Moving a music system from one room to another is an interesting process. Sometimes the new space will lack the life, sense of space, or the low frequency warmth of the old room. Or the music may sound blurry and poorly defined.
Will performing acoustic measurements in the new room provide an accurate guide as to the treatment required? Well, yes and no. Yes, it will identify frequency response issues and reverberation times that need to be addressed in order to improve the accuracy of the room. And no, if the aim is to reproduce the acoustics of the old room. The original room may have had significant acoustic issues that the listener found appealing, for example, exaggerated very low frequencies. This can make kick drums sound huge and give very low frequencies in movie soundtracks extra impact. Obviously, for music production applications, accuracy is paramount.
I’m being lazy with this week’s blog but this is a really interesting acoustic treatment profile that a client has kindly taken the time to write. Identification removed to thwart any would be burglars!
The system sits in an eight by five by 2.4 metre room of standard construction – wood frame with plasterboard sheeting with a concrete underfloor. A couple of softly padded leather recliners, carpet, and a number of large “bookcases” which actually hold a thousand, or so, DVDs and Video Tapes, plus, the racks for CDs and LPs. Yaaaaawwwwwnnnnnnn!! Yes, I know. This is just by way of introduction to the acoustic issues, not an attempt at literary anodyne.
The noise making end of the system (see associated pictures) is comprised of stacked pairs of original Quad Electrostatic loudspeakers in custom built, rigid aluminium frames with a very heavy base. The lower pair of speakers is raised approximately 40cm from the floor. The speakers stand approximately 180cm high with a bass panel radiation area of eight square feet per side and treble panel radiation area of about 3 square feet per side. The reader might like to translate that into metric – these are old “imperial” speakers! The Quad ESL is a cosinusoidal, dipole radiator. That is, it has considerable output to front and rear, but negligible output sideways, as with an ordinary “box” speaker – there is no box! This system has more than the usual rear radiation at bass frequencies since the jute mats present in the original speakers are removed. The speakers stand about 1.75 metres from the rear wall.
Acoustics? There is a primary eigentone in the bare room at around 44Hz, another at ~66Hz and one at ~138Hz. This last is so close to a multiple (x3) of the first as makes no odds, so re-inforcement around that frequency (~138Hz) is a given; and a nuisance. I have had some type of “room treatment” for many years, mainly comprising bass traps in the form of DIY pressure (tube) traps, which were very effective, if not the most cosmetically appealing apparatus. It is undeniable that a speaker of this size in a relatively normal ‘domestic’ space is a bit of overkill in terms of activating the air in the space, easily producing 90-100dB. However, if you can make that space acoustically “larger” then you’re on to a good thing. In fact, properly controlled, it becomes a magnificent listening space. In fact, one that recently evoked applause from a visitor following a “performance” of the William Tell Overture by the Montreal Symphony.
The changeover to Sound Acoustics products (exclusively) was a change not lightly undertaken. While Sound Acoustics bass traps and wall panels exhibit excellent cost/performance ratio, there is still the matter of removing the old room treatments, and, as with anything, the small niggling worry that it just might not be as good as you hoped. Fortunately, the Sound Acoustics products not only performed to specification but yielded a few side benefits, such as higher SAF (Spouse Approval Factor) and a definite ease to the installation and manipulation of the panels that is not apparent with a 1200mm tube trap made with steel, wood and dacron! Experimenting with the relatively light (even the BT120/80) bass traps was straightforward. Positioning of all panels and traps was initially performed by listening. Bass traps (of course) predominantly belong in the corners of the room, as the associated pictures show. In fact, to control the bass wave coming from the rear of these speakers it was necessary to trap the corners behind the speakers with four BT120/80 traps and ten SA600/150 panels – still might not be quite enough! The “unusual” feature of the room arrangement is the use of two BT120/80 bass traps dead centre between the speakers and about 40cm from the rear wall to damp the longitudinal mode of the room. Some folks in the acoustics business refer to this type of arrangement as the “imaging trap”, and indeed, it substantially improves the sound stage, revealing a pin point placement of performers in large orchestral works to a degree I had not previously experienced. This is saying something, since the Quad ESL is very well known for its extremely pure mid range and very accurate sound stage. In other words, the Sound Acoustics products allow the speaker to be heard correctly. Additional panels were affixed to the door of the room which was flexing away at 140Hz-160Hz and another BT120/80 was placed in one of the rear corners of the room towards the ceiling. Small pressure zone traps were used to damp out (~1100 Hz) flutter echoes from the boxed beams that form part of the ceiling and hold the house up!
