The Listening Room Reality

Hi Thomas, got a question for you please. Just ordered a GIK Monster bass trap ( full range ie no limiter) as I’m suffering a rumbling at times (pressure increase) behind my listening sofa. The back of the sofa is 50 centimetres off the back wall, and I will place said panel 5 cm. off the wall horizontally. Do you think that it would be beneficial to raise it say 5cm. off the floor to allow more airflow around it ( as per rule of velocity absorption) ?? Enjoy your weekend :+1:t3: Peter

@Thomas (or anyone else that used amroc), do you happen to know what the ’ critical distance’ parameter means? I mailed the Austrian owner, but he doesn’t reply.
My first axial room mode turned out to be at 40Hz, with my listening position just on the edge of a pressure zone. I figured I could try to move the sub out of its original position in the middle between the speakers to around 1.2m out into the room to the side, just to see what happened. (bought myself a 5m RCA cable to do so). The sound changed indeed! Airier is probably the best way to describe the first impression. Will probably keep twiddling happily now with the sub for a number of weeks :slight_smile: so this was a really good tip.

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These 2 spare panels are not enough atm.!

It would help if you could take a picture of the whole area.

Unfortunately, ceiling treatment has to be permanent, but not necessarily ugly. Using nice fabric matching your walls colour could be pleasant.

The link posted above shows a simple and effective way to mount the panels to the ceiling.

As for the climbing, I have some nice gear and a dozen of bolts on my balcony ceiling, but no acoustic treament… yet :joy: I should post a picture.

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Not sure it’ll help with your sub.

As for positioning a sub, either you do it with REW and a mic, or one of the methods available on the web.

One cool way to do it, is to place the sub at your listening position then search the room for the best spot, were bass sounds the best, were it is the tighter. Then place the sub at that position.

Critical Distance :

In short :

Extracted from the “Bible” :

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Be gentle, I can’t hear anything over 11 KHz. :roll_eyes: Best Peter
Got a Vicoustic panel behind left curtain btw. and 20 cm gap under the sofa.

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This is how I treated the ceiling.
It is a permanent solution.
But we own the apartment, so it’s ok to drill, glue, etc.

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11kHz is good enough to fully enjoy your system :smiley: :blush:

You only loose an octave or so from the spectrum, and there isn’t a lot information up there. So, nothing to worry about :partying_face:

I suppose your issue is related to frequencies below 100Hz. :thinking:

You need A LOT of porous material if you wish to hit below, let’s say below 65Hz.

Capture

I wouldn’t buy GIK’s Monsters. It won’t do much if wish to hit 65Hz and below.

I would buy a lot of RockWoll and build a nice Peter’s Mega Monster Bass Trap (45cm thick), positioned like so.

Or buy two PSI AVAA C20 Active Bass Trap

EDIT : it’s not 43%, it’s nearly 50% absorption with 40cm thick absober

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Great - very helpful indeed. The French Cleat idea for surface mounting on the ceiling is inspired!

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@PeterR

Do you mind taking another picture from back of the room show everything floor to ceiling.

I’ll then show you what I would do. Something a tad extreme :sweat_smile:

Have you time aligned (i.e. delayed) the signal to the main speakers to account for the group delay of the sub?

The best way to do this is to look at the minimum phase plot of the entire system to ensure a smooth phase transition from the mains to the sub.

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Unfortunately that method completely fails to take account of the phase relationship through the crossover between the mains and the sub. It can result in a situation similar to badly designed DIY speaker that has a serious misalignment of the crossover from the bass/mid to the tweeter.

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As in semtex…?:thinking:

:rofl: :rofl: :rofl: :bomb:

Got this on file, but if you mean a photo from the front wall back to the listening position, you’ll have to wait till our black cat Buddy decides to abort my lap :blush: Best Peter

We have touched on the ceiling before btw. and I’m not touching it, having tried just about everything and beyond and didn’t like it. I do feel that we need to tune our rooms to our own liking and hearing ability. :smirk:. ATB Peter

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But Thomas, if that’s the case wouldn’t a 17cm thick absorber then attenuate by nearly 25 % then? ATB Peter

Unfortunately, it’s not linear :

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Deary me Thomas, this is increasingly looking like the hope of coming out of the Covid lock down! :face_with_head_bandage::rofl: ATB Peter

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Haven’t tried that yet. Another tweak I will try while moving the sub around. I’ll now be seriously busy for weeks finding the best position - what a wonderful hobby during lockdown :slight_smile: