wiring queston

[bre's dad]

I've got a set of speakers that the mid seems to be playing louder than the other drivers. I was told by a few different people to put a resistor on the mid to pull it down a little. The question is would this go in parallel with the driver (across the + & - terminals) or in series on the + side of the driver? I've hear this trick before and was pretty sure you would hook it up in series but one person I talked to swears up and down it should be in parallel. Which is it?

[gabel87]

Re: wiring queston

Both, an L pad would have a series and a parallel resistor

http://www.sengpielaudio.com/calculator-Lpad.htm

[Chris Roemer]

Re: wiring queston

In series. You MIGHT get about a -3dB reduction per 3 ohms of series resistance (dependent on various factors).

[bre's dad]

Re: wiring queston

I mean just a standard resistor, like a 10 ohm resistor. I'm not wanting to use an L-pad

Specifically I'm wanting to lower the output on a midrange horn on some Klipsch Heresys. I've also been told I can use different taps on the autoformers in the crossover but I don't know what outputs are on which taps. A resistor would be easier.

[gabel87]

Re: wiring queston

An L pad is 2 resistors. It's for exactly what you want to do, lower the dB of a tweeter or mid. You could put a single resistor in series and also lower the dB but it will alter the phase or impedance seen by the crossover and thereby alter the crossover.

If you go to the link I posted above you can calculate the resistor sizes you need for whatever reduction in output you think is called for in either an L-pad or single series. I tried a series only resistor on a mid in a three way I had and it would get very hot. I would use @ least 20w wirewound resistors, and gang parallel them to get the value(s) you need for added heat protection. Wire the resistors in at/near the driver if you prefer. You could try it both ways and see which you prefer, series only vs L pad. I've had better luck with L-pads and I don't think they get so hot.

[Chris Roemer]

Re: wiring queston

The filter slope (and Fc) shouldn't change much if you put the resistor AHEAD of the filter (so . . . amp, to SERIES RESISTOR, to BP filter, to driver). If you put it on the opposite end (next to the driver) it CAN alter the shape of the filter's transfer function.

[thekorvers]

Re: wiring queston

I've had better luck with L-pads and I don't think they get so hot.

The series resistor in an L pad will get hotter than a series resistor of the same value by itself (without the parallel resistor).

[gabel87]

Re: wiring queston

Edit: Yep, in my mind the parallel resistor was before the series resistor. Went and looked at a diagram again ;)

In any case, power rating is something to keep in mind, especially with midrange attenuation. Parallel banking is your friend.

OP, I'd try them all, series before and after the filter and L-pad. It's certainly cheap insurance on getting the result your after.