Simple Design Questions?

[Vespasian]

Recently assembled the ar.com 2 way kit which has gotten me back into listening and has also sparked an interest in understanding the basics of loudspeaker / passive crossover design. Have done some reading on the internet and played with LPSCAD4demo a little bit...

My first question is - is it ever ok (or common), for a two way, with second order networks, to have a few hundred Hz difference in the cutoff frequencies between the bass and treble networks to flatten out the summed response?

Second - is it foolish to design and build simply based on theory / formulas without conducting any measurements along the way?

TIA Ed

[hermanv]

Originally posted by Vespasian
My first question is - is it ever ok (or common), for a two way, with second order networks, to have a few hundred Hz difference in the cutoff frequencies between the bass and treble networks to flatten out the summed response?

Anything that flattens the end result is not only acceptable, but desirable. Adusting values to arrive at the desired real world results is quite common.

Originally posted by Vespasian
Second - is it foolish to design and build simply based on theory / formulas without conducting any measurements along the way?

Yes, IMHO. All parts have tolerances, especially drivers. Unless you are going for high volume production adjusting your components for optimum results will usually get you an improvement.

[Willitwork]

Originally posted by Vespasian
My first question is - is it ever ok (or common), for a two way, with second order networks, to have a few hundred Hz difference in the cutoff frequencies between the bass and treble networks to flatten out the summed response?

The gentler the crossover slope the more common it is, especially with non-matching slopes, a common example being a 6dB crossover on the midbass coupled with an 18dB circuit behind the tweeter. In such a configuration the frequency "hole" can be of significant value. Naturally, a high-quality midbass driver with a very smooth roll-off is required otherwise you'll end up with a hollow midrange response. Over a decade ago I had bought Camber speakers which had such a crossover.

Bass response was nothing short of astounding and highs were perfect but midrange left a lot to be desired unless the speakers were driven pretty loudly, outherwise they sounded as if they were missing a third driver. In the end I had to build a third-order crossover for the midbass with a significantly higher cut-off frequency in order to get a satisfactory midrange response. Unfortunately this tended to highlight the midrange response limitations of the 8-inch midbass driver (it had a smallish magnet system) at high volume so power handling was greatly reduced.

[Vespasian]

Thank You