Need some help with low frequencies and atmos

[Poulk]

Hello all
First of all, if this topic placed in the wrong place, I'm sorry (I'm a bit new here ) Please tell where it must be posted.
I have a home theatre, a budget one.
7.2 with Marantz sr7010 avr+jamo speakers and two subs, Sunfire hrs 12 + Wharfedale SW 150
A month ago I got my first calibrated mic, UMIK-1 and here the fun starts
I run a lot of measurements and try many different options of placement subs. But nothing can help me with one trouble.
Huge spike on 35hz. I try all i can with setting on avr and sub, and i try different locations for subs. Nothing help.

I even begin thinking it's some trouble with Sunfire, the same spike i see on jamo floor standing speakers in direct mode.
So I pretty sure it's room trouble,
The room is about 16,5 x 11,5 feet and it has a big hole (arc) in the left wall.
No acoustic treatment at the time.
Any ideas how fight with this?
Acoustic panels (dampers), diffusers, or both? Or i need external DSP/equalizer?
AVR Audyssey xt32 doesent help much

And one more little question.
I plan do 7.2.4 atmos
But stuck with heigh channels placement.
Now i can't do them with in-ceiling speakers, so i plan to use small shelf speakers.
And here im stuck with two options.
1)

classical top atmos placement above the head
and 2nd

this more like auro -3d style placement. but this one much more preferred because much more easy to install.
But wich one better from point of atmos playback?
How much I lose if I use the 2nd option?
Any thoughts?
I will be thankful for any help!

 

[Sonnie Parker]

Then post your graph. It may not be as bad as you think, although Audyssey should take care of it. Typically a spike like this is due to the sub being in a corner.

 

[Poulk]

Not it's not a graph

ye it's in corner. but i try different locations. all the time this 35 hz mountain

 

[Sonnie Parker]

Change the Freq. Axis to Logarithmic ... then graph limits from 10Hz to 300Hz...

 

[Poulk]

Idk what I'm doing wrong
hope this time it ok
full spectrum (7.2 speakers)

sub 10-300 hz

and this is the measurement for flor standing front only jamo speaker in direct mode

 

[Marc Lombardi]

The 35Hz resonance is to be expected. The fundamental mode from the 16.5' length of the room is 1130/(16.5x2)=34.2Hz. This can be tamed somewhat with a LOT of very thick bass traps or with tuned membrane traps. But it is VERY difficult to reduce resonances at that low frequency. I have a similar problem. Currently I use Dirac Live room correction in an Emotiva XMC-1. Alternatives would be a MiniDSP 2x4 and create a parametric filter using your measurement in REW. Another solution that worked for me before I had Dirac is the DSpeaker Antimode 8033.

You might try the REW Room SIM to experiment with sub locations. You might also try putting the sub 25% from the front and side walls, if that doesn't intrude too much into the room.

 

[Sonnie Parker]

The Audyssey in your Marantz should be able to tame it... not sure what's going on with that, but as Marc suggested, moving the subs around and even firing them into the walls or corners can make a difference. We were dealing with a nasty 30Hz peak in my room once and Mark Seaton starts punching in numbers on his calculator... a minute later he turns one of my subs around and fires it into the corner and the peak was gone. If you can get the Bass Management software in the miniDSP, that would give you parametric eq's and allow some timing variations to experiment with too.

 

[Marc Lombardi]

I'm compelled to remind everyone that low frequencies - below 80Hz and certainly at 35Hz - are omnidirectional. You can turn that sub any way you want. The only thing that makes a difference is how FAR it is from a massive reflective surface, not the direction of the cone. Corner is the worst place for exacerbating room modes. Center of a wall is better. Moving out about 25% from both front and side walls may be the most neutral in terms of both peaks and nulls. I've done extensive measurements in my 12.5x26.5 room and the 25% is the most neutral, albeit least aesthetic. And, two subs at opposite wall centers are better than one, because they cancel some room modes. Lots of research from Floyd Toole and Sean Olive of Harmon to be found on this topic.

