Integration of Two Subs with miniDSP Flex

You should take your REW questions to that forum, but generally speaking, sub integration is not that complicated.  miniDSP has a really good document on how to do so here.

Fritz is an excellent choice of main speaker.  Before integration though I’d suggest you consider your room acoustics.  Fritz travels with 4-6 panels in hotel rooms for a reason.  A  highly reflective room will make those speakers sound unbalanced and lack bass.  I’d strongly suggest you deal with that before making further adjustments.  

A couple of other tips is to go as high as you can with your subs. 80 Hz is great.  Measure with the speaker ports sealed.  I use 100% virgin alpaca wool from a hidden tribe in the Andes who only come out to trade with others once very 50 years.... OK, sorry, that’s a joke.  Just clean socks in the ports.  This is a tip for almost any ported speakers when you have enough subs.  It makes integration a little easier and reduces distortion a little.  Of course, it’s reversible so if you hate it you can pull the socks out. 

Unfortunately many audiophiles fall into the trap of "I bought main speakers that go down to 25 Hz so I only need a sub for 5 Hz more!"  

Seriously, eff that, especially with high pass filters via miniDSP.  Plug your mains, set the high pass filters at 80 Hz and try to do 4th order.  That will make crossing to a sub with 4th order low pass super simple. 

Good luck! 

@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.

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.

It's true and in the right rooms you almost don't need a sub at all, but if you are going to go that route... you may be surprised just how much better your mids and even imaging will be with proper integration with the subs.

Another good source of information is the AM Acoustics room mode simulator which will help you find ideal spots for your subs, main and listening location. 

@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.

Hi OP!! 

Those are very good results though personally I might lift the bass some more.  The severe dip after 2 kHz would be conderning if this was on tweeter axis. 

Looks like you have an anti-mode around multiples of 25 Hz or so.  

Besides EQ, you can look at the AM Acoustics room mode simulator to compare those frequencies with room modes and see if you can move your listening location or subs out of the primary mode locations. 

This is also the ideal situation for corner bass traps from GIK or ATS.  Check the specs to make sure the traps you consider go down low enough for your needs. 

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. . .

You don’t mention sub placement.  Where are your subs located and how did you determine those were the best spots for them?  The crawl method is effective, and Todd Welti, a foremost subwoofer expert, recommends (for two subs) placing the subs at the midpoint of the front and back or left and right walls if that’s feasible.  EQ can only do so much and in some cases (nulls for one) can’t counteract sub-optimal sub placement.

I have acoustic panels placed somewhat randomly around the room. 

Why randomly?  Did you try putting them at first reflection points on the side walls and maybe even the ceiling?  Sounds like there may be some low-hanging fruit here that could yield meaningful improvements, and they’re free!  Just a couple thoughts FWIW.  

 

@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.

I’d try placing the front sub between the front speakers at the midpoint of the front wall and move the rear sub to the center of the back wall (basically as Welti recommends) and see if you get some improvements.  Hey, it’s free and reversible so why not?  BTW, what’s that floorstanding speaker in the back of the room?  Looks familiar but can’t place it.  Avalon?

@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.