EQ to achieve flat response down to 20 Hz.  And it was flat, as I proved with measurements.  Sounded great, too -- as long as I didn't turn it up too loud.  Problem was, the EQ's 12 dB of boost at 20 Hz made the power amplifier quickly run out of headroom.  And even if a more powerful amp was used, the woofer quickly ran out of excursion room.  To top it off, with a first-order passive crossover design such as this, that 12 dB of boost meant that the midrange driver actually saw a level of 20Hz as if it weren't even high-passed.  You can guess which driver failed first.

Anyway, while having some potential in low-power applications, I'm not a fan of such "interesting" designs for Pro audio.
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Arnold B. Krueger

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Re: Quality of Components?
« Reply #23 on: February 22, 2011, 07:58:41 am »

My home loudspeakers used to be a full-size model of sealed-box design which used a manufacturer-provided line-level EQ to achieve flat response down to 20 Hz.  And it was flat, as I proved with measurements.  Sounded great, too -- as long as I didn't turn it up too loud.  Problem was, the EQ's 12 dB of boost at 20 Hz made the power amplifier quickly run out of headroom.  And even if a more powerful amp was used, the woofer quickly ran out of excursion room.  To top it off, with a first-order passive crossover design such as this, that 12 dB of boost meant that the midrange driver actually saw a level of 20Hz as if it weren't even high-passed.  You can guess which driver failed first.

The above is an example of how to do it wrong. I can tell you how to do it right, with examples. I have a friend who is a well-known speaker designer - he's an AES Fellow of which there are precious few. He figured out the desired  parameters for a high-powered, high excursion driver that would work well in a minimial-sized box, and proceeded to house two of them back-to-back in an enclosure that was just barely big enough to hold the drivers. This resulted in a system that naturally rolled-off some place around 50 Hz.

He then lined up some amps that were so powerful that he had to run a 230 volt line dedicated to them, but were within the power ratings  of the speakers and drove them  to displacments that were clearly within their design limits.

A parametric eq was used to equalize response to 10 Hz, which required fairly massive amounts of eq. This system has been in daily use, driven hard from time to time, and has been reliable for a number of years. It sounds great. BTW, the upper range drivers were themselves nomiinally full range speakers and were used within specs.

My point is that if you know what you are doing and can apply proper engineering princlples , that this like many other seemingly radical approaches can work very well.  I had a 14 cubic foot subwoofer in my listening room for over a decade, and can thus appreciate the attraction of physically small speakers that haul the mail.
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Re: Quality of Components?
« Reply #23 on: February 22, 2011, 07:58:41 am »


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