[Conrad]

I carried on testing with various combinations of bass management and crossover settings in JRiver and here's where I've ended up:

All EQ on the sub defeated and the built in crossover set to 199Hz.
Jriver -> output format -> set to 5.1 mixing to 2.1 when stereo sources are detected
Jriver -> output format -> subwoofer set to silent (crossover is managed in Room Correction)
Jriver -> room correction -> L and R set to cross over at 80Hz with bass copied to the sub

I then ran sweeps, let REW apply some filters and added them in Jriver. Sweeping after those filters were applied brought me to this:



This is sounding much, much better. There's less boominess, the devore on the walls blows in the breeze of a 20Hz test tone, individual bass notes are clear and individual now, and the bass seems more linear, probably because of the removal of that trough from 60 to 120Hz.

I'm pretty happy with that result. I still plan on buying a proper mic and doing full range. I also know that I'm really not getting the most out of the speakers and they need more space to breathe. I'm thinking of that as a free upgrade when we move into somewhere with a more suitable room.

Thanks for the assistance and comments so far. Now to stop tweaking and start enjoying!

[artur9]

That is a beautiful graph and should sound fantastic.  Can you also post your waterfall?

[Conrad]

That's less good.
I've changed the scale to 500ms so that I see when some of the ringing stops.



Looking at the distortion chart in REW shows that the 50 - 60hz ringing is actually the noise floor. I'm assuming it's background noise from, well, I don't know. 50 - 60 is right in the electrical range, isn't it? So it could be the amp transformer, or the projector or PC fans? It could just be noise on the cheap phono extension I'm using to to the SPL meter, or even the SPL meter itself.

The 100Hz is probably a room mode (94Hz as richidoo schooled me on), and I don't think there's much to be done about the 10-20Hz ringing, short of putting 6ft thick bass traps in the room.

[Conrad]

A better waterfall, now on the same scale as the FR, and colour.

[artur9]

There some guy somewhere with a picture of his room on the 'Net where every conceivable surface is covered in pink fluffy.  I mean, I like my music but not that much

I wonder if the 100Hz ringing can be a harmonic?

Searching for absorption with Roxul shows people saying that 4"-8" inches should be enough for 30-100Hz.  Do you have any panels at all?  I did the DIY thing and that worked well.

[Conrad]

No treatments at all yet.
94Hz is my fundamental mode, so I think that's what we're seeing in the chart. As far as I understand it, I have the options of rearranging the room, changing the speakers, or applying treatment. I'll look at some treatment options and see what I can get in the UK. I think we have fewer options here. Or I might investigate making some of my own. I love the look of those 2x2 diffusers, but I don't know that one of those will get WAF approval.

[fado]

I don't understand most of the technical aspects discussed here but I immediately focused on the 1/4" plywood "membrane" covering the window at the end of the room. Is it fastened at intervals sufficient to eliminate movement? If not, even with treatment, maybe it needs to be thicker - more rigid.

[Conrad]

Interesting. It's actually a sheet of chipboard and it's about 4 feet square. It's pretty heavy.
The window is recessed into the wall by about 6", the sill sticks out into the room by about 1/2". The board is big enough to cover the entire recess and is held in with tightened screws in keyholes at the top and it rests on the sill at the bottom.

I hadn't ever thought about it moving. How would that manifest itself, I wonder.

[artur9]

I wonder if you can turn that into a Helmholtz resonator at the right frequency.