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Genelec GLM Review (Room EQ & Setup)

soundwave76

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Fyi there is an indie product called Gevol which is designed to implement GLM volume control in a very nice way

https://gevol.fi

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Tangband

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The purpose of room compensation in professional monitoring is to trim the frequency response of perceived-direct sound to become flat, at the listening position. It depends on the room, the loudspeaker, the placement and the listener what is perceived as direct sound.

"The use of single point equalization is a safe choice for measurement of studio monitoring rooms having relatively low reverberation times and well controlled room modes… Spatial averaging across a wide area may come with the risk of compromising the result at the main listening position.”

Quotes from our AES and Tonmeistertagung studies (2016-18), recognising also how spatial averaging is more relevant in other applications, e.g. recreational.

Another topic discussed in this thread, bass management using distributed sub woofers, is generally not ideal in pro monitoring. You want to know exactly what is in the source, and a flat frequency response is not the only goal. Room + monitors (“setup”) create a structure capable of conveying a qualitative experience of envelopment, so a fine setup should also faithfully reproduce envelopment-contrasts in the source, rather than wishy-washy pleasantness.

In a good room with good monitors, nothing beats acoustical summation with listener movement, also at VLF. To me, the experience of envelopment is one of the most precious sensations/feelings of listening to music in a great concert hall, or from a decent reproduction setup.

Thanks for input.:)
I understand that the main purpose with GLM is a neutral sound and monitoring in a studio. But Genelec is also very good to be used as a hifi-loudspeaker in a normal room, and one can use GLM to fine-tune the sound until it sounds subjectively best for the listener.
Tuning the sound with GLM manually means that absolut neutrality ( wich I suppose is Genelecs goal ) can be trade to a more ”subjectively pleasant” sound, even though the main purpose in the beginning with GLM was different.
As an example, one can use the shelving filter in GLM to bring down the treble from 2,5 kHz to 20 kHz - 1 dB , if using Genelec 8340 in a normal livingroom. I do that, and the sound is subjectively better for me and my family, maybe because of the undamped concrete walls in our flat.

One can also adjust the input gain in GLM which can be saved into the loudspeaker. From factory, the gain is set very high. I use my 8340 with -20 dB gain in GLM, making it more compatible with Hifi-gear for home use.

One nice feature with GLM is once set up, you can save the data into the loudspeaker and disconnect the GLM unit with all its cables, making the Genelecs look very clean with a high WAF ( wife acceptance factor ) .:)
All one needs after doing that, is a preamp or streamer with volume regulation.
 
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Sean Olive

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GLM can do multiple microphone measurements for each monitor/subwoofer as many as the user wants. After the calibration is done the user can set shelving filters to taste and change it without any new calibration needed.
That sounds better.
 

blamphos

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Just an e-mail for contact, as far as I could see.

On the Genelec forums he has a short thread for the various versions: https://community.genelec.com/forum/-/message_boards/message/1149257#/
Hi, I'm the developer of GEVOL. Yes, it's fancy device and the journey has been long. The first version was quite simple microcontroller based implementation, only 7-segment display to display current volume level and IR control to change volume via GLM adapter. Later I added more electronics to decode S/PDIF stream and switching capability between sources automatically. With the current version 3.0 the implementation was ported to use Raspberry Pi, where added self made tiny HTTP server for web control and designed PCB's/mechanics. Currently there are issues with availability of some components due to Covid19 situation and chassis factory informed me that the price of raw aluminium in China has increased 35%. The price will settle around 300 euros but let's see how the situation evolves.
 

HooStat

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@blamphos Is it possible to simply create an iOS app to display and control the basic functions controlled by GLM? I am not suggesting you need to do this. I am really just wondering if that can easily be done. It sounds like you have done something like this already with your HTTP server.
 

blamphos

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@blamphos Is it possible to simply create an iOS app to display and control the basic functions controlled by GLM? I am not suggesting you need to do this. I am really just wondering if that can easily be done. It sounds like you have done something like this already with your HTTP server.
That will depend what you are meaning. Thus the GEVOL device simply emulates wired volume controller (https://www.genelec.com/9310b-wired-volume-controller) it also extends the control interface so it's possible to create iOS or Android app to control the volume level in GLM via GEVOL. However, to control GLM directly is not possible due to full GLM control is available only via USB and using GLM SW in Windows or Mac. Genelec does not provide any API for GLM adapter either SW.
 

HooStat

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That will depend what you are meaning. Thus the GEVOL device simply emulates wired volume controller (https://www.genelec.com/9310b-wired-volume-controller) it also extends the control interface so it's possible to create iOS or Android app to control the volume level in GLM via GEVOL. However, to control GLM directly is not possible due to full GLM control is available only via USB and using GLM SW in Windows or Mac. Genelec does not provide any API for GLM adapter either SW.
OK -- thanks for clarifying. So one can emulate the wired volume controller and that is it. Well, thanks for putting in the work to create a more consumer-friendly device.
 

hege

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GLM control is available only via USB and using GLM SW in Windows or Mac. Genelec does not provide any API for GLM adapter either SW.

