Room Setup .... REW .... Umik-1 ......Advice Please

Probably does not matter which is first. Don't expect huge impacts or corrections from the traps unless they are very large and can address the modes you are certain to uncover. Look at your initial sweeps and they kinda start you down a path. Most folks struggle with getting the subs and mains to cross nicely and play well together. And you have more options to place the sub than the mains so I would personally start with the mains location. 

Don’t go for flat. Start with a target curve of +- 4 DB from 30 Hz to 10 kHz or so.

Use EQ to flatten any peaks in the sub.  If you are going to be using Roon as your media player app then I strongly encourage you get familiar with the DSP capabilities.

After you have gotten to flat but tilted adjust the subwoofer level by ear. +3 to +6 is often preferred.

Consider plugging the ports in your speakers. Especially good if you are using an EQ.. It will reduce distortion and improve dynamic range.

You might find this post helpful in terms of setting expectations.  The post is about how I avoided using a sub, but the measurements and examples will give you a good perspective on your goals.

 

 

I would keep the bass traps out until you have everything as flat as you can/like, then add the traps and place then where you need them to finetune your setup. Otherwise you will be fixing the traps signature as an add on to your system and you definitely do not want that.

Making the first measurements with traps in the equation, is like someone showing up to an emergency room with a big headache, and the doctor giving a medicine that you are allergic without knowing and adds another symptom serious symptom. Now the diagnostic becomes all more difficult. which was the original cause for your headache and what was the medicine that caused a bigger headache.

Each measurement is followed by listening and notes.

My system is all analog/tubes, no EQ or DSP.

This is how I did it.

1. Set up the speakers as good as I could by ear.
2. Find the best compromise between what you can achieve and like using my ears and REW. One speaker at the time. Due to your room’s geometry, furniture and other items in your room it very well be that the speakers are not at the same distance and angle from the listening position. We are not seeking visual symmetry, we are seeking acoustic symmetry. My speakers are about a foot different from the listening position and 9degrees delta. Ideally I would have the left speaker about 3 inches taller than the right but it was too much for me. I moved some furniture to tame the reflection points.
3. Add the sub at around 70-80Hz and find the compromise between energy and decay. You do not want much of either.
4. Plot the speakers SPL with the SUB SPL and see where the actual crossover is.
5. Adjust the crossover and volume in the SUB to bring them to the speaker’s db. One speaker and sub at the time. This is the most tedious part find that compromise between left and right with the sub.
6. Measure the speakers and sub together, now make very small changes to the speakers and find what you like. Only after you like the sound move on to the sub.
7. Measure again one speaker + sub at the time look at the crossover and adjust. Just like in 5
8. Measure the 2 speakers and sub. By now you should understand what happens when you do something, so do your final(s) measurements until you find what your ears like.
9. Add the traps if needed and measure and listen again.

I have 2 subs, so the results are about an order of magnitude better than I could achieve with one sub.

I did not believe that 2 "crappy and small" subs are better than one larger and good. But I bought another 510/s and not only the room measured better, but it sounds SO much better, the stage widened, the 3D /holographic image got defined, the dark is dark, the sound dynamics, energy and coherency are beautiful. If this room was bigger I would add a 3rd little sub but it is living room not a sound room.

these examples for step 2

 

 

 

 

 

 

These are examples of step 5

You want as much blue as you can, and that doted line as straight as you can/like

This is where the room is now kind of before and after without any sound treatment. Traps for 45Hz and lower have to be very deep, 12+ inches, to seriously make improvements. I tested quite a few, from GIK to state of the art traps as big as armchairs.