Need some help with acoustic treatment, opinions…

The area that is causing the problem lies between 100-300Hz.

What is it that makes the mentioned area much louder and what is it that makes some frequencies resonate?

STANDING WAVES - Another problem created inside is parallel walls and standing waves. Standing waves are when a sound reflects off walls that are opposite each other and a wave equal to the distance is formed. As you move around a room with standing waves you can hear as you walk in and out of a standing wave. In one spot the bass is booming yet in another there is hardly any bass. Makes it hard to figure out how much bass you have? What happens here is that if you stand at the high point of an in phase standing wave you hear double the volume of the frequency yet when you stand at the same point in an out of phase standing wave the waves cancel each other and you hear nothing. It's pretty hard to figure out your sound frequency balance when this happens throughout your control room. It happens at all the octaves of the frequencies as well so if the frequency is 440Hz it also happens at 880Hz , 1760Hz ,3520Hz,etc. This is what creates coloration in the room. As you move around the room the frequency response keeps changing causing room coloration. It's also a problem in the studio if your mic is sitting directly in an out of phase node!! So the first thing you must do is eradicate all the parallel walls in a studio design. I believe that a wall must be at least 12 degrees off parallel to stop parallel wall standing wave interference. That's either one wall at 12 degrees or two walls at 6 degrees each. If you can afford to make the angle bigger, do so. Also you can create angled walls within a rectangular room by adding acoustic treatment. (I'll demonstrate that in the pages on wall treatment). (Note: having non parallel walls doesn't entirely stop standing waves - they still form within a room but along different lines of repetition). The main reason for having angled walls in a control room is because of reflection control of the high frequencies for true imaging from your speakers. This effect also happens between the floor and the ceiling so to stop the effect you must angle one! well it's not going to be the floor is it. I must state here that putting angles into the ceiling is expensive so I would recommend that for the home studio you use the acoustic treatment to break up the ceiling. http://www.saecollege.de/reference_material/index.html

What is the best way to solve this problem? Should I try to Build broadband absorbers, bass traps ore Helmholtz resonators? Which solution do you think suites me most?

There are basically two ways to control low frequencies. Acoustic Hangers. This is a system of fibre board panels that are wrapped with insulation and are hung freely using wire or rope. The large hangers 1.8m x 500mm work in the low frequency range whilst the panels 1.2m x 300mm effect the low mid frequencies. It is common to have up to a 1.2m space at the rear of the control room with the large hangers whilst the smaller hangers are effective if suspended in the ceiling cavity created by a false ceiling. Panel Absorbers. A panel of plywood or particle board is placed over an air cavity with insulation glued to the back of the panel. The panel has a resonate frequency and when it occurs in the room it resonates and the insulation absorbs the energy. http://www.saecollege.de/reference_material/index.html

Aloha and welcome to the forum, Daniel :D

Your english is fine. :wink: Sometimes you got to hang in there, because the guys get pretty tied up.

Good call. It's closer to 137Hz

Excerpt from the SAE website: STANDING WAVES - Another problem created inside is parallel walls and standing waves. Standing waves are when a sound reflects off walls that are opposite each other and a wave equal to the distance is formed. As you move around a room with standing waves you can hear as you walk in and out of a standing wave. In one spot the bass is booming yet in another there is hardly any bass. Makes it hard to figure out how much bass you have? What happens here is that if you stand at the high point of an in phase standing wave you hear double the volume of the frequency yet when you stand at the same point in an out of phase standing wave the waves cancel each other and you hear nothing. It's pretty hard to figure out your sound frequency balance when this happens throughout your control room. It happens at all the octaves of the frequencies as well so if the frequency is 440Hz it also happens at 880Hz , 1760Hz ,3520Hz,etc. This is what creates coloration in the room. As you move around the room the frequency response keeps changing causing room coloration. It's also a problem in the studio if your mic is sitting directly in an out of phase node!! So the first thing you must do is eradicate all the parallel walls in a studio design. I believe that a wall must be at least 12 degrees off parallel to stop parallel wall standing wave interference. That's either one wall at 12 degrees or two walls at 6 degrees each. If you can afford to make the angle bigger, do so. Also you can create angled walls within a rectangular room by adding acoustic treatment. (I'll demonstrate that in the pages on wall treatment). (Note: having non parallel walls doesn't entirely stop standing waves - they still form within a room but along different lines of repetition). The main reason for having angled walls in a control room is because of reflection control of the high frequencies for true imaging from your speakers. This effect also happens between the floor and the ceiling so to stop the effect you must angle one! well it's not going to be the floor is it. I must state here that putting angles into the ceiling is expensive so I would recommend that for the home studio you use the acoustic treatment to break up the ceiling. http://www.saecollege.de/reference_material/index.html Sound familiar?

Excerpt from SAE Website: There are basically two ways to control low frequencies. Acoustic Hangers. This is a system of fibre board panels that are wrapped with insulation and are hung freely using wire or rope. The large hangers 1.8m x 500mm work in the low frequency range whilst the panels 1.2m x 300mm effect the low mid frequencies. It is common to have up to a 1.2m space at the rear of the control room with the large hangers whilst the smaller hangers are effective if suspended in the ceiling cavity created by a false ceiling. Panel Absorbers. A panel of plywood or particle board is placed over an air cavity with insulation glued to the back of the panel. The panel has a resonate frequency and when it occurs in the room it resonates and the insulation absorbs the energy. http://www.saecollege.de/reference_material/index.html

Helpful links: SAE Website - http://www.saecollege.de/reference_material/index.html Wall Unit Plans - http://www.johnlsayers.com/HR/index1.htm Reference Section - http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2125 More Reference - http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1168 This might seem to be a lot of stuff to absorb. :shock: It is. Take your time digesting the info, formulate your questions, and ask. It'll be well worth the effort. :wink: Hope this helps,