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Old 24th January 2013, 04:43 PM   #11
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Quote:
Originally Posted by ORNJ View Post
...
GAH! audio is such a pain sometimes....maybe i'll just get a divorce ahah!
Tell me about it... It just never stops.

You have not mentioned exactly what your size demands are yet. Have you looked at all your placement options? Maybe you could use a new table? Stereo bench? Is IB an option?

turbodawg:

Force>Power

Edit:
It's not deep bass until all your cabinet doors start shaking a lot, the room itself resonates but you can hardly hear the sound at all. Great fun! But I settle for less.

Last edited by KaffiMann; 24th January 2013 at 04:55 PM.
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Old 24th January 2013, 04:54 PM   #12
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Quote:
Originally Posted by KaffiMann View Post

Force>Power
Not sure I follow your point here............

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Old 24th January 2013, 05:08 PM   #13
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[QUOTE=turbodawg;3340436]Not sure I follow your point here............

Force:
In physics, a force is any influence that causes an object to undergo a certain change, either concerning its movement, direction, or geometrical construction.

Power:
The rate at which work is performed or energy is converted.

See, we all want a signal to convert to a physical force, sound. In order to do so we amplify the signal with power, but the power is wasted if the system cannot convert it in an efficient way.

Edit:
I see there should have been something else there. But anyway, they are both related, but it is all a balance act.

Last edited by KaffiMann; 24th January 2013 at 05:14 PM.
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Old 24th January 2013, 05:10 PM   #14
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Originally Posted by ORNJ View Post
Some one else commented to me the other day that 15" would be more than enough as well.
I think my problem is that I don't know what compromises I like best.

A dual 15" in a sealed cab will most likely meet all my needs but like what was mentioned earlier, the EQ can cause phasing issues.
EQ does result in phase shift, but when used for corrective purposes, it reduces phase shift, which is a positive feature, not an "issue".

As you can see in the examples below, the flatter equalized response also results in a flatter phase response.

The Mackie HD1502 uses built in equalization, note how flat both the frequency and phase are.
The DSL SH-100 has a dip in FR around 125 Hz, and a bit much HF above 8K, notice how both areas smooth out in phase response when corrective EQ is applied.

The trade off is whether the EQ will cause audible distortion when applied liberally.
With speakers like the B&C 21" (or their high powered 18"), the suspensions "put the brakes" on high excursion, it is almost impossible to make them sound bad. I can't say the same about the Lab 12, even though I'd agree with Sreten that 2xLAB12's in 100L each tuned to 20Hz, 500W each,
is more than enough for nearly all domestic systems.
My observation with listening to movie sound tracks is that most VLF is accompanied by enough other upper noise that LF distortion tends to be hidden, unless it is really severe, like voice coils hammering on the top plate.
That said, without some measurements, we are guessing what is enough for you, the PC12-NSD is not enough, but a Gjallerhorn would obviously fail the WAF.
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Old 24th January 2013, 05:58 PM   #15
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Originally Posted by weltersys View Post
EQ does result in phase shift, but when used for corrective purposes, it reduces phase shift, which is a positive feature, not an "issue".
OK....but boosting the low end on a sealed sub with either a low shelf, linkwitz transform, or PEQ will produce phase shift and group delay, similar to a ported box.
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Old 24th January 2013, 09:02 PM   #16
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Just happened to stumble across this as a (somewhat) compact sub that gets down to 35hz or below........

Cubo Sub
(scroll down to see plan)
cubo sub - Speakerplans.com Forums - Page 1
Best sub
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Old 26th January 2013, 12:11 AM   #17
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Quote:
Originally Posted by turbodawg View Post
OK....but boosting the low end on a sealed sub with either a low shelf, linkwitz transform, or PEQ will produce phase shift and group delay, similar to a ported box.
That is not true, at least not with the Alesis DEQ830 I use for monitor EQ for live sound and on my stereo, inserted in the tape loop.

