My take on "rear fill"

[DIY Audio Guy]

I am struggling with this right now. I am using a Dayton Audio DSP-408. It don't see a way to set up L-R, if there is one I would like to know.

[Mr Marv]

I am struggling with this right now. I am using a Dayton Audio DSP-408. It don't see a way to set up L-R, if there is one I would like to know.

I'm not too familiar with that one however if not shown in the manual all it needs is to be able to combine l/r inputs and reverse the polarity (my twk88 does not show the process in the manual however a quick call to JL is how I found out how to do it)

[Hillbilly SQ]

I am struggling with this right now. I am using a Dayton Audio DSP-408. It don't see a way to set up L-R, if there is one I would like to know.

If there's no way to do it in the dsp then you could always just twist the negatives of each rear together and stick each positive into the amp. This will give you the same effect as what a lot of dsp's can do. If you need to attenuate one of them resistors should do the trick with trial and error. You have an aftermarket headunit in the dash so you can use that to help get the necessary delay. I'd try it the way Marv describes it in this thread first if you haven't already since rears in stereo and rears in L-R are two totally different effects and processes to make them happen.

[Jdunk54nl]

I am struggling with this right now. I am using a Dayton Audio DSP-408. It don't see a way to set up L-R, if there is one I would like to know.

The dayton DSP only delays a max of 8ms, so that is going to be one issue you will have. It also technically "can't" do L-R in the software. The cool work around option would be to reverse the polarity (from input 1 and 2) on input 3 and 4 to the DSP and then you can use inputs 1 and 2 as the +L or +R and then 3 and 4 for the -L or -R

[Jdunk54nl]

I'm also a single cab truck guy and figured rearfill would be a waste. Might see about doing it at some point in mine but don't have the amp or processing power right now. Well I have the processing power but it would mean my cdsp8x12 would have to go back in and I'm quite fond of my Helix dsp.2. I might go back to a 2-way front with rears like I had in the Grand Cherokee and see how far I can take that. I did l-r rears with the stock d-pillar rears that were high and wide and that gave really nice results depending on the song and recording. Have also heard a few cars with rears playing regular and bandpassed and couldn't tell they were playing but they obviously were adding something nice to the overall presentation. This will be a project for the coming years.

If you are doing 3 way + sub, and the sub is using 2 outputs, you could use one channel of of the dsp to go to your subs and then the other channel to go to your rear fill. That way you have 3 way + sub + rear fill. It does have the limitations of only being able to adjust the rear speakers as a pair, but it seems that was pretty common in the old threads when you tied the negative side of the speakers together.

[DIY Audio Guy]

It can reverse the output polarity but not the input polarity. I suppose I could wire up some DIY RCA cables backwards...

I am assuming that I just need to flip the polarity on one input channel. What would happen if I did a mono output for the rear fill?

[xTHANATOPSISx]

You don't want mono. You specifically want to remove all the common information from the signal.

[Jdunk54nl]

It can reverse the output polarity but not the input polarity. I suppose I could wire up some DIY RCA cables backwards...

I am assuming that I just need to flip the polarity on one input channel. What would happen if I did a mono output for the rear fill?

If you accomplish L-R somehow and just use one output channel of your DSP, that would work. But again the BIG limiting factory is that the dayton can only delay 8ms max. You have probably already used a couple of ms for normal delay so it is only really going to be delayed like 6ms.

[DIY Audio Guy]

You don't want mono. You specifically want to remove all the common information from the signal.

[Hillbilly SQ]

You don't want mono. You specifically want to remove all the common information from the signal.

Well, when you set it up in the Helix and Minidsp 8x12 you have to sum the left and right channels as mono before you can flip polarity within to create the L-R. I'm not sure if it goes back to stereo after you do the polarity swap to create the L-R or if it stays mono. Maybe Erin or Skizer can verify.