FLAT OUT
Recording Bon Iver’s ‘I,I’
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DYNAUDIO ACOUSTICS BM5A MKII

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July 15, 2013

BM5A_mkII_persp_reflect copy

The original BM5A developed quite a reputation after its release back in 2004, and users of this modest looking nearfield still pledge their solemn allegiance. Now the MKII has arrived sporting several improvements.

Text: Al Craig

I must admit I have a certain fondness for Dynaudio speakers. A little over 10 years ago, when I was designing the broadcast control rooms for the Sydney Olympics, the question of what monitors to use inevitably came up. I had no favourites at the time and thought the fair thing to do would be to organise a ‘shootout’ – of the speaker variety of course.
I contacted Michael White at Sound On Stage and he organised a double-blind listening station in his showroom, where he assembling bookshelf-sized speakers from most of the current speaker manufacturers. Steve Mitchell, Trevor Bird and I then took on critical listening duties. With roughly 10 pairs of speakers to audition, we scored each pair in turn and determined the best overall performer. It was only when the speakers were revealed to us we realised that all 10 pairs were passive. We then asked that our first choice be included in a second test alongside some active nearfields. A week later, we returned and repeated the process, this time with six pairs of active speakers and the passive winner from the previous session once again setup in a double-blind test.
Again, we listened to our favourite music, some voice-only tracks and recordings of actual Olympic commentary. Scoring was based on clarity, apparent frequency response, fatigue factors, damping factor and eventually size and cost.
The Dynaudio BM6A was the overall winner and 10 pairs were subsequently ordered. Nine of these went into the control rooms that looked after track & field and gymnastics, while the 10th pair went into my Quality Control listening room. I believe all 10 pairs are still in use in studios and OB trucks here in Australia some 10 years later (there’s that number again).
I now have the honour of reviewing the latest speaker in the Dynaudio Acoustics range – the BM5A MKII. This is the little brother to the BM6A and offers several improvements over the original BM5A. Although they look essentially the same, the MKII has had its woofer re-engineered to allow for a longer excursion and to minimise distortion, while the tweeter now comes with a waveguide that’s designed to tighten up the sweet spot. Both speaker elements are handmade at the Dynaudio factory in Skanderborg, Denmark using aluminium coils and other high-grade materials. The low-end response has been extended by 5Hz and the maximum output has been increased to 117dB SPL.

FLAT OUT

Of all the equipment in your signal path, speakers must have a flat frequency response. Combined with the acoustics in your room, if things are not as they should be, then you’re essentially being lied to and your mixes will suffer. Mics don’t need to be flat; preamps don’t need to be flat; plug-ins and outboard gear don’t need to be flat. Indeed, all of these devices, with their varying responses, shape the colour and character of our audio world. The response of a Shure SM58 for instance is nothing like a Neumann U87, but in certain instances the SM58 is the mic to choose because of its character.
One of the fundamental tasks a mix engineer must perform is to deliver a mix that will play out no matter what the consumer is listening through. For example, if our speakers (in combination with the room) are bass heavy, then we are likely to unwittingly mix bass thin. If there’s a rise in the midrange, then we’re likely to unknowingly adjust the EQ to compensate. Ask any mastering engineer and they can tell you any number of horror stories about mixes that have arrived on their doorstep sporting more lumps than a camel train.
So how do we know that we have flat speakers? Well, most manufacturers print their specs in the manual of course. It’s very common to see something like: “20Hz – 20kHz (±3dB)” printed proudly in a specifications page, and the Dynaudio BM5A MKIIs, under scrutiny here, are no exception. These have a published specification of 48Hz – 21kHz (±3dB). We’d like to believe we can trust the manufacturer, but I’m much too sceptical to believe the marketing and would rather test them myself.
But how can you test your speakers? Unless you have an anechoic chamber, a calibrated test mic, some sort of Real Time Analyser and appropriate software its nigh on impossible.
Or is it?

