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High End Absorption / Dullness Condenser Microphones
Old 30th July 2014
  #1
Gear Nut
 

High End Absorption / Dullness

Dear Gear Enthusiasts and Geeks

As you can note from a previous post I did some months ago, I had a huge BASS problem in my room which I proudly fixed by constructing 4 Soffit Style Bass Traps and installed them in the front corners (They look like columns) and Installed an acoustic false roof ceiling with 5 layers of 40kg/m3 mineral wool laying all over it...

Now I've got a little bit of a problem in the mid/ high end 5K+ Range .... It simply rolls down to a point where you don't hear the clarity of drum samples and it is sounding DULL!

If I boost 3.5db shelf EQ with low Q at 5K+ the problems seems to dissappear. The mix becomes crystal clear and LIVE as it should sound....

Again, I need your expert advise hear, Should I Just EQ in this case or should I return for another 6 months of continuous constructing and destruction of my studio to fix this problem?

One more question Should I use vicoustic panels instead of Auralex foam panels for the first reflection points? i.e diffusion/absorption. Anyone uses Vicoustic here?

Thanks and Good day
Old 30th July 2014
  #2
Gear Guru
 
Glenn Kuras's Avatar
Quote:
Again, I need your expert advise hear, Should I Just EQ in this case or should I return for another 6 months of continuous constructing and destruction of my studio to fix this problem?
You could use a slate design over the panels things you have now to retain some of the upper frequencies.

Quote:
One more question Should I use vicoustic panels instead of Auralex foam panels for the first reflection points? i.e diffusion/absorption. Anyone uses Vicoustic here?
For early reflection points you want to use absorption (unless your room is LARGE). And for absorption I highly recommend rigid fiberglass or mineral wool that is no less then 4"
Old 30th July 2014
  #3
Gear Guru
Dull

Steve, play some reference tracks. Great sounding commercial releases that you know intimately from hearing them everywhere. Do they sound dull in your room?
DD
Old 30th July 2014
  #4
Lives for gear
 
adrumdrum's Avatar
 

it probably needed more bass absorption, less than high absorption. The problem is probably that the most of the absorption in the room is to thin, short dacy time att highs and low problems that masking the highs.
When treating a room it's important to have a good balance between (thick)absorption with and without reflective surface on (wood slats).
It's also important That it is the right geometrics on reflective traps. (30 degree traps on the fron wall, NOT square in front corners / front wall)
you can read more here: https://www.gearslutz.com/board/10293632-post31.html
Old 30th July 2014
  #5
Gear Guru
Focus

As I read this, the OP's mix sounds dull. When he adds treble it gets brighter.
Now, if he is listening nearfield were are talking about a dull mix here, not a dull speaker to ear path. Unless the speakers are dull.
In my experience removing the early reflections in a room makes the speaker to ear path clearer.
Let's see what he says about playback of other peoples mixes.
Also of course a quick test with a Calibrated mic would tell us exactly what is coming out of those speakers and how much room is involved.
Measuring Room Acoustics
DD
Old 31st July 2014
  #6
Gear Nut
 

Thanks for your replies guys!

Yes DanDan, when I play Commercial CDs and other artists mastered mixes in my room it is sounding DULL.

I was going to take some room measurements but my audio interface's mic pre decided to stop working :'(

Buying a new AI today and will post measurments and photos asap!
Old 31st July 2014
  #7
Gear Guru
 
Glenn Kuras's Avatar
Quote:
Originally Posted by Stevefire View Post
Thanks for your replies guys!

Yes DanDan, when I play Commercial CDs and other artists mastered mixes in my room it is sounding DULL.

I was going to take some room measurements but my audio interface's mic pre decided to stop working :'(

Buying a new AI today and will post measurments and photos asap!
You can use the following program for testing. Be sure to test each speaker, then both.
Room EQ Wizard Tutorial - GIK Acoustics
Old 31st July 2014
  #8
Gear Guru
Confused

Steve could you clarify a few things for me/us please?
What was your bass problem? Too much or too little bass or lingering decay? Is that fixed now? Have you installed any side reflection absorbers yet?
What speakers are you using and where are they in the room. Photos or a sketch can be very helpful.
The notion that adding absorption to a room makes the sound dead abounds here.
In reality there are two sounds to consider.
1 Direct the sound from speaker to ear. Due to proximity this is louder and arrives earlier than the room tone.
2 Presuming that we are listening in the Near Field, Room tone kicks in later at a much lower volume.

