For posting here it can be easier to sketch and photograph!
It might be worth describing (or better still drawing) the rest of the room layout and furniture etc, also any doorways. And perhaps clarify why anything particular is fixed (apart from genuine fixtures), other than because that is where it is now. And what are the other room uses?
Acoustically, that’s… well… um… complicated!
I’m working tonight so I’ll need time to think later, probably tomorrow.
I have returned to using DSP again to add the finishing touch. When I changed to smaller speakers last year to the Tabs it did help solve a lot of my problems and everything vastly improved over using the floor standers I had. The Tabs sounded great and I felt I didn’t need to use any DSP any more also i wanted them to run in.
I have optimised their position now but still felt the Room was adding in its own thing. It’s a lively room and I have no way of adding treatments. Been down this route already and the Mrs outright refused any. I dont blame her as they are just not fitting for a living space if you ask me.
So even with the Tabs I still had a bass bump at certain frequencies that was noticeable and a slight null at around 200hz and the bass overall was not always present. Yes they are a small speaker but they are very capable.
So I finally decided to redo my measurements and send them back off to Home Audio Fidelity to get some updated filters to use in Roon( can be used in most software that supports DSP) for the tabs. They have their own measurement software now so no need for REW and it’s far simpler and easier to setup and use.
Got my new filters back within a few hours and wow just the icing on the cake. The vocals and midrange which are the. Tabs strong point are just so much better, more focused centre and so much clearer. Bass is so much fuller across the spectrum and treble is just lovely it’s lost any hint of glare and reverb that the room added. Overall a much more balanced affair and no drawbacks to me.
His service is unique for DSP and offer these that other systems just don’t touch.
If you can’t use treatments I strongly recommend you look at this as an alternative. DSP has come on leaps and bounds. I know lots of users of HAF not one has gone back to no DSP when they hear the filters in use in their systems it makes that much of a difference for very little outlay and hassle. If t doesnt work for you you don’t pay or you ask him to tweak it until you do.
I’m really confused now. I was playing with speaker position, and now I seem to have much less issues in the lower end of the spectrum, but a massive spike at 9kHz. Even when I put them back in their original position!! (I had used tape to mask the location, so sure it’s correct)
I don’t think much changed in my room, so not sure what it could be. Don’t assume the exact location of a small sidetable will make such a difference. Perhaps because I used Bluetooth for the sweep? I’m at a loss. Giving up for tonight, will try again at the weekend.
Did you get the same 9KHz +20db peak on each of channels when measured independently?
Does it only occur when both channels are measured together?
It’s worth trying doing the measurements again (L, R, L&R) without the side table, it could be due to something resonant associated with the table.
Oh yes, the beauty of measuring… 
I would be worried about getting 2 so different readouts from just having tweaked the speaker positioning slightly. 
Are you speakers set up with equal distance to the sidewalls and what are you actually hearing from your replay, if the 20 Db lift at 9 K Hz has cropped up out the blue please? ATB Peter
In more general terms I can’t really see the purpose of trying to get your head around measuring and the fretting, which invariably goes with it. You are only ‘allowed’ one single acoustic panel why bother?
Speaker positioning and listening position is surely something done ‘by ear’, with the possible domestic restraints, that it seems you will have to adhere to. Hence finding the best compromise without having to wear a hard hat. 
Peter
I had it on all three measurements, L, R and L+R. Also the other issues on the previous measurement are much less, the big null for example is completely gone. It’s a really small table, I doubt it would have any such significant effect, but will try without.
The previous measurements had been repeated on multiple occasions, so I know they weren’t a one-off. I’ll try again over the weekend and see what happens.
I’ll also pick up my AMB gamma2 DAC to use as a USB → S/PDIF converter to exclude bluetooth doing something silly with the REW signal.
I don’t think it’s from the movment, because as mentioned when moving the speakers back (position had been marked with masking tape), the measurements were still very different from the originals.
No, the room is an irregular shape. The right speaker has no sidewall boundary. See a few posts back for a plan and description of my room.
Interest really. I understand why you wouldn’t bother, but I find it interesting, even though I except it won’t be perfect. And hey, maybe a (small) improvement can be found within my constraints. Who knows?
Sorry n-lot, must read more focused. Well as discussed earlier the only thing you can really do is to stick a tweaked monster bass trap ( ie thicker than standard) in you top left corner on your computer generated diagram and get the prayer mat out 
Best Peter
Another thought on that HF peak…
I assume you did have the curtains over the windows in the same position this time.
I actually thought of that at the time. I couldn’t remember the curtain situation in the original measurements. But measuring with them closed or open didn’t seem to make any difference in the grand scheme of things (didn’t look in detail as concerned about the peak / difference with previous measurements)
Suddenly something occurred to me. I needed to get the microphone up to ear height. The first time I used a stack of (empty) boxes, this last time a stack of magazines. I can imagine these would actually have a very different effect acoustically. Probably much more than a small side table.
Perhaps that can explain the different measurements.
Indeed! In fact need to put the microphone where your ears would be in the listening position - same height, same distance from whatever is behind whether that is a chair headrest or the wall, etc. And ideally take multiple measurements around the various positions they would be in, averaging the response, as you not only have two ears but unless strapped rigidly against the chair your ears will be in slightly different positions at different times, and at the treble end just a few centimetres can make a big difference. If your mic positin was significantly different in any direction between the two occasions above that might well account for the differences.
Mic position was the same every time, at ear height in my listening position.
But there was a (big) difference in the objects I used to get it up to that height. Empty boxes vs (glossy) magazines.
Is there any recommendation on what to use? I guess something most similar to your body as that will have an effect as well.
I use a microphone stand! However, if you can manage to have control of REW at the same time, positioning the computer so as to minimise either reflection or blocking of sound, you could even sit in position with your hand just below and against the front of your shoulder holding the mic so as to position the tip close to your ear (it is omnidirectional so does not need to be pointing in the speaker direction), your hand firmly against shoulder to keep steady. Repeat at other ear. Apart from possible effects of the computer before you, that would get closest to the real situation.
Interestingly, wherever you are in the room can have an effect on the sound at the listening position, though is not in the main direct or primary reflection paths, and if some distance from the listening position, it may be very small.
I would invest in a proper mic stand. You can get them for little money and it will help get more accurate readings. I also add on a usb extension lead to the mic cable to allow myself be out of the room when taking readings so what ever affect I have being there is removed.
I’ll look at one of those stands, but not sure about taking yourself out. After all, I’m usually there when listening.
I liked @Innocent_Bystander’s idea of just holding it up to your ear when in your listening position.
Many years ago I was forced to use bungs in my ES14’s I hated them so eventually used straws…packed them together and tightly slid them into port…bingo I seemed to get the best of both worlds…its worth a try… The foam bungs seemed to slow the bass …they are worth avoiding at all costs…
I found inserting the supplied bungs did indeed marginally tame the lower bass overhang but at the expense of a slight loss of detail in the upper bass/lower mids. No bungs and the lower bass was slightly too flabby.
The best compromise I found was to replace the supplied foam bungs with rolled up speaker wadding (acoustilux). Thanks to @Mark84 for this suggestion.
I tried that it was better…than the foam…try the straws…big paper ones for milk shakes are really good…I found they tamed the port by around 25% but still maintained the tightness and timing…
