Impendace rise: is it worthwhile to compensate it ?

teodorom · 2nd May 2004, 05:54 PM

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

pinkmouse · 2nd May 2004, 06:02 PM

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.

5th element · 2nd May 2004, 06:04 PM

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.

teodorom · 2nd May 2004, 06:05 PM

... more scientific ?

Ron E · 2nd May 2004, 06:06 PM

Heres your "assignment", since you understand the theory:
Plot the LowPass Transfer function with and without Zobel.

sreten · 2nd May 2004, 06:20 PM

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.

Ron E · 2nd May 2004, 11:25 PM

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....

AudioGeek · 4th May 2004, 03:13 PM

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

Thanks!!!

phase_accurate · 4th May 2004, 03:34 PM

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

Jay · 4th May 2004, 04:03 PM

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.

2nd May 2004, 05:54 PM	#1
teodorom diyAudio Member Join Date: Apr 2004 Location: Milano	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 __________________ Teodoro

2nd May 2004, 06:02 PM	#2
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	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. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

2nd May 2004, 06:05 PM	#4
teodorom diyAudio Member Join Date: Apr 2004 Location: Milano	Anything ... ... more scientific ? __________________ Teodoro

2nd May 2004, 06:06 PM	#5
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	Heres your "assignment", since you understand the theory: Plot the LowPass Transfer function with and without Zobel. __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

4th May 2004, 03:13 PM	#8
AudioGeek diyAudio Member Join Date: Jan 2004 Location: Minnesota	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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2nd May 2004, 06:20 PM	#6
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	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.

4th May 2004, 04:03 PM	#10
Jay diyAudio Member Join Date: Feb 2003 Location: Jakarta	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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