Help Me Understand Active XOs

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cOz

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Help Me Understand Active XOs
« on: 14 Mar 2006, 10:32 pm »
Hello All,

I have been thinking about active crossovers and have a few questions.  My understanding of optimal components is as follows: Analogue Source -> Active XO -> Pre-Amp -> Amp -> Driver.  Nothing special here except I get confused as how to match the volumes of the different drivers.  I assume this happens in the Pre-Amp through individual gain controls on each channel.  Once adjusted the pre-amp then has a master volume control.  

My questions are in regard to the PT-2, PT-3, and Audiophile.  The Audiophile makes sense because it combines the Active XO and Pre-Amp.  I assume it will have gain controls for each set of drivers?  How will individual driver volume be controlled with the PT-2 and PT-3?  Will there be a Pre-Amp made that can handle the Six channels of the PT-3?  (I suppose it could be 3 channels since the drivers are a matched pair).  Will a separate Pre-Amp be created in the future to handle the PT-3?  

My other question is assuming that I start out simple the Audiophile seems the perfect beginner set-up?  I already have my cabinets and I know what drivers I want, I know where they should be crossed.  Is that enough information to get started?

Thanks,
Robert

jeffreybehr

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Help Me Understand Active XOs
« Reply #1 on: 15 Mar 2006, 06:57 am »
The chain goes source > preamp > active crossover > multiple amps > drivers.

Active crossovers split the frequencies before the poweramp channels and obviate the passive crossovers in the speakers.  It's not nearly as easy as it seems.

Almost all active crossovers have level controls.

Curt

Re: Help Me Understand Active XOs
« Reply #2 on: 15 Mar 2006, 02:00 pm »
Quote from: cOz
Hello All,

My questions are in regard to the PT-2, PT-3, and  ...


The Audiophile has a master volume control that controls all channels and also level controls to match each LF & HF driver level. Once you set each drivers level matching you can forget about it and just use the master VC. If you replace a driver you should readjust that driver's level control.

We believe most people will use the Audiophile to integrate 2-way loudspeaker systems (leaving the passive crossovers in place) with subwoofers.

We have no plans at this time for integrating the PT-3 into a preamp but we have not ruled it out either. We will wait and see what happens when we release the Audiophile. Demand drives all businesses.

A PT-3 type preamp would be used by the more serious audiophile to remove their loudspeaker passive crossovers which in mid-priced loudspeakers can make huge improvements. Much knowledge is required here, it's not a one way suits all solution. In well designed more expensive loudspeakers removing the precision passive crossover system which usually includes enclosure compensation circuits can actually degrade the loudspeaker's performance. I believe 3-way active crossover systems (when removing passive crossovers) should be approached only by knowledgeable and experienced audiophiles. Done well with the right components this type of system can be very rewarding.

cOz

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Help Me Understand Active XOs
« Reply #3 on: 15 Mar 2006, 03:18 pm »
Thanks for everyones help.  Does this mean that the PT-2 and PT-3 will have level controls to match the different sets of drivers?

Curt

Help Me Understand Active XOs
« Reply #4 on: 15 Mar 2006, 04:35 pm »
Quote from: cOz
Thanks for everyones help.  Does this mean that the PT-2 and PT-3 will have level controls to match the different sets of drivers?


Yes. The PT-2 and the PT-3 both have driver level matching controls, one control for each driver.

(i.e. the PT-2 has L(LF) + R(LF) + L(HF) + R(HF) level matching).

Matching driver SPL levels is always required since drivers vary in efficiency. Also understand if different amps are used amp gains may vary and level matching can compensate for this too (unless it's a big gain difference).

It's not hard to set up bi/tri-amp systems but they do require some planning.

kfr01

Help Me Understand Active XOs
« Reply #5 on: 15 Mar 2006, 04:37 pm »
Some great articles on active crossovers here:

http://sound.westhost.com/articles.htm

cOz

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Help Me Understand Active XOs
« Reply #6 on: 15 Mar 2006, 09:12 pm »
Thats great!  This would be very easy to incorporate into a Home Theater that is also trying to do 2 ch music.  Very cool.