Active Crossovers

[consistent]

Hi All,

Me not being too technically minded, I was wondering how an active filter/network actually does its job? If you employ one of these devices does it feed from a source (say a CD player) then provide output to an amp and the amp then feeds direct to a speaker (without a network)? Does this mean if you have a Khorn (3 way) you will require 3 amps to feed woofer, mid and tweet? How do you control the different resistance loads each speaker puts up or is there a mechanism in the active crossover to assist, say a 'pot' of some sort, or does each amp require a pre-amp?

Anyhow your help with these Q'S would be very much appreciated

Thanks

[Marvel]

The active filter/network IS the crossover. You would feed it line levels (preamp, CDP, tape), and the output of the active would be line level as well, but divided into the freq. that go to separate amps for the woofer, mid, tweeter. As you mention, you need more amplifiers this way.

The crossover has adjustments for the frequency and levels for the different outputs to the amps. Some of the models incorporate programmable eq and delays to tailor the response and time align the different speakers.

The graphic is for a single channel on a two-way speaker system. You can read Rod Elliot's explanation here:

http://sound.westhost.com/biamp-vs-passive.htm

Bruce

[consistent]

Thanks Bruce,

So you put a pre upfront that takes lines from cd et al, then feed to the active, makes sense. Are there any active networks that have have their own pots to control volume thus avoiding a pre? Also reading Rod Elliot's work I don't fully understand how you would deal with a 16ohm driver, a 4ohm and an 8ohm in a 3 way, like if I wanted to 'activate' a Khorn.

Cheers

Steve

[tigerwoodKhorns]

Thanks Bruce,

So you put a pre upfront that takes lines from cd et al, then feed to the active, makes sense. Are there any active networks that have have their own pots to control volume thus avoiding a pre? Also reading Rod Elliot's work I don't fully understand how you would deal with a 16ohm driver, a 4ohm and an 8ohm in a 3 way, like if I wanted to 'activate' a Khorn.

Cheers

Steve

Just adjust each amps gain to match. Not a problem at all.

[Guest " "]

the path is source>pre-amp>active network>amps

I have a marshall 4 way active tube setup.

I find less adjustments in individual gain need to occur if you start out with different wattage amps.

I used bridged pairs of 120/120's for the woofer (240WPC) , a 9200 (100wpc) for the mid bass, a 9100 (50wpc) for the mids, and a el20/20 (20wpc) for the tweets.

[consistent]

Thanks for your replies. Anyone had experience with Fane gear? What are some of the better actives around?

Cheers

[Don Richard]

So you put a pre upfront that takes lines from cd et al, then feed to the active, makes sense. Are there any active networks that have have their own pots to control volume thus avoiding a pre?

I'm running a setup similar to what you want. My crossover does not have a pot that could be used for a volume control, but my CD player (OPPO) does and it is remote controllable. No preamp at all, straight from the CD into the xover.

[colterphoto1]

Do you mean Rane?

DBX Driverack, EV DX38 (what engineer Roy Delgado specifies for his Klipschorn Jubilees), and there is a new Yamaha unit out that can do stereo three-way.

The number of Parametric EQ filters and number of sections (stereo 2-way or stereo 3 way), and quality of A/D D/A converters is of primare importance in choosing a unit.

SF- what Marshall crossover are you talking about? Didn't know they made anything like this?

[Marvel]

If you want to go analog and don't want the delay and eq, you can start at $150 for a stereo three way. dbx, and ashley, among others provide this. The price goes up for the digital and all the added features.

[consistent]

Oops, I mean Rane...I had just been poking around the 'Fane' site. Some of the Rane gear looks very much high end (EQ/Dealys etc) but I like the idea of starting with analog first. I have already 'split' my Khorn with an amp for the mid/top and another for the bottom each with their own pot/pre. What a diff that makes! So I can see how going to an active network with separate amps would be the 'bees knees'.

Cheers

[joessportster]

phil marschand in new york sales some of the best crossovers available today kits or built by phil, and he backs up his gear 100 percent he has tons of variations available and is very happy to discuss your needs/wants if memory serves his web site is marshand electronics dot com,

Joe

[DrWho]

So you put a pre upfront that takes lines from cd et al, then feed to the active, makes sense. Are there any active networks that have have their own pots to control volume thus avoiding a pre? Also reading Rod Elliot's work I don't fully understand how you would deal with a 16ohm driver, a 4ohm and an 8ohm in a 3 way, like if I wanted to 'activate' a Khorn.

The actual impedance of the driver doesn't matter when active bi-amping...all that matters is the sensitivity of each driver - and the sensitivity is based off the voltage. The voltage output of the amp doesn't change when you change the driver impedance (unless it's a bad amp).

It sounds kinda complicated saying it that way, so just look at it like this...If your tweeter is 100dB and your woofer is 96dB, then your active crossover will have a gain setting of -4dB on the tweeter. It actually doesn't matter if your tweeter is 1ohm, 8ohms, or a thousand ohms.

The only time speaker impedance matters is when doing passive xovers, but that's the beauty of active xovers: it's load independant.

But to answer your question, every active xover will have the ability to control the gain of individual drivers. Sometimes it's a pot, sometimes it's a digital setting, and sometimes it's both.

Also, the reason you put a preamp before the active xover is mostly for source selection. You would actually achieve the best sound quality by running the digital output from your cd player directly into a digital input on the active xover since this avoids an extra D/A A/D stage. In other words, even though an active xover has analog inputs and outputs, it's converting the signal to digital in the middle. Doing the DSP on the original digital signal and then running 6 D/A's on the output is going to yield better sound quality (one D/A per driver).

[Kudret]

Mike, If I were to connect CDP--->DX38--->amp, what do I use for volume control?

Kudret

[DrWho]

Ear plugs? []

The Dx38 doesn't have digital inputs so there's really no advantage to bypassing a preamp...there are two volume controls on the input and then four for the output - manually controlling even two together can get annoying real fast.

Ideally, the active xover should have a multichannel volume control built into the output stage too (which the Dx38 doesn't have either).

Btw, I'm just talking ideals here....I don't think there is anything on the market right now that provides these options.

[Kudret]

Ear plugs?

LOL.

There is one other unit with digital input but it still requires ear plugs.[]

Kudret

[consistent]

Getting some real good stuff, thanks to you all for your help. I have been to the Marchand sight and is pretty impressive but I see that Rane have now an AC 24 Active Crossover which looks like it does everything for (as I understand) a little more than Marchand's top network, even a knob for horns!

[cjgeraci]

I tried a Rane and was not impressed with the sound quality. For me, it was a step backwards, and I took it out after two days. Your ears may be different, however.......

Given the two, I would opt for the Marchand.

Carl.

[tigerwoodKhorns]

Mike, If I were to connect CDP--->DX38--->amp, what do I use for volume control?

Kudret

Email sent.

[Kudret]

Can you send it to kkibrisli at hotmail? I am not sure what's happening to the emails sent through the forum software.

Kudret

[tigerwoodKhorns]

email sent