Can someone explain how an external adjustable crossover works? (1 Viewer)

[AaronNWilson]

I can't understand how this things work with a reciever such as the Denon 3801 which has its LFE out set a 80hz.
It is my understanding that if u place a unit such as the paradigm X30 onto the LFE out then if you adjusted the crossover to say 60 hz, does that mean that the information between 80hz and 60hz is removed?
Can someone please explain this to me. I was at a paradigm reference dealers shop and he couldn't explain it to me.
Aaron

 

[Robert A]

Yes, All frequencies above 60Hz will be cut off.

 

[LarrySkelly]

Below is an old post where I describe how I'm using an X-30. Essentially you are correct, you have the ability to set a specific crossover frequency, below which content is routed to the sub, and above which content is routed back out the high-pass out outputs, presumably back to an amplifier. I use the low-pass signal only, as per below.
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Here is how I have it set up:
Marantx SR8000
- Sub='no'
- Front='large'
- Rear='small' (as I don't want to damage them, they're old B&W bookshelf's. If they were designed for HT, or a bit less 'delicate', I'd probably set rear to 'large'.
X-30 is a continuously variable crossover. You set the x-over frequency, phase, and gain (signal level). It has left/right inputs, which it blends into a mono signal for a sub. It routes all content below the x-over frequence to the sub, all content above the x-over frequency to a pair of high-pass out outputs, intended to be fed back into the receiver.
- My front's are driven right off the receiver speaker outputs as per usual
- Rears are driven off the receiver speaker outputs as per usual
- The X-30 is connected to the receiver's front/left pre-amp out. Since sub ='no' the LFE content is routed out the front's, to the X-30. The X-30 routes the content below the x-over frequency to the Samson amp driving the subs. Note that this means the receiver is routing the same signal out the front speaker outputs and out the front pre-amp out output.
Why did I do it this way? I wanted to use the subs to fill in some of the lower frequency for music, AND I wanted to use Source Direct mode. In source direct mode the receiver disables bass management completely, to get the purest signal, and the sub out is disabled. If I didn't use source direct I might still use the X-30. In my opinion the fixed 100hz x-over frequency sucks, you really don't want to be sending all that content to the Samson and the subs unless you have front's that need help in that area. I know the guys at SVS will say to set sub='yes' and front='small', so that you offload as much bass as possible from the receiver and front's, but I found the 100hz to be way too high.
So my subs and front's have an overlapping signal. Normally one would route the high-pass out signal from the X-30 to the receiver's left/right amplifer in, but I don't want anything to colour the signal going to the M-L's, especially for music, so I drive them directly off the receiver as per usual, and set the sub cross-over frequency pretty low so that they pick up the frequency where the M-L's start to drop off, minimizing the overlap. I usually have it set between 40-50 hz, so the sub level ramps up below there to fill in where the M-L's fall off.
There are better crossovers out there (e.g. Behringer), but I did not see any at local dealers. But I got a good price on the X-30 ($150 Cdn) and so far it seems to be fine. Really I'm just using it to control the cut-off for the subs.

 

[AaronNWilson]

Larry thanks for your informative post.
I am using a 3801 actually with no separate amplifier. I guess it would still work for me though if I use the phono L/R outputs, put them through the X30 send the LFE signal then to the Sub and send the new signal (sub 80hz info removed) back into the 3801s L/R analog inputs.
This doesn't seem like it would be too much of a problem.
I have kept asking guys in audio/video stores to explain this to me, but I guess these guys don't even know what they are selling.
I couldn't figure out how one of these things could work if it was placed on an LFE out which was fixed at 80hz. It makes absolutely no sense.
It makes perfect sense although that it is connected via the LR speaker outputs.
I have never even used one of those external adjustable crossovers so I never even knew the validity of paying for one.
Aaron

 

[KevinMcL]

I believe when x-overs are cascaded, the more extreme of the two would be the set point. i.e. in a low-pass, the lower of the two would be the cutoff freq.