The screen shot shows my stereo sub out driving a sealed 2x12" sub measured in room, near field (on the floor next to the plenum output), with no EQ, and with EQ flat to 25 Hz, the lowest band on the DEQ830.
No group delay has been added by the EQ as evidenced by the phase in the upper portion of the band pass being unchanged.

As you can see, the phase response in the area of EQ has actually flattened compared to the EQ'd response.

The DEQ830 is a non-combining filter type, the EQ's response below 25 Hz goes back to flat response, resulting in the relative phase change below 25 Hz.

At any rate, not all EQ is created equal, but the DEQ830 does not produce any undesirable phase shift or group delay.

Although more difficult to accomplish than using Smaart, even with your Radio Shack dB meter you could determine whether whatever EQ you use introduces group delay.

Art
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Old 26th January 2013, 01:52 AM   #18
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Quote:
Originally Posted by weltersys View Post
That is not true, at least not with the Alesis DEQ830 I use for monitor EQ for live sound and on my stereo, inserted in the tape loop.

The screen shot shows my stereo sub out driving a sealed 2x12" sub measured in room, near field (on the floor next to the plenum output), with no EQ, and with EQ flat to 25 Hz, the lowest band on the DEQ830.
No group delay has been added by the EQ as evidenced by the phase in the upper portion of the band pass being unchanged.

As you can see, the phase response in the area of EQ has actually flattened compared to the EQ'd response.

The DEQ830 is a non-combining filter type, the EQ's response below 25 Hz goes back to flat response, resulting in the relative phase change below 25 Hz.

At any rate, not all EQ is created equal, but the DEQ830 does not produce any undesirable phase shift or group delay.

Although more difficult to accomplish than using Smaart, even with your Radio Shack dB meter you could determine whether whatever EQ you use introduces group delay.

Art
That graph clearly shows an increased rate of phase change with the EQ, which would translate into increased ramp up of group delay. There is no way that can be considered an improvement in phase response.

Last edited by turbodawg; 26th January 2013 at 01:57 AM.
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Old 26th January 2013, 06:39 PM   #19
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Quote:
Originally Posted by turbodawg View Post
That graph clearly shows an increased rate of phase change with the EQ, which would translate into increased ramp up of group delay.
Smaart 6ís automatic delay locator finds the time offset (delay) between two input signals by measuring the impulse response of the SUT. This measurement was performed automatically for the frequency and phase response measurements posted, without doing it phase traces would not be valid.
The delay measurement requires both reference and measurement signals.

If there was a "ramp up of group delay", it would show as a change in the upper pass band's phase response, and it would have changed the delay noted in Smaart 6ís automatic delay locator, neither of which occurred.

If there is something I'm missing in the interpretation of the Smaart phase response graphs, please point it out.
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Old 26th January 2013, 09:27 PM   #20
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The GD does indeed increase at the EQd area. But not due to EQ per say, it is just following miniphase behavior where a change in frequency response (here a steeper change in rollof) produces a related change in phase. Phase improves above EQ point due to flat frequency response, and it worsens below due to steeper rollof.

As Art pointed out the same happens when flattening the frequency response the phase flattens as well.

No matter what you do you will have increasing GD at lower frequencies due to LF rollof, making it less steep will produce less GD, by design or by EQ does not matter.
The only way to make it completely flat is to have a sealed sub in a sealed room and EQ the response flat to 0Hz.

EQing a sealed to the same response as a ported cab will produce the same GD. Unless the ported is not miniphase, but all I have measured have been miniphase.

Having a flat phase/amplitude down to where the rollof starts is IMHO better than having a change starting way above that point. Even if the steep rollof due to EQ will produce lots of GD in a big spike, when transforming the frequency response back to time domain (or just feeding the speaker with music) you will have a less altered attack and decay of transients as more of the passband can pile ontop of each other to create a pressure impulse without spreading it out in time. If that makes any sense.

Big bass horns have a very bad GD spike at the rollof point due to the high dB/oct the small back chamber + acoustical loading produces, yet the attack and decay seems to be unparalleled. And the slower rollof of a BR with it's lower GD can't seem to keep up.
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