Very often the removal of early reflections from above and sides, and even the floor, eliminates a lot of HF destructive comb filtering. This results in a much clearer sparkly HF. The direct sound becomes very clear, while the later quieter room tone is made less harsh or dulled if you wish.


DD
Old 31st July 2014
  #9
Lives for gear
 
jim1961's Avatar
 

Until we see some measurements, we cant possibly know what is going on.
Old 2nd August 2014
  #10
Gear Nut
 

Hi guys,

Thanks for your reply here are some pictures of my 'play room'.
REW measurements to follow in a bit!

Thanks
Old 2nd August 2014
  #11
Gear Nut
 

pics here
Attached Thumbnails
High End Absorption / Dullness-dsc_0001.jpg   High End Absorption / Dullness-dsc_0002.jpg   High End Absorption / Dullness-dsc_0003.jpg   High End Absorption / Dullness-dsc_0004.jpg   High End Absorption / Dullness-dsc_0005.jpg  

Old 2nd August 2014
  #12
Gear Nut
 

Ceiling and Floor
Attached Thumbnails
High End Absorption / Dullness-dsc_0006.jpg   High End Absorption / Dullness-dsc_0007.jpg  
Old 2nd August 2014
  #13
Gear Guru
Dull

Acoustic Measurement would give us some sort of absolute reference here.
Presuming the ceiling is new, seeing the hard floor, I guess the sound in here before treatment may have been overwhelmed with bright harsh reflections. Maybe it's better now and needs getting used to. What are those speakers? Are the tweeters healthy? The clarity of the sound from speaker to ear at the moment is probably suffering from HF cancellations caused by the desk and possibly the side walls.Desktop Reflection Revealed We would normally use 100 mm fibre plus 100 mm air gap for such reflection killers, and two 600 x1200 traps each side would be a start. So, definitely more at the sides and think about that desk.
I hope the ceiling tiles are fully absorbent and not the type that include a blocking layer. The void above could be fully filled with cheap light attic insulation, this works better in deep amounts than the more expensive dense ones. The denser panels could then be framed and used at the sides. The back wall could do with extensive deep trapping, but that is probably not possible.

DD
Old 3rd August 2014
  #14
Lives for gear
 

It may be worthwhile to use QRD diffusers above the rear first-reflection panels, oriented horizontal to diffuse floor to ceiling.
Or PRD diffuser even, amplitude depending.
Old 3rd August 2014
  #15
Gear Nut
 

Thanks For your pro review Dan Dan : Here's my replies:

Acoustic Measurement would give us some sort of absolute reference here

-Just Discovered my Behringer ECM8000 stopped working... I need to grab another mic asap for this matter...

Presuming the ceiling is new, seeing the hard floor, I guess the sound in here before treatment may have been overwhelmed with bright harsh reflections.

-You are 100% right, The reflections in this room before treatment were so harsh and boomy that I couldn't even stand the sound of my voice in this room!!

Maybe it's better now and needs getting used to. What are those speakers? Are the tweeters healthy?

-My Speakers are : KRK VXT4's coupled with a KRK sub 10". I used this in my late old studio and they used to sound beautifully from bass to highs... I use the NS10s for reference only.

The clarity of the sound from speaker to ear at the moment is probably suffering from HF cancellations caused by the desk and possibly the side walls.https://www.gearslutz.com/board/studi...-revealed.html We would normally use 100 mm fibre plus 100 mm air gap for such reflection killers, and two 600 x1200 traps each side would be a start. So, definitely more at the sides and think about that desk.

-MY problem here is that I have a lot of high frequency absorption.. from 5000Hz upwards it seems as if someone installed an invisible EQ in this room and sloped from 5k downwards...Don't you think IF i add MORE absorption I will REduce MORE high Frequencies? Just asking...
Yes the desk is huge and I intend to change it in the future... But I used to use the same desk at my old studio and I didn't have these problems before.

I hope the ceiling tiles are fully absorbent and not the type that include a blocking layer. The void above could be fully filled with cheap light attic insulation, this works better in deep amounts than the more expensive dense ones.

