Need Advice on Cross Over Freq.

[gilga]

Hi everyone,

I recently bought a Polk CS1 center channel and Polk t15's for the rear surrounds. I am a dunce when it comes to setting the speakers up properly. With the receiver I have, I can select from seven possible settings: 40Hz, 60Hz, 80Hz,100Hz, 120Hz, 150Hz or 200Hz.

I am not sure what the ideal crossover settings should be based on the specs of my speakers.

Polk CS1 (Center Channel)
Overall Frequency Response 55Hz - 25kHz
Lower -3dB Limit 65Hz
Upper -3dB Limit 24kHz
Nominal Impedance 8 ohms
Recommended Amplifier Power 20 - 125 w/channel
Efficiency 89 dB
Crossover 2.3kHz, second order high and low pass

Polk T15 ( Rear Channel)
Overall Frequency Response 60Hz - 24kHz
Lower -3dB Limit 65Hz dB
Upper -3dB Limit 20kHz dB
Nominal Impedance 8 ohms
Recommended Amplifier Power 20 - 100 w/channel

Any help is greatly appreciated. Take care

[paulspencer]

There are many ways to do it, but the ideal is to use measurements to assist. Ideally you would buy a mic, mic preamp and download some free software to do it. It's not expensive, and it's not that hard, and the result is likely to be better than the advice anyone could give without having done those measurements.

Still, for starters, here's 2 options:

1. Set speakers to small and cross at 60 Hz

This will limit output a little, but frankly many subs don't do a great job when crossing any higher. It may be a good choice.

2. Plug the ports, set the speakers to small and cross at 120 Hz

Sub placement now becomes more critical, there is more chance of localisation and there is also more risk of boomy bass, depending on how accurate your subs are. The speakers when plugged will roll off an octave higher - around 120 Hz for both, but the slope will be shallower. This is easier to integrate with the sub.

I suggest you try both, listen for SQ and also watch driver excursion and do a bit of a stress test. See which offers the best overall balance.

The problem of course is that things never quite work as you expect, and measurements tell you when everything is integrated correctly. So ideally you would spend a little more on some inexpensive equipment, spend a bit of time learning a few new tricks and it will most likely be the one of the best investments you'll ever make in your system. Then you can take off the dunce hat. When I started getting into this stuff, I had a big smile on my face when I did my first demo. I remember thinking "wow, this is awesome, and it only gets better from here ..."