In this article Julian shares how he used Genelec’s free GRADE Acoustic reports to learn about his space before starting a refurbishment.

I’m currently reworking my studio. My studio is a converted garage, at my home. Something I recently heard referred to as a ‘grannexe’ - very good! The potential of this for a studio is a lot of the reason why I bought the house. However anyone who has bought a house will understand how you end up doing an awful lot of things in a very condensed amount of time and my moving into the studio was very much a rush job. The studio has served me well thus far with a largely improvised approach to treatment which would be familiar to many home and project studio owners. I have however wanted to start again with a clean slate for sometime and to this end I recently cleared the studio and considered something we’ve talked about before on the blog: Is it okay to work across the studio if the layout suits you that way or should you work what is for acoustic reasons held to be the ‘right’ way - i.e. lengthways down a studio that is longer in one dimension than it is in the other?

Why Is the Long Axis “Correct”?

A lot of the reason for this rule that working down the longer dimension of a studio is considered better is because it is easier to place the mix position in a better location relative to the standing waves in a studio the size of those found in typical home studios. The 38% rule is often repeated online. This refers to the ideal distance along the axis of the room to best avoid sitting in a null. It is of course more complicated than this when you get into the details but it is still the case that in many domestic sized rooms, after the desk is installed you’ll often find yourself sitting in a deep null which compromises the bottom end response!

Russ has been through this process of working across a studio which has both a long and a short axis, originally working across his studio, swapping to lengthways and has now returned to working across the studio. In his very ambitious new studio build James Ivey has chosen to work across his studio which rather than adapting to an existing building was a planned use of a purpose-built studio.

On our recent podcast on mastering we discussed this with Ian Shepherd who also works in a converted garage but works lengthways. The fact remains that in my studio, because of the placement of patio doors at one end and a doorway into a bathroom at the other, the easiest and most practical way to work is across the studio and it is in this orientation that I've been working thus far.

Having stripped out the studio completely and having suitable equipment with which to run some tests I thought I should find out what I stand to gain if I were to work lengthways in my studio. In this article I'm going to look at how Genelec Smart Active Monitors (SAM), GLM software and calibration kit and the GRADE (Genelec Room Acoustic Data Evaluation) reporting offered by Genelec helps with this assessment.

To help understand the nature of the problem here are some images of my empty studio. As you can see in place of where the garage doors used to be there are patio doors. There is this a bathroom at the other end, the door to which is in the middle of a stud wall at the other end of the studio. Studios need to work practically for the people who use them as workspaces and as such being able to use the patio doors, which are lovely on a hot day, particularly as I can see the sea (just) from my computer, is important to me. The main door into the studio is at the other end of the room and the door into the bathroom is in the centre of the wall against which I would otherwise probably install my gear, although having the main door into the studio adjacent to it isn't really ideal either. There are plenty of practical reasons why I want to work what many would describe as acoustically being the ‘wrong way’ in the studio.

Genelec 8341 ‘The Ones’ And 7350 Subwoofer

To help assess the room Genelec were kind enough to lend me a pair of 8341 SAM monitors from the Ones range, a 7350APM Subwoofer and the GLM calibration kit which comprises a USB network adapter and a calibration mic. I've used a pair of 8331 monitors before and thoroughly enjoyed them and I've previously tested a pair of the flagship 8361A’s, both of which have impressed me.

While I'm not specifically talking about the monitors it would be an omission not to share my thoughts. I'm a huge fan of the approach taken by Genelec with the Ones. The three-way coaxial design is an ideal example of form following function so if you've ever thought they look a little odd, they look exactly the way they should do to do the job that they set out to. I like this.

The idea is that with the HF driver mounted coaxially with a mid range driver, which also forms part of the waveguide for the HF driver, time of arrival differences are eliminated. Two-way coaxial designs such as those produced by Tannoy, amongst others, have been around for a long time but an issue with a two-way coaxial design is that if the mid-range/bass driver is reproducing low frequencies, this can introduce Doppler shift into the HF driver which is using that midrange/bass driver as its waveguide. Behind the baffle of the 8341s are a pair of oval bass drivers mounted either side of the mid range/high frequency assembly and with this arrangement a proper three-way, point source monitor is created.

With all of the clever SAM features shared with the other SAM monitors in the Genelec range The Ones are extremely practical, very scalable and happen to sound great. Last time I had a pair of these monitors in the studio it was without an accompanying subwoofer. It's been a couple of years since I've had a subwoofer in the studio and I must admit the extension of that bottom octave is kind of addictive. Like any good subwoofer it doesn't add bass level if properly set up but it does add bass extension, an important distinction.

What I wanted to achieve while I had this gear available was to run the GLM software first in a position firing across the room and then again firing down the room. Using the data gathered from these tests I could generate a free GRADE Report, study the results and draw some conclusions before putting any work into ‘Studio Version 2.0’.

Calibration Process

Conducting the test is very straightforward. After setting up the monitors and sub in position for each orientation I was going to investigate in the room, it's simply a matter of connecting the interface box for GLM calibration to a USB port on the host computer and making a network connection to the monitors, which also have to be connected together using CAT5 network cables. With all hardware discovered by GLM, after connecting the supplied calibration mic and inputting the serial number of the mic into GLM so its frequency response data can be imported, it's simply a matter of hitting calibrate in the GLM software.