-The ceiling tiles are made of a sandy and very fragile material used for sound attenuation (according to my supplier). Above it I have 2 layers of 18kg/m3 rockwool, 2 layers of 40kg/m3 fibran geolan and 1 layer, 4 sheets of 100kg/m3 rockwool. In total there is 5 layers of rockwool...

The denser panels could then be framed and used at the sides. The back wall could do with extensive deep trapping, but that is probably not possible.

-unfortunately this is a small room and I cannot sacrifice a lot from the rear wall...

When I get hold of a working Measurement Mic I will repost the measurements! Do you suggest any good brands not over 100euro? I saw the Dayton Audio EMM-6 with calibration file and I'm getting interested. Anyone used this?
Old 3rd August 2014
  #16
Gear Guru
Counter

It is counter intuitive that added absorption will increase the clarity of signal from tweeter to ear. But it does. Consider a vocal booth. Dead dead dead. No reflections whatsoever. Do vocals coming from such booths sound dull?
Obviously not. The reason being that the absence of HF DESTRUCTIVE reflections leads to a clear unhindered delivery of HF from Tweet to Ear.
The UMIK-1 from Minidsp.com is a fine Measurement Mic with USB interface included.
I am worried about those ceiling tiles. Can you get the brand name?

DD
Old 3rd August 2014
  #17
Gear Nut
 

Thanks for your quick Reply on a Sunday Dandan

The Ceiling tiles are the following Armstrong Dune : 120 cm x60 cm

Dune Square Lay-In and Tegular

Do you think they are reflecting HF causing cancellations?
Old 3rd August 2014
  #18
Gear Guru
Specs

Steve you will have to google aggressively or search the Armstrong site. I am heading to the sea side to play some blues! Unfortunately when I searched for Dune specs I immediately see an NRC of 0.5 which is not promising.
Replacing these tiles with fully absorbent ones e.g. Armstrong Optima, should help a lot.

DD
Old 4th August 2014
  #19
I agree with DD all the way.

When you add much absorption (from foam or thin fiberglass) to the room, high freq are absorbed more than lower freq, then the reverberation time decreases towards Highs, making the room kinda boomy, too much body and darker.

When you dont have any mid high treatment in the reflection points, the phase changes due to diferent time arrivals from the direct sound and reflected sounds creates canellations among the the spectrum. This gives you the feeling of dullness, and poor defined highs.
THis at first glance seems to be your problem. Measurments shall set this clearer.
If you cant measure, walk around the room, and clap strong, if you hear the echo of the clap repeating very fast like a delay with very short time, or worst, a high freq tone after the clap, you can easily find out problematic surfaces and add foam =)

Remember as long as you add treatment, the untreated areas become more evident!
Old 4th August 2014
  #20
Gear Nut
 

Thanks Dan Dan. I will look more into this...

Thanks Sebastian for your Reply. As you can see from the photos, I applied Auralex acoustic foam spaced with 4 inches foam on my walls at the reflection points. I did this because I read on a book that spacing foam panels from the wall will absorb more low frequencies since my main problem was a Boomy room filled with huge room modes.

and Yes I do not have any flutter echo issues especially at the sweet spot.

I need that Measurment mic so badly a the moment!
MY Behringer ECM8000 is giving a lot of hiccups and it's just unreliable :(
(just at the right time!!!) gggrr
Old 18th August 2014
  #21
Gear Nut
 

Hi Guys I'm back to this.

I hired a Studio Designer from my country who have worked on numerous Studios / Cinemas and Radio Stations locally.

He suggested I should get rid of all my absorption and bookshelf on the rear wall and replace it with a 600HZ specific Diffusor measuring 180cm x 360 cm. After some measurments, the RT60 of the room is too low in the 600 HZ area and he said that is not good in a recording studio. He also said this might also help in the 5k+range.

what are your opinions guys?
Old 19th August 2014
  #22
Gear Guru
Close

I cannot envisage any benefit from a Diffusor so close to and behind the listener.
DD
Old 8th September 2014
  #23
Gear Nut
 

Hi Guys,

Finally my Dayton Audio EMM 6 arrived and here's my Room Measurments. Would be grateful for your opinions!
Thanks
Attached Thumbnails
High End Absorption / Dullness-spl.jpg   High End Absorption / Dullness-waterfall.jpg  
Old 8th September 2014
  #24
Gear Guru
Measurements

Probably best to post the .mdat File directly so that we can tweak the views.
Change the scales on the Waterfall to make sense of it. A 45dB span is plenty to see the room tone decay.
Measuring Room Acoustics

DD
Old 11th September 2014
  #25
Gear Nut
 

Thankyou for your valuable help on the forum. DAN DAN. I will post the .mdat file when I go home tonight.

