Small room bass

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ruffrecords

Well-known member
Joined
Nov 10, 2006
Messages
16,152
Location
Norfolk - UK
I am in the process of moving house. My old 'studio'  was about 13ft square and the new one is about 12ft by 9ft. In the old one I had plenty of acoustic tiles to dampen early reflections and a couple of corner bass traps. There was a big hole at 150Hz but other than that it was not too back when monitoring on my 10 inch Tannoy Monitor Golds. I always do a final mix check on headphones to make sure the bass is well balanced.

We are now in rented accommodation and my temporary studio is almost exactly the same size my new one will be. There is no acoustic treatment and absolutely no bass! Nothing wrong with the system because headphones sound fine. I am firing across the shorter side which may be part of the problem but I was surprised by how much the bass has disappeared.

I clearly need to address this before setting up my new studio in the new house but the question is what to do? I did not expect such a drastic change. Is there any way I can restore the bass response in a room this size?

Cheers

Ian
 
since its a temp studio, try move back -  forward in the room, c if u can find a nice spot where u can hear some bass... also, push the monitors back-forward to the back wall too...
small studios are always problem for the bass, due length of waves... in ur new studio i would add plenty of bass traps. especially add some bass traps to the ceiling, above ur sitting position, like cloud*
150hz dip is famous one... heavy bass cloud will help alot...

* doesnt necessarily need air gap, if ur ceiling is not high enough, u dont wanna turn ur room in to a cave... just use 4" thick rockwool or similar, ~50kg ones...

 
Hi Ian,
I've got a small studio in the basement as well and I use the Neumann KH-310 together with a K&H O-800 Subwoofer. The subwoofer is not intended to deliver extra bass, on the contrary, it's used as an electronic bass trap to eliminate standing waves. Klein & Hummel had the O800 ARAM, a specialised version with built in delay unit, in their portfolio, but had problems with the patent owned by Genelec.

So, in case you've got a solid Subwoofer and a simple delay unit you can build your own electronic bass trap.
In my studio  I took a line splitter for my monitor signal, sent the signal  through a delay unit to the subwoofer, which was installed at the back wall with the speaker pointing towards the ceiling.  After some delay tweaking and level adjustments I achieved to get a perfect bass signal from the main monitors. When you're  standing just over the Subwoofer, you don't hear any signal coming out of the speaker.

Here is a link with further details. Download the manual for the O800 ARAM as well. Lots of interesting information .

http://www.neumann-kh-line.com/neumann-kh/home_en.nsf/root/prof-monitoring_discontinued-monitors_studio-products_O800ARAM

Cheers
Bernd

 
What you need is LF absorption to control the roommodes. They interfere with the directly radiated sound and cause bumps and dips in the frequency response, depending on the location in the room.
Fibrous materials are not good for lowend absorption because they lower air particle velocity which is nearly zero at the wall, anyway. So they cannot be effective in small rooms. You need absorption which reduces air pressure which is at a maximum at the wall.
Plate-resonators, Helmhotz resonators, VPRs (http://publica.fraunhofer.de/documents/PX-88453.html), limp membranes etc are the weapons of choice there. Esp. VPRs are incredibly effective, broadband and have a depth of only 10cm. Afaik there´s nothing better out there currently.
 
Before buying expensive treatment and / or fancy EQs, move your speakers & listening position around until you get the best results.  If you see a big peak or dip, bass traps, EQ bla bla can only stick a band aid on it.

At least try firing down the long length of the room.

A 13' square room will have emphasized bass at  26.5Hz and all multiples including the important 106Hz.  This may be what you miss.

If you are 'modding' the new room, try to get opposing walls skew whif.  Two degrees is enough.

If you have exactly parallel walls, you will need an INORDINATELY LARGE amount of fancy expensive treatment to get rid of EVIL flutter echoes and it will still not sound as good as the skew whif room cos you will have fallen off the bottom of the RT60 recommendations.

The best sensible wall treatment for small rooms is open bookshelves with books.  It's no coincidence that the music room in stately homes was always the library.

Does your temp. room have flimsy walls ceiling & floor?  Solid construction is best for bass.  And you lose bass through flimsy doors too.

I'm not a fan of tiles, bass traps & getting rid of early reflections.
 
Room eq wizard is good for simulation of rectangular rooms.  It can tell you where the problems are and what needs to be treated.

How  high is the ceiling and what type of floor is it?
 
Thanks everyone for all the tips, some of which I was aware of and some of which are new.

I am not a fan of EQing a room - this was demonstrated to me back in the 70s at an APRS studio engineers course I was sent on by Neve. They had these huge 6ft high Cadac speakers. They measured the room response and used a graphic eq to flatten it. The they played some music with and without the eq. Everybody preferred the sound without eq.

Firing the length f the room I can try easily. In the old room, which was very nearly square, this was not an issue.

There is not much I can do to treat the walls in the rented place but the good news is we complete our purchase of the new place today so I should be in th new room in a couple of weeks and I can treat it any way I like. Currently the ceiling in both rooms is about 8ft high and the floor is carpeted. The rented room has two stud walls and two outside brick walls. At present I am firing from a stud wall. In the new room, all four walls are brick (breeze block) and one of them has a window in it. I'll do a sketch of the new room if it would help. Making the new room wall skew whiff sounds like a good idea. I was also planning hanging curtains floor to ceiling to mop up flutter echo - is this a good idea?