Puff, puff, wheeeeezzzzzze! In short, it was well worth the effort. Measurement (ETF software) confirms most of what my ears tell me about the acoustics of the room now, plus a few ‘foibles’ that probably also need to be adjusted – more panels James! Many products, both DIY and commercially manufactured exist in this field. It is my good fortune to have access to most of them. Why use Sound Acoustics? It comes down to acoustic effectiveness, cost effectiveness, ease of installation and appearance, in that order. Your imperatives may vary, but the excellent acoustic performance cannot be denied – the ears have it!
For more information on Quad
I was sent this link by DMC records in Prahran, demonstrating how a client had installed a RK1 room kit. I like the way that the corner traps are doubling as a recording booth. Clever! DJBonez
I was having an interesting discussion with a colleague of mine who works in broadcast audio, and who also has a home studio. I was bemoaning the fact that a I couldn’t afford a Neumann U87 or an Avalon 737 (more to the point, my wife wouldn’t allow me to spend the cash!). His reponse was, do you really need it? His argument was, by the time you have processed the signal the listener would not be able to tell the difference between, say, a U87, a Studio Projects C2 or a Rode NT-2A. Yes but wouldn’t the U87 would inject some magic to the vocal, add a quality that would be more engaging to the listener? It’s an interesting question, it possibly depends on the style and the artist. I suspect that Jack White’s vocal on Seven Nation Army could be recorded on anything. Maybe Nora Jones really shines using microphone esoterica. And Bono is reported to be happy with his Shure Beta58 for recorded vocals. Maybe you could record a hit song on an iphone. So is high end gear going to be the difference between a hit song and an also ran?As my wife says, when I suggest I need a new microphone pre, the question is why? You already have one! I still want a Neumann. 
One of the most interesting products to emerge for some time would have to be the Solid State Logic X-desk. I think this really demonstrates where traditional manufacturers of high-end gear see the recording market heading.
http://www.solid-state-logic.com/music/Xlogic%20X-Desk/index.asp From all reports it truly does sound like an SSL (without the price tag) . While home recording gear has vastly improved over the last few years, what a small recording set-up can’t reproduce is the nice acoustics that a well designed pro studio can provide. That said, it can be worth exploring the acoustics of your own home. Hallways, bathrooms and even kitchens can sound great. You might be able to create a truly unique sound!
I’ve noticed in some opinion pages that the Melbourne Recital Hall is copping some flack for uneven acoustics, perhaps unfairly. It would be great to hear from anyone who has seen a performance there to comment on their own experience.
Achieving even acoustics in a live space is a notoriously difficult thing to do.
We have finally got the new site up and running. Hopefully there won’t be too many bugs to sort out! Coming up in the next few weeks I will be profiling the acoustic treatment of a new control room, from the ground up. I have already performed the preliminary testing, as well as the first level of treatment. I will also be sorting out a control room with a severe 50Hz lump, which will be interesting. I will also be looking forward to getting feedback to help the site grow into a useful resource for all things acoustic and musical.
Cheers
James
The control room at Incubator studios already had some polyester built in panelling that wasn’t quite doing the job. Initial measurements revealed some significant “lumpiness” below 200Hz so we decided to install some of the BT600/150 bass traps in some of the available ceiling corners. This is where the staple gun channels in the BT600/150 come in very handy. After the initial treatment the room was greatly improved, with Adrian noticing an immediate improvement. Post measurements revealed a flatter response, but there was still a persistent dip at 180Hz. As a trial we loaded the rear wall with 6 x BT600/150 which totally dealt with the issue. It’s always nice when the first option works!
