Crossover settings

[gdougherty]

Per Bill's advice in the Delay posting I switched my crossover slopes in my DCX from 24db/oct to 48db/oct. My crosover point is set at 90Hz. The result was a notable increase in clarity in the low-bass. I switched back from aux-fed to full-range split subs after and liked the sound as much as aux-fed on recorded music. I don't have to mess with auxes and I pick up another out for running monitors or effects, but I do lose the ability to specify what goes in the subs and give an individual instrument just a bit more boost on the bottom. I'll have to see how much I like it. On the plus side it'll help prevent me from making the occasional gaffe of over-boosting a kick or bass into the subs and dominating what's coming out of the mains. It should take all the hastle out of finding the right sub balance in an aux in different venues with different wall/corner loading opportunities. I can RTA the tops, keep my sub EQ curve, and just use some pink and the RTA to make sure the subs and mains are balanced across the board. It also frees up a snake channel to let me run stereo if I wanted to as long as the crossover is in the amp rack.
If you've got 48db slopes, use them. Two big thumbs up.

[DAVID_L_PERRY]

Using a 48db slope will be better served with Aux fed subs not the other way round.

Recorded music should sound the same, the whole point of the Aux fed subs is to remove elements that you don't want in the subs for the live mic environment, and not boosting elements that you want to add more sub to, changing your slope to 48db does not change this at all...all mics will still be fully open into your subs, and the more mics you have the more that low end can start to lifts up even with the filters engaged.

Using Aux fed subs does complicate matters and requires more sends, but gives you a lot more scope to clean up a mix. If it is just for a small mainly backline PA then it may not be worth the effort, but if you are providing full PA support with everything going through the system then its a great option.

For CD playback /DJ use aux fed subs is of no benefit at all, other than being able to lift the sub level when music is very low level,and still have a big sound effect...

Dave

[Chris_Allen]

Dave,

In your Aux fed subs, do you use a high pass filter when sending a pre fader mix to the aux removing any high end content above the crossover frequency? Or do you run the subs full range with limited content?

Chris.

[gdougherty]

Using a 48db slope will be better served with Aux fed subs not the other way round.

Recorded music should sound the same, the whole point of the Aux fed subs is to remove elements that you don't want in the subs for the live mic environment, and not boosting elements that you want to add more sub to, changing your slope to 48db does not change this at all...all mics will still be fully open into your subs, and the more mics you have the more that low end can start to lifts up even with the filters engaged.

Using Aux fed subs does complicate matters and requires more sends, but gives you a lot more scope to clean up a mix. If it is just for a small mainly backline PA then it may not be worth the effort, but if you are providing full PA support with everything going through the system then its a great option.

For CD playback /DJ use aux fed subs is of no benefit at all, other than being able to lift the sub level when music is very low level,and still have a big sound effect...

Dave

If you set your crossover point lower, the 48db slope helps ensure that stuff being hit with a low-cut above the crossover point (100Hz cut on my Soundcrafft) stays out of the subs even more. Before, the low-cut didn't really help because the subs still audibly tackled some of the range up above the crossover point. The 48db slope is steep enough that you can really hear the horn's refusal to pass the typical harmonic distortion.

True, there is still benefit to running aux-fed, but properly configured I'm starting to see where I could get by without them and not have a muddy mess on my hands.

[gdougherty]

Dave,

In your Aux fed subs, do you use a high pass filter when sending a pre fader mix to the aux removing any high end content above the crossover frequency? Or do you run the subs full range with limited content?

Chris.

Whenever you run a sub you need a crossover whether active or passive. With Bill's designs it's even more important since they get more efficient above 100Hz. Aux fed just feeds the full-range signal off like you would for a monitor mix so you're still sending a full-range signal when you only need the range below your tops.

[Bill Fitzmaurice]

The main advantage to a higher xover slope is elimination of overlapping bandwidths between the subs and mains. Doing so cleans everything up in general, irrespective of your signal routing scheme.

[Chris_Allen]

Aux fed just feeds the full-range signal off like you would for a monitor mix so you're still sending a full-range signal when you only need the range below your tops.

I realise this as I already run aux fed subs. I was just wondering if there was a frequency overlap and what kind of range you were looking at. I was trying to establish the possible effects of interference.

Chris.

[gdougherty]

Aux fed just feeds the full-range signal off like you would for a monitor mix so you're still sending a full-range signal when you only need the range below your tops.

I realise this as I already run aux fed subs. I was just wondering if there was a frequency overlap and what kind of range you were looking at. I was trying to establish the possible effects of interference.

Chris.

Sorry, misunderstood the question. I've experimented with both a small overlap (tops @80Hz, subs at @100Hz) and the same. The small overlap can be nice in some situations as it boosts that 80-100Hz range and can add a bit more "chest thump" to kick and the like. However, it added more than I liked for things where I didn't want that boost, such as keyboards and CD playback so for my own tastes I kept it the same as if it were just a full-range system with one crossover point.

As to the effects of interference, that's the purpose of the steep slope, to minimise the content produced by both, localisation effects and phase interactions/cancelations.

[Mark Coward]

Sorry, misunderstood the question. I've experimented with both a small overlap (tops @80Hz, subs at @100Hz) and the same. The small overlap can be nice in some situations as it boosts that 80-100Hz range and can add a bit more "chest thump" to kick and the like. However, it added more than I liked for things where I didn't want that boost, such as keyboards and CD playback so for my own tastes I kept it the same as if it were just a full-range system with one crossover point.

As to the effects of interference, that's the purpose of the steep slope, to minimise the content produced by both, localisation effects and phase interactions/cancelations.

On the SMAART site there is a case study about a club system that seems to apply here. It states that overlapping frequencies are more of a problem when the subs & mains are close together. They raised the crossover point leaving a "hole" to correct the problem, which was muddy bass and uneven coverage.

http://www.eaw.com/info/EAW%20Smaart/Ca ... /case9.pdf