FFW07: Lessons in coupling & isolation

Setting up studio monitors is never as simple as it sounds; not if you want to get the best performance from them. After finding the right positions within the room, you've got to make sure they're properly mounted and isolated. This First Word, written sometime in 1999, discusses simple things you can do to improve the sound of your monitors by paying attention to mounting, coupling and isolation.

Lessons in coupling and isolation
“Yikes, those Questeds are making my ATCs sound bad!” I cried. Brad was somewhere behind the console, fossicking for test CDs in a dirty blue milk crate. “Ha!” he laughed, “I dare you to print that!” “No, no,” I explained, “my ATCs don’t sound right when those Questeds are sitting next to them... the low mids have gone all lumpy!”

Brad and I had just unpacked the Quested VS2108s and, noting their size, decided to sit them flush beside my ATCs for a quick and easy A/B comparison. But at 34cm wide, the Questeds’ imposing baffles were playing havoc with the dispersion of the considerably slimmer ATCs, coupling the lower frequencies and making them sound dull and ordinary.

Interesting? Not really. It’s simple physics, and it’s something that PA operators deal with whenever they stack multiple boxes side by side. But it’s been about 15 years since I stacked a PA system, and acoustic coupling was the last thing on my mind as we lined up the Questeds beside the ATCs.

Switching between the ATCs and Questeds showed that neither pair were sounding worthy of their respective price tags. Taking the Questeds off the bench returned the familiar ATC sound. Likewise, removing the ATCs and listening to the Questeds in isolation revealed a much higher level of sound quality, certainly more in line with their reputation.

Lesson #1: Never compare monitors in any kind of side-by-side situation. It may seem like a good way to make a direct A/B comparison, but all you’ll actually be testing is how badly each monitor affects the other one. Retailers, take note…

Later that week, during an AudioTechnology ‘Spontaneous Human Consumption’ event at Brad’s place, Michael Stavrou spent a critical moment listening to the Questeds, rubbed his chin for another critical moment, then said, “You got any marbles?” “Dunno,” said Brad, “take a look around.” “How about washers?” Stav asked. “Ditto…”

You can dig up all kinds of interesting stuff while fossicking around Brad’s place but his marbles and washers were too well hidden, so Stav returned with half a dozen beers. He carefully removed the top from each bottle, and placed three tops under each Quested in a triangular shape (one under each front corner, one half way across the back). The performance increase was obvious to all, and became a hot topic for the next half hour or so. Just long enough for the beers to go flat…

Lesson #2: Lifting a monitor’s bottom off the surface it rests on minimises physical contact, thereby reducing the amount of sound energy being drained out of the monitor and into the surface. This ‘draining’ of energy out of the monitor causes a decrease in performance, but it gets worse: if the surface is not sufficiently well-damped, it will re-radiate that energy back into the room, causing an even further decrease in performance.

Brad’s monitor bench is about six feet long, reasonably rigid, and supported at each end. But the Questeds have a large and squarish footprint that provides a good contact area with the bench, and they generate a lot of low frequency energy for their size. Combine these factors with their 22kg weight per box, and you’ve got a powerful source of low frequency energy with a large footprint and considerable mass pressing down onto the bench, allowing an even better draining of energy.

Interestingly, my ATCs are designed with three feet fitted in place for this very reason – and never suffered this problem when mounted on Brad’s monitor bench. But why three feet? Why not four or more?

Lesson #3: Proper monitor performance requires stability. Powerful small monitors, such as the ATCs and Questeds, really need to be held stable. If the box wobbles or rocks in any way, it causes loss of output, blurring of the stereo image and smearing of high frequency detail. JBL’s Doug Button discussed this concept, which he calls ‘inertial grounding’, in my review of JBL’s LSR32s [Vol. 1, Iss. 4.]

So why three feet? Three points defines a single plane, and therefore offers maximum stability - that’s why microphone stands, camera tripods and my favourite ‘non-rocking’ café tables are all designed to stand on three feet. (Of course, ‘tripod’ literally translates to ‘three feet’. Duh!). Increasing the number of feet beyond three increases the possibility of instability and wobbling - not a good thing for microphones, cameras, steaming hot cappuccinos or studio monitors.

While Stav’s beer bottle tops demonstrated the benefits of isolation, they were only a temporary solution. Brad has since replaced them with height-adjustable brass cones designed specifically for decoupling speakers, which are available from your local hi-fi shop. Due to the squarish footprint and weight distribution of the Questeds, he’s using four cones - one under each corner. Being height adjustable, he’s able to fine-tune them for maximum stability. His Questeds are now sounding better than ever.

So if your monitors are sitting flush on their bottoms, get some cones under them ASAP! You won’t regret it. But make sure you put the cones the right way around – which is upside down. Their large flat end connects with the bottom of your monitor, while their small pointy end connects with the surface your monitor sits on. When done correctly, your monitors will look like they’re standing on tip toes. (In fact, the first commercially available cones were called ‘Tip Toes’.)

