Bass Traps & Room Acoustics

Dragonheart

Active Member
Yes sure.The easiest way if you try it.Just put a bookshelf with books or similar and you can hear the difference.It is science, not woodoo :)
 

Rob Sinden

Distinguished Member
AVForums Sponsor
I’ve just come across this thread and would like to share my thoughts and experiences.

You cannot achieve even bass response with room treatments. It simply does not work.

Mid and high frequencies have short wavelengths. So, if you have too much energy at a wavelength that is 10cm, putting 5cm treatment on your wall will very effectively absorb it. When you consider there are 20,000 frequencies we are trying to even these out with say 3 different types of materials you can see treatment is far too low resolution to a very high res problem.

With a bass wave that is say 10-foot-long, obviously putting 5 foot of treatment is impractical. There are different types of treatments that claim to be able to fix long wavelengths but again these just do not work.

I have built a truly purpose-built room designed by one of the worlds leading acoustic design firms. It had 60 hanging bass bats in the ceiling. These just sucked all the bass out of the room and have since been thrown away. You can see the whole sorry process here if its of interest.

Building The Perfect Cinema - Gecko Home Cinema

I’d highly recommending watching this video that details a money no object listening room with custom designed and installed Helmholtz bass traps in every corner of the room. As the customer said “it did not work, we needed 10db reduction and this only delivered 2db.

PS Audio – Dem Room
I can deliver accurate bass consistently in any room with a combination of one or ideally two subs Lyngdorf bass management and room correction. If anyone would like to try it, please let me know.
 

swiftpete

Distinguished Member
That post including the link is basically an advert for Steinway systems. I understand everyone has to make a living but it’s a bit blatant.
 

Rob Sinden

Distinguished Member
AVForums Sponsor
I’m sorry if you read it that way.

My point was about how ineffective room design and treatment is. I have made every possible effort to get great sound with the best room design and treatment combined with every permutation of sub placement and it didn’t give results I was happy with.

Room correction has the potential to restore the even frequency response your speakers should give. No other method does.
 

Timbo21

Well-known Member
To get the best results both are needed.

Room treatment to reduce bass frequency decays

Room EQ to even bass response
 

Rob Sinden

Distinguished Member
AVForums Sponsor
Most UK home cinema rooms have plenty of seats and carpets so reverb time and the decay in bass frequencies is not an issue. The odd room requires some reduction of reverb time at higher frequencies but specialist treatment isn't essential for this.

I have had several dem rooms with bass treatment and the bass wasn't right. Electronic correction is the only way I know of achieving. I can now demonstrate 3 cinema systems that sound exceptional with no treatment if anyone would like to assess this for them self.
 

Timbo21

Well-known Member
Well, my room treatment massively helped.

At the end of the day this thread’s subject is Bass Traps & Room Acoustics
 

Timbo21

Well-known Member
Room Correction is about Room Acoustics.

There are countless threads about room eq, less is discussed about room treatments themselves. Fine if Rob wants to mention the system he sells, but as far as I’m concerned this thread deals with room treatments.
 
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mattkhan

Distinguished Member
Room Correction is about Room Acoustics.
It quite literally is not. Acoustics is about how sound waves interact with a room, electronic room correction changes the spectral response of the waves put into the room but does not change the response of that room (which is what this thread is about)
 

mattkhan

Distinguished Member
you don't have to post if it bores you you know :) unless you mean the necropost in which case yes, fair point
 

Ultrasonic

Well-known Member
Some may be interested in this little report on some measurements I made yesterday:

 

Timbo21

Well-known Member
Some may be interested in this little report on some measurements I made yesterday:


Perhaps try making some soffit bass traps
 

AndreNewman

Active Member
Perhaps try making some soffit bass traps
Some may be interested in this little report on some measurements I made yesterday:

I went through a similar process last year, got very disappointed with the effects, not, of the four 100mm panels I built! I ended up stacking all the insulation I bought in one corner to try to get something to happen.

After a few months of debating, I decided to go for it and build some bigger bass traps, do or die.

I built two 300 x 300mm x2.4m traps for front corners and that made a difference, not a huge difference in the REW SPL measurements but sounded a good bit better, well I thought it did anyway.

Then I built a 300x500mm 3.5m trap to go above my screen, effectively a soffit trap, wow what a difference. That beast makes the room it's in sound a lot different. I did the final assembly in our really echoey dining room, all glass and hard furnishings and it made that room a great deal nicer to talk in.

I don't have Dirac but I noticed that YPAO applies a lot less correction now the panels are in and now it's an improvement to sound, where before it was different after correction but debatable if it was better or worse.

My conclusion was that a few carefully placed panels makes a difference to a hugely echoey room but if the room isn't bad to start with you need huge traps to make a significant difference.

I think I'm going to use any insulation I have left from the Cinema room to make a couple of panels for the dining room too.
 

Ultrasonic

Well-known Member
I went through a similar process last year, got very disappointed with the effects...
In case you and others didn't read to the end of my link, I got surprisingly good results in the end with the panels arranged in two blocks in the back corners: 1200 X 600 X 600 mm in the back right corner (HWD) and 1200 X 600 X 400 mm in the back left corner.
 

Ultrasonic

Well-known Member
Here's the example graph of good results. Grey is without panels, pink is with panels, and blue was with EQ applied as well. I was surprised how big the reduction in the 47 Hz peak was but the 37 Hz peak needs EQ to go anywhere.



In practice I don't EQ to a flat response like this though but rather have a boost at the bottom end. I've also now got the sub in a better position which has improved the response above 120 Hz.
 

Ultrasonic

Well-known Member
In case anyone's interested here are a couple of examples of full-range measurements with different bass region EQ options that I've been experimenting with (1/48th octave smoothing applied) . This is for stereo music use rather than movies.

Full range EQ examples.jpg
 

Timbo21

Well-known Member
In case you and others didn't read to the end of my link, I got surprisingly good results in the end with the panels arranged in two blocks in the back corners: 1200 X 600 X 600 mm in the back right corner (HWD) and 1200 X 600 X 400 mm in the back left corner.

Excellent results, but 600mm is a beast of a soffit.

Any waterfall results of before & after?
 

Timbo21

Well-known Member
Then I built a 300x500mm 3.5m trap to go above my screen, effectively a soffit trap, wow what a difference. That beast makes the room it's in sound a lot different. I

Interesting, any pics of it in situwould be good to see.
 

Ultrasonic

Well-known Member
Interesting, any pics of it in situwould be good to see.
Check out my original link for photos and waterfall plots.

Edit: note I'm just experimenting - nothing is in a presentable finished appearance. The whole room needs decorating too.
 
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AndreNewman

Active Member
Interesting, any pics of it in situwould be good to see.
I posted some in this thread:
 

Pugs1

Well-known Member
Check this out to. Worked for me.
 

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