Active vs passive crossover

@erik_squires ​​@phusis , there needs to be no additional adc/dac conversion if one chooses his front end gear wisely, i.e., keep it digital --> high quality dac+dsp+crossovers processor all in one device. A couple of minidsp devices come close, but have poor quality control...some units are defective.

Two stereo amps (boxes), 1 lower power class A for mf+hf, 1 high power stereo amp for bass drivers.....one 4 channel amp or 1 additional low power stereo amp if going 3 way, i.e., number of extra boxes can be kept low (it is not an issue as compared to purist passive systems).

The elephant in the room is having competent speaker measurements and the ability to understand them to accurately implement an active system. For guys lacking the technical prowess to do the latter, an active system is dead. Hence, passive systems remain popular.

For multichannel guys who’ve gone through the rigor of setting up prepros and so on, this isn’t complicated, it falls in the general wheelhouse. If a guy is used to purist plug n play devices, it could get complicated until he goes through the learning curve.

@deep_333 wrote:

there needs to be no additional adc/dac conversion if one chooses his front end gear wisely, i.e., keep it digital --> high quality dac+dsp+crossovers processor all in one device. A couple of minidsp devices come close, but have poor quality control...some units are defective.

The digital-input DSP isn’t necessarily better. I use a Xilica unit with an analogue input (and so an A/D to D/A conversion), and it’s a great DSP - meaning it’s sonically quite transparent. Many however seem to believe avoiding the A/D conversion step is paramount, but as a single parameter it’s really moot in the greater scheme of things.

Two stereo amps (boxes), 1 lower power class A for mf+hf, 1 high power stereo amp for bass drivers.....one 4 channel amp or 1 additional low power stereo amp if going 3 way, i.e., number of extra boxes can be kept low (it is not an issue as compared to purist passive systems).

Oh, haven’t I been there, experimenting with different power amps in my outboard active 3-way setup (incl. subs). It was my initial route as well, going with a high-end, lower wattage class A amp (Belles) for the mids/tweeter compression driver-driven horn, and 2 high power, different class D variants (Crown and LabGruppen) for the mid bass and subs respectively. It sounded very, very good, but once I got 3 virtually similar class A/B power amps from MC² Audio for the entire frequency range, things really started to fall into place. I tried all permutations with a range of power amps, and one of the real eye openers was adding the same amp as the ones used for the top section and mid bass to the subs; a vital part of the tonality imprinting rests in the subs region, but few seem to realize this and instead resort to using cheaper, typically class D variants (that are different amps compared to those used in the frequency span above) for the lower octaves, with all that implies. The thing is, you don’t find out the significance of this unless you try swapping amps and trust your ears as the final judges here. That’s one of the beauties of outboard active, and as implemented with subs as well gives you a range of amps to experiment with here, instead of whatever is used preassembled in the SVS, REL, JL Audio sub or other.

The challenge of using similar amps top to (subs) bottom is finding a high quality, high power amp that does it all, but once you get your head around it quite a few options lend themselves for this purpose, and actively you only harness a bigger potential of a given amp. 

The elephant in the room is having competent speaker measurements and the ability to understand them to accurately implement an active system. For guys lacking the technical prowess to do the latter, an active system is dead. Hence, passive systems remain popular.

Sure, it’s not the easy plug-and-play.

Using all the same amps in a multi-way DSP active setup (with subs) seems unusual. It's like having a set of screw drivers that are all the same.

@koestner 

I don't think having the same amps in an active multiway is a bad idea at all.  It's usually avoided due to cost but there is a big advantage: sonics: all the amps present exactly the same "sound" or character to all drivers.  This removes one variable in achieving an integrated system when you go active.  It also assures the user that the system has little chance of compromised dynamic range.  Headroom in amplifiers is never a bad idea.

BTW-active does not have to be a digital.  ATC makes all analog active systems and has done so for many years.  ATC also uses the "same amp" design principle, but they build three amps using the same topology and parts and outputs but with  3 different output power capabilities to match up drivers sonically, without spending extra on larger power supplies, output devices etc where you don't need them.   ATC actives enjoys an excellent reputation for dynamics, perhaps proving the point.  Its one of the reasons they are popular in studios where dynamics are definitely excessive when tracking.   In the mix stage, one applies compressors or other methods to reduce dynamics, but in the tracking (capture) phase most engineers prefer to leave the signal as untouched as possible.  

Brad