Thoughts on these graphs...

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Re: Thoughts on these graphs...
« Reply #20 on: 16 Feb 2022, 07:56 pm »
The peak is still +10 dB relative to the next highest bass peak. I agree it's an improvement, but it's curious that no attempt was made to reduce the peak by another 10 or 15 dB to better blend with the surrounding frequencies. Thoughts?

I can think of three reasons:

1. A bass boost at around 40 Hz is always pleasant as long as it's not too big.

2. It looks like lowering the peak also lowers the 73 Hz dip, probably a compromise.

3. The parametric equalization was maxed out.


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Re: Thoughts on these graphs...
« Reply #21 on: 18 Feb 2022, 07:38 pm »
Thank you!

Also, I've got those graphs as well...

Yeah for sure some bass trapping will help a lot, those are very uneven decay times. There are a lot of very strong resonances at 70Hz, 90Hz, and pretty much everything under 50Hz (which isn't uncommon in small rooms, lots of rumbling in the noise floor is common, even background noise as part of the noise floor, etc). The screenshot only went up to 150Hz, but I always look at the entire bass range up to 300Hz or so. Bass trapping helps with all this.

Also there is a LOT more energy under 120Hz than above it -- this can sound exciting and pleasant but if you are after accuracy you might turn the subs down a bit. I usually prefer the subs to be about 6dB louder than the rest of the range but for you it looks more like 20dB louder.

Definitely bass trapping will be hugely important for you.


Re: Thoughts on these graphs...
« Reply #22 on: 19 Feb 2022, 12:40 pm »
Yes, extremely pronounced (a.k.a. - very annoying) resonance at 70Hz & 90Hz, but especially at 70Hz, but those peaks are from the mains, not the subs.

Also, the subs are a bit lower now, tweaked by ear after listening for the past week instead of sitting in the back corner of the room with the mic in my spot. The subs got lowered by a couple dB, but honestly it doesn't sound as loud as it looks. In fact, the majority of time I don't even think the subs are on unless some really low bass shows up that I know the mains are incapable of.

And yes, bass trapping will definitely help, but all of that low bass energy in the room is nowhere near as noticeable or annoying as those darn 70Hz/90Hz peaks.

Just for fun, giggles, whatever you want to call it, here's full range waterfall and spectrograph charts from the same measurements from last weekend.

I was going to be doing more tuning/tweaking today, but we have decided to go to the instead, but I'll have all day tomorrow to mess around with REW and the system.


Re: Thoughts on these graphs...
« Reply #23 on: 6 Mar 2022, 11:14 pm »
Been at it again today with REW, but with the Revel M16's in the system as well as my Topping A90 headphone amp in preamp mode since I sold my Schiit Freya+. The little A90 is quite surprising!

Anyway, started with just the Revel's playing by themselves, measuring and adjusting placement of each one separately of course. I'm still getting that 70 Hz peak as I was with the other speakers, but I was able to lessen it some with placement. They ended up about 10" closer to the front wall and about 12" closer together.

After I got the Revel's playing as nicely as possible on their own, I went back to the left channel only and added in the sub, adjusting gain, crossover point, crossover slope, phase and PEQ. Once that one was as good as I could get it, blending with the Revel, I muted that channel and started on the right channel.

Once each channel was to my liking, I then started tweaking them as a stereo pair. More gain adjustments, and more importantly, more phase adjustments on both subs. Not only are the subs blended extremely well with the Revel's, but the subs are "locked in" on each other now, something I wasn't able to do with the other speakers in the system.

I gotta say, this system is sounding splendid right now. With the PEQ and phase on each sub tweaked to the gills, I've been able to smooth out above and a little below that 70 Hz peak, as well as greatly lessen the dips centered around those 45 Hz and 60 Hz nulls.

Stage width and depth have improved drastically, creating a more lifelike, involved and enveloping sound stage. That 70 Hz peak isn't anywhere near as annoying as it was before, and the subs are working together cohesively, not against each other like before. You can easily tell this as the foundation and overall grunt is stronger, tighter and much cleaner now.

Finally, it feels like I'm actually getting somewhere with this system and room. The next big tweaks of course will be room treatments. Most likely, I'll start with some corner traps up front and a couple absorbers on the wall behind me. After that, some diffusers on the front wall. Lastly, most likely a couple more diffusers on the side walls and maybe a couple more smaller absorbers one the side walls right along side my listening seat.

For now, here's a few shots and measurements...

All graphs are with both channels driven.

12 dB Smoothing...





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Re: Thoughts on these graphs...
« Reply #24 on: 2 Apr 2022, 08:55 pm »
The quarter wavelength of six feet is 47Hz. This looks like boundary interference with the front wall.

Try placing the subs against the wall and crossing over at 80Hz. This should eliminate the problem. You will have to delay the speakers to get them time aligned. REW can be used for this by using the acoustic timing reference when you take the measurements.