Sound Advice Regarding Bass Traps

[cortexdnb]

Hi Everyone
This is my second thread so please be gentle. I have been making music for quite a few years now and have got to the point where i am getting very frustrated with translation issues. I have moved house quite a few times so have had to put up with various problematic rooms. All of them with low end to mid range problems. I havent used any software to test my room yet as i do do not have an omnidirectional microphone, however i sense peaks at around 100 Hz and multiples of. Within the next couple of weeks i will borrow one and find out where the problems are by analyzing waterfalls from fuzzmeasure and EQ graphs in ARC


I tend to produce drum and bass music and get very frustrated trying to judge low mid and sub levels as my room is tricking my perception. I would really like to even out my rooms frequency response.

my question is that should I try and make some really thick (100mm) bass traps as the genre that i mix requires special attention to lower mid and sub frequencies? My perception is the longer the wavelengths the bigger you need to make the traps. Im thinking of using this method but making it 100-200mm thick using ra45 or rw5 rockwool
http://www.basstraps.net/DIY-BASS-TRAPS-MADE-EASY.pdf

Any direction on this matter would be greatly appreciated. I just want the right information so I dont make my room even worse.


I have attached a diagram of my room and size if that makes any help. If you need any other that will help inform your advice then please don't hesitate to ask.

regards

Gwilym

[cortexdnb]

Is anyone going to help?

[Jens Eklund]

http://www.gearslutz.com/board/6735096-post21.html

[Glenn Kuras]

Originally Posted by Jens Eklund

http://www.gearslutz.com/board/6735096-post21.html

Your links (which I think are great) are turning into a jenweb. Every time I click on one it takes me to some other post with another link and so on and so forth. http:/jenweb.acoustic.com .

[DanDan]

The position of that Fridge looks dodgy....

Try playing some Sine Waves in your room.
Sweep very slowly and carefully from say 30 Hz upwards. Go slow, modes can be only a few Hertz wide. Signalsuite is excellent, as is the Generator in REW. You will encounter modal resonance. The earth will move for you....;-)
While the room is throbbing with this, walk about, forward and back, left to right, try near the floor and ceiling also.
You will find areas of high energy and amazingly quiet nulls.
Make a map of it. It will tell you where not to place your speakers or listening position, and where Bass Traps will be most effective.

200mm is of course better, but if you go deeper than that it is better to use lighter cheaper insulation.

DD

[cortexdnb]

Originally Posted by DanDan

The position that fridge looks dodgy...

DD

What's dodgy about the fridge?

I'm hiring an omni next week so I can see where the problem frequencies are.
I am now going to make traps using 2by 1 and rwa45. I sense that there are peaks in the lower mid frequencies within the room.
I am going to start by putting bass traps in all corners of the room and then at each reflection point.

Is there anymore information that I need to provide so that I can get more accurate advice from my fellow slutz ?

[DanDan]

Fridge?
It will not sound warm.
Sorry....

If it is tall it would mean a large reflective metal object next to the L speaker.
If it's low, maybe ok, but check for resonance by thumping it. Metal panels can ring like drum heads.

DD

[cortexdnb]

Originally Posted by DanDan

Fridge?
It will not sound warm.
Sorry....

If it is tall it would mean a large reflective metal object next to the L speaker.
If it's low, maybe ok, but check for resonance by thumping it. Metal panels can ring like drum heads.

DD

i see what your saying, might have to find somewhere else for it within my house. Here is a waterfall from fuzz measure, ignore the times as i used a cardioid. I plan to borrow an earthworks QTC1 omni next weekend for more accurate room analysis

now you can see where the problem frequencies are. Namely 125HZ and big troughs in the sub bass area.

this is the first time i have used FM so might not have the settings right.

[cortexdnb]

This might also help you guys give me more information about treating my room. i dont really understand much about room modes. However this is not exactly a fair test as my room is not 100% rectangular as you can see in my floor plan.










would really appreciate more advice about optimum placement of the traps and if my previous ideas are going along the right lines

[DanDan]

When viewing modes try 20-300Hz or even less of a range if you want to zoom right into the details. No smoothing.

Don't know what the offset does, zero would be my choice.
Duration needs to be long enough to see the modes tail off down to the noise floor. Try 1000mS. You may need to change the window length to suit.
Try different lengths to clean up the graph. 600mS should be OK.
I have never seen "multiple' in the min magnitude. This should be set to your noise floor. Usually somewhere around -35 to -45 dB.
No need to calculate the modes you will see them but it can be useful to have a second opinion. Focus on the first half dozen axials and see if any correspond to the Waterfall. They won't be exactly the same.

As it stands, if you play a sine wave at 125Hz. Tune around that frequency slowly until you hit strong resonance. You should be able to identify the mode or modes by walking through the peaks and nulls. Find hot spots at the corners and whole walls. Place most traps where it's hottest.
If you find another significant mode in the Waterfall sine that too.



DD

[cortexdnb]

Originally Posted by DanDan

Focus on the first half dozen axials and see if any correspond to the Waterfall. They won't be exactly the same.

DD

sorry i don't understand this. do you mean focus on the peaks within the waterfall. I really dont understand what axials are. i just provided information that i thought might be helpful.

there seams to be peaks in the listening position and in bottom right corner and then a trough about 4ft behind listening position at 125hz

[DanDan]

Axials are modes which exist on the room axes. Length Width Height.

Try the Sine wave thing, it will all become very obvious to you.

DD

[cortexdnb]

Is this better?