So how do the cones work? Physically, their pointed ends provide a solid connection between the monitor and the bench, which keeps the monitor from wobbling. But their small contact area with the bench creates a very high acoustic impedance, the sort of thing that sound energy prefers not to travel through. With the weight of the monitors pressing down on them, the cones are able to firmly anchor the monitors to the bench while simultaneously providing acoustic isolation. Amazing, huh?


I first met Brad Watts during the days of AudioTechnology's miserable predecessor, Sound Australasia. I was looking for a Mac-savvy guy to write a regular Macintosh audio column, and Brad came highly recommended from the people at AudioMedia magazine. We made an appointment to meet in my office at Pacific Publications. While waiting for this 'Brad Watts' to arrive, a feral-looking bicycle courier walks through the Pacific Publications cubicle farm, dreadlocks flowing and talking into the air with some kind of assertive certainty, just like a crazy guy. He stops at the door of my office. "Simmo? I'm Brad Watts, hang on a minute mate". He then proceeds to pace in and out of my office door while finishing the phone call taking place on his hands-free kit; obviously helping someone get their Mac working again. It was the first time I'd seen someone using a hands-free kit in such a brazen and open manner. It was also the first time I ever saw Brad Watts.

Two years later Philip Spencer and I saunter out of an important meeting that secured the future of our yet-to-be-published magazine. It’s a beautiful Sydney day and we’re feeling as good as the weather, so we stop at Mo’s, the outdoor café belonging to the Museum of Sydney, for a celebratory drink. The attentive waitress is buzzing around wiping tables and keeping us well stocked with refreshments.
“By the way, my name’s Jackie. What are you guys celebrating?”
“We’ve just launched our new magazine, called AudioTechnology. It’s about sound recording equipment.”
“Really? My boyfriend writes about that kind of stuff. Maybe he could write for you…”
“What’s his name?”
“Watts is his name! Brad Watts, actually.”
“He’s in our first issue…”

Fast forward a few more years and I find myself sharing a warehouse conversion at the top of Hibernian House, Surry Hills, with newly-weds Brad and Jackie Watts. Crazy and intense days, in retrospect, littered with marine aquariums, astroturf, huge televisions and way too many fried chicken wings from the Thai takeaway down stairs. But we had a lot of fun. We both had our own studio rooms; Brad with the Quested VS2108s mentioned above (which he promptly bought after the review) and me with my ATCs. Between us, there was probably not a single piece of audio gear on the planet that we could not review the heck out of.

Brad's Mac Notes column has been a regular fixture in AudioTechnology since the first issue, along with his prolific product reviews. He's probably the smartest Mac audio guy on the planet. A year or two ago he became a full-time employee of AudioTechnology, a position he well deserved. To be honest, I don't know where the magazine would be without him...

FFW02: Learning to listen

My initiation into audiophilia! After spending a night listening to some serious audiophile recordings through my high quality ATC reference monitors, I was somewhat impressed by the vocabulary used by audiophiles to describe subjective aspects of sound. I was also somewhat concerned that I had never thought to listen for those things, let alone assign words to describe them. I learnt a lot about the art of listening that night; stuff that has affected my approach to recording, mixing and mastering ever since. [In fact, my quest for realism in recordings morphed into a search for reality in recordings - a search that took me to the Himalaya and, ultimately, into the arms of my beautiful Nepalese wife Punam!]

Issue 02 of AudioTechnology contained interviews I'd done with David Chesky and Bob Katz regarding a CD released on Chesky Records called 'I Ching: Of the Marsh and the Moon'. Chesky Records are a well-known audiophile label, and I thought it prudent to write a First Word that provided a subtle linked to the interview and also put across an audiophile point of view.

The Chesky/Katz interviews went beyond the engineering/recording technique and ventured into the design and circuitry of the recording equipment itself, which sat nicely alongside part two of my three-part interview with Rupert Neve (further discussions of sound quality from a designer's point of view). As an editor, I was always on the look-out for an emerging theme within an issue, and this one was staring me right in the face!

