Best mix for stereo subs?

[jkscherk]

I want to use stereo subs in conjunction with my mains. I plan on using the programmable channels to accomplish this. Has anyone done this with good results? What mix was used to make up the sub channel? For example: 100%L+60%LFE ???

I need to make sure I get the correct coverage in both HT uses and 2 channel audio-only applications. In other words, because I'm no longer using the 'sub' output, I want to make sure that the low frequency info from all channels set to small are correctly routed to my new stereo subs.

Do I need to include my surrounds in the mix?

[Scarp]

In the manual there is one recipe for side subwoofers:
Left sub = 100% Left + 60% Center + 100% LS + 60% LFE.
Right is with the right and right surround.

But in your case that would not be appropiate, since you want to place them adjacent to your fronts.

The problem also is that when you apply a lowpass filter to these programmable channels, that your filter works on the total signal I assume. So also your LFE is lowpass filtered (and LFE in Dolby Digital goes to 120 Hz). Besides that you also don't want bass doubling on your fronts, so you would need to set your fronts to small and set the crossover to whatever u use for filter here.

Simple case
1) Just a stereo setup. Fronts are set to small with a crossover of 80 Hz, i.e., the fronts have below 80 Hz filtered away (note that crossovers are not brickwalls, so they extend lower than 80 Hz). Then programmable channel setup will be 100% Left with a lowpass filter of 80 Hz. This will divert all bass from your left speaker to the subwoofer. Some you also do for your right front. This results in hardly any bass doubling.

2) 5.1 with a small center, small fronts and small surrounds.
left sub channel: 100% L, 50% center, 100% LS + 50% LFE
right sub channel: 100% R, 50% center, 100% RS + 50% LFE
(lowpass filter to 80 Hz and also the crossover in your speaker setup set to 80 Hz).
If my assumptions are correct, then this will recreate a left subwoofer and right subwoofer. You might opt to reduce the LS/RS percentage, but since below 80 Hz is none directional it might not matter. The only thing that could ruin this is timing.
Hmm..as I'm writing this I notice its nearly what Parasound gives, but they have 60% for the center and 60% for the LFE. But I would think this will give too much center and LFE (120 % LFE and center).

Since you have them to the front left/right of your fronts, reduce the LS/RS i think. If you have large surrounds, then you could leave them out all together. Same for the center. Usually there is not a whole lot of bass in a center channel.

Any speaker that is set to large and does extent below the lowpass filter will create bassdoubling effects.

Long story, hope it helps at all

[Chris D]

Hmmmm... instead of fiddling with programmable output mixes, for dual subs I was just planning on using the primary subwoofer output and P2, the "programmable" output that just doubles the primary subwoofer. I don't really see much benefit in having one subwoofer reproduce the bass from one half of the room and the other sub doing the other. In my mind, since bass is non-directional, the purpose of two subs is just to add more horsepower to the bass that's already there. Like a supercharger. Both subs doing full bass reproduction from the entire theater.




CHRIS
Luke: "Hey, I'm not such a bad pilot myself, you know"

[jkscherk]

Hey guys,

Thanks for the input. After reading your thoughts I began to wonder myself about the real advantage I gain in trying to mix for stereo subs. Maybe the solution is to just split the basic 'sub' output (or use the sub-redundant programmable channel) and not worry about a stereo signal. This certainly would ensure that nothing is lost from all the other speakers.

I'd be using an 80Hz crossover point, which may be low enough to not notice any directionality in the subs. I do tend to be very aware of the location of low frequency material so I'd be a little leery of settling on this approach until I could do some tests.

Another solution would be to mix left and right subs just like the recipe in the manual. I was concerned about what that might do for just 2-channel material but I guess the absence of surround information shouldn't have any detrimental affect on 2-channel.

I guess I need to play around a bit!

[Scarp]

Yes, just try if that works for you.

Let us know what the final result is.

[larabee]

There may be an advantage to using a programmable channel for a mono sub. My sub and speakers do not blend well with a 24/db per octave slope that the C2 uses for the lowpass or sub channel. At first I used my subs 12/db octave crossover set to approx. 60hz and set the C2 sub crossover to 60hz with sub filter on the C2 off. This way the 5 speakers were rolled off below 60 hz and a full range signal went to the sub with it's internal crossover rolling off the sub above 60hz with a 12 db slope instead of the Halo's 24db slope. The best slope depends on your speakers and room behavior tho. The great thing about the programable channels is if you select a single lo-pass filter it will have a 12db/octave slope in 5hz increments for your sub and simply select 2- lo-pass filters of the same frequency if you want a 24db slope. It works better for me than the standard Halo subfilter or my subs internal filter. This 12db slope for each programable lopass filter is not mentined anywhere in the manual, it is something I found out from experimenting with the C2. As a bonus you get to adjust sub levels for each speaker in the mix levels menu. My rear speakers required a lower mix than the 3 fronts due to the room causing more bass output from the rears. So in my case better sound and 100's more possible settings to play with until I force myself to turn it off and go to bed.




Larry Stinnett

[Chris D]

Larry, you're the best. A tweaker at heart.

Aren't the programmable channels great? So many potential uses, two of which are full range. You can even make 6 different zone outputs! (main, tape, record, zone, P9, and P10) One would be 7.1, or even 7.3 using Pro 1 and Pro 2, three more stereo, and two more mono. (or one more stereo instead of two mono) Front effect speakers, extra surrounds, ceiling speakers, subs, fully programmable tactile transducers, etc.




CHRIS
Luke: "Hey, I'm not such a bad pilot myself, you know"

[larabee]

Thanks Chris. There is one more thing I forgot to mention when using the P9 or P10 channels for subwoofer or lo-pass filtering. Since I don't use the C2's subwoofer channel at all I thought the subwoofer delay setting in the speaker distance menu would be of no use and proceeded to adjust the delay in the P9 channel instead. I could not find a delay setting that sounded right. Realizing the sub is further away than the 5 main speakers in my room, the sub needs no delay. The 5 main speakers need their delays adjusted since they are all closer to me than the sub. Come to discover the sub distance adjustment does just that and does nothing to delay the subs timing. It simply adjust delay to all 5 or for some of you,7 speakers as you raise or lower the sub distance setting. I can clearly hear the change in bass response even tho I am adjusting a sub channel to which nothing is connected. Makes it easy to set up the Pro channels for bass use. I left the Pro channels delay setting at 0ms and the sub distance where it sounded best, 3.7 meters, the actual distance of my sub.




Larry Stinnett

[Chris D]

Larry, that's pretty fascinating. I wouldn't have ever guessed that.




CHRIS
Luke: "Hey, I'm not such a bad pilot myself, you know"