Genelec GLM Review (Room EQ & Setup)

[thewas]

A single sweep usually doesn't have significant deviations compared to a single seat region MMM when done sensibly as I had shown here, https://www.audiosciencereview.com/...ement-using-the-mmm-method.24131/#post-815429

Also the linear superposition of the filters usually works well unless other filters are used than the ones shown by the DRC so a re-measurement after EQ wouldn't really bring anything to GLM. An exception are L+R sum measurements which can have different peaks and dips after EQ due to phase rotations but GLM doesn't do them anyway.

Myself I used to find the GLM correction strategy too primitive in the past and used more "detailed" IIR and FIR DRC tools and strategies as their responses looked nicer but thanks to Toole who correctly says that our two ears and brain are hearing very differently to a mic and a classic transfer function analysis, I tried also simpler strategies close to what GLM does and find them usually more satisfying at my setups with loudspeakers that don't need much correction above transition frequency, so like the Genelec monitors.

So I can strongly only recommend everyone to try different DRC strategies themselves and not just look at the related FR curves. If there is interest I can also post my current REW based method which is similar to the current GLM 4.1 in the next week as I am currently on a holiday trip.

 

[daftcombo]

Thanks for this review, @amirm ! Very welcome one.

Did you change your mind about the SPL handling capability of the 8330, once calibrated with GLM?

 

[Walter]

... it would not be fair to test it with Room EQ and not other speakers.

I completely agree. If the room EQ is built into the speaker or comes included at no additional cost, then it would be fair to see how well it works to correct issues AFTER the speaker has been through all of its tests in a normal fashion. This is what Amir did on the iLoud MTM, but the initial results were not good and he did not spend the time to see if that was correctable--unfortunate in my opinion, but understandable given how prolific he is with his reviews. I think that using Roon when necessary gives a much more level playing field in all other cases.

Now, a separate thorough study of how various room EQ systems compare is something I would love to see, but to do well, it would take a lot of time. You would need to test in multiple, very different rooms. You'd need before and after measurements, of course, preferably at both a single "sweet spot" listening position and at multiple ones. You'd need multiple speakers if you wanted to include proprietary systems like GLM and MA-1, and each speaker would need to be tested with all applicable software packages. Ideally, you'd also want a mixture of 2.1/2.2 and floor standers so that time alignment abilities could be checked. And to top it off, it would be really nice to have subjective opinions from a mix of trained and untrained listeners in a DBT.

That sounds exhausting just writing it, and I'm sure I just scratched the surface of the requirements. Anyone here doing a Master's degree in an appropriate field looking for an idea for a thesis?

 

[Masza]

You can use MMM with GLM by using multipoint calibration if you want. But the first measurement position is the primary one and if I recall correctly it has a higher weight. But then again you can do center and 10 cm to left from center and 10 cm to right.

Would be nice to have Autocal 1 and 2 comparison. If I recall GLM 4.1 provides an option to select the version. Version 2 is more advanced based on the manufacturer. Which one did you use @amirm ? Also, did you select Individual EQ or Symmetrical EQ?

 

[hege]

Sorry, I meant sharing the hardware itself. You'd copy the results from the GLM software to something like EqualizerAPO/Peace and then never need the hardware again. A bit like a monitor display calibration tool/colorimeter. Or doesn't that work?

I don't think you understand how it works. You can loan the box to friends no problem. There is no need for APO.

The GLM box is just a command interface to connect to the speakers, so that you can change their settings.

All EQ parameters are stored into the speakers themselves. You don't need the GLM box after doing calibration, the speakers will maintain the saved settings.

Only reason needing the GLM box after calibration is if you want to control digital volume volume directly at the speakers (for "best" quality) and not somewhere else externally. Or if you want to have multiple EQ settings (groups) to switch on the fly, the speakers can only store one setting at a time.

 

[Chromatischism]

I don't think you understand how it works. You can loan the box to friends no problem. There is no need for APO.

He is asking if you can use the filters in APO. I had this same question of ARC in the iLoud speakers, and the answer was no. In the end it was fine because I was able to get a much better result doing EQ with REW based on a moving mic average.

 

[Pearljam5000]

I completely agree. If the room EQ is built into the speaker or comes included at no additional cost, then it would be fair to see how well it works to correct issues AFTER the speaker has been through all of its tests in a normal fashion. This is what Amir did on the iLoud MTM, but the initial results were not good and he did not spend the time to see if that was correctable--unfortunate in my opinion, but understandable given how prolific he is with his reviews. I think that using Roon when necessary gives a much more level playing field in all other cases.

