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> Helmholtz Resonator, Need advice from some studio veterans
Darius Wave
post Jun 23 2013, 11:06 PM
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Hi guys. Currently fighting with my new room. Need a lot of improvements. I've got a question to some of You, who did built or just have an idea about the Helmholtz Resonators. Tell me how big resonator would You advice me for the 60 Hz resonance. I know it woulkd be good to have at least 50 x 50 x 100 cm but...I suppose it's also a matter of volume I usually work with and...it's not that loud. Maybe some smaller resonator will be enough for my home studio purpose?

Question 2: Do I have to do a multiple wholes + tubes? Would be much easier to make precise freq adjustment by changing the length of only one tube....while...much harder with multiple.

I'm just wondering about doing the DIY resonator - wooden box with only one tube going into....


Is this idea ok or this won't work fot shure?


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Mertay
post Jun 23 2013, 11:49 PM
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Never built one but I had a bookmark incase it was needed someday smile.gif

http://www.acousticmodelling.com/helmholtz.php


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bobg
post Jun 23 2013, 11:51 PM
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QUOTE (Darius Wave @ Jun 23 2013, 10:06 PM) *
Hi guys. Currently fighting with my new room. Need a lot of improvements. I've got a question to some of You, who did built or just have an idea about the Helmholtz Resonators. Tell me how big resonator would You advice me for the 60 Hz resonance. I know it woulkd be good to have at least 50 x 50 x 100 cm but...I suppose it's also a matter of volume I usually work with and...it's not that loud. Maybe some smaller resonator will be enough for my home studio purpose? Question 2: Do I have to do a multiple wholes + tubes? Would be much easier to make precise freq adjustment by changing the length of only one tube....while...much harder with multiple. I'm just wondering about doing the DIY resonator - wooden box with only one tube going into.... Is this idea ok or this won't work fot shure?

Might be easier to use compressed fiberglass but using thicker versions.
Check this out by Ethan Winer: http://audioundone.com/do-it-yourself-bass-traps



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Darius Wave
post Jun 24 2013, 12:10 AM
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Thanx guys! Some useful and clearly written stuff. I went through tons of information but need to confirm some of them wink.gif


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Mertay
post Jun 24 2013, 12:17 AM
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QUOTE (Darius Wave @ Jun 23 2013, 11:10 PM) *
Thanx guys! Some useful and clearly written stuff. I went through tons of information but need to confirm some of them wink.gif


Probably you know more than me about acoustics but just wanted to mention, did you try moving your monitors closer to the wall?


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Darius Wave
post Jun 24 2013, 12:38 AM
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Yep I tried but then it's worse than ever because of the desk reflexes. I have to keep them on the edge. The main problem are the corners behind the listener's chair. I will handle the space behind the monitors with some difussion panels


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Mertay
post Jun 24 2013, 12:56 AM
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QUOTE (Darius Wave @ Jun 23 2013, 11:38 PM) *
Yep I tried but then it's worse than ever because of the desk reflexes. I have to keep them on the edge. The main problem are the corners behind the listener's chair. I will handle the space behind the monitors with some difussion panels


Oh sad.gif I have no idea about the room but hanging monitors to walls (with a simple shelf angled-or something placed under monitors like glasswool) might also work facing you from a little above (tweeters can face upside-down for better sweetspot if needed), the 60hz area as far as I know usually generates behind the monitors but those diffusors will probably have to be really thick to handle that frequency.

triangular basstraps for corners might work? you can make them pretty thick as usually the very corners of the rooms aren't occupied much?



I bet building a resonator will be a real challange so I'm just shooting alternative ideas, good luck!

This post has been edited by Mertay: Jun 24 2013, 12:58 AM


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Saoirse O'Shea
post Jun 24 2013, 09:51 AM
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As above - bass trap set at an angle in the corner. A tuned trap like the Helmholtz isn't the best solution for a small room as you will be dealing with broadband bass issues. They're also difficult to make and are nearly always much, much larger then you think they'll be.

For a corner bass trap use high density rockwool - foam doesn't work - and layer it. Depending on your room you'll probably need it to be layered to 6'' or more deep. Floor to ceiling bass traps work better than short/mid length. Positioning your monitors so that they are correctly distanced from the rear and side walls and mounting them on rigid stands will also help. For a small room you usually need to add mid/high frequency adsorbers at the ideal 1/3rd listening distance and mirror points.


