Rep Power: 0

I want to have some discussion on this topic because it's been much misleading. I wonder why some people like active and some people like passive. I don't know if it would be allowed or repeated.

Here's my opinion:

Active vs. Passive

Active crossover requires external power to operate. It controls the frequency cut off on the line-level instead of speaker level. It can be classified as analog active crossover (frequency domain response to sine wave) or digital active crossover (frequency domain reponse to unit step, 0 and 1 continous function).

Personally, I believe that active analog crossover does not have peak right before cut-off and constant phase. A good analog active crossover should have good dampening before cut-off frequency. It is the same concept as having a passive crossover. For every frequency domain, phase will change, no matter how much power it is. If you have access to Matlab or whatever engineering program, it will show a Bode Diagram. Both slope and phase change will be shown in the diagram. High dampening requires high gain in the controller(I'm not talking about the gain on signal input) which transfers to cost.

*(Even Bode diagram works on DECADE instead of octave, it gives a good example on crossover design anyway).

Digital active crossover is another story. It is either a hybrid digital, a digital crossover that takes analog signal and divide into different output then convert back to analog, or a true digital, which takes 0 and 1 directly from optical or coaxial digital line and divide into different channel.

The quality of hybrid digital completely rely on BOTH of the input and output. However, for every analog-to-digital convertor, it has an approximate 2% of loss in data(look at any EE basic books it will tell you), as well as error are introduced. Digital-to-analog usually has low error and loss that can be neglected. For this reason, a true digital crossover is preferred, because signal divided in the controller passes through independent DA, but no AD conversion is needed at the input.

This is why to keep things simple. Having HU output analog, go to crossover, then equalizer, etc. will deteriorate sound more than improve it.

Passive crossover behave the same as active analog, but the main point is that, it is designed for that particular speaker, for either on-axis or off-axis listening position. Any boost of dampening at the crossover region can be designed to fit that speaker. One may say using an EQ will create the same effect. However, equalizing sound in crossover region is completely a headache. Phase change, instability, everything can occur at that region.

Conclusion, I would prefer passive over active unless if I have a crossover that is truly digital and with EQ embedded into it.

 
Rep Power: 0

I on the other hand, prefer the active cross over. Yes it's a lot more costly.. but in an analog cross over network, you can easily fine tune things much more nominally than in a passive network. Also in an active cross over network, you can easily hook up an oscilloscope to any given point in your system and fine tune it that way. This way, you can visibly see your wavelength and tune accordingly.
I do however, agree that equalizing sound in a crossover region is hard and very difficult to do. I'm not sure if they still do now, but you were scored on how well your system is equalized in IASCA.

But definitely a good thread. Good job. I am proud.

 
Rep Power: 346

I think some terminology is getting confused. Analog vs. Digital, Passive vs. Active. From what I've learned, an active filter is really a passive filter with an am amplifier built in. Active crossovers available now are usually much more adjustable. I know that in things like speaker design, they are very useful for testing speaker combinations with different rolloff slopes and attenuation.

I believe a passive crossover commonly included in component kits are just a general crossover that probably sounded perfect in their environment, but when actually put in our cars, sounds different, with peaks and valleys to be adjusted with the equalizer. That could possibly be achieved with an adjustable active crossover, but that's not necessarily always true. A peak in a narrow bandwicth could only be fixed with an EQ. a dip or valley around the crossover frequency could be adjusted by changing the crossover fequency on the crossover, passive or active.

I don't remember where i was going if i was going anywhere with this. I wasn't disputing anything, just replying?

 
Rep Power: 0

Hope this thread will continue and generate more opinions~~

 
Rep Power: 0

oh i get it