Adding a resistor in a parallel wiring system


I was inquiring about adding a resistor between the amplifier and a DIY speaker (1.8 ohm) and learned that only the "Zero Former" by Paul Speltz could solve the problem. Paul was nice and explained in layman's term to me why using a resistor could not work because it basically "kills" the damping factor.

Now I got a pair of zero's coming, I got another problem. 3 out of 4 drives are 8 ohm and one is 4 ohm. Will adding a resistor between just this drive and the binding post mess up the damping factor of the whole system, or will it only affect the damping factor of this one drive?

Thanks,
Ryan.
angelgz2
Doing that won't affect the damping factor of the other three drivers. But perhaps you don't even have to add the resistor. Three nominally 8 ohm drivers in parallel with a nominally 4 ohm driver results in a nominal overall impedance of about 1.6 ohms. If you step that up 4x with the Zero, and probably also 3x or possibly even 2x, your amp should be happy (in terms of the load impedance it sees; I'm assuming the amp can supply sufficient power for your application).

Keep in mind, though, that without the resistor the 4 ohm driver would receive twice as much power as each of the others, while with a 4 ohm resistor the 4 ohm driver would receive half as much power as each of the others.

Regards,
-- Al
Hi Al,

Thanks for the response. Now I'm thinking, since the zero has several input wires, maybe I could use the 3X wire on the three 8 ohm drive and then connect the 4 ohm drive by itself on the 2x wire. That way all of them will practically be 8 ohm. Would that work or will that just burn the amp? Thanks.

Thanks,
Ryan.
As I interpret the information provided at zeroimpedance.com, if the Zero is being used to increase the load impedance seen by the amplifier (as opposed to decreasing it) there is one and only one pair of output wires on the Zero that can be connected to the speaker drivers. The choice of 2x, 3x, or 4x impedance multiplication is made based on which pair of input wires on the Zero is connected to the amplifier. So it appears that you would not be able to connect the 4 ohm driver (plus any resistor you may place in series with it) to the Zero any differently than the 8 ohm drivers.

Regards,
-- Al