teodorom said:
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.
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.
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.
sreten said:
... 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....
phase_accurate said:
Actually the amp is loaded more by the impedance rise compensation than otherwise. The current drawn by the resistor in the compensation is wasted power drawn in the sense that it poduces no acoustic output.... but one could say not wasted if it improves FR by tuning the crossover better.
In tube amps with high output impedance, the Frequency response tends to roughly follow the impedance curve.
If your bass peak is high (high Qms driver) you will get a bump at resonance peak(s) in the bass. If the inductance is high (it rarely is in fullrange drivers), you will see exaggerated highs. The response variations are perhaps +/- 1-2 dB worst case.
Solid state amps are much less fussy about load impedance changes. As long as it doesn't go too low or get too reactive, you will be fine - and all amps can drive most inductive loads all day - it's the capacitive ones that get you....
If your bass peak is high (high Qms driver) you will get a bump at resonance peak(s) in the bass. If the inductance is high (it rarely is in fullrange drivers), you will see exaggerated highs. The response variations are perhaps +/- 1-2 dB worst case.
Solid state amps are much less fussy about load impedance changes. As long as it doesn't go too low or get too reactive, you will be fine - and all amps can drive most inductive loads all day - it's the capacitive ones that get you....
specifically Jordan JX92s
So, really I should compensate these??
I want to do a bipole with a switchable driver on rear from either 0.5 or full.
So, 1 impedance compensation circuit on each driver??
Then switchable inductor for 0.5 way.
How does impedance compensation affect phase??
Thanks!!
So, really I should compensate these??
I want to do a bipole with a switchable driver on rear from either 0.5 or full.
So, 1 impedance compensation circuit on each driver??
Then switchable inductor for 0.5 way.
How does impedance compensation affect phase??
Thanks!!
I couldn't tell you the best way to accomplish your goals. I would say, depending on how load sensitive your amplifier is, you might get away without any impedance compensation.
Your topology is rather complex. You are making a 1.5 way and the 0.5 way is switchable as either a 0.5 way in combination with the front driver or a fullrange bipole? Depending on your crossover frequency, you might be better off to use the 0.5 way all the time for baffle step, and add a third driver on the rear for switchable bipole (and/or dipole) duty...
If you are using spendy drivers, the 0.5 way could probably be something else so you wouldn't have the added expense.
Your topology is rather complex. You are making a 1.5 way and the 0.5 way is switchable as either a 0.5 way in combination with the front driver or a fullrange bipole? Depending on your crossover frequency, you might be better off to use the 0.5 way all the time for baffle step, and add a third driver on the rear for switchable bipole (and/or dipole) duty...
If you are using spendy drivers, the 0.5 way could probably be something else so you wouldn't have the added expense.
I always flatten out the impedance of a finished XO. This is because I mostly design series XO, and simple zobels cannot compensate enough to match a resistor. Thus it becomes a pain to design the XO.
Does it make any audible difference? It depends on driver performance and how much one really cares. Most of the time the difference is small, but can be easy to catch if other performance aspects are good.
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