Learning to listen
A couple of guys I know are building a D/A converter. While most readers will think that’s a pretty impressive feat, those familiar with digital electronics won’t be so impressed. Any half smart technician can knock together a ‘quick and dirty’ D/A converter with a small collection of LSI chips, a handful of op amps and a late night session with the soldering iron. Given the right chips, it’s a bit like Lego blocks…

But these guys, Terry and Craig, have spent most of their spare time over the last three years working on this converter. Why spend so long building something that can be thrown together in an evening? Because Terry and Craig are serious high fidelity listeners, and their converter is designed for audiophiles who demand a high standard of sound quality. That means lots of designing, redesigning, building and listening. And that’s how I got involved…

While planning the first issue of AudioTechnology, I got the following phone call. “Hello, Greg? Terry here, mate. We’ve built a D/A converter and need to borrow some super accurate studio monitors for our listening tests. Still got your 20s?” He was referring to my trusty old ATC SCM20 passive monitors, which I had sworn by for years. Little did he know that I was, at that very moment, reviewing ATC’s new SCM20A PRO active monitors, but finding the sonic quality of my ‘pro’ studio equipment to be hopelessly under-specified. Knowing Terry and Craig’s hi-fi leanings, this was the perfect win/win opportunity – they get to hear their D/A converter through a pair of very accurate studio monitors, and I get to connect said monitors to some very good audiophile equipment. I bundled the ATCs in the car, grabbed a pile of my favourite reference discs, and hit the highway.

The evening that followed was surreal, to say the least. In an earlier draft of this column I wrote 600 words describing what we did and what we heard that night – listening to the differences between silver and copper interconnect cables, hearing the detrimental effects of placing little wooden cones under the D/A converter, and so on. Then I deleted it all because you probably wouldn’t believe it anyway, especially if you’re a dyed-in-the-wool sound engineer who thinks hi-fi guys are nuts and everything is hunky-dory in studio land. Let me tell you, it isn’t.

My collection of reference discs contains the same discs you’ll find in other engineers’ collections, all representing good sound engineering. But against some of the audiophile standard discs we played that night, my discs were embarrassingly inadequate. The ATCs, on the other hand, were superlative and easily rose to the audiophile challenge. As did Terry and Craig’s D/A converter.

The biggest revelation of the night, however, was not what we were listening to, but how we were listening to it. Sound engineers in the studio have the luxury of soloing a channel to get a fix on a particular instrument. Once your ear/brain system gets a lock on that instrument in isolation, it’s much easier to identify it within a complex mix. Audiophiles, on the other hand, never have that luxury because they only have access to finished and mastered stereo mixes. By necessity, they develop very different listening skills and a different vocabulary – a broader language evolved to describe and ‘isolate’ individual aspects of a recording in the absence of a solo button.

The sound engineer’s vocabulary contains a handful of simple words for describing the sonic qualities of individual tracks, such as warm, cold, bright, and dull. It also contains words for describing the mix, such as clarity, separation, width, and depth, plus terms like dynamic range and signal-to-noise.

The audiophile’s vocabulary extends to phrases like midrange purity, visceral impact, focus, rhythm and pace, blackness, and holographic imaging. These aren’t just fancy ways of saying simple things, they represent intangible and unmeasurable aspects of sound quality - aspects you may not even consider if your understanding of sound quality is limited to the sound engineer’s ‘track by track’ vocabulary.

So there I was, alone with my sound engineer’s vocabulary, flanked by two well-versed audiophiles. I don’t know if they heard the qualities I enjoyed on my reference discs, but I had certainly never noticed the aspects they were criticising, until they pointed them out to me in the vocabulary of the audiophile. Like so many subjective things, you often can’t hear something in a recording until someone brings it to your attention. From then on, you know what to listen for and you’ll always hear it.

In his book ‘Word Power’, Edward de Bono explains how words represent concepts. When you understand a word, you understand the concept. Like many concepts, the subjective aspects of sound quality are intangible. Without the right word, you have no way of communicating what you’re hearing. In fact, you may not even know what to listen for. As a sound engineer or recording musician, if you can’t communicate what you’re hearing or don’t know what you’re listening for, you’re in trouble.

There’s a layer of sound quality beyond that which most sound engineers, recording musicians and equipment designers are aware of, because we don’t have the concepts to explain it or the equipment to reveal it. But it’s real and not hard to demonstrate. All you need is access to a proper audiophile hi-fi system and the right reference discs. I’d highly recommend ‘The Ultimate Demonstration Disc’ from Chesky Records. It contains a selection of tracks demonstrating the audiophile’s vocabulary, with narration between tracks describing what to listen for. If you buy this CD and don’t notice the sound qualities they’re demonstrating, get a better playback system!

The audiophile point of view will become increasingly important as we enter this era of larger word sizes and higher sampling rates. When you hear a recording that satisfies both the sound engineer and the audiophile, you’ll also hear a level of musicality rarely found on commercial CDs. And isn’t ‘musicality’ what it’s all about? The more musicality we can get into our recordings, the better. But first, we have to learn to listen.


My association with Terry and Craig continues. Most notably, from 2000 to 2003 Terry designed, built and continually refined a beautiful two-channel microphone preamplifier for use with my Royer SF12 stereo ribbon microphone. As part of that process he became a keen mountain biker (it's a long story) and enjoyed some serious air time on the trails around the Royal National Park. In 2003 the two of them joined forces to design and build a number of precision digital clock generator/distributors, to my specifications, for use at the Sydney Opera House.