First time AVR user: room correction practically mutes my sub

I have no experience with accueq so wont comment on that.

You will probably be much better off manually changing the speaker crossover to 80Hz. (Feel free to test 60 and 100 also after a while to check)

There is no sub crossover, you are probably talking about the low pass frequency used on the LFE track. Its at 120Hz by default because thats whats expected by those making movies and tv shows. Basically the bass effects channel is only used up to 120Hz because they dont want higher frequencies played by the sub, but you also dont want to remove something that is supposed to be there by lowering it below 120Hz(unless you know what you are doing and have a good reason for doing it).

Finally keep the subs own “crossover” knob at LFE or max so it doesnt mess with the AVRs bass management. Its only supposed to be used when there is no bass management in the AVR/pre-amp/integrated amp.

If that receiver only has Onkyo's "AccuEQ" correction, you're better off not using it and just calibrating by ear. It's a joke or at least that was the case a few years ago. Does it still only measure a single position?

The AccuEQ room correction solution that comes with the NR6100 isn't great. It's not very accurate and does odd stuff like you're seeing.

I would just manually adjust the crossovers post calibration. Leave the levels alone but adjust the crossovers.

I am by no means an expert, but I have been using AVR‘s with room correction for quite some time. There will definitely be people better suited to comment but in my experience at my house, the sub gets dropped every time by room correction. My sub is currently attenuated by 13 dB. I also typically put my own crossover at 80 despite the size of my speakers and let the sub handle everything below

i am not a believer. sure i did it. with the beeps and the tones and all the bs. it was garbage. i set up the speakers to sound the way that makes me happy.

I would just raise it to your preferred levels. Most of the AVR systems I have used(Denon, Onkyo, Panasonic) turn the bass way down when using room correction(especially if your room isn't sound treated), and I just bring it up 4-6db to match my listening needs(my older Panasonic AVR was the worst and had brought the sub down -13db when I used room correction).

Room correction is great for LCR speakers and rear surrounds, but very much hit or miss when it comes to bass levels(which is also incredibly subjective IMO)

if the sub gets lowered by 6,5 and the mains raised by 3,5, reduce the gain on the sub slightly.

ideally, you want it at 9 o'clock or therabouts, so that the AVR sends a higher voltage to it. (for auto on)

make sure to have the LFE on sub at max (120, 180, 240.. whatever) and the phase at 0.

then run the auto eq again.

if the sub is now at 0 or slightly positive, great.

Now, set crossover to 80Hz (LFE 120 is good) there's not much music content below 40Hz, that's why it was inactive

if you still find the bass meager, you can add a bit in the AVR (or increase the gain on the sub directly.)

Just customise to your preferences, it's all good.

As long as you're getting better curves after the correction.