Now, a separate thorough study of how various room EQ systems compare is something I would love to see, but to do well, it would take a lot of time. You would need to test in multiple, very different rooms. You'd need before and after measurements, of course, preferably at both a single "sweet spot" listening position and at multiple ones. You'd need multiple speakers if you wanted to include proprietary systems like GLM and MA-1, and each speaker would need to be tested with all applicable software packages. Ideally, you'd also want a mixture of 2.1/2.2 and floor standers so that time alignment abilities could be checked. And to top it off, it would be really nice to have subjective opinions from a mix of trained and untrained listeners in a DBT.

That sounds exhausting just writing it, and I'm sure I just scratched the surface of the requirements. Anyone here doing a Master's degree in an appropriate field looking for an idea for a thesis?

I actually disagree, because they're designed to sound their best with the GLM and no one will ever actually use them without the GLM, so why "punish" them because other speakers don't have a built in room correction?

 

[hege]

He is asking if you can use the filters in APO.

Better let him clarify. Why would one use APO, if the speakers already have the same EQ stored? Of course you can copy the parameters from GLM to APO too if you want. It's just simple PEQ settings.

It's beside the point if GLM provides "good" results or not. The point is that you can save any arbitrary EQ settings in the speakers. You can measure with REW and store in the speakers. Or not use GLM at all like me, and just EQ externally..

 

[hege]

I actually disagree, because they're designed to sound their best with the GLM and no one will ever actually use them without the GLM, so why "punish" them because other speakers don't have a built in room correction?

I don't use GLM. I didn't buy 1237A because they have a DSP chip inside. It probably doesn't raise the cost that much.

I bought them because of their performance. External EQ works better too, since they only provide 2+4 notch filters. Obviously newer models with 16 filters are more flexible, but it's still fine to EQ externally. (Obviously this is a bit different value proposition, than say 8030C vs 8330 for external EQ)

 

[Walter]

I don't use GLM. I didn't buy 1237A because they have a DSP chip inside. It probably doesn't raise the cost that much.

I bought them because of their performance. External EQ works better too, since they only provide 2+4 notch filters. Obviously newer models with 16 filters are more flexible, but it's still fine to EQ externally. (Obviously this is a bit different value proposition, than say 8030C vs 8330 for external EQ)

Also, many people pair them with other brand subwoofers, since the Genelec subs are insanely expensive, and GLM will not work with that combination.

 

[Sancus]

Also, many people pair them with other brand subwoofers, since the Genelec subs are insanely expensive, and GLM will not work with that combination.

You can still use GLM to correct the speaker response in that case, just not the subwoofer response.

 

[Vict0r]

I don't think you understand how it works. You can loan the box to friends no problem. There is no need for APO.

The GLM box is just a command interface to connect to the speakers, so that you can change their settings.

All EQ parameters are stored into the speakers themselves. You don't need the GLM box after doing calibration, the speakers will maintain the saved settings.

Only reason needing the GLM box after calibration is if you want to control digital volume volume directly at the speakers (for "best" quality) and not somewhere else externally. Or if you want to have multiple EQ settings (groups) to switch on the fly, the speakers can only store one setting at a time.

Very helpful, thank you! I was under the impression that you needed the interface connected to the GLM software for the DSP to work.

 

[peng]

No offence to you @amirm, fine review. But I don't get it. How is this room eq? I would expect something more like this:

View attachment 151767

This is what one should expect from "state of the art room" eq. As I have shown in multiple posts on ASR, it is not just at one listening point either...

There is a big difference between PEQ and room eq that is based on high resolution FIR filtering. I would be happy to prepare some FIR filters for you if you send me some REW measurements.

Kind regards,
Mitch

That looks very nice but you do that with Audyssey XT32 with the App just as good up to about 120-160 Hz quite easily, and likely up to 600 Hz as you did too, time permitting.

 

[Frgirard]

The valleys that we see in the low frequencies are not corrected. When standing speakers are used, no acoustic treatment, the eq does not work miracles.

talking about success is abusive

 

[Helicopter]

Thanks Amir. Though not unique to Genelec, this sort of tech is obviously the future of mainstream active sound reproduction.