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Darius Wave
post Jun 24 2013, 10:48 AM
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Thank You for Your help...I think I'll experiment with the corner bass traps because they will also so be much less space-taking and the room is pretty small....3 x 3 x 2,5 m. As for the monitors placement...I'll experiment some more and do the meter the results but it's a bit of "practical aspects" limitations. See...there is a window just behind the monitors. I will glue something on it ...maybe a rockwool panels or something...here's my next question....what would You advice to cover the window? Some kind of Scheoeder difusor or some simple absorbing panel?


P.S I'm using the foam only for some soft high end absorbtion ...like while recording the acoustic guitar etc...I don't expect it to "do the mirracles" smile.gif))

This post has been edited by Darius Wave: Jun 24 2013, 10:48 AM
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Mertay
post Jun 24 2013, 12:18 PM
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QUOTE (Darius Wave @ Jun 24 2013, 09:48 AM) *
Thank You for Your help...I think I'll experiment with the corner bass traps because they will also so be much less space-taking and the room is pretty small....3 x 3 x 2,5 m. As for the monitors placement...I'll experiment some more and do the meter the results but it's a bit of "practical aspects" limitations. See...there is a window just behind the monitors. I will glue something on it ...maybe a rockwool panels or something...here's my next question....what would You advice to cover the window? Some kind of Scheoeder difusor or some simple absorbing panel?


P.S I'm using the foam only for some soft high end absorbtion ...like while recording the acoustic guitar etc...I don't expect it to "do the mirracles" smile.gif))


Hi,

I'd start with area the monitors are (behind ans sides) as I bet those windows are causing a lot of reflections besides added bass freq.s.

Try finding hard but not very thick glass or rock wool, something like this;

http://www.izocam.com.tr/tr-tr/urunler/yal...ger/izopan.aspx

Notice its actually made to place behind radiators to keep the heat from absorbed by the wall. I bought a bunch of these for my ex-home studio, it works but don't expect miracles smile.gif its very thin but very dense, you can cover it with cloth and keep in mind its better that the aluminum side facing you (absorbes little more bass freq.s). It should be a good solution for reflections too in such small space. Its hard to bend so probably you can mount them with minimum damage to the wall or windows.

After than try build or buying a stand for monitors so you won't have reflections from desk. I'd place them high but directly facing me so not only they can be closer to the windows, reflections from desk would occur less. Also personally I like some distance from monitors. Something like this but with stands;



If you don't have good absorbtion I don't recommend deffusors specially in a small room. What will happen is most probably you'll end-up fixing one freq. and creating another problem freq. .

But I do recommend diffusors for recording. Imagine a triangle of mic., guitar and diffusor. Placing a diffusor close to a guitar or mic. can have nice benefits and cool alteration on sound for recording.

This post has been edited by Mertay: Jun 24 2013, 12:19 PM


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Todd Simpson
post Jun 25 2013, 10:32 PM
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You can probably build something to go over the glass to tame reflections a bit, maybe even wood blinds that could be adjusted if you have carpentry skills. If not, you could make something of a panel that you could move if you wanted some light to come in and werent' mixing.


QUOTE (Darius Wave @ Jun 24 2013, 05:48 AM) *
Thank You for Your help...I think I'll experiment with the corner bass traps because they will also so be much less space-taking and the room is pretty small....3 x 3 x 2,5 m. As for the monitors placement...I'll experiment some more and do the meter the results but it's a bit of "practical aspects" limitations. See...there is a window just behind the monitors. I will glue something on it ...maybe a rockwool panels or something...here's my next question....what would You advice to cover the window? Some kind of Scheoeder difusor or some simple absorbing panel?


P.S I'm using the foam only for some soft high end absorbtion ...like while recording the acoustic guitar etc...I don't expect it to "do the mirracles" smile.gif))



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Darius Wave
post Jun 25 2013, 11:07 PM
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I have to analyze all possibilities before inviesting any cash. I was even wondering of making some "all-wall length" storage spaces/boxes just under the roof/top so I can organize the space a bit smarter and have even a tiny improvement because of the boxex absorbtion and irregular sizes, material, shapes of things inside those. As for the windows I'll hang some thick cloth for now and I'll do portable panel - I'm not a vampire - daylight will be wellcome while doing some less demanding midowns, renderings, composing...etc. Thanx for advices. They give some point of view for those things especially some of You really dig the topic smile.gif)))


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Darius Wave
post Jun 28 2013, 12:52 PM
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I have some idea how to combine practicality, mobility and usefulness.


