8351 not sounding good, acoustic issues in treated room - Forum

Hello, and I'm sorry for late reply.

Thank you for the good background information. Could you please be kind and send few pictures of your room where the listening position and monitors are visible, and also the GLM calibration setup. If you can't attach the pictures to this forum, please send them to support@genelec.com 

You can get the GLM calibration setup by opening GLM|Help|Export Setup to Desktop| attach the .zip file from the desktop to this forum or send it to the e-mail mentioned before.

I will get back to you with any suggestions possible after that, thank you!

Best Regards,
Jani Oksanen
Customer Support Team

Hey jani, thank you for the reply. 

I didn't notice that my initial uploads never appeared. I updated my post with pictures of the room and the GLM EQ curves now, as well as the GLM calibration setup zip. I suppose it's pretty obvious that I need to combat my 1k dips by getting stands for my monitors and elevating them up and away from my desktop, but regarding the rest of the problems I'm quite puzzled. Working on borrowing stands for them. Looking forward to hearing more.

Best, 

Jonas Magnussen

Hi Jonas,

Thank you for the great pictures and the setup file. There indeed something that could be improved on the freq. response, and the higher frequencies should be quite easily to be solved with the stands. We also have available table stands for 8351A's, that could be also good option. The table stand part number is 8000-325B. With the table stands you could also bring the monitors closer to yourself, to have more direct sound coming to your ears and less room effects. 8351A can be listened from quite short distance (50cm).

I would first solve the position of the monitors first, and then start to dig more deeply what else could be done to improve overall frequency response. Subwoofer would of course help on the low frequencies, but first, lets not hurry, and please try the stands/table stands and let us know the results! 

https://www.genelec.com/sites/default/files/media/Studio%20monitors/Accessories/23276_tischstativ_genelec.pdf 

Best Regards,
Jani Oksanen
Customer Support Team

The treatment was not succesful at all. The room modes at 40 & 80 Hz are there, evident in the plot that you uploaded. With the 8351 are more evident since these speakers are better than the 8020 in low frequency response. If you had the 8020 with a sub then you would realize the same problems. The 8351 is by far a better monitor. 

To my view these are the steps for better sound:

- Better position of the 8351 (as already mentioned), this will require to move also the desk away from the front wall. See what Genelec recomends about the placement.

- Better treatment from a specialized professional with better sound material. 

- A subwoofer (close to the wall) will help to best position the 8351 (away from walls)  

Thanks for the answers, guys. I’ve been working slowly on getting to the source of this, and have managed to get ahold of König & Meyer stands. 

The bass response is flatter after putting them on stands! The node on 40hz is peaking high as always, but GLM calmly takes care of that. The right speaker has more low frequency cancellation than the left one. The comb filtering on 1000hz is gone, but it has simply moved down to about 500hz. Still very annoying. Can I do something with the desktop to remove this? 

I also talked to a professional acoustician about my situation, as it was before I got the stands. The first he was worried about was the symmetry of the room, and suggested using either concave diffusing absorbers or tilting the walls 10 degrees to break the symmetry, and fight the nodes. When I mentioned the roof height he also stressed that I should consider tilting my roof. This is not an option for me, but I figured I have some options to improve the room. 

— I can make some big standing plates made of “kryssfiner” and place them towards my front wall behind my corner traps to break the reflections somewhat. 

— I can possibly modify some of my bass traps with perforated metal plates bowed for a concave surface. (Is this appropriate for diffusion, will it break up my nodes, and how many do I need?) 

— I can add more absorbing ceiling clouds above my listening position. 

— I’m not able to buy a dedicated subwoofer, but I do have a 7050 from my previous setup still. Can I use this with some clever positioning and tuning to improve my bass? Will this be a big waste with my GLM and 8351? 

What do you think guys? What is the way moving forward? I'm attaching some new pictures of the setup and calibration. 

Hello

Symmetrical placement is a good thing :) Using diffusing absorbers is also a good thing :) Please see what Genelec suggests about treatment and speakers positioning. This is the best that you can do. You can ask the acoustician to give you his proposal and expected results. Treating also the ceiling is a good thing but in your case, by using the 8351 it becomes less neccesary. If you also use mutliple subs elevated from the ground then it is also less neccesary. 

In the end of the day, you cannot work miracles in a small room. The standing waves cannot dissapear. The GLM is a nice solution but, as all DSPs, it cannot turn a small room into a perfect one. 

If I was in your position I would buy two 7350 subs (in case that 2 7360s are not affordable). This would help you to control the standing waves (see about mutli-sub placement). I would also increase the distance of the 8351 from the back walls. 

Don't go off generic acoustic treatment advice alone. Get rew and a measurement mic. Test where it's actually best to put treatment and position speakers not just what the textbook says. Then use glm.