If you use Audyssey, MiniDSP or other room EQ, it may actually be best to put the sub in the corner and let the resonance boost everything. Then when you pull the peaks down with EQ the nulls will be filled in. Note that you can't lift nulls with EQ ... won't work, and will just strain your amp and sub driving the direct and reflected waves in opposite directions.

 

[Poulk]

I tried many places in the room (look at the picture) for sub 1 (sealed Sunfire). All the time i got this spike at 35 hz ( but peaks and nulls change significantly )
Audyssey doesn't help much with bass in my case (as well with mids and highs if you looks close to a graph, they far from linear on all range )
Maybe a little later i add mini-dsp (now i want upgrade atmos to 7.2.4 with high channels) for EQ.
Now i want to add some acoustic treatment.
I want try to use mix of membrane absorber(s) for bass, maybe some corner bass traps with mineral wool, acoustic panels with wool (for mid and highs) and barrel diffusers.
And all this stuff must be DIY because in place i live nothing like this available in store (or it cost like plane wing )
And somehow try to make it work
This how all placed now

 

[Marc Lombardi]

For DIY treatments there's a lot of info out there. Ethan Winer of RealTraps is very generous with Info. I have a lot of bass traps that I made with Owens Corning 703 or 705 semirigid fiberglass. At least 6" thick is best (stack 3 pieces 2'x4'x2") and either buy the FRK for the outward facing piece, or glue some heavy kraft paper to the outer piece (I tested, and the paper gets you another 2-3db). Because traps work best when away from a wall, stack them in the corners first, floor to ceiling. You can also hang them across the tri-corners or angled from ceiling to wall.

According to the Harmon research the best places for two subs is either center of the front/back walls, or center of the side walls. The symmetry is important, being on opposite walls. I see your current challenges with the room, and your current setup is not bad. Might be better of you could get the subs behind the TV stand in the center, and behind the couch in the center.

 

[JStewart]

I'm not familiar with Audyssey XT32 but the OP's AVR has SubEQ-HT. https://www.us.marantz.com/us/products/pages/productdetails.aspx?catid=avreceivers&productid=sr7010
Shouldn't it be capable of taming that peak?

 

[Poulk]

Marc Lombardi
Yes, I have seen Ethan youtube channel (pretty informative).
Now i make research, what works best and how to do it.
Placement is a pain in a**. It's a living room and i have two big dogs (Sharpei and American bulldog ) so i need to be very careful with placement. At the moment all you've seen on a picture it best i can
Maybe later i change room for HT or build a special room for it, where i can place all ideally.
Now I'm only thinking that do with the arch?
It's connected a room with other houses space and has no door.
I'm thinking do i need use some kind heavy curtain to separate room.
Do it make acoustic better? More controllable sound?

 

[Poulk]

I'm not familiar with Audyssey XT32 but the OP's AVR has SubEQ-HT. https://www.us.marantz.com/us/products/pages/productdetails.aspx?catid=avreceivers&productid=sr7010
Shouldn't it be capable of taming that peak?

hmm i don't see separated eq tuning for sub in the receiver. only some settings for boosting and settings for night watching (lows subs). you can see on the graph with full frequency a lot peaks and nulls, so it seems xt32 doesn't do it's work fully.

 

[Marc Lombardi]

Aha the arch .... it's in the same place as the entry to my room, also without a door. I have thought of putting some absorption there like a padded door ... maybe a curtain made from mass-loaded vinyl. You're on the right path though. Good luck!

 

[Poulk]

Aha the arch .... it's in the same place as the entry to my room, also without a door. I have thought of putting some absorption there like a padded door ... maybe a curtain made from mass-loaded vinyl. You're on the right path though. Good luck!

I thinking about a heavy blanket which i use only at time i watch movies. Something from thick fabric with some kind filler inside (maybe mineral wool).
The same blanket i plane add on the window on the opposite wall (it's an old window, which now i can't change and it has some time make funny noises )
Maybe vinyl will be a good base for a blanket at one side. But i can't find good thick vinyl here
ps.sorry I'm not a native speaker. what is "FRK"?

