Genelec GLM 4.2

DSP‑equipped loudspeakers are only as good as the software that configures the DSP — in Genelec’s case, their GLM package.

Digital signal processing is becoming an increasingly accepted part of studio monitoring. Although it’s not a get‑out‑of‑jail‑free card for poor acoustics, it can optimise speaker response for a given space in a way that simply isn’t possible otherwise. This is particularly vital in immersive monitoring, where you typically have 12 or more loudspeakers that can’t all be in acoustically perfect positions.

DSP optimisation can be implemented in several ways. In a software‑only product like Sonarworks’ SoundID Reference or Dirac Live For Studio, corrective equalisation and phase alignment are handled either by a plug‑in running on your DAW’s monitor output, or a ‘systemwide’ app that sits between DAW and audio interface. Hardware systems such as the Trinnov MC Pro and Nova process the audio between your audio interface and your loudspeakers, while some audio interfaces have calibration features built in. Or, finally, you can choose loudspeakers with built‑in DSP capability.

All of these options have their own pros and cons. A software‑only solution is the cheapest option, and potentially supports an almost unlimited number of EQ bands, but it can introduce practical hurdles into the music‑making process. Hardware systems, by contrast, are ‘set and forget’, and often include hands‑on monitor control; but they can get expensive, and can be complex to install.

On paper, integrating DSP into the monitors themselves offers most of the advantages of a dedicated hardware system, without the additional wiring and setup hassle. But, of course, it’s only an option if your loudspeaker manufacturer provides the appropriate tools. Some monitors have no equalisation facilities at all, while others offer only basic analogue filtering to compensate for generic issues such as corner placement. And at the other end of the scale, there are speakers that have very sophisticated, network‑controlled DSP engines built in.

G Force

A good proportion of the studio monitors on the market today have enough DSP built in to implement detailed corrective EQ. However, the accessibility of that DSP varies. In some cases, you’ll need to calculate and transfer individual EQ curves yourself using a utility such as Room EQ Wizard or FuzzMeasure. Other manufacturers allow Sonarworks profiles to be uploaded directly to their loudspeakers, while others still have developed their own software speaker management and control utilities.

Foremost among the latter are Genelec. Most of the studio monitors in the Finnish manufacturer’s range now bear the SAM (Smart Active Monitor) moniker, meaning that they have built‑in DSP that can be configured over Ethernet. This is handled using a software package called Genelec Loudspeaker Manager, or GLM for short. What was initially a no‑frills utility with few concessions to user‑friendliness or visual design has evolved over the years, and GLM is now a pretty sophisticated package.

Although it was labelled as a mere point upgrade, the recent 4.2 release incorporated a huge amount of new functionality. In conjunction with SAM‑enabled monitors, GLM will now handle speaker/room calibration in stereo and surround, bass management, some monitor control functions, loudness calibration and more.

Pop Groups

The GLM software is available for Mac OS and Windows and is free, but you’ll need Genelec’s Loudspeaker Manager User Kit in order to carry out measurements and calibration. This comprises a microphone and a small black ‘network adaptor’ that connects to your computer over USB and to your monitors over Ethernet. Helpfully, all SAM monitors come with a lengthy Ethernet cable, and you’re free to connect the speakers in any order that’s convenient. In order to put GLM through its paces, Genelec loaned me a 7350APM subwoofer to try with my existing 8330A monitors.

Genelec provide excellent documentation that holds your hand through the process, and includes numerous example setups.

GLM detects and identifies your speakers automatically, and prompts you to update their firmware if needs be. You then define a speaker Layout by dragging each speaker to a hexagonal cell within a grid — a surprisingly intuitive and straightforward approach. Optionally, you can also enter extra information such as the dimensions of your control room. Genelec provide excellent documentation that holds your hand through the process, and includes numerous example setups.

Once you’ve established a Layout, you can then define one or more Groups of speakers within it. For example, in an immersive setup you might have one Group comprising all the speakers, another for 5.1, a third for 2.1 and so on. Each Group can have its own calibration settings. Again, the process is very user‑friendly, and guided at every step by helpful prompts.

Two important decisions have to be made at the start of the calibration process. You can choose whether the calibration should be based on a single measurement at the listening position, or whether it should be a ‘multi‑point’ calibration that takes into account additional measurements at different positions. You can also select whether each speaker should have its own individual EQ, or whether symmetrical left‑right pairs should be equalised identically. In an ideal control room, the latter is preferable, but the Individual option can be helpful in irregular rooms or where the listening position is not central on the front wall.

You can then begin the AutoCal measurement process, which involves the usual sine sweeps played through each speaker in turn, captured on the measurement mic at or around the listening position. When you’ve taken a sufficient number of measurements, the data is uploaded to the Genelec Cloud to be crunched into suitable EQ and delay values. If you’re using a subwoofer, you can also carry out an optional AutoPhase calculation, which plays a series of chirps through the sub and one of your satellites in order to optimise phase alignment. Finally, you can then store the resulting settings within the speakers themselves. Should you wish to inspect or manually edit the EQ settings for each speaker, clicking on it will bring up a pop‑up window where you can do exactly that.

Go GLM?

As I said at the start of this review, an integrated system from a single manufacturer has the potential to offer both ergonomic and functional advantages over hybrid systems involving plug‑ins or additional hardware. GLM 4.2 bears this out, and if it was a separate commercial product in its own right, Genelec would easily be able to justify charging top dollar for it. As it is, you have to pay for the User Kit to get the benefits, but that compares pretty favourably with existing alternatives. For example, Sonarworks’ SoundID with a measurement mic costs €299$299 for the stereo‑only version, with the multi‑channel edition coming in at €549$549, while the stereo‑only IK Multimedia ARC3 is €249.99$249.99 with measurement mic. The MA1 calibration kit for Neumann DSP monitors is £239$299, but is currently stereo‑only. GLM supports all surround configurations at no extra cost, controls many other functions such as bass management, and eliminates the hassle of using plug‑ins to perform speaker equalisation — though, admittedly, you don’t get SoundID’s headphone correction capabilities or ARC3’s virtual monitoring.

I can’t say how the GLM calibration compares with third‑party options sonically, but in my space it made a subtle but wholly positive difference compared with using the speakers in their uncalibrated state. And although the 8330As are nominally flat down to 40Hz, the difference that adding the subwoofer made was palpable, even at low volumes. They say that you shouldn’t be aware of the existence of a sub until it’s switched off, and GLM’s calibration and bass management achieved that effortlessly. The 8330As are fine speakers anyway, but GLM makes them even better.