WSDG: Architecture and Acoustics

Using Two Sub Woofers in a Control Room Environment

From my recent experience of using two sub woofers in a control room environment, I can say that this is definitely a much easier and better way to achieve an even frequency response of a sound system at low frequencies. However, there is no doubt that room acoustics is the most important issue to be solved before one can start playing with the audio system – a bad sounding room to start with will never allow a balanced response.

There is no doubt that equalizers play a very important role in the room tuning process but they should be viewed as the final tool and used in moderation to make good sounding space sound even better. Two or more sub woofers provide a path of adjusting low frequency response without introducing any additional artifacts to the sound chain.

The best options will be those units that provide polarity, phase, crossover and equalization adjustments. To place them correctly in the room, one should follow a cautious process of acoustical measurements with the proper equipment and most importantly, a good pair of ears to make the final decisions. This process should involve an acoustician and one or two other audio engineers – in the end what really matters is how it sounds.

- Renato Cipriano

Inside Expression's Studio 2

Expression College has been a client of WSDG's for many years. Ben Versluis recently blogged about Studio 2, which recently opened providing even greater flexibility to students.  Here is an excerpt:

"Expression College recently opened their new room, Studio 2. It was designed to be a hybrid tracking/mixing/mastering room (in fact, it’s the only room at the school that is deemed as a mastering room). It is, of course, a Pro Tools HD3 rig running on OS X Leopard with a Control 24 and a whole bunch of outboard gear. Custom ATC monitors, too." Photo courtesy Ben Versluis. Read the entire post here or visit the WSDG project page.

Seven Myths and Common Mistakes in Studio Design/Construction

Some time ago, Tape Op did an interview with John Storyk and included a very interesting sidebar--"Seven Myths and Common Mistakes in Studio Design/Construction." Since that article ran over two years ago, we have had requests from all over the world--in fact as far as Poland--for copies. So here is the "7 Myths' piece (below) as well as the entire article in PDF form.

 Seven Myths and Common Mistakes in Studio Design/Construction

1.  Parallel walls are bad. This is simply not true.  People confuse the fact that hard reflective parallel walls can (sometimes) cause flutter echo, which (sometimes) is not a good thing.  Flutter echo is very easy to correct.  In fact, rectangular spaces can often be quite beneficial, more economic to build and for low frequency modal analysis, much easier to analyze.

2.  Acoustical ceiling tiles are really acoustical.  Ridiculous - they are just absorptive at speech frequency and they are the benefactor of a very old marketing effort.  If you look up acoustical contractor in the yellow pages, you will usually find a list of people who simply know how to install acoustical ceiling tiles!

3.  Standing waves are bad – Again, ridiculous.  Standing waves happen whenever you have sound in an enclosed space. What can be troublesome is standing wave frequencies (eigentones) that are piled up at the same frequency, causing rooms to appear to reinforce certain frequencies more than others.

4. One common mistake is to apply too much absorption in studios.  Deadening critical listening rooms with foam or similar products usually causes mid and high frequencies to disappear but does little to affect low frequencies, thus causing even more discrepancies between the low frequency ranges.  Put mid –high frequency absorption only where reflection control is really required.

5.  Always orient a control room with the long dimension front to back.  Actually I would try not to do this in general.  Having the side walls further apart usually assist in controlling first order reflections from the front stereo speakers.

6.  Bass traps have to be deep. Not true. They can be, but in fact, some of the most efficient base management architectural devices are membrane type absorbers which do not necessary have to be deep.  Placement is probably more important than depth.

7.  Curtains or other similar sound absorption devices will keep unwanted exterior noise out through my windows. Usually not! The curtains will control sound that is generated from inside the space, but will have little or no effect on transmission.  You would be better to try to seal the glass edges, or install a better glass window unit with higher transmission values.  Without a doubt, the holy grail of acoustic isolation inventions would be acoustic paint! – I am still waiting for this.

Low Frequency Behavior in Small Rooms

One of the hot topics in small room acoustics is low frequency behavior. WSDG is undertaking various internal research projects regarding this specific issue in an effort to strive for a better understanding with the goal to specify correct and budget conscious treatments for our client's projects. A compilation of our recent research has been presented at AES Amsterdam and is entitled Commercial Low Frequency Absorbers: A Comparative Study (AES Convention Paper #7431 by Gabriel Hauser, Dirk Noy and John Storyk of WSDG)

This paper presents a current set of commercially available passive and active low frequency absorbing devices and ties in to a previous AES Convention Paper by the same authors (AES 115th Convention, 2003, #5944).

A number of different devices have been tested: Conventional devices (3 Cylindrical Bass Absorbers, 3 Corner Bass Absorbers, 3 Cuboid Bass Absorbers) and two types of special devices: One type being a wood box loaded with conventional membrane loudspeakers. These are not connected to an amplifier, but to a variety of different passive electronics networks (parallel, serial). And the other type being an electronically controlled, active low frequency absorber (basically a low frequency loudspeaker driven by appropriately designed electronics).

Our conclusions can be summarized as follows:

(A) Membrane based low frequency absorbers appear to be more efficient than other construction techniques (Helmholtz, porous materials)

(B) Passive loudspeaker membranes appear to be an interesting candidate for use instead of popular rubber, wood or metal membranes.

(C) Active electronically controlled low frequency absorbers appear to be extremely efficient.

The full version of the paper can be downloaded here: http://www.aes.org/publications/preprints/ (available from June 2008).

