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Old 5th January 2013, 07:26 PM   #1491
OllBoll is offline OllBoll  Sweden
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Hmm.

One of the things I want to test is to remove room gain. How important is it for all the subs to work in phase or close to at 20-40 hz? An idea would be to test to instead of having 3 dipoles use 2 monopoles and a dipole as HF sub where each of the monopoles works in inverted phase. That should solve that and they should be able to be spaced far apart enough such that fairly little efficiency is lost due to cancellation.

Last edited by OllBoll; 5th January 2013 at 07:39 PM.
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Old 6th January 2013, 12:39 AM   #1492
gedlee is offline gedlee  United States
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Good old "room gain"! Doesn't happen.

There is no answer to your question except "It depends on the room and the sub placement." The subs might want to be in phase, out of phase or even in quadrature - it all depends ... And this would certainly change with frequency.
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Old 6th January 2013, 06:52 AM   #1493
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Originally Posted by gedlee View Post
Good old "room gain"! Doesn't happen.
So you're saying there's no difference between 4pi, 2pi, etc? Or were you referring to something else?
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Old 6th January 2013, 08:17 AM   #1494
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I think he means most rooms are too leaky (openings, plus construction that's mostly transparent at bass frequencies...) to provide useful "room gain".
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Old 6th January 2013, 05:39 PM   #1495
gedlee is offline gedlee  United States
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Quote:
Originally Posted by m R g S r View Post
So you're saying there's no difference between 4pi, 2pi, etc? Or were you referring to something else?
Rooms are neither 2 Pi or 4 Pi, they are modal, and that is a completely different thing. The 2 Pi and 4 Pi arguments do not apply to real rooms.

There is a DC mode in a perfectly sealed room, that is sometimes called "room gain", but real rooms are too leaky to see this effect.
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Old 7th January 2013, 08:25 PM   #1496
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Was just looking at the Gedlee sub and noticed a couple things:

1) He's really not messing around with that sub driver! If I'm not mistaken the 12TBX100 has the same ginormous motor as it's big brother the 15TBX100. Parts Express doesn't stock it, likely because most people opt for the lower priced options, which don't have this wildly over-engineered motor

2) I have no idea how he's selling the sub so cheaply, considering the driver is $300 at usspeaker. Considering the parts cost, I'd expect the sub to cost $2000-$3000
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Old 7th January 2013, 09:26 PM   #1497
djn is offline djn  United States
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I wonder if that level of sub is needed for music only: at moderate listening levels. OR, is it more of a HT thing?
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Old 7th January 2013, 09:30 PM   #1498
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I'll bet it's more a keeping-up-with-the-main-speakers thing!
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Old 8th January 2013, 02:55 AM   #1499
gedlee is offline gedlee  United States
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Quote:
Originally Posted by Patrick Bateman View Post
Was just looking at the Gedlee sub and noticed a couple things:

1) He's really not messing around with that sub driver! If I'm not mistaken the 12TBX100 has the same ginormous motor as it's big brother the 15TBX100. Parts Express doesn't stock it, likely because most people opt for the lower priced options, which don't have this wildly over-engineered motor

2) I have no idea how he's selling the sub so cheaply, considering the driver is $300 at usspeaker. Considering the parts cost, I'd expect the sub to cost $2000-$3000
One correction: The motor is not "over-engineered" it is optimal. the voice coil is enormous and the magnet structure also needs to be. All this leads to huge thermal capacity and a sound quality unlike any other. The 12TBX100 and the 15TBX100 have identical motor structures, just different cones. To me, they both represent the best woofers available - bar none.

That the "brand names" charge ridiculous prices is quite true. People pay it so they do it!

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Originally Posted by djn View Post
I wonder if that level of sub is needed for music only: at moderate listening levels. OR, is it more of a HT thing?
Its about thermal modulation, not SPL.

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Originally Posted by Russell Dawkins View Post
I'll bet it's more a keeping-up-with-the-main-speakers thing!
That is true as well. My speakers are loafing at normal levels and as such the thermal modulation is negligible. Small two ways are maxed out at even reasonably high SPls and even if they are not totally distorted, they are thermally modulating and losing dynamics as a result.

This whole concept is simply not understood.

Last edited by gedlee; 8th January 2013 at 02:59 AM.
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Old 8th January 2013, 08:42 AM   #1500
Omholt is offline Omholt  Norway
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How important is high efficieny? Is efffiency related to dynamics?
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