Ohms question. What resistance will my amp see.

[bryantramos79]

I have a pair of 3 way x-overs that x at 300hz and 6500hz. Can i use a 4ohm woofer if i have 8ohm tweets n mids? If so what resistance will my amp see? The x-over is a cerwin vega E310.

[event horizon]

It'll probably see an impedance with a minimum of about 3ohms or a tad less.

The thing is unless you know exactly the impedance of the original bass driver that was used with that crossover you might find that you'll have all sorts of nasty holes or peaks in the response. It was obviously built to work with certain drivers (that are never totally flat in there own response) & the rolloff of the bass unit might have been tailored to get rid of a rising response or vice versa. Likewise with the mid & tweeters if they are not the originals

Don't expect good things from messing about like this.

[Loren42]

Originally Posted by bryantramos79

I have a pair of 3 way x-overs that x at 300hz and 6500hz. Can i use a 4ohm woofer if i have 8ohm tweets n mids? If so what resistance will my amp see? The x-over is a cerwin vega E310.

I don't think the impedance that your amp sees is going to be your real problem.

Consider that a crossover is a collection of resistors, inductors and capacitors that all interact to create a series of filters.

The voice coil impedance (not its resistance) is a prime function of that system's performance.

For one thing, sticking arbitrary drivers onto a crossover that it was not specifically designed for will surely impact the frequency response of that filter and it can only get worse.

Even if the drivers you use have the same Re resistance as the original, the driver impedance and its output level over the frequency spectrum are most likely to be a mismatch for the crossover's original design.

What you are proposing is not unlike trying to put one 13" radial tire on a 14" rim, one 18" tire on a 15" rim, and a space saving spare thrown in for good measure. You are not in for a pleasant ride.

Bottom line is that you will need to design a crossover for the chosen drivers you have (assuming that they can be even be matched together) from scratch.

Why not start with telling us what drivers you have that you want to put together. From that information we might be able to propose a design.

[bryantramos79]

I kinda get what you two are saying, i remember reading that x-over points go up as ohms go down or something like that. Looks like i got some studying to do. thanks.

[Loren42]

Originally Posted by bryantramos79

I kinda get what you two are saying, i remember reading that x-over points go up as ohms go down or something like that. Looks like i got some studying to do. thanks.

It is not a trivial task to understand so while you are doing your reading be sure to ask lots of questions and it will all start to gel after a bit.