 

[Marc Lombardi]

Sorry ... FRK means foil-reinforced kraft paper. The fiberglass panel has a heavy paper glued to one side, and that paper is covered with a thin sheet of aluminum foil.

Your window is around the first reflection point on the wall and it's generally good to have absorption there for mid-higher frequencies.

I have a weighted blanket for sleeping. it's quilted and filled with plastic beads. I wondered if that would make a good absorber over the doorway.

 

[Poulk]

I'm not familiar with Audyssey XT32 but the OP's AVR has SubEQ-HT. https://www.us.marantz.com/us/products/pages/productdetails.aspx?catid=avreceivers&productid=sr7010
Shouldn't it be capable of taming that peak?

LOL first topic at google

https://www.reddit.com/r/hometheater/comments/a0kwwu

 

[Poulk]

Marc Lombardi
Yep, i just think this two "blankets" can be all absorption i need in-room

I have a weighted blanket for sleeping. it's quilted and filled with plastic beads. I wondered if that would make a good absorber over the doorway.

hehe yes. at least it's not a crime to try it in that way

 

[Marc Lombardi]

Maybe a similar set of issues, but I use Dirac Live. My Emotiva XMC-1 has two sub outputs, and Dirac gets the distances right, but it doesn't play the two subs at the same time. So frequency response of the two together is not right. No way to manually adjust distances with Dirac either. So I got a Y cable and attached both subs to one sub output. The subs are center front and rear and within 2ft same distance, so Dirac ends up with a reasonable average distance and frequency response is pretty good. Best answer .... put a MiniDSP 2x4 on the sub output and attached the two subs to that. Independently set the distances in the MiniDSP and also gain-match the subs. Dirac sees it as one sub and adjusts frequency response and timing. Could also fine tune frequency response with the parametric EQ in the MiniDSP ... even do it with Room EQ Wizard and load the filter parameters.

 

[Poulk]

Hm i think DIRAC additional sub plugin do all in the right way
I think about buying the next receiver with Dirac. Or if all things with work going well, a proper av-processor with Dirac.
Maybe Dirac will fix this trouble with time.
But anyway before that, i will take minidsp.

 

[Marc Lombardi]

Yes Dirac 2.0 will do bass management better - from what I just heard from Emotiva, at least for their XMC-2 and RMC-1. The first bit of better bass management may not come in the first release this year, but soon. Dirac Bass Management upgrade will be available for an additional charge with more features sometime in the future.

Measurements I did today with Dirac Live room correction and MiniDSP (timing and levels only, no EQ)

 

[Poulk]

Not bad

 

[JStewart]

LOL first topic at google

https://www.reddit.com/r/hometheater/comments/a0kwwu

I can see sub-eq getting the distances wrong and creating nulls (phase cancellations) but a peak from a room mode is entirely different. That's why I'm thinking whatever is wrong is fixable. Just wish I was more familiar with Audyssey so I could be helpful. Hopefully someone who's familiar will chime in.

 

[Sonnie Parker]

I'm compelled to remind everyone that low frequencies - below 80Hz and certainly at 35Hz - are omnidirectional. You can turn that sub any way you want. The only thing that makes a difference is how FAR it is from a massive reflective surface, not the direction of the cone.

Hmmm... not really so... as we have proven over and over that the direction can yield a different response... as already eluded to with what Mark Seaton did with one of my subs. Just a few months ago I was placing two subs and firing it to the side had a better response than firing it any of the other 3 directions. I got a different response with down firing a sub vs. firing it the other 4 directions back when I had my down-firing SVS subs years ago. I would say try it and see what you get.

If you use Audyssey, MiniDSP or other room EQ, it may actually be best to put the sub in the corner and let the resonance boost everything. Then when you pull the peaks down with EQ the nulls will be filled in. Note that you can't lift nulls with EQ ... won't work, and will just strain your amp and sub driving the direct and reflected waves in opposite directions.

This is pretty much what I have always recommended, but again, nothing replaces experimenting with different placements.