building zobels

Just did a Google search for zobel networks. There is a wealth of information there.

If I recall correctly the Merlin speaker website has instructions and examples that you can see. You can also call Alpha Core. Their speaker cables sometimes require Zobel networks so they can probably instruct you as well.

Clio09,
I always thought that a Zobel network should appear after the x-over & directly across the woofer terminals. I use the word "after" if one traces the signal path from the speaker terminals to the woofer terminals. IF Merlin & Alpha-Core provide Zobels these must be appearing before the x-over! Doesn't this negate the use of a Zobel?

Bombywalla,

You bring up an interesting point which I am not sure of myself. With the Alpha Core Goertz MI-II Veracity cables I have, the Zobel network is integrated in the cable and is positioned where the spade terminations are. I hook those ends up to the woofer binding posts on my speaker.

If I recall the Merlin diagram correctly the Zobel they were showing was on the tweeter (upper) binding posts. Of course they had jumpers connected as well so I don't know if this makes a difference.

I would be interested to know what you think of my Alpha Core configuration. Based on what you said it appears to be after the crossover.

Clio09,

"Based on what you said it appears to be after the crossover."
Based on what I wrote, the A-C Zobel appears BEFORE the x-over. :-)

Anyway, I'm no expert in this never having built my own speakers. So, it would be safer for me to say that I don't know whether or not before or after the xover makes a diff. I think that we might need a 3rd person in the know to straighten us (atleast me!) out.

Just thinking out loud: they say that the speaker manuf uses a Zobel to make the speaker load freq insensitive to the amplifier. I looked @ the ckt in the link provided by Distortion & if I work out the impedance xfer function of the Zobel & draw its Bode plot I see that there is a pole @ DC (0Hz) & a zero at 1/RC. This zero negates the pole at DC such that the eff freq response is flat over freq. So, if the values of R & C are chosen such that the zero cuts in well below the -3dB point of the speaker, the amplifer will see a constant (over freq) impedance. So, maybe it does make sense to have the Zobel across the speaker binding posts (rather than across the woofer terminals). So, I wonder why, then, all the diagrams in the literature show Zobels directly across the woofer terminals?

The Alpha-Core Zobels works in the range above audibility to maintain a stable load for amps that are sensitive. Another use of the Zobel is to make drivers appear more linear/resistive. In the first case, you want it to be seen by the amp while, in the second, to be seen by the network.

Kal

Kal,

Does the quality of the resistors that make up the Zobel with the Alpha Core cables matter as it relates to sound quality? I was wondering if it made sense to use better quality resistors, although with the way the Zobel is integrated into my cable it might be hard to swap out.

I doubt the quality of the resistors would make any difference since they are operating/effective at frequencies beyond normal hearing range.

Kal