Basic setup and views for REW subwoofer modes

[Paul Anderegg]

New to REW, picked up a UMIK-1 and have gone through many of the tutorials. Bought a new SVS PB-1000 Pro, so that gave me Room Correction and PEQ filters to play with, the reason I got REW and UMIK-1. A new Yamaha with YPAO RCS Multi coming soon, but for now, just trying to ensure my REW is setup correctly, and that I have a marginal enough understanding of PEQs and nodes to start working on my bass.

First question...REW webpage says to set at -20db instead of the default -12db, which I see on most tutorials. -12db or change to -20db? Second question...setting speaker levels to 75db, then I do a sweep, obviously when changing PEQ's and such, do I want to keep PEAKS at 75db or am I aiming to keep 75db as the average with peaks and dips going over and under on REW? Third question, for viewing my sweeps, 1/6 octave (REW suggested) or what is the recommended viewing/smoothing for looking at them?

OK, with that out of the way, I threw the 40Hz 12db Room Gain Compensation at my system, which made the REW sweep flat instead of an enormous slope at the beginning. I started throwing PEQ corrections at the thing starting at the lowest node which was a huge spike around 40-45Hz. I then threw a second PEQ at a large null that was visible at around 55-60Hz. Lastly, I tried throwing the third and final PEQ at 130-135Hz where I had a rather large null. The effect was a shifting of the node locations, with slight if at all flattening of the curve, but an actual audible difference when turning the PEQs off and on again. It was at this point I saw the tutorials talking about rainbows and waterfalls. I was only using the sweeps. My room is small, the TV is at an angle on a dresser, the SUB blasting off across the room 45 degrees to the screen setup behind it, so placement is not something I can adjust.

So I can accomplish sweeps, and I can access Room Gain Compensation and have 3 SVS PEQs to work with. I am guessing I may need to add waterfall to my workflow in trying to deal with the modes? Can someone suggest a simple proper workflow for attacking these...my understanding or misunderstanding of this process (brain was beginning to fry after several hours of reading and YouTube videos) would be to use the waterfall, adjust lowest PEQ first, aiming to lower delay and not worry too much about how the frequency response curve looks, as the dealys are what will change how I am hearing these peaks (ringing) and nulls?

Paul

 

[DanDan]

REW has grown and grown. It is now an AlectroAcoustic Laboratory and a University Faculty...... or to drive it.... a Helicopter. Take the time to play with it. If there is a problem with 20 or 12 dB it will tell you. 75-80dB sweeps are perfect as REW adds another 20dB or so of dynamic range down into the noise floor. 85dB starts to get uncomfortable, so this is kinda self limiting.

 

[Paul Anderegg]

This is the best I can do messing with a couple of PEQs...still can't understand the waterfall, it looks the same no matter what I throw at a PEQ, some of the dips getting bigger as they come at me, like audio monsters. I set my sub level using the sub cal option instead of the Speaker Cal option, was that wrong? To my eye the peaks on my sub make it look like I will have too much bass on the low end?

 

[John Mulcahy]

Aim for 75 dB as an average level. Var smoothing is recommended. Don't try and use EQ on deep dips, it is only suitable for broad, shallow dips and even then likely to make things worse at other positions. Play with position (speakers, sub, listening) as far as you have scope to find places with the fewest/least severe dips in the measurements. Peaks in the frequency response have a much greater subjective effect than slow decays, though in practice they go together.

 

[Paul Anderegg]

Thanks John. I tried to be more conservative with my PEQ adustments, and experiemented bracketing each change with db Hz and Q until I saw the dip or peak reduce with as little change to the surrounding frequency response as possible. Without figuring out the waterfall (mine looked like a slice of cake not a mountain range) I was able to get things more in line with my ears, playing you typical sub Hz sweep on YouTube the tones in 5Hz incriments are pretty much the same level to my ears, before they would have several that would be much louder or much quieter.

Will def use Var Smoothing for my Yamaha EQ when it arrives.

Paul