Impendace rise: is it worthwhile to compensate it ? - diyAudio
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Old 2nd May 2004, 05:54 PM   #1
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Default Impendace rise: is it worthwhile to compensate it ?

Now I know, at least theoretically, how to compensate the
Z=Re+Le*(iw)^n
behavour of a driver (typically a woofer or a mid-range).
Now I ask: is it worthwhile ?
If a Zobel network is NOT included, what are the audible effects ?
Thanks
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Old 2nd May 2004, 06:02 PM   #2
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It depends on your taste/hearing and on the specifics of the driver in question.

Sometimes you can get away with no IR correction, and sometimes it's vital. You really need to look at the measured response of the driver to know.
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Old 2nd May 2004, 06:04 PM   #3
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Default Re: Impendace rise: is it worthwhile to compensate it ?

Quote:
Originally posted by teodorom
If a Zobel network is NOT included, what are the audible effects ?
None whatsoever, zobels are added to make xover design easier. If you dont have design software to optomise networks then chances are it probably will make it sound better because the xover values you calculate will work more accurately if the impedance has been flattened.

With software you can make the xover have a zobel or no zobel and end up with the same frequency response, if you did that then it would sound pretty much the same.
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Old 2nd May 2004, 06:05 PM   #4
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Default Anything ...

... more scientific ?
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Old 2nd May 2004, 06:06 PM   #5
Ron E is offline Ron E  United States
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Heres your "assignment", since you understand the theory:
Plot the LowPass Transfer function with and without Zobel.
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Old 2nd May 2004, 06:20 PM   #6
sreten is offline sreten  United Kingdom
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Fundamental resonance compensation and Zobel networks
are useful for odd order parallel c/o networks and even order
series c/o networks.
FRC's are more useful for mids and treble than bass,
as bass does not usually have a high pass filter.

For even order parallel c/o networks and odd order serial
c/o networks they are of limited use, and usually redundant.

sreten.
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Old 2nd May 2004, 11:25 PM   #7
Ron E is offline Ron E  United States
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Quote:
Originally posted by sreten
Fundamental resonance compensation and Zobel networks
are useful for odd order parallel c/o networks and even order
series c/o networks.
FRC's are....
... but the person was speaking specifically of the inductive rise, not the resonance - as evidenced by the equation with Re and Le.

I say prove it to yourself whether they are useful.

If you are unable to analyse the circuits yourself, download speaker workshop, import some data and play with topologies to your heart's content. I have read about the "damping qualities" of even order crossovers (due to the parallel low R inductor), yet the FR effects of an impedance rise remain unchanged. The greater the rise, the greater the deviation from response predicted by assuming the driver is a resistor. If you don't assume the driver is a resistor, you may get away without compensation....
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Old 4th May 2004, 03:13 PM   #8
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Default how about for a FR driver???

If the speaker has NO xover, is there an advantage to add an impedance compensation network???

Thanks!!!
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Old 4th May 2004, 03:34 PM   #9
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Quote:
If the speaker has NO xover, is there an advantage to add an impedance compensation network???
If you compensate the rising impedance, your amplifier might "see" an easier load. Whether that matters or not is mainly depending on your amp.

Regards

Charles
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Old 4th May 2004, 04:03 PM   #10
Jay is offline Jay  Indonesia
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Yep, FR drivers.
Because it is FR, let's assume the amp is tube. And because it is tube, let's assume it is a transformer coupled. Then when will the zobel matter.
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