# Help with Dual Sub Calibration



## TrevorW (Jan 8, 2019)

Hi there! First time poster here. I have been working through learning how to calibrate my home theater over the past year (much to my wife's amusement) and have made the investment in REW (including donation!), a Umik-1 and a proper mic stand. I have been doing my best to balance my discretional time with reading guides and working with the hardware/software. I feel like I am getting close to having the basics figured out and am requesting assistance to get me past a few hurdles I have encountered!

First the aspects of my system/room that matter:


Yamaha RX-A2070 AVR
2 x SVS PB 2000 subwoofers (placed 1/4 wall on either side of my screen; sub crawl completed)
Theater size is ~15' long by 14' wide. Room size is approx. 15' long by 25' wide (my theater is at one end of the room separated by a custom acoustic curtain). Subs are on the long wall.
MLP is middle of a three seat couch placed ~1/4 off the back wall adjusted for max SPL

I have attached the following graphs for reference (apologies they are just a bit off the requested parameters):
Graph with 4 lines showing the results of sweeps completed with YPAO OFF (PEQ = Through) for the left sub (green line), right sub (red line), both subs together (blue line). The gold line is post-YPAO w 8 measurements.

Now, the other graph with 2 lines shows the post-YPAO results and following sub distance adjustments in the AVR (-4' for the left sub and +3' for the right sub). The purple line is what I have been living with for the last while. My latest efforts to flatten the response led me to the try a few different settings... The green line is with *Extra Bass ON *(a Yamaha option for subwoofers that in known to kill low end bass, but really leveled out my response). The results are pretty incredible to my eye! Seems like problem solved.


My questions:
*Any thing I should be aware of related to my graphs?

*Does the green line look acceptable (+/- 3 db seems pretty good)

*Why is the average SPL (~100 db) so high on my graphs? I leveled my subs at ~78db (using REW) prior to running YPAO and have my AVR set at -20. The SPL doesn't seem consistent with what I'd expect. I am using the 90 degreee calibration file. 

*I'm trying to figure out how "hot" I can run my subs. I ran compression sweeps with +6 db through the AVR sub trim and there was no noticeable compression. I then increased the level through the AVR manual setting +5 db (total +11 db) and still no noticeable compression. I can post graphs of my compression sweeps if helpful. 

Any help or input would be very much appreciated!

Trevor


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## TrevorW (Jan 8, 2019)

Seems quiet in here...


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## Wayne A. Pflughaupt (Apr 13, 2006)

> The results are pretty incredible to my eye!


Hopefully it sounds as good as it looks? Because that’s what really matters!



> Any thing I should be aware of related to my graphs?


Nope – looks great. I envy your extension below 20 Hz! The Yamaha setting obviously flattened response with a house curve in the 8-10 dB range, while the purple curve shows a steeper ~16+ dB slope. Which sounds better to you will probably be determined by the size of your room. Look for the article on house curves in my signature for more info on how to determine which is the better option for your room.



> Why is the average SPL (~100 db) so high on my graphs? I leveled my subs at ~78db (using REW) prior to running YPAO and have my AVR set at -20. The SPL doesn't seem consistent with what I'd expect.


Sorry, I have no idea about the discrepancy. Maybe John will weigh in.



> I'm trying to figure out how "hot" I can run my subs. I ran compression sweeps with +6 db through the AVR sub trim and there was no noticeable compression.


Most people seem to want to blend the subs with the main speakers, not run them just below the point of blow-up. Typically ~10 dB hotter than the mains is a good starting point. Decide from there if they need to be turned up or down.

Regards,
Wayne


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## TrevorW (Jan 8, 2019)

Thanks Wayne - Your response is much appreciated! I had a chance to run some heavier bass movie scenes last night and the bass sounded a bit tighter and cleaner, but not as impactful (chest slam). I attribute this to the ~5db drop in SPL up to 50 hz. I need to do some more testing though.

I'll check out the house curves you referenced (one I get my post count up apparently).

Any recommendations related to how to manually adjust the Q and gain to achieve a house curve? I am having a hard time finding step by step information and explanations for those of us that are learning.

Cheers!


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