Lowering crossover point with shallow slope?

[Spire]

right now we've got one T48 (building a second right now), and it pounds out the higher bass notes, the lower notes (down to the 35hz range) come out clean too, but of course a little quieter, i was just wondering if its a bad idea to set the crossover lower to "combat" the rising db's in the T48 design, something like 55-65hz at a 12 or 18db per ocave slope instead of the 90hz at 24db per octave. just to smooth out the response without using eq.

good idea? bad idea? other thoughts?

[Bill Fitzmaurice]

right now we've got one T48 (building a second right now), and it pounds out the higher bass notes, the lower notes (down to the 35hz range) come out clean too, but of course a little quieter, i was just wondering if its a bad idea to set the crossover lower to "combat" the rising db's in the T48 design, something like 55-65hz at a 12 or 18db per ocave slope instead of the 90hz at 24db per octave. just to smooth out the response without using eq.

good idea? bad idea? other thoughts?

We've recommended exactly that on many occasions. You'll find things will shift quite a bit lower with a second cab, and lower still V coupled.

[gdougherty]

IMO, bad idea.
The point of a crossover is to keep things operating in the proper region. Tighter slopes keep the low-mids out of the subwoofers and allow you to cut the power draining bottom end out of the tops. The ideal is matching 24 or 48db/oct Linkwitz-Riley filters on the tops and subs. This provides a phase neutral output from multiple sources.
OTOH, the point of an EQ is to shape the response of a speaker. I put a -7db cut at 100Hz and a bandwidth of .8 to 1 octave on my T48's with a single or pair and much preferred the response of my T48's. This essentially eq's them flatter down to about 50Hz but with a good bump in the 75-85Hz region. The overall output sounds lower but it sounds less "mushy" to me without the emphasis on the 100Hz+ region.

As Bill points out, more cabs will flatten things out, but IME, you'll need more than two cabs to have a major impact. V-plating helps a bunch too.

[Bill Fitzmaurice]

IMO, bad idea.
The point of a crossover is to keep things operating in the proper region. Tighter slopes keep the low-mids out of the subwoofers and allow you to cut the power draining bottom end out of the tops.

High orders are a must on high-pass, but lowering the low-pass frequency and slope to reduce the power input to the subs near the top of their range is perfectly OK.

[Spire]

cool, thanks for your input.

[gdougherty]

IMO, bad idea.
The point of a crossover is to keep things operating in the proper region. Tighter slopes keep the low-mids out of the subwoofers and allow you to cut the power draining bottom end out of the tops.

High orders are a must on high-pass, but lowering the low-pass frequency and slope to reduce the power input to the subs near the top of their range is perfectly OK.

Right, but if the goal is phase neutral summing of the two sources, as it is for me, only matching slopes and frequency points will achieve that.

[Israel]

I generally set the crossover matching one of the bands of my shaping eq ussually 100hz and use that slider to "comb stealth" the sub

[Bill Fitzmaurice]

Right, but if the goal is phase neutral summing of the two sources, as it is for me, only matching slopes and frequency points will achieve that.

The goal is the best sound. Ideally one would have separate EQ on the tops and bottoms, allowing them to have flat response and matched sensitivity at the crossover frequency. But if you don't have the capability to separately EQ your choices are either perfect summing with humped response or smooth response with phase glitches. The latter sounds better.