TESTING, TESTING

I placed the Dynaudios on the ledge next to my ATC SCM Series and Auratone 5s speakers. The ATCs are being driven from the monitor section of my SoundWorkshop 34 mixer. I connected the BM5A MKIIs to a pair of aux sends, fired up my Sadie DAW, routed a bus out from the desk into track 1 and recorded a sweep tone from 20Hz to 20kHz across three minutes. (I don’t own an SPL meter so I adjusted the volume to somewhere in the area of 80dB SPL – for those of you with iPhones, there’s an app for that.) I then set up a B&K 4007 mic two feet from the speakers and routed it through my Wendt x4 ENG mixer and sent that to another bus. (If you don’t own a B&K 4007, dig out the original packaging on your best mic and see if it came with a frequency plot. Otherwise, set your best mic up using the omni pattern and test away.) I put Track 2 into record, played out Track 1, repeating this procedure a couple more times and recorded the response of the ATC SCM20s and Auratone 5s for comparison.
The screen grab below shows the results:
As you can see, the amplitude of the direct feed (Track 1) is constant across the entire range. The speaker/mic combination shows remarkably similar amplitudes, except for in the bottom-most octave (20Hz – 40Hz) as per the spec. The wavering amplitudes in the mids is mostly due to reflections off the mixing desk.

DETAILS OF THE MKII

The new Dynaudio BM5A MKII – the baby brother of the BM6A – is a two-way active monitor that houses a seven-inch woofer and a 28mm soft dome tweeter. The power amps are rated at 50 Watts each (I know it doesn’t sound like much, but man these babies can get loud). There’s a bass reflex port on the back tuned at 55Hz, and the two drivers cross over at 1.5kHz. The speaker weighs just under 9kg and its physical dimensions are 186mm wide, 320mm tall and 320mm deep. It sports several switches that allow you to contour the frequency response if you so desire, and there’s also a three-position high-pass filter switch featuring ‘flat’, 60Hz and 80Hz positions. This is provided for anyone who might be working with a sub. There’s also a boost/cut shelf switch for the low end: (+2, flat or –2), which allows you to compensate for nearby walls; a bell for the mids (+2, flat, –2 or –4), which allows you to compensate for reflections that might come off your work surfaces; and another shelf for the highs (+1, flat or –1). My biggest gripe with all these controls is the distinct lack of numerical detail about exactly where the knee frequencies and slope rates kick in. There’s nothing in the literature or the back panel. Finally, there’s an input sensitivity switch (+4, 0 or –10).
There’s a fair degree of built-in protection to keep you from blowing up these things too. An overall thermal switch will shut off the amps if they get too hot. Another on the tweeter will specifically shut down the high amp if the tweeter coil gets too hot. There’s also a limiter on the woofer to protect it from extreme excursions.

SOUND DESIGN

So, how do they sound? Pretty damn good. When I fired them up in the studio I immediately loaded my latest album project. I was captivated by the clarity and richness of a mix that had previously left me feeling a tad, well… flat. The richness in the low end was smooth and warm; the mids had none of the bark I’ve come to expect with modern monitors of this size. The high end sizzled without being strident. The sweet spot in my studio is usually a pretty small sphere, but the Dynaudios delivered a broader coverage, both horizontally and vertically. Even out near 180 degrees (where my co-writers often sit) I was impressed by the response.
If I were to have any complaints about the BM5A MKII it would be that the power switch and gain pot should be on the front rather than around the back, although many would no doubt disagree with this. I power up all my electronics from a single breaker and the speakers deliver a not-so-healthy thump when powering down.
The BM5A MKIIs are a very respectable speaker that would perform very well in any studio or OB truck. They would also be the perfect choice for a surround system. (Hmm… I wonder if I could buy five speakers?) AudioTechnology is gonna have to chase me to get these babies back. I think they’ve found a permanent home.

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FLAT OUT
Recording Bon Iver’s ‘I,I’
READ ONLINE NOW
Online
Issue 65