Need Bass Redirection Plugin That Mixes Signal To Sub

[GraysonPeddie]

I am using Echo Gina3G as my surround sound card with 6 outputs routed to my home theater receiver by using 6 quarter-inch plugs to RCA adapters. In other words, I am using my audio interface as a general purpose sound card even when it comes to making music.

I really want to route low frequency information to my subwoofer. I have tried routing 5 signals to my subwoofer output by using Calf Filter set to 36dB low pass at 60 Hz (all my speakers have a low frequency response of 60 Hz, which is what I'm using); however, by doing so, I made the subwoofer sound louder than what I intend to do (I use Carla in KXStudio 12.04). In other words, this sounds less like a bass redirection and more like 1 + 1 + 1 + 1 + 1 = 5 (front left + front right + rear left + rear right + center = subwoofer). I don't want to add up all the signals; I want to mix all the signals together so that all the signals can be routed to my subwoofer. Besides, all the processing done by the receiver gets bypassed if I'm using multi-channel inputs.

If I am going to write code that accomplishes my task, I'd like to say that I have no prior experience in writing DSP code at all.

So is there any way that I can do so I can mix all the subwoofer before it hits a low pass filter and then route the signal to my subwoofer?

[ssj71]

well, mixing IS adding signals together and applying gains. It sounds like you don't really want to mix different channels in at different levels so I would just put a simple amplifier in line or use something like the invada lpf which has a gain setting.

This will be very source dependant, because perhaps on some recordings all channels will have low freq. content so you are mixing 5 copies together, and other recordings only a few channels carry the low stuff.

[GraysonPeddie]

But adding signals together makes it louder and louder as you add in more signals. I don't want the bass signal to be too loud so I've had to add an amplifier to turn it down.

(Testing out Calf Stereo Tools...)

I think I got it! If I add left and right signals together and route it to my subwoofer while both speakers are heard, the signal will sound louder.

Here's a bad example even if I use an amplify plugin to turn it down:

SignalExample.jpg (101.46 KiB) Viewed 743 times

Add 1 + 1 and you will get 2. Divide the added signal by 0.5 and you will get 1, which I may think I intend to do, but add 1 + 0.5 = 1.5 and divide it by 0.5 via an amplifier and I will get 0.75, which is not what I want.

It took me a while to come up with a solution, but I thought I'd come up a solution by using Calf Stereo Tools.

SignalsMixedTogether.jpg (107.06 KiB) Viewed 743 times

Here's an inner workings of the patch bay:

SignalsMixedTogether_Patchbay.jpg (110.01 KiB) Viewed 743 times

Lines 1 through 6 are for routing all 6 channels through an LPF without boosting any signals at all as shown in the bad example. Any frequencies above 60 Hz will get rolled off for the subwoofer whereas frequencies below 60 Hz will get rolled off for all 5 channels. For lines 1, 2, and 4, the stereo mode is set to LR > L+R (Mono Sum L+R) and for lines 3 and 5, they are set to LR > LL (Mono Left). Everything else is intact. For line 6, I'm using Glame Low Pass Filter with cutoff frequency set to 60 Hz with stage (2 poles per stage) set to 2. Same with line 9 but with high pass filter. Lines 6 and 9 are both mono plugins. Lines 7-8 are stereo plugins and I use Calf Filter DSSI for that. It's set to 60 Hz with 36dB/octave high pass filter (can't do 48dB/octave, as that's considered a 3-pole filter, is it not?).

That is what I call "bass redirection" or "bass management" if some people would call that instead. Overall, that really worked but that required me to have so many plugins, so I'm wondering if I could write a plugin that would accomplish such a task, but I have never taken a look at Calf Stereo Tools just to see how it works

[ssj71]

glad you got something that works. You surely could write a single plugin to do all that, but I still don't quite see why not to just put all 5 channels into an amp set at .2 (1/5) and then the amp out to a lpf, then hpf the original 5 signals to your speakers. You are adding them all together still. 1 + 1 + 1 + 1 + 1 = (1+1) + (1+1) + 1. Perhaps there's something I don't see?

[GraysonPeddie]

I could do that, but I'm going with what works for me.

Thanks.

[male]

I could do that, but I'm going with what works for me.

Thanks.

Then why bother asking for advice?

[GraysonPeddie]

How many times have you had some trouble figure something out and you come to the forum for advice and then a couple of days later you figured something out yourself? Don't people do this all the time? How would anyone feel if I ask them "then why bother asking for advice?" My point is, it's okay to be stuck. No offense but I found your post to be rude.

That's what the forum is for, right?