Integration of Two Subs with miniDSP Flex


Hi All,

I have a pair of bookshelf speakers (Fritz LS7 Illuminators) and recently purchased two SVS SB 1000 Pro subs. All of these are in my dedicated audio room.

The second sub is a recent purchase.  I integrated the first sub with the mains using REW measurements and manually tweaking the phase, level, and 3 available PEQs on the SVS.

The results weren’t bad, but I had to run the sub up to 80Hz to address a null and my mains are spec’d down to 38Hz, so quite a bit of overlap.  I thought I’d get another sub as I’ve head that having two with adjustable phase and PEQs can really help smooth out the bass region.

Not having faith I could manually configure the two subs or that their included limited DSP levers could give me the best overall response for my room, I just purchased a miniDSP Flex to help integrate the subs as well as give me options to EQ for my specific room. I haven’t purchased the Dirac Live option and would like to see what I can achieve with the standard Flex features before spending more $.  I will use the Flex as my preamp as it has enough inputs for me.

I’ve read through the Flex manual once and have used the measurement options of REW already, but the recommended or best-practice process for sub integration and EQ is completely new to me.

I understand that REW has an AutoEQ option that can generate a PEQ file that can be uploaded to the Flex.

My initial questions are:
1) Do I generate an AutoEQ file for each bookshelf speaker separately? So I do a separate sweep and AutoEQ for L and R speakers individually?

2) Similar to above, do I sweep each subwoofer individually and generate an individual AutoEQ for each?

3) Even if I have experimented previously and have found an optimized phase setting for each SVS, do I sweep each sub with phase set to 0 degrees and somehow REW will compensate. . .or do I run the initial sweep with phase already set to what I believe is the best value?

4) Once I set generate AutoEQ files for all 4 speakers (L/R/Sub1/Sub2), how do I know where to set the LPF for the subs and HPF for the mains?

5) Once I load all the AutoEQ files to the Flex and set LPF and HPF, then I run a REW sweep with all 4 speakers simultaneously driving and the resulting sweep should get me close to the target curve?

6) If the resulting sweep curve above has issues, what iterative process do I go through to refine things? Or is it just manual tweaking at that point?

6) Should I not worry about FIR filters and Compression at this point?

I know Dirac Live is supposed to automate a lot of the room correction stuff, but looking at the Dirac website, it says that the Flex supports the base Room Correction module, but not the Bass Control module.  So if my initial focus is two sub integration with my mains, I’m not sure how much buying the Dirac license does for me without the use of the Bass Control module.

 

Thanks all.

captouch

Showing 5 responses by captouch

@erik_squires This is how have gone so far with Flex and two sub integration.

Decided against using MSO even though it's no doubt better for a multi-sub situation.  Just tried to optimize the flatness of the sub curves with both running and using the available PEQs on each sub.  Then ran AutoEQ in REW to get filters to apply in the Flex.  This is a before and after (bold is after):

So it cut the range in roughly half and everything is within a 5dB band.

Set the crossover at 80Hz and ran the corrected bass with uncorrected mains, got a curve, then ran the AutoEQ on the main section of the FR curve to get filters to apply to the mains.

Here's the before and after, again bold is after Flex applied the filters:

So this is pretty good as far as I'm concerned.  There's a 3dB null near my crossover point, so I need to try and smooth that out by maybe playing with the overlap or slopes.

But so far, so good.  The Flex is a pretty cool device.

I was able to work on this more - this is all pretty new to me, so I'm experimenting at this point.

I added a delay to my closer (to LP) sub and did separate EQs for L and R mains.  Also was less aggressive on the high frequency attenuation - that was more my not using the EQ tools properly.  This is the latest curve.

In an ideal world, I'd lift that 55Hz dip, as well as ideally the 200Hz and 1K dips.  but all in all, it's much better than where I started. . .

@soix 

The subs are placed where they would fit to avoid blocking a door from opening or having it firing directly into the back of my listening chair.

So one sub is here:


 

So it’s there to the right of the Kallax.  That 2 x 1 cube doesn’t need to be there and can be removed.

The other sub is in the back of the room as shown:


 

So it’s also on the left side of the room, but more center left than hard left.  I could move it to the other side (center right) of the back wall by relocating that beverage fridge and single speaker, but wasn’t sure if that would make a big difference, so I didn’t relocate everything.

About the acoustic panels, here’s the front of the room:

So you can see I have one on the left near the corner and 3 on the right against the wall.  Then comes the door which is untreated.

Here’s the back of the room:

There are some short black panels in the corner that are stacked on top of each other - but they’re not purpose built panels - just cheap ones from Amazon.  I bet them do little to nothing.

All those canvas pictures mounted on the doors of the wall cabinets are filled with foam, as are most of the canvas on the wall.

This is what I mean by random.  The three panels on the right wall - the one closest to the door may catch the first reflection point - not sure.

The overall attempt was to avoid a live room and not make it overly reflective.

I have done REW measurements with pictures off the wall, wall cabinet doors open - doesn’t make a big difference.  Though I did remove two of the panels on the right today and the higher frequencies were boosted some without them.

But my mains, if swept with no EQ, have a wide depression at lower frequencies.  Here’s the left channel:

And the right:


 

Especially the left channel, from 60-300Hz or so.  I’ve tried covering up the window, moving the speaker front/back, left/right, but it’s pretty much always there.

So the AutoEQ ends up cutting the higher frequencies to match the lower ones.

This is my ceiling:


 

I have 4 recessed lights, one vent, and 4 Atmos speakers (and one smoke alarm).  The whole center width of the room is open maybe 5.5ft wide between lights or speakers, front to back, and maybe an 8x8 section in the front third that doesn’t have anything there.

So it feels like my options are somewhat limited.  Even the corners of the room are restricted by wall cabinets, my TT, etc.  So any triangular bass traps would be limited to maybe 12” on their face.

Hope all the above makes sense.

@soix would you have the rear sub firing to one side or the other, or into the back of my listening chair?

The single speaker is a Sony SS-M7A.  I used to be a fan of

this line and had the SS-M7, SS-M7A (had 3 speakers), and SS-M3.  Now only the single is left for a potential mono setup in another room.

@erik_squires Thanks Erik.  You’ve posted several times on Fritz speakers in the past, so good to hear from you here.  I was actually able to visit him and listen to a couple of his models at his home.  Great guy.

One of the things I really like about the LS7’s that use the Illuminator mid/woofer is how fast and detailed instruments like acoustic bass get rendered.

I have acoustic panels placed somewhat randomly around the room.  Given how full the room is and my efforts to tone down reflective surfaces, I think I’m probably okay and the room isn’t excessively live/reflective, but I’ll keep this in mind.

I’m going to have to just bite the bullet and dig in and read a bunch of app notes and other documentation about integration.  There’s always the desire to jump to the end and reap the fruits of the end product, but I will have to do my best to enjoy the process/journey as I learn how to best do this.

Thanks again for the reply.