Decay Rate in Audio Control Rooms

This is an old debate - what are good values for RT60 in audio control rooms? Even better: is the notion of RT60 (a statistical measurement) even valid in rooms that are this small?

Debating the notion of RT60 (time to measure 60dB loss in energy at any given frequency – usually measured in octave bands or third-octave bands) seems to be academic.  The fact is that even small rooms (less than 10’000 cu. ft. or 300 cu. m) have decay rates – and they can be measured. More importantly, they can be perceived and most certainly contribute to the acoustic signature of the environment.

As a guideline the ITU  offers a recommendation for typical stereo and 5.1 surround control rooms. This recommendation gives an upper and a lower limit for the Reverberation or Decay Times as a function of the room’s volume.

Shown below is a comparison graph of the ITU limits for a specific room with a measurement curve (black) and a simulated curve (red). The simulation was made during the planning phase, before the actual room existed! This approach can be used for doublechecking certain acoustical behaviors during the design phase.  The below measurement was taken from TSR Broadcasting, in Geneva, Switzerland--click here for WSDG project page.

 

^₍₁₎ International Telecommunication Union - Recommendation ITU-R BS.1116-1 „Methods For The Subjective Assessment Of Small Impairments In Audio Systems Including Multichannel Sound Systems“

We have often employed the mentioned ITU specification during design, and do in fact experience a high-class work environment when all is built and done in the field, hence we continue to stick to the spec.

However, these rooms most definitely have frequency dependent decay rates and they are perceptible. 


- John Storyk

Gothamist Blogs on Manhattan's Poisson Rouge

On May 19th, Jen Carlson of The Gothamist blogged on Poisson Rouge, a NYC-based WSDG designed entertainment venue. Here is an excerpt:

"With venues closing down left and right, it's nice to see some opening as well -- especially in Manhattan where most are getting priced out. "(Le) Poisson Rouge is "an 800-capacity multimedia art cabaret founded by musicians on the site of the historic Village Gate." The space, located at 158 Bleecker, will be opening once their ongoing major remodeling work is complete. Right now there are some events booked for June, but they tell us they'll be officially opening in September."

We can't say much more on this one yet, but let's just say it is indeed a very interesting and exciting project to be involved with......

Placement and adjustment of monitoring systems

In a recent issue of Broadcast Engineering World, Genelec's Christopher Anet discusses in brilliant detail the importance of room geometry and placement of monitoring systems.  Here is an excerpt:

"...monitors are built in anechoic conditions, and their response changes when placed into a listening room because of room boundary loading, reflections, reverberation time characteristics, etc. Precise adjustment of the monitor's response is needed for optimal loudspeaker-room interaction and flat frequency response at the listening position."

Anet goes on to detail some common mistakes that become audible a result of room acoustics, and then talks about how proper placement of monitors is key. Access the full PDF here.

Report from AES Amsterdam

Hi all!

Our team is currently at AES Amsterdam. While the exhibition is relatively small, the convention part is  quite interesting and popular. It looks as if AES Europe is going back to what it once used to be - an academic event with a scientific programme of papers and workshops - and a number of booths of manufacturers that appreciate the attention.

WSDG provided a workshop about Small Room Acoustic Modeling and also did a paper on low frequency absorbers, which garnered high attendance numerous 'after presentation chats'. The subject seemed to be at the top of everyone's mind--there seems to be a lot of voodoo science in this area.....

 There was one interesting paper at AES that caught my attention, about "voluminous diffusers;" hanging perforated sheets in "free air" (suspended from the ceiling), one above the other (a few inches between them), all with different perforation patterns. The paper showed that one has to be careful though that it's not simply a reflector - there is some math required.

Let us know your experiences at AES Amsterdam.....

Dirk Noy

Relevance of Acoustical Design

First, let me personally welcome you to the WSDG blog! Hit 'subscribe to this feed' on the right to make sure you receive our updates.....

In these times, everybody that owns a laptop with a decent soundcard and a microphone calls himself or herself a studio owner. This is a good thing, for it places the creative tools - only a few years back tightly held by corporate big-money decision makers and shakers - back in the hands of tens of thousands of talented musicians, producers, composers, programmers and DJs all over the world.

What's missing in this picture? It's the steps in between the music-making, programming, DJ'ing and the final product - a demo CD, a commercial CD, an MP3 for one's Facebook friends and/or iTunes or any combination of the above.

The processes that compile the recording and sampling process are editing, mixing and mastering. These steps require an acoustical accuracy of the monitoring environment - to make sure that no low frequency rumble, harsh high frequencies, unintelligible vocals, distortions and other anomalies leave the hand of the creator - unless he or she specifically wants them!

Proper acoustical design in this regard can be seen as cleaning the magnifying glass when studying insects - one wants to be sure that it's the insect you're looking at and not a speckle on the magnifying glass.

What are your thoughts?

- Dirk Noy, WSDG

WSDG Announces TEC Entries for 2007

WSDG is proud to announce that seven of its studios have been submitted to the TEC nominating committee in consideration of its 23rd Annual Technical Excellence & Creativity Awards, for the category of recording studio design. The projects are as follows: Paradise Garage (Robert Clivilles), Murray Arts Center, Diante Do Trono, Oven Studios (Alicia Keys), Tangerine Mastering and Inner Machine (Goo Goo Dolls). Take a look at any of these studios by visiting the project pages (via links) above.