I have just removed all my purple auralex 2" foam from the walls and all of a sudden the room is bright again!!
I removed the first reflection points from all walls.

Should I keep it this way without any absorption at the early reflection points???
Old 11th September 2014
  #26
Lives for gear
 
Jens Eklund's Avatar
Quote:
Originally Posted by Stevefire View Post
Thankyou for your valuable help on the forum. DAN DAN. I will post the .mdat file when I go home tonight.

I have just removed all my purple auralex 2" foam from the walls and all of a sudden the room is bright again!!
I removed the first reflection points from all walls.

Should I keep it this way without any absorption at the early reflection points???
https://www.gearslutz.com/board/7293796-post2.html

https://gearslutz.com/board/7237454-post133.html

Quote:
Originally Posted by Jens Eklund View Post

...

If absorption is used, make sure to use thick panels so that you don´t simply “EQ” the reflections, only removing the high midrange and highs from it, leaving the low mids and bass frequency range unaffected. Use at least 120 mm, preferably 200-300 mm or deeper (and make sure to use a wool with appropriate flow resistivity for the given depth). Only use broadband absorption where needed, or you´ll struggle to keep the energy needed to keep the room “alive” (in order to reach the desired gain of the ISD-gap termination).

Use the ETC to track down your early reflections and figure out what areas needs attention.

...

A note on low frequency treatment (modes and SBIR related issues): I recommend pressure based absorbers for the bass region for two reasons: First, they don´t need to be ridiculously deep in order to be effective at low frequencies and secondly, they don´t absorb the upper range that one usually struggle to preserve in order to achieve a proper termination of the ISD-gap and the semi diffuse field that should follow it (assuming LEDE/RFZ/CID design or Ambechoic with decent “decay times”).

For proper use of any acoustic treatment; measure and analyse your room and decide on a response model to use as a guide when deciding on different treatment options. I know this might sound daunting, but the alternative is usually a less than perfect outcome but if you´re happy with that: build/buy some panels and fire away!


More on topic here:
eigenmodes calculator
ISD gap for my room help pls!
My diffusor design - is it ok?
Help: Studio is too loud
Old 11th September 2014
  #27
Gear Guru
Reflections

I wonder if the spacing foam you used under the Auralex was open or closed cell?
You absolutely will need to diminish your early reflections and as Jens suggests, with as full range an approach as possible.

DD
Old 11th September 2014
  #28
Gear Nut
 

It was open cell DAN.

All I know is that it was sucking up all highs from my room.

I'm considering buying Vicoustic Wavewood for the early reflection points. Since they deflect some of the highs back to the room. Anyone has experience with these around here??
Old 11th September 2014
  #29
Gear Guru
Highs

Steve, removing early reflections typically increases the clarity. The signal path from tweeter to ear is no longer damaged by cancelling reflections.
I would have thought your original plan with good acoustic foam over a non intrusive spacer/gap was valid, clever, and good.
Thin absorption may well unbalance the room tone, but if this is a Mix Room, the goal here is to hear the speakers not the room.
It would be well worth your while posting that .mdat. Or a new one. Let's see what's really going on.
DD
Old 11th September 2014
  #30
Lives for gear
 
adrumdrum's Avatar
 

Quote:
Originally Posted by Stevefire View Post
It was open cell DAN.

All I know is that it was sucking up all highs from my room.

I'm considering buying Vicoustic Wavewood for the early reflection points. Since they deflect some of the highs back to the room. Anyone has experience with these around here??
you don't need to add reflection at early reflection area, you need to cover larger area with thicker absorber. If the absorbers used in a room is too thin to absorb bass or ony absorbing highs , adding reflection to them will not make it absorb lower in frequenzy(unless you make it a resonator).
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