100dB @ 1W to 20Hz 12" driver sound nice? - diyAudio
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Old 2nd August 2011, 08:34 PM   #1
Boscoe is offline Boscoe  United Kingdom
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Default 100dB @ 1W to 20Hz 12" driver sound nice?

After going through a lot of shite designs on the net for a decent sized TH that would get to 20Hz I soon got very thrustrated. So I though I would design my own using some drivers that I have the Eminence Delta 12LFA. All in a 88l equivalent box.

Here's some specs.

At 2.83V

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At 14.5V

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At 2.83V

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Acceptable GD.

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Anyone interested in this?
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Old 2nd August 2011, 09:15 PM   #2
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so it takes, what, 30 watts to skip past xmax at 38hz?
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Old 2nd August 2011, 09:16 PM   #3
Boscoe is offline Boscoe  United Kingdom
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Around 25W yes.
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Old 2nd August 2011, 10:20 PM   #4
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What's the fold look like?
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Old 2nd August 2011, 11:56 PM   #5
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I have been eyeing TH designs lately but have read there are phase issues that have to be dealt with in the crossover design. Is this true?
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Old 3rd August 2011, 08:10 AM   #6
Boscoe is offline Boscoe  United Kingdom
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Quote:
Originally Posted by chris661 View Post
What's the fold look like?
Don't know yet I haven't bothered because I don't know how to do the bends in it.

Quote:
Originally Posted by buzzforb View Post
I have been eyeing TH designs lately but have read there are phase issues that have to be dealt with in the crossover design. Is this true?
Not that I've heard but I have no idea.
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Old 3rd August 2011, 09:57 AM   #7
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Originally Posted by buzzforb View Post
I have been eyeing TH designs lately but have read there are phase issues that have to be dealt with in the crossover design. Is this true?
Depending on how far the driver is away from the mouth, a certain amount of delay may be required.

The ones linked in my signature are furthest from the mouth that I've seen, but there's no audible delay.

Apart from that, the phase can vary through the pass-band, so steep crossovers tend to be used (this also gets rid of the hash higher up), then just try reversing polarity to see which integrates better.
When I first tried mine, there was a narrow notch at ~80Hz when used with the satellites- it wasn't particularly noticable. Reversing the phase of the satellites made an audible difference, though, filling in some of the "texture" of the bass guitar.

Chris
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Old 3rd August 2011, 10:58 AM   #8
AndrewT is offline AndrewT  Scotland
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25W limit at 38Hz and ~4W limit at 20Hz, i.e. ~<102dB at Xmax @ 20Hz
But would four of them randomly located around the room sound good?
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Old 3rd August 2011, 01:35 PM   #9
Boscoe is offline Boscoe  United Kingdom
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25W limit at 38Hz and ~4W limit at 20Hz, i.e. ~<102dB at Xmax @ 20Hz
But would four of them randomly located around the room sound good?
You say 4W due to estimated impedance or due to xmax, lookling at about 5.5mm xmax at 20Hz at 25W 4.8mm is limit.
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Old 3rd August 2011, 08:52 PM   #10
AndrewT is offline AndrewT  Scotland
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Using graph1 from post1, I think I can see:
96 to 97dB @ 20Hz using your Standard Voltage Input.

Graph3 seems to show:
1.7 to 1.9mm travel @ 20Hz using your Standard Voltage Input.

If your Xmax is 5.5mm, then the extra dB available @ 20Hz is 20log[5.5/1.8] ~9.7dB
Add that to the ~96.5dB and the Xmax limited 20Hz output is ~106dB using Standard Voltage +9.7dB.

Is your Standard Voltage 2.83Vac?

I had quickly assumed 4mm and 2mm for an extra 6dB using 4W (using 5.66Vac)
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