1. On the right wall (listeners view) I'll install a hang for photo backgrounds. I'll hang very thick cloth as a first layer and than at least 2 or 3 different backgrounds for the video purpose. They will always be rolled down while doing mixes. This will kill some reflexes for the right wall.

2. On the back wall I'll install sort of "whole-wall-bookstand. There'll be tons of different items + some wood and rockwool to reduce back wall reflexes and diffuse lower end.

3. right wall and back wall corner can be fixed...just by opening the door. Longer sound waves will go out of the room. Already did some meterings and it helps a lot indeed...also lossen the pressure in whole room. Not 100% fix for the problem but at least for the critical mixing moments and recording bass solution

4. Now this gonna be funny....I'll collect shoe boxes and fill them with rockwool and wood. I will cover whole left corner and the left wall with one layer of boxes (wall) and a bit more (corner). Using boxes as a puzzles will give me ability to replace each box while doing metterings and also will be easy to modify if moving to different place or just changing the furnishing smile.gif Mix of wood and rockwool will absorb some freqencies and diffuse some that couldn't be absorbed

5. I'll make a huge pnale to cover the windows only when recording.

6. In the front wall and left wall corner is a huge wardrobe. It's wooden and full of some cloths and other stuff. It probably does some good job for the low end absorbtion.


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Saoirse O'Shea
post Jun 28 2013, 01:50 PM
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Just a couple of things with the window. Sorry if I'm just repeating what's already been said...

The window will probably cause a variety of issues. You'll get broadband reflection and flutter echoes. The reflections will probably be particularly noticeable in the high frequencies. You also have sound proofing issues and you may find that there are some resonances from the glass and possibly the frame itself. What you actually get will depend on the construction of the window, the type of glass used and if its single or double glazed, etc. Without seeing it I think you'll need to put some absorption on the window Darius; even a heavy curtain woud help a lot. If you can try and position the monitors so that they don't fire back at the window. Also, if the window is parallel to the wall it faces then you should try to put some broadband absorption on the rear wall.


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Darius Wave
post Jun 28 2013, 02:37 PM
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QUOTE (tonymiro @ Jun 28 2013, 12:50 PM) *
Just a couple of things with the window. Sorry if I'm just repeating what's already been said...

The window will probably cause a variety of issues. You'll get broadband reflection and flutter echoes. The reflections will probably be particularly noticeable in the high frequencies. You also have sound proofing issues and you may find that there are some resonances from the glass and possibly the frame itself. What you actually get will depend on the construction of the window, the type of glass used and if its single or double glazed, etc. Without seeing it I think you'll need to put some absorption on the window Darius; even a heavy curtain woud help a lot. If you can try and position the monitors so that they don't fire back at the window. Also, if the window is parallel to the wall it faces then you should try to put some broadband absorption on the rear wall.



You got the point - I know about the window surface making the resonanses. Window is right behind the monitors. I'm considering to mout the curtain to the foam right above the window...so I could easily bring some daylight when do some other stuff (like cleaning the tracks or editing the video) and roll down the curtain when I make recordings or mixes. All the place around the table with monitors is filled with 5 cm high density foam to remove some high frequencies. Now I have to get rid of the reflexes from behind - that why I'm thinking of making the racks on that wall and improve them a bit for better absorbtion.

I did a separators made of 50cm foam so the monitors have no contact with the table. Also...they sit directly on the edge to avoid table reflexes.

One important thing...I usually do not work with the volume level know from regular studios so once the monitors are closer ( keeping the triangle rule ) and the twitters at my ears height...than with lower volume I think that even tiny room improvements will fix the overall working atmosphere.


I work on Adam A7 but adding a sub (not yet at this room) I also found that my Senheiser HD280
Headophones are surprisingly trust worth as for the low end so I can handle things for now. I also use traditional pc 2+1 set, Yamaha NS30 hi-fi class and logitech stereo little speakers. Each of them has different, more trust-worth range so I'm used to do corrections using them.

Worse thing as usually is the bass. From my observations veeeery many untreated rooms have the the 110 - 128 Hz resonanse most annoying. Not many regular listeners have an equipement that can produce the true volume level of 40 Hz (even if the written speakers frequency response is from 40Hz then looking at the diagram we see something like -7dB or lowre at this range) so I think for me the most efficient improvement for the room would be to remove resonance a bit above 100 Hz because it will be more noticable at most of the listeners rooms. Especially that 110 Hz is root freq for A note (A string on the bass) and it's a very blues/rock/metal key...and it's very often a na issue in the mix...




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