The pricing seems right for the interface and microphone with software. The obvious catch is the need for their expensive subs. I still like the value proposition.

 

[Tangband]

This is a review and detailed measurements of the Genelec GLM "SAM Loudspeaker Management System." Its main use is automatic and manual room equalization for select Genelec speakers with such support. It is on kind loan from a member and costs US $299.

I was pleased to see it come with a nice looking microphone and an audio interface:

View attachment 151754

At first I thought the communication was through Ethernet so plugged in the speaker into my home network but nothing happened. Then I read the manual. I realized that the RJ-45 is a custom connection and protocol for the above adapter to talk to speakers in a daisy chain manner. Once I plugged the speaker into it, the GLM software recognized it and I was able to configure it. FYI the version I tested is the 4.1.

The interface is a bit tricky in that you have to drag and drop the speaker onto this unusual grid to then group speakers and manage them:

View attachment 151756

Post calibration to see how the filters are setup, you need to click on the Genelec speaker icon in that grid which was not easily discoverable. I found it by accident.

For testing, I used the Genelec 8330A which I had recently reviewed. The process could not be simpler. You tell it to start calibrating and next thing you know, this super loud chirp signal plays and that is that. No multiple measurements. No averaging. I would have wanted some control over volume on this but I did not realize the role of the vertical slider until later. The good news is that the whole affair was done in just a few seconds. Compare this to automated Room EQ on AV products that can be very time consuming with multiple measurements and such.

Before I show you the measurements, I really appreciated a couple of other cool features. First, you can calibrate the SPL level where you sit with the microphone. Once there, you can then leave the microphone there and watch the real time SPL values shown at the bottom level ("77" in this snapshot). I was able to go into low 90s before the speaker clipped with the speaker icon turning red above that. With all other systems, once you are done calibrating, the mic and software collect dust. Nice to see that is not the case here especially if the displayed SPL values are correct.

You can also preprogram a couple of SPL values as you see on the left. Once again, I could not discover how to change them. There are presets for the system/speaker but I could not figure out how to edit them.

The whole interface is very responsive which makes the included volume control slider useful.

Gelenec GLM Room EQ
The main event here is how well the automated GLM calibration performs. Per above, post correction you can examine what it did and thereby also understand its underlying technology:
View attachment 151757

I truncated the above display as it goes to 16 filters. The system is not different than automated filter creation in Room EQ. The system is simply using a combination of shelving and parametric EQ to build an inverse of the response with some care. For example, the sharp dip around 80 Hz which is caused by cancellation, is left alone sans a constant boost provided by the shelving filter. On the other hand, the peak at 200 Hz is attacked strongly with a complex curve created out of a nearly a dozen filters to invert it. The filter response is in blue and the measurement is in red. Filter applied to measurements is the green.

From what I can tell, it didn't attempt to make any correction above 300 Hz which is fine but then there is a lonely filter at 818 Hz with just a -0.3 dB gain. Such a filter will not have an audible effect. I wonder if it is using the knowledge of the speaker to make a tiny correction there?

Sadly as with all of its competitors sans JBL ARCOS, the corrected response is a simulation. No post calibration measurement is performed to see if that is the results that is generated. That is left to us to mess around with another microphone and measurements software to use. Problem with this type of verification is that the microphones will be different as will the absolute positions so we can't do a precise determination. But we can get close.

I used my Earthworks measurement mic with my RME Babyface Pro FS in combination with REW software to make a before and after measurement. I used 1/12 octave smoothing to keep detail there but soften the results some so we can make sense out of it:

View attachment 151759

Please ignore the levels. They are not calibrated.

The graph in red is the measurement prior to calibration. We see the standard impact of the room causing similar dual peaks around 55 and 180 Hz as GLM software showed. There is also the same dip at 100 Hz or so. We have a peak between 400 and 500 Hz that was not in the GLM measurement but this may be due to me not matching the mic location.

It is interesting that the correction for the first peak around 55 Hz is almost not there and much less so than predicted by GLM software. I can't explain this other than the filter implementation not having the resolution it thinks it has. Maybe the Q should have been lower.

On the other hand, the second peak around 180 Hz is corrected well with a response that actually matches the peak for the 55 Hz one.

Genelec GLM Room EQ Listening Tests
Turning the calibration button on and off is very fast allowing for quick AB comparison and boy is this a stark comparison (as it usually is with Room EQ). Turning on the EQ instantly removed some amount of low frequency boominess but importantly, it brought the vocals forward which I really, really liked. Once you listened to the calibrated sound, you just did not want to go back to not having it.

