Corner Trap Nonsense

[Randyman...]

A presentation for audiophiles, where Early probably referred to the common 5 inch thick absorber panels sold on various websites. So lets look at the effects of 16inch/40cm thick porous absorption stacked 35inch/90cm high against 3 of the 4 walls in another studio:

View attachment 404862

You can see how absorbtion killed multiple resonances around 35Hz and 50Hz and in other places filled in dips (where EQ is not a solution as you know). Around 50Hz the absorption removed a peak of 7dB in the frequency response (everywhere, not just on the listening position), solving the main problem the client was struggling with.

The RT30 graph might give a clearer visualization of the effect in the low end:

View attachment 404866

Maybe the discussion can become a bit more nuanced after the different examples given in this thread. There's a difference between porous absorbers don't work in the low end versus I don't have the space to install a sufficient amount of it. And of course there are other types of acoustic panels which might be better suited for certain problems, but they will also require a serious area of walls to be covered.

Looks like a huge improvement! Who can argue that isn't addressing the modal region?

 

[Bjorn]

When are people going to learn that reverberation doesn't exist in small rooms and such measurements are meaningless?

There's no Dc and no mixed diffuse sound field, which are requirements for RTx measurements. Instead we have room modes and specular energy.

 

[Sokel]

A presentation for audiophiles, where Early probably referred to the common 5 inch thick absorber panels sold on various websites. So lets look at the effects of 16inch/40cm thick porous absorption stacked 35inch/90cm high against 3 of the 4 walls in another studio:

View attachment 404862

You can see how absorbtion killed multiple resonances around 35Hz and 50Hz and in other places filled in dips (where EQ is not a solution as you know). Around 50Hz the absorption removed a peak of 7dB in the frequency response (everywhere, not just on the listening position), solving the main problem the client was struggling with.

The RT30 graph might give a clearer visualization of the effect in the low end:

View attachment 404866

Maybe the discussion can become a bit more nuanced after the different examples given in this thread. There's a difference between porous absorbers don't work in the low end versus I don't have the space to install a sufficient amount of it. And of course there are other types of acoustic panels which might be better suited for certain problems, but they will also require a serious area of walls to be covered.

At a similar made studio I probably heard the best glissando in my life down low.
But it was smallish at first and treatment made it even smaller leaving about 35-40m² for actual use.
It's work after all,so...

 

[Geert]

When are people going to learn that reverberation doesn't exist in small rooms and such measurements are meaningless? There's no Dc and no mixed diffuse sound field, which are requirements for RTx measurements.

Like I said, it's an attempt to visualize how energy is removed. Just another view on the same data. Not intended to give an accurate RT number according to the definition of RT.

 

[Randyman...]

When are people going to learn that reverberation doesn't exist in small rooms and such measurements are meaningless?

There's no Dc and no mixed diffuse sound field, which are requirements for RTx measurements. Instead we have room modes and specular energy.

Ok - Not "reverb" or "RT" in small rooms. Is "Decay" or "Ringing" a suitable term? And is it agreed the amplitude and decay of the bass problems in the example is reduced with porous absorbers?

 

[Geert]

At a similar made studio I probably heard the best glissando in my life down low.
But it was smallish at first and treatment made it even smaller leaving about 35-40m² for actual use

In small rooms you often have to deal with room modes and strong comb filtering effects due to direct reflections (SBIR) at the same time. That's where broadband absorption can come in handy.

 

[Wesseling Audio Lab]

Can you give us a sense of how thick the porous material was and what proportion or surface area of the space the material covered?

A suspect fairly thick and a lot of surface coverage.

I have achieved similar results with broadband absorption. Filled full ceiling, bulk heads and corners. Walls were drywall on resilient channel with hanging curtains.

The room I'm working on now is framed to accept full surface coverage with 6" total porous absorbers on walls and 12" in ceiling.
The aesthetic in considered so that the entire room appearance has no acoustic treatment.
To dead is not a concern for me personally, but many round and angular objects can be positioned in the room. Also quadratic diffusers can be mounted if necessary.

 

[Randyman...]

In small rooms you often have to deal with room modes and strong comb filtering effects due to direct reflections (SBIR) at the same time. That's where broadband absorption can come in handy.

And a good argument to treat the front wall as well (SBIR)

 

[Randyman...]

To dead is not a concern for me personally...

Same. I prefer too dead over too live for small listening rooms.

 

[Bjorn]

Ok - Not "reverb" or "RT" in small rooms. Is "Decay" or "Ringing" a suitable term? And is it agreed the amplitude and decay of the bass problems in the example is reduced with porous absorbers?

Yes. Decay and ringing are correct terms to use and can also looked at with measurements.

As I have shared with measurement graphs in this thread, both amplitude and decay can ble greatly and effectively reduced with porous material. The best commercial ones are probably the RPG broadsorbors. Highly effective with fairly little depth. The BAD panels also go lower in frequency vs traditional absorbers with same depth.

 

[Randyman...]

4" OC703 and some Guilford of Maine fabric is hard to get wrong for DIY wall/ceiling panels for very reasonable outlay ... Go for something less dense (less flow resistance / more fluffy but will need rigid framing) for deeper traps/soffits.

 

[Tim Link]

I also remember someone pointing out, that there is nothing called "room gain", but rather a build-up of reflections, which we perceive as more bass - especially if we stand in corners. Which is where I believe the trend of corner-traps come from.

Good older post on room gain.

Analytical Analysis - Room Gain

-Introduction- The term 'room gain' is often seen used when the topic of subwoofers and the low frequency sound reproduction comes up. As I see many explanations that are lacking or incorrect, I thought I might try and clear up the topic once and for all. In all rooms there are so-called...

audiosciencereview.com

 

[ozzy9832001]

I personally, use 14.5" thick on my rear wall and 7.25 everywhere else. Leaving air gap between wall and panel increases their effective range.

Mine are fairly effective down into the 50hz region. I don't listen to a lot of content lower than that, so it's not a huge deal.

 

[Tim Link]

Ron Sauro generously offered to do an extra test with them distributed around the room in other locations to see if they work as well. He thought they might, and was curious to find out. They didn't.

I reviewed the data we got from Ron's experiment, and I should give a more nuanced answer. Turns out the traps had a peak absorption coefficient at 400 Hz when distributed in the middle of the room. In the corners the peak was 100 Hz. Both peaked at about 1.1.

 

[Tim Link]

I personally, use 14.5" thick on my rear wall and 7.25 everywhere else. Leaving air gap between wall and panel increases their effective range.

Mine are fairly effective down into the 50hz region. I don't listen to a lot of content lower than that, so it's not a huge deal.

What density of fiber are you using?

 

[ozzy9832001]

What density of fiber are you using?

I, honestly, couldn't tell you. I think it's comfort batt 7.25", which was not all that easy to get. I think Lowes had it but nobody else did. Data on it was limited.

While I haven't fiddled with my system in quite awhile, from what I remember during the installation was a made a significant difference in the low to mid (50-1khz, which not really touching the highs all that much.

I can see if I can find the before and after measurements going from 4" thick panels to 7.25 and 14.5 respectively.