Hello venerable owners -

I think I've read enough literature on sound system setup to realise that I know next to nothing worth knowing about what to twiddle

 

Uh - hang on - I am not very good at reading things properly it seams. I now see that HIGH MID and LOW correspond to Front Rear and Sub respectively. Therefore that's why low has no effect on the front speakers...

Would be nice to have one of the heavywights answer my Q's though

I understand that the bottom of the slope defines the point where the lowest frequency will not pass to that channel and the top of the slop defines the where the highest frequecy will not pass to that channel. What's the level for? I can only think that's to balance out power bewteen the various speakers since with only one channel it seems pointless?

 

Finally - really just answering this for anyone else who's interested...

I set a filter point of 100Hz with a 24db rolloff which is an agressive slope to make damn sure were going nowhere near the speakers rated minimum of 45HZ. I rekon according to the iPersonalize tool I looked at I am touching 65Hz before being cut off...

Now let me tell you about the results - the system is very very good - it's very very loud with NO distortion I can run it all the way to vol 30 without any noticable degregation of performance. Above that it clips a little. Playing Chemical Bros "Three Little Birdies Down Beats" and Bach's Toccata & Fugue In F Major, BWV 540: (Organ music) with some VERY low frequencies.

Very very happy - just can't wait for the sub to complete the picture.

Problems solved - just want to drive round so I can enjoy it now!

 

There are four crossover filters when the head unit is set in 3-way mode:
LOW: filters out signals above the corner frequency, for to the sub.
MID-LO: filters out signals below the corner frequncy, for the mid/woofer
MID-HI: filters out signals above the corner frequency, for the mid/woofer
HIGH: filters out signalsbelow the corner frequency, for the tweeter

Each crossover filter has three numbers:
Level (0 to -12): How much volume reduction on all signals that are pased through to the driver. Used to adjust for differences in sensitivity between the tweeters, mids, and subs.
Order (0 to 4): How sharp the cutoff is at the corner frequency. A setting of 1 results in -6dB in level reduction every octave (doubling or halving of frequency). 2 = -12 dB/octave. 3 = -18dB/octave. 4=-24dB/octave. 0 results in no filter (flat).
Corner frequency (every 1/3 octave from 20 through 20k). The frequency where the filter begins to cut off the unwanted signals.

The best plan for a novice is when crossing over two different speakers, make the order and corner frequency the same for both speakers. Generally 4th order is the best when the two speakers are not close enough to be touching.

 

The bit I am still not clear on is the following...

Lets say were driving the system really hard with some high amplitude bass.

The set corner freqency is the point at which the system starts to restrict the amplitude of frequency sent to the channel according to the rolloff set.

Does this mean that it would still be possible to damage the speaker by allowing large amplitude low Frequency signal down the channel becuase the rolloff wasnot aggressive enough?

My Kappa's are rated down to 45Hz. Can you tell me therefore where to set the corner frequency and what sort of rolloff you would suggest based on everything disucssed so far?

Thanks

 

That's actuall a very complicated question, and there's no quick and easy answer I can provide, but I'll try to give you a better feel for how to approach it.

First of all, the 45Hz rating on the Kappas just says that that's the frequency where the sound starts being less audible. Below that frequency in a "sealed" enclosure, the woofer cone will still move in response to the input signal but it's not moving enough to make noise.

Musical signals generally have more energy in the bass frequencies -- so with certain tracks a lot of power is getting sent to your Kappa mid-woofers in a frequency range that will make the cones flap but not make noise. In addition, it takes larger movements of the cone to reproduce lower frequencies. Ultimately, how loud and low your speaker can play is determined by a parameter called Xmax, which tells you how far the cone can move back and forth before the voice coil bottoms out inside the magnet gap, or jumps out of the magnet gap.

So here's what I would advise: set the low crossover point for your Kappas to 4th order, 0dB level. By the low crossover point, I mean if the Kappas are hooked up as "front/tweeter" you should use the HIGH or FRONT crossover setting, and if they are hooked up as "rear/mid" you should use the MID-LO or REAR crossover setting.

Start out with the crossover frequency set at 60Hz and listen to the tracks that cause problems at the loudest volume level that you plan to use. Move the crossover frequency lower until you start hearing the problem, then back off to the last setting that was okay.

When you get your sub(s) you can use that frequency as the crossover frequency on the sub channel. Or you might want to move the crossover point for both the sub and the main speakers about an octave above the cutoff for the main speakers, somewhere around 90Hz.