One of the key benefits of the GML is that you have full visibility into all the filters and you can add your own and turn them on and off and see which version you like better. So I added a filter at 449 Hz to fix the third peak with a Q of 5 and gain of -3 dB. This was a subtle change but it brought even more clarity to vocals. What I was hearing then was stunning! The vocals in one of my reference and favorite tracks, Biscuits from the live album by Fink had a realism and fidelity that was just a joy to listen to:

There, I did the obligatory thing of putting in some music in a review! But really, it was just wonderful and showed how good these Genelec speakers are when you take out the impact of the room.

Note that the overall signature was somewhat bright as is typically the case when you take out the excess bass. Genelec provides dual shelving filter overrides to boost the lows and reduces the highs. This is limited 3 dB max correction however. I found the effect subtle even at maximum correction and wanted to have more room for adjustment.

Conclusions
The Genelec GML Room EQ is a straightforward automatic generation and execution of filters. This makes the system easy to understand and modify but perhaps takes out the mystique of something magical going on. I personally may take a shot at just programming the filters manually or measuring and then modifying. While I have accepted the fact that consumer EQ products don't want to provide transparency on what they have done, I wish a Pro product like GLM would make a post EQ measurement and show that rather than simulated, feel good but made up response. It would take just a few seconds. Heck, that measurement could be used iteratively to optimize the filters more.

As is though, the system provides 90% of what an expert could do on his own in almost an instant. The improvement is dramatic and you would be silly for not using it if you have a Genelec SAM speaker. Indeed any system used without an EQ is producing incorrect and far less than satisfying sound in your room. You must have an EQ strategy and if you can't provide it upstream, having it this easily programmed into each speaker is a great help for very little money.

Overall, I am going to recommend the Genelec GLM. It should be mandatory for anyone buying a SAM speaker that works with it.

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Thanks for the testing amirm .

As a user of GLM since a year ago, and done many calibrations with my 8340 monitors, its nice to see an extended review like this.

A couple of things:

Manually in GLM, you can easy correct for the small peak at 1,8 kHz that the 8330 has. The result is absolutely flat, and the sound becomes state of the art.

You can also use extra shelving from, say, 150 Hz after the automatic measurements of GLM has been done.
I prefer a slight shelving of + 4 dB from 150 Hz downwards.

If you use 8330 or 8340 as domestic hifiloudspeakers , listening from 3-4 meters away, it might be beneficial with a slight downshelving with GLM in the high frequencies, with -1dB shelving from 2500 Hz and upwards. The result mirrors the best sound you have ever heard, in my opinion.

 

[audafreak]

I'd like a comparison of GLM and Neumann's MA-1

I can show real world example of MA1 work in my living room 20m2, Neumann KH80 DSP, KH750 DSP, 7 measurements in each direction, final measurement by REW was very similar to Neumann MA1 "after" prediction.
Before calibration:


After calibration :

 

[Walter]

You can still use GLM to correct the speaker response in that case, just not the subwoofer response.

Yes, but that would be rather useless since bass frequencies are the most important ones to EQ, and trying to integrate a sub set up using one EQ system with mains using another would be ridiculously complicated compared to using the same EQ for both.

 

[Masza]

Yes, but that would be rather useless since bass frequencies are the most important ones to EQ, and trying to integrate a sub set up using one EQ system with mains using another would be ridiculously complicated compared to using the same EQ for both.

Probably but still possible. You can find the phase and/or delay for the sub by hand with a mic and REW. I've used that approach with Yamaha YPAO for speakers and miniDSP 2x4 for subwoofer with success, the only limiting factor regarding frequency response for speakers was the YPAO and limited PEQ of Yamaha AVR.

 

[Walter]

Probably but still possible. You can find the phase and/or delay for the sub by hand with a mic and REW. I've used that approach with Yamaha YPAO for speakers and miniDSP 2x4 for subwoofer with success, the only limiting factor regarding frequency response for speakers was the YPAO and limited PEQ of Yamaha AVR.

It just seems to me like trying to force yourself to do things the hard way just because you paid extra money for a system that included EQ. I've read where people did this--I think there is even a topic on this site--and I just couldn't understand why they were willing to go to the trouble. But maybe they (and you) just like the challenge. Nothing wrong with that.