Cheers

Ian
 
I would discourage hanging too many curtains.  Too many and it can easily be a muddy mess. You would be better off building some absorptive sound panels using insulation.  I like the recycled denim insulation for this.

 
ruffrecords said:
Making the new room wall skew whiff sounds like a good idea. I was also planning hanging curtains floor to ceiling to mop up flutter echo - is this a good idea?
Open bookshelves (with books) are far better than curtains or fancy $$$ panels.  But skew whif walls are even better.

The problem with curtains, fancy $$$ panels etc are that to have a real effect on flutter echoes (by FAR the most EVIL of room faults) you have to use so much stuff that the room ends up lifeless with its RT60 well below what you want.

The 3 top speaker makers in the UK all built purpose designed listening rooms in the 80s.  They all got it wrong.  Guess how I know this  :-[
 
ricardo said:
Open bookshelves (with books) are far better than curtains or fancy $$$ panels.  But skew whif walls are even better.

The problem with curtains, fancy $$$ panels etc are that to have a real effect on flutter echoes (by FAR the most EVIL of room faults) you have to use so much stuff that the room ends up lifeless with its RT60 well below what you want.

The 3 top speaker makers in the UK all built purpose designed listening rooms in the 80s.  They all got it wrong.  Guess how I know this  :-[

To summarise, diffusion is far better than absorption?

Cheers

Ian
 
I think that absorption is needed in low frequency, up to 200Hz.  In order to treat room modes

For high frequency, diffusion is usually better. A bit of absorption can't hurt, but it's easy to get too much.

I just finished my own home studio and my mixing room is about the same as yours (3m x 4m x 2m high) and i'm in the process of designing some bass-traps and diffusors. As it is, the room is pretty good already. I have drywall all around with 10cm rockwool behind and a drywall ceiling with 5cm rockwool.

I found that my monitors are better with a little space behind them, but that should depend on your monitors. Mine are Genelec 8030a and the bass-reflex vent is in the back. it could make a difference.

Thomas
 
jensenmann said:
VPRs are incredibly effective, broadband and have a depth of only 10cm. Afaik there´s nothing better out there currently.
I have googled Verbund Platten Resonator, got a lot of links in German, tried to find a translation, to no avail. It seems the concept has not permeated to other countries... :eek:
Do you have names of commercial products so I could find if they are distributed in US, UK, France...?
What I read so far on VPR's makes me think they are flat panel absorbers where the damping is provided by suitable material affixed to the thin resonating plate; I would like to understand in what it is different than traditional flat panel absorbers where damping is due to the combination of intrinsic damping and additional acoustic damping via stuffing rockwool or fiberglass in the cavity.
Maybe reading the whole patent may enlighten me, but German is really not my forte, and GoogleTrans is really challenged.
 
bernbrue said:
Klein & Hummel had the O800 ARAM, a specialised version with built in delay unit, in their portfolio, but had problems with the patent owned by Genelec.
That's a very interesting link; unfortunately there is not much theory supporting their operation. The set-up is in fact very similar to that of cardioid subs as commonly used in sound reinforcement applications, but here the listener is between subs, not away. I'll have to think about this.
To my knowledge, Genelec never had a patent for such a concept, maybe you're referring to another design aspect...?
 
Composite panel resonator is the other name for VPR.
Googling that land you directly to Fraunhofer's Verbund-Platten Resonator patent.
 
metalb00b00 said:
Composite panel resonator is the other name for VPR.
Googling that land you directly to Fraunhofer's Verbund-Platten Resonator patent.
It's an abstract of the patent, that seems more orientated towards the fireproof performance than acoustic absorption!
The most useful description I found so far is in
Handbook of engineering acoustics by Müller & Moser but I'm not ready to pay 300 Euros (including p&p)...
One issue is that some manufacturers use the same designation for Perforated Panel Absorbers, which have very different absorption characteristics.
 
abbey road d enfer said:
That's a very interesting link; unfortunately there is not much theory supporting their operation. The set-up is in fact very similar to that of cardioid subs as commonly used in sound reinforcement applications, but here the listener is between subs, not away. I'll have to think about this.
To my knowledge, Genelec never had a patent for such a concept, maybe you're referring to another design aspect...?

That's what the head of development department from Neumann said to my buddy Reiner when he was there for a workshop. We tried it in my studio and the results are stunning.  In my setup the Subwoofer is about 3 meters behind me.
Afaik there is only one commercial product. Search for "bag end etrap"
Cheers
Bernd
 
Afaik there are few manufacturers of VPRs. I´ve installed VPRs made by Renz Systeme. I´m not aware of maufacturers outside Germany, but I haven´t looked much either...
They consist of a steel plate glued to 10cm thick foam (Isobond Caruso or Basotect).  It´s mounted directly at the wall, all four sides are acoustically open. It´s recommended to leave 10cm of open space between the VPR and sidewalls/floor/ceiling to let air enter behind the plate.
One absorption mechanism is that it´s working similar to a panel absorber, but the plate isn´t working against a closed rear volume but against a damped open back (compressed air can leave the area behind the plate through the open sides.
The other mechanism is a flexural resonator. This origins in the difference of path-length hence time difference between the airpressure arriving at the front and rear of the plate.
1mm steelplates work between 40-300hz effectively, while the thickest available steelplate of 2,5mm works between 30 and 200Hz. Their absorpion coefficient is dependent on the placement. The highest efficiency is in  the corner because air pressure is highest there while it´s lesser efficient in single room boundaries (e.g. floor-wall with significant distance from the corners).

Sorry for my clumsy english  :mad:
 
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