Stereo L+R AND LFE in a pair of manifolds

[jsilas]

I'm in the planning phase of my IB build.  Due to limitations of my room and a heavy bias toward music (as opposed to movies), I will be implementing a pair of 2x18"IB3 manifolds.  The manifolds will vent into the room directly aside the main loudspeakers.  I want to run L+R in stereo to the two manifolds respectively.  This would mean that I would have to connect the subwoofer amp via the L+R main pre-outs.  

However, this has left me wondering how I can get the LFE signals into the mix.  I don't think my current Denon AVR provides for this - sending LFE signal into the main pre-outs.  I have to assume others have run into this same issue - how do you all get around this?  Do I have to buy a new processor?  

[ThomasW]

If you want everything to go to the L/R speakers it gets a bit complicated.

First it requires the AVR or pre/pro to have preamp level outputs for the L/R speakers

If you only want to run a stereo signal put the processor settings to 'large mains, no sub, no center, no effects speakers', this directs everything to the L/R speaker preamp outputs.

If you're running say 5.1 put the settings to 'large mains, no sub, small center and small effects speakers'. This redirects all the bass to the L/R speaker preamp outputs, while continuing to send content minus the bass to the center and effects.

Next you'll need to buy an external active crossover, this is used to filter out the bass from rest of the signal.

The signal from the L/R speaker preamp outputs is sent to the inputs on the active crossover. There the bass signal is split from the L/R signal sending it to an output that will feed the amp powering the sub.

[jsilas]

So I think what you're saying is that the receiver WILL mix the LFE information into the mains if I set the Subwoofer to 'Off' and mains to 'Large'? If so that would be excellent as it would meet my needs perfectly.

Thanks!

[underthebottom]

I have been using a separate 2 channel active crossover for 2 subwoofers since back when there were only 2 channels.

The owner's manual for my current processor has considerable detail for "speaker configuration: custom configuration". It recommends setting Front L/R to SMALL unless they really can handle full range or you have a separate crossover. It also says that setting subwoofer output to NO will route the LFE channel to any front, side or rear speakers configured as LARGE. So what ThomasW suggests is spot on for my situation. If your processor configuration will allow it, should work for you too. Of course, since LFE is a single channel, it will play equally thru both subs. But at these long wavelengths, that's OK. (double the fun) Stereo music will play thru the subs in stereo, and is clearly better than using a single summed sub. (evil laugh)

[jsilas]

Great news.  I think this is how I'll configure the system.  I've been drawing up plans for the manifolds the last couple days, and I'm getting really excited.  The mains are Sonus Faber's Grand Piano Domus.  A bit older, but I've always really liked them.  I run them in full range now, and they do fine.