Notch vs. Zoebel vs. Lpad

[squidbait]

I understand that a notch filter helps rid the peak at resonance.

I thind a Zoebel equalizes rizing impedance? And an L-Pad attenuates a specific driver to match SPL's?

If I am correct, how do you design them all together?

Maybe someone can point me to a schematic that has all these different "areas" labeled.

Also, do these affect the crossover point?

I am slowly getting there! ....slowly....

[hiendaudio]

Hi.

You are in the correct way...

The noch filter for correction the resonance of the driver, is a R-L-C
series circuit in shunt with the driver.

The L-pad is a voltage divider!!!!

....And the zoobel red, is a cap and a resistor in series!!!! of course they are in shunt with the driver.

The x-over poit change with Z, so if the Z change because you put a zoobel, or noch filter, then the x-over point will change.

The L-pad is used for driver spl match, but you can afect the resistive (real) part of Z for a given driver.......this can be used for match a desired Z. (unusual, but possible)

[sreten]

Often correct use of L-pad values will make a
impedance notch circuit for a tweeter redundant.

The impedance notch circuit is only really useful for odd
order parallel networks and even order series networks.

Tweeters seldom require zobel compensation, midrange
and bass midrange can, but again of real use for for odd
order parallel networks and even order series networks.

Zobelling a mid / bass unit reduces system impedance
and IMO should only be done if definetely needed.

For even order parallel networks and odd order series
networks the "shunt" component means a rise in the
drivers impedance does not cause problems.

JMO but some component suppliers are rather too keen
on full impedance compensation and high order filters.

sreten.

[BobEllis]

Originally posted by sreten
...
The impedance notch circuit is only really useful for odd
order parallel networks and even order series networks.

<snip>

For even order parallel networks and odd order series
networks the "shunt" component means a rise in the
drivers impedance does not cause problems.

JMO but some component suppliers are rather too keen
on full impedance compensation and high order filters.

sreten.

Sreten,

Could you explain (in imaginary number challenged terms) why the shunt component is less effective for even order parallel and odd order series networks?

Thanks

[sreten]

Originally posted by BobEllis


Sreten,

Could you explain (in imaginary number challenged terms) why the shunt component is less effective for even order parallel and odd order series networks?

Thanks

Because in this case the network has a shunt component across
the driver, bass units are "shorted" at high frequencies, tweeters
are "shorted" at low frequencies.

For odd order parallel and even order series networks :
bass units are "open circuit " at high frequencies,
tweeters are "open circuit " at low frequencies.

sreten.

Even series and parallel :

[sreten]

And odd order series and parrallel :

The principle is the same for higher order networks.

Consider Zobelling the bass unit here (1K c/o):

By the time the Zobel comes into effect the parallel
capacitor in the series network makes it redundant.

Similarly a RLC circuit for the tweeter will be redundant
due to the action of the inductor in the series case,
as long as you assume Fs of the tweeter is below
the c/o frequency which it nearly always is.

For the parallel case an RLC and Zobel will have much
more effect on the response either side of the c/o point.

sreten.

[BobEllis]

It should have been so obvious. Thanks for the education.