first order crossover

[svokke]

Is there any reason why first order ACTIVE crossovers aren't used?Besides the slow rolloff that is. In my system (4-way) this isn't a problem for the sub to bass crossover.
The advantage is that they can be very simple, just using some buffers to ensure controllable input and output impedance.
Greetings, Svokke

[richie00boy]

Probably because since you are going active, you can use far more effective higher order crossovers, so why bother with the poor mans version?

[svokke]

I want it as simple as possible, why making the crossover more complex while messing up the phase response more?

[leadbelly]

Originally posted by svokke
Is there any reason why first order ACTIVE crossovers aren't used?Besides the slow rolloff that is. In my system (4-way) this isn't a problem for the sub to bass crossover.

You best be sure about that. Using 1st order crossovers in a 4 way system sounds like a recipe for disaster. I hope there is facet you are not telling us like sharp acoustical rolloff and wide as possible crossover points.

[mike.e]

From what ive read,1st order filters sound no better than 4th order LR.

http://www.woodartistry.com/linkwitzlab/x-sb80-3wy.htm

http://www.geocities.com/kreskovs/

[David Gatti]

Yes, there's no reason why you can't use 1st order active crossovers, the main benefit of which is sensitivity matching. The reason they're not so common is that 1st order filters are relatively simple in passive form, so why bother with complex active.
Also, 1st order fans tend to be purists & aren't keen on using op-amps.

[5th element]

Originally posted by David Gatti
Also, 1st order fans tend to be purists & aren't keen on using op-amps.

I always find that funny, little do they realise (or do but dont like to admit it) that their precious music has been sent thru hundreds of them prior to reaching our ears.

Anyway yeah there is no reason really to use 1st order especially in a bass application. You really want really steep filters on the sub to ensure that no nasties get thru from the break up subs usually suffer at around 300-500hz. Also if your going to the trouble of using active anyway, 4th order electrical filters are not much more complicated then a 1st order.

You also dont have to worry about phase issues so much at low frequencies because the wavelengths are so long.

[David Gatti]

Does that explain the processed quality of many of todays recordings compared to 30 years ago?

[richie00boy]

No, that's due to the much heavier use of compression and also tailoring the sound to mass market taste and equipment. Also there are a lot of small studios now and recording techniques have changed in that time.

[planet10]

If your speakers are suited to 1st order, you can do an acive XO very elegantly by implementing the filter in the amp -- either at the input or in between 2 stages....

In a hi-pass you just shrink the value of a coupling cap to an appropriate value, for a low pass you need to add a series R, alnong with a cap shunted to ground.

No op-amps, no extra stages.

dave