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Going 'active'
A further improvement is the use of active crossovers. Unlike passive crossovers which are situated between the amplifier and the 'speaker drive-units, the active version is placed between the output of the preamplier and the input of the power amplifier.
Active set-up
Adding active crossovers is even better.
One of the major benefits of active crossovers is that the amplifier has more direct control over the 'speaker drive-unit and can therefore control it more accurately. Think of it like this. If you (the amplifier) sit in the back of your car giving directions to a chauffeur (the crossover), who is driving the car (the drive-unit), you may get on fine at slow speeds, relaying your instructions, but if you were in a race, it would be much better for you to have (direct) control of the car yourself. Click HERE for a fuller explanation of active crossovers.
Changing from passive to active control of your 'speakers will involve the following:
* A separation of the preamplifier and power amplifier stages. If you currently use an integrated amplifier you will need to know where the circuit for the preamplier joins the power amplifier section.
* One or more extra power amplifiers (you need one mono power amp channel per drive-unit ie one stereo power amplifier will drive two drive-units) These amplifiers need to have an identical specification as regards gain.
* An active filter (crossover) circuit. You can either build one from scratch, from a kit or buy one ready built.
* The removal (or disconnection) of the passive crossovers.
* The possible alteration of the cabinet size and port tuning.
I am a very big fan of active crossovers, having experienced the improvements they bring. Once you have an active crossover, it is also much easier to alter it to suit different 'speaker configurations than it is with a passive crossover.
On the negative side, an active system costs more than a passive set-up due to the cost of the extra amplification. However, as sound quality is our ultimate goal, I feel that this extra expense is well worth it. And remember that building your own amplification will keep the cost down. See the Build your own section for links to some of the good amplifier kits available.
There's only one thing better for 'speakers than an active crossover, and that is no crossover as I have discovered with my most recent 'speaker project which utilises some full-range drivers. (Click Here for details) However, even full-range 'speakers aren't perfect, often needing another unit to 'help' them cover the full frequency range.