Subs in an active xo, DSP system: mono or stereo?

[LewinskiH01]

My system is active, built around crossovers and filters on Acourate, convolved by HQPlayer, and driving a pair of subs, a pair of monoblocks for the midbass, and a stereo amp for midrange+tweeters. Subs are Rythmiks playing in stereo up to 60Hz. Rythmiks have a fair amount of control over phase and PEQ, and I try to smooth bass response first with the built in PEQ, and what cannot be tamed otherwise is then treated with Acourate.

 

But multiple sources of bass help smooth response, like Geddes proposed approach, which I'm missing by playing each sub as a single source. And signals under 80Hz are not directional. So maybe it's best to run the subs summing L & R under 60Hz and have both subs play the same signal and use the flexibility in the plate amps to smooth response, and then apply Acourate?

 

How do you guys run your subs in your active system? Stereo subs or mono?

 

I am considering the addition of two subs with the goal of increasing the sense of impact and smoothing response further. Per Geddes, with 4 subs response should smooth quite a bit. But that would be using 4 subs all playing the same signal, right?

[dziemian]

I am using 4 subs  summed mono with free Multisub optimizer software and Dirac Live. MSO creates filters for 4 individual channels in minidsp to smooth out the response for three seats on the sofa.  In details I run Jriver player where I implement bass management and Dirac Live Vst plugin as 2.1 setup. Sub channel is mono from Jriver but is divided into 4 filtered channels in minidsp. Dirac Live is run for 2.1 at the end to further improve the response.

[LewinskiH01]

13 hours ago, dziemian said:

I am using 4 subs  summed mono with free Multisub optimizer software and Dirac Live. MSO creates filters for 4 individual channels in minidsp to smooth out the response for three seats on the sofa.  In details I run Jriver player where I implement bass management and Dirac Live Vst plugin as 2.1 setup. Sub channel is mono from Jriver but is divided into 4 filtered channels in minidsp. Dirac Live is run for 2.1 at the end to further improve the response.

 

Thanks for the input!

 

Interesting. I wasn't aware of MSO. So Jriver outputs 2.1 with Dirac. What does that output to? The computer card sends two channels to a stereo DAC and the .1 is sent to a MiniDSP that in turn replicates the same signal into channels that are managed by MSO and drive the subs. Does Dirac optimize also the .1?

 

Did you try optimizing or stereo subs and ended liking this better, or went straight into optimizing summed mono subs?

 

[dziemian]

Jriver is set for 2.1. In its bass management it sends all sub frequencies to minidsp (external crossover). Minidsp nanoAVR is set as a dac, crossover and subwoofer matrix. It gets mono sub signal which is further divided into 4 channels (four subs). Each channel has its individual filters created earlier by Multisub Optimizer software. When everything is set I run Dirac Live for both mains and sub channel. Dirac Live is implemented in Jriver as VST plugin, right after bass management as it should be. I prefered 4 subs in mono then stereo. It makes the bass smoother and gets rid of nasty room modes. I used stereo subs before but it makes bass perfect for one position only. If you listen to music alone it makes sense otherwise I would recommend optimized multisubs. I would like to change minidsp to a multichannel dac (RME/ Lynx/ Audiofire) soon as I need more channels and I have issues with HDMI handshake. I would also like to try either Audiolense or Acourate but both these software treat subs individually so I guess I would have to go back to stereo subs for a while. 

 

BTW. I am using Geddes Abbey speakers and he recommends multisuboofer setup. Crossover is set at 80hz. I am in process of changing Abbeys to active CBT36K and that is a reason why I want to try Audiolense or Acourate as Dirac Live doesnt optimize crossovers. 

 

[LewinskiH01]

Interesting!

 

I have in the past read Geddes papers on subs and placement, this time I went onto searching YouTube as well and found a couple interesting talks from him. Still arguing for mult subs, but now said 3 was enough. Also he doesn't like delay among them (unlike Floyd Toole, who argues for delay with multisubs). Tried MSO and didn't like because he's conceptually against delay in subs. He runs his speakers full range and augment the low end with subs rather than xo at say 60 or 80Hz to the mains.

 

You mention your xo is done at miniDSP and you'd like to go to a multichannel DAC such as Hilo and incorporate Acourate. I have a Hilo and use Acourate. This implies digital xo inside the pc. On Acourate you create filters that you later input into JRiver and JRiver outputs multiple channels. I used to use JRiver but moved to HQPlayer as I was looking to integrate Tidal.

 

Today I have an active 3-way: HQP outputs a 3-way signal thru USB to Hilo which is mapped to send the first two channels carrying mids and treble to XLR outputs (this feeds a tube amp that feeds the speakers that still have the passive mid to trebble xo). The second two channels are routed in Hilo to the second set of analog outputs (driving the midbass amps connected directly to the woofers). The third two channels are routed in Hilo thru S/PDIF out to a Metrum Octave 2-channel DAC I used to use, now driving the subs.

 

Your post got me thinking I could replace the Metrum with a miniDSP such as the 4x10 HD, send L & R sub signals to it, and map the miniDSP to sum L & R and to send the same signal to all 4 subs. Apply MSO to the subs, set miniDSP to equalize that response, the leave it alone. And when I run Acourate that whole sub setup would be treated as two channels, like today.

 

in fact I could also try Geddes approach of not xo the mains in the lows: run the woofer from 20Hz despite their inability to reprodce that, and sumplement with the subs instead of a hard xo in between. My current setup doesn't allow to do that.

 

My head is going into gear! Thanks for the input!!

 

cheers