Some progress here..

 

blamphos

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Some progress here..

Ok, good to know. I've been also thinking to investigate that a bit more and do some reverse engineering. My only concern is that Genelec can enable crypting to the protocol if they see that this goes too wild.
 

JRS

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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 have been using room correction for nearly 20 years, and back then there was only TACT and DEQX. The DEQX has been my weapon of choice (and has served me well)--I favor the philosophy of first EQ'ing the driver response at 1 meter with phase correction, and then and only then judiciously applying room EQ. Anyhow I have been looking for something newer, and between REW, Audiolense, Acourate, MiniDSP using Dirac, etc. it would be a great gift to have a shoot out of sorts. From Mitch's comments, I gather that as much as I like the Acourate approach, the sheer tedium is a huge turnoff. Nor am I inclined to buy a product where the forum is the owners manual.

Wouldn't be lovely to have an $1800. killer unit that could accommodate say a stereo 3 way active speaker with crossovers, a lot of built in automation, have a near SOTA DAC and both balanced, unbalanced, and digital outs all with 24/192 capability? Along of course with all out assault for audio only with whatever latency is required filter bank that is switchable to a more humble video choice filter set that keeps it synced. While we are at it offer modules/licenses for all the room EQ standards such as Dirac.
 

JRS

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Thanks for the link there, I want to learn more about mitcho's process, so I've just bought this book right now & will be delivering it to my Kindle.
It's a relatively easy read and well worth the time. While it's geared toward Acourate, the same principles apply across most all of the DSP flavors of driver/room correction, only the details differ.
 

tktran303

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I have been using room correction for nearly 20 years, and back then there was only TACT and DEQX. The DEQX has been my weapon of choice (and has served me well)--I favor the philosophy of first EQ'ing the driver response at 1 meter with phase correction, and then and only then judiciously applying room EQ. Anyhow I have been looking for something newer, and between REW, Audiolense, Acourate, MiniDSP using Dirac, etc. it would be a great gift to have a shoot out of sorts. From Mitch's comments, I gather that as much as I like the Acourate approach, the sheer tedium is a huge turnoff. Nor am I inclined to buy a product where the forum is the owners manual.

Wouldn't be lovely to have an $1800. killer unit that could accommodate say a stereo 3 way active speaker with crossovers, a lot of built in automation, have a near SOTA DAC and both balanced, unbalanced, and digital outs all with 24/192 capability? Along of course with all out assault for audio only with whatever latency is required filter bank that is switchable to a more humble video choice filter set that keeps it synced. While we are at it offer modules/licenses for all the room EQ standards such as Dirac.

The closest I know is the miniDSP DDRC-88A (analog i/o) or D (digital I/o) + BM (3 way speaker + subs or 4 way crossovers) option.

Unfortunately there’s no D/A model… and it still needs some know-how.

How does DEQX auto-mate the measurements? If there a step-by-step prompt or something?
 
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HooStat

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It’s a pity and a judgement error from Genelec that they refuse to offer an open GLM API. Many have requested it and these two threads show a clear demand for it. Ping @Ilkka Rissanen - it’s time to open the API.
I agree completely. However, having to support an API while you are still heavily developing the software can be difficult. Especially if software development is not the main strength of your company. So, I don't blame them.

I would at least like to see a few key things open, like volume control, mute, and power. Just critical functions for listening that work across all products, not functionality for configuration. That would be a good place to start since those seem to be fully baked.
 

HooStat

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API is often the product nowadays
That is very true. It is absolutely possible to do nowadays. And I think it would be worth it if they did.

But the company has to be ready to do it. There is so much hidden work involved with software. Their software is dependent on other software that will change (e.g., Windows, Mac OS). They have to build their version control, testing, and build platform. They have to interact with software developers who use the API. They have to provide support for their API. They have to provide documentation (harder to do it for an external audience than an internal one). They have to decide what is in scope of the API. They have to commit to keeping a reasonably stable API, which can slow their own internal development. They have to address security. It is a bigger commitment than "just doing it". I look at Dutch and Dutch -- they still have not released Roon readiness and it has been years. It is not easy to develop public-facing specialized software correctly.
 

soundwave76

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Yes, but one can start small. API for just volume control would not be rocket science nor introduce major risks to the software. Which is better from Genelec’s perspective - offering their own API versus customers hacking and tinkering their own APIs, which are all outside of Genelec’s control?
 

HooStat

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Yes, but one can start small. API for just volume control would not be rocket science nor introduce major risks to the software. Which is better from Genelec’s perspective - offering their own API versus customers hacking and tinkering their own APIs, which are all outside of Genelec’s control?
I agree. That is essentially what I was suggesting in #256 . It would be very helpful to people to control a few basic functions that are extremely unlikely to change and are constant across products.
 
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