There is a choice of single or multi-point measurement and unlike Sonarworks, a calibration process with which I'm extremely familiar, the multipoint measurement involves as many measurement points as you decide you need, The Sonarworks calibration process is always multipoint and takes up to 20 minutes, capturing data from many, many points. Using a single point measurement is extremely quick and after a short period of the data being processed in the Cloud, the calibration is downloaded and if you want to you can upload this calibration data to the speakers, eliminating the need to run the calibration in software. There is also a very effective phase alignment process to line up the subwoofer with the top boxes.

GRADE Reports

So having run the analysis in both orientations and checking the generate GRADE report box in GLM, the free reports arrive via email. You can access the calibration data directly from within GLM so if you want to see what horrors lie in the bottom end response of your studio you don't need a GRADE report but what a GRADE report does is use that data to generate a meaningful, and very detailed, acoustic report. This report can be used in consultation with an acoustics professional and additionally GIK Acoustics accept GRADE reports as a basis for advice on suitable treatment for studios, something they also do with data generated in Room EQ Wizard, though having experience of both I have to say GRADE reporting is far less of a commitment in terms of learning.

Interestingly, although both single and multi point measurement options are available in GLM, the advice from Genelec when measuring a room for a report is to stick to a single point measurement as while multipoint measurements are valuable for creating a larger sweet spot for listening, they do affect the clarity of results provided compared to a single point measurement. In both of these GRADE reports there were some interesting conclusions to be drawn. Nothing which someone familiar with acoustics and the behaviour of sound in rooms would necessarily be surprised by, but it was definitely useful to see which aspects of room response were affected by a change in position and those aspects which were less affected.

Advantages Of Subwoofers For Low End Behaviour

The tests were made in an empty room and the reverberation time analysis reflected this. That isn't what I was trying to ascertain by running these tests and the performance of the room in terms of its RT60 was terrible. It sounded like an empty room. The room modes don’t change with orientation but where the transducers are in relation to the standing waves does. Something very significant was the advantages presented by using a 2.1 stereo system with a subwoofer as opposed to using full range monitoring. This is something that isn't spoken about as much as it might be but subwoofer placement is important as precisely where subs are placed has a significant impact on bass response. But if low frequency information has been generated by full range monitors there is a restriction on exactly where these are placed in the room because they need to fulfil their role as the source of midrange and high frequency information too. Decoupling the source of low frequency information from the midrange and high frequency information means that you are free to place subs in the position which is most advantageous at low frequencies irrespective of the production of a stereo panorama.

Working across the room at one end of the room as I previously have been doing has a significant impact on early reflections and stereo imaging but less impact on the low frequency performance of the room. Looking at the data from the measurements, unsurprisingly there is a significant asymmetry between the left and right hand channels because one speaker is relatively close to a corner and has glass at the mirror point whereas the other speaker is a significant distance from its side wall. At the bottom end there are very deep dips in the frequency response and quite a few peaks. The graphs look bad…

However all is not lost. Peaks can be addressed using speaker calibration and GLM does an excellent job of this. Dips are more of a problem because while you can address a peak by introducing a cut with a filter, this doesn’t really work in reverse. If you are in a null the energy is being cancelled out. If you put more energy into the room at that frequency it will still be cancelled. A boost isn’t the solution, only bass trapping is going to fix it. However a subwoofer can really help here. Typical subwoofer placement is advantageous for low end performance. Particularly as they tend to be on the floor and near walls. Thankfully the correction with the contribution of the sub ended up looking much better than the initial data suggested.

A significant source of issues which is often overlooked is speaker height. While fine tuning speaker placements around the room can make a big difference, often the height of the speaker isn’t experimented with. While the rule that speakers should be at ear height is true, there is flexibility in this and a speaker can be tilted to still fire at the listener’s ears without necessarily being level with them. This height element is a complication for me as usually I have my monitors mounted on my motorised sit/stand desk with switchable calibration profiles for each position.

Lengthways Or Across The Room?

The GRADE Reports have been informative in helping me make some decisions about how I use my space. Acoustics is complicated and no acoustic report will change that but these reports can really help in guiding your decisions. We’ve all heard the general advice and much of it holds true but if you have a specific issue, and you will have specific issues in your space, then these reports will help you avoid installing treatment of the wrong type in the wrong place.

Speaker calibration is one element of setting up a listening environment. Bass trapping is unavoidable if you’re serious and placing adequate absorption in the right places, particularly first reflection points, will help.

As for whether I am going to work across or down my room. I’m yet to make the call. Acoustically, across the room is inferior to down the room. Glass behind the speakers isn’t as much of an issue as it is on one side as it will be if I work across the room. However on a purely practical level If I work blocking the patio doors at the end of my studio I’m losing the use something I really value. That’s not trivial.

One thing I have definitely decided is that if I were to install an Atmos monitoring system I’d have to work down the room. I’ve considered lots of potential ways to make Atmos work across the room and I’ve concluded that it just wouldn’t work out in a way which was practical. However for stereo I’m less convinced and regardless of what is measurably better, it’s my studio and I have to spend my days in there. A sea view and a patio door I can open up on a sunny day is a swap I’ll consider in exchange for a slightly compromised stereo image.

More On GRADE Reports

GRADE reports contain a wealth of information and it’s structured in a way which guides you to the data which really matters. They have been free to users of SAM monitors since they were introduced in GLM 4.2 last year but that was always something which was potentially open to change. Genelec recently announced such a change. From September 2023 users will be able to access 12 free reports with further reports being chargeable.

For more information on GRADE reports check out the video above. In this Marcel from Genelec explains the reports in detail. For more information on GRADE Reports click the button below