Hi...

[Amp_Nut]

Hi nuRoXX,

Thanks Again for your very helpful feedback.

1. Listning chair ... most likely will be a single seater sofa with fabric upholstery. Its an extra sofa in the house, so I will use it .... atleast initially.

I may move to a "Lazyboy" leather chair later. I tried and found a one with a High headrest very conmfortable, but I guessed that for listning it would be a bad choice, since it would block sound from rear reflections...

2. You adviced :

BTW, good alternative material, if you have not that ease access to professional stuff for wall panels and corner trapps are mattresses covered with any kind of cotton... advantage here, you can use any color for the covers fitting your room colors or interior

Great suggestion.

However, some of my readings on the net indicate that a Bass Trap .. to be effective cannot consist of only sound absorbant material, but should have a hard but flexible surface, like thin ply or ( I guees ? ) even very thick paper. When the Bass wave hits it, the membrane will flutter, and absorb the energy of the bass. The Flutter of the material will be damped by the sound absorbant material.

What are your thoughts / experiences on this ?

As a continuition of the same thought.... would the 4 wall sound absorbant panels / boxes that you have made ( each each 100cm x 100cm x 5cm ) be more effective if you gave a sheet of thick paper behind and immediately touching the rear of the sound proof material ?

Ditto, to wrap a thin Plywood or thick paper along with a mattress as a bass trap ?


3.The 4 Panels that you have made, each of each 100cm x 100cm x 5cm... you have given a clearence of 20 Cms from the wall ( refered to the outside surface of the panel (?).

I am planning 4 inch ( 10 cms ) panels, but plan to make these up of 5 cms thick Fibre Glass wool and a 5 cms gap.

Can you tell me the advantage of having 30% Material + 70% gap that you have used, compared to 50% material + 50$% gap that I plan to use ?

Thanks once again..

Can you please advice why you chose only 5 cms

 

[dinyaar]

I hope we are only talking dried leaves from plant genus nicotiana

YA Neo am referring to the same at least on the forum!! Wonder what all our gurus views are on NICOTINE enhancing the musical experience?

 

[nuRoXX]

Hi Amp_Nut,

yep, you are getting deeper and deeper into that theme

Regrading the listening chair, if that leather chairs you are looking for has a back- or headrest not that wide (my was about one meter) then it should not be a big problem. But for sure the sofa seat is a better choice for that purposes, even if not that comfortable

The bass traps; that what you have mentioned with a kind of plywood taking energy (resonator) is a more complex story and is used for certain frequencies. That requires a measurment of your room to find out which low frequencies creating problems / an overload and the bass traps has to be build exactly for that frequencies. Some shops offering traps of that kind for a certain range of low frequencies. Should your room has no "problems" exactly in that range bass holes might be the result.

To build in general a mix of resonator and absorber in my eyes is too "risky" as you could take away wave/bass energy where is it not necessary.

Just try the following:

A step which would improve bass modes and which should be done first before you are thinking about bass trapes is the positioning of the speakers. Experiences (not only mine) shows that putting speakers approx. 1/5 of the room lenght from the rear wall and the listening position approx. 2/5of the room lenght (I know that your position is about 2,5 feet from the wall / door but try just to see) will eliminate modes very effectively. The distances might differ -> i.e. 1/6 : 2/6, you have to play around. That should improve already modes (provided you have some which are really disturbing the overall sound).

Now, to give it a try whether and how your rooms profits from bass absorbers: Just put all kind of soft stuff you have like pillows, covers, jackets etc. into the room corners behind the speakers (try to create a little tower at least of a meter hight) and test the result. Preferably with music containing low frequencies. While music is playing, walk through the room and listen where you can locate an overload of bass and where you have the feeling that almost no bass is existing. Place on that place(s) where you have an overload also some material and check again.

A great help to locate bass modes (overloads) is a dB measuring device and a CD with low frequencies (i.e. in 5 Hz steps - from 30 to 120 Hz or so). Place that measuring device where your listening position is and play that CD. Make notes showing the frequency and the measured loudness (dB). Put that values into an spreadsheet and create a curve. Done this you can see which frequency, based on the present position of speakers and listening position, creates an overload and which falls into a hole. A theoretical optimum would be having a straight curve (to be honest, not everybody like it). Of course your speakers playing as well a big role here, depends how they are "sounded". A lot speaker having a higher mid tone and high bass level in order to sound more voluminous. If yours are sounded likewise and you like that sounding then of course this must be considered.

How I would proceed now: position your speakers as above and try to have a distance between the speakers and listening position less, respectively not greater than 3m -> this will reduce early reflections. Check regrading bass modes and maybe play around with the speakers and listening position until satisfaction. Now put all soft stuff you can find in the corners behind the speakers.

After that place wall panels behind the listening position and on the sidewalls. An easy method to find out where to put panels on the sidewalls: sit in your chair and let somebody (your friend or wife...) walk with a mirror along the sidewalls. Where you can see the speakers in the mirrow, put the panels there, if possible. Best is to have absorber mounted at the same hight as the high- and mid tone chassis.

Certainly it will improve already a lot. And now think about bass traps. Maybe just ordinary absorber / corner blocks or similar are sufficient already. If not we can go further realizing resonators you need.

Some of your questions should be answered. The remaing questions:

"...As a continuition of the same thought.... would the 4 wall sound absorbant panels / boxes that you have made ( each each 100cm x 100cm x 5cm ) be more effective if you gave a sheet of thick paper behind and immediately touching the rear of the sound proof material ?"

No, as they have been built to absorb high- and mid frequencies only, reducing reflections. They are not for low frequencies. Wall panels of this kind aborbing low frequencies must be much thicker ~ 50cm or so, depends...

"Ditto, to wrap a thin Plywood or thick paper along with a mattress as a bass trap ?"

I would not without calculating what low frequencies must be reduced respectively taking off energy.

"3.The 4 Panels that you have made, each of each 100cm x 100cm x 5cm... you have given a clearence of 20 Cms from the wall ( refered to the outside surface of the panel (?)."

Exactly. The frame's side having a deepth of 20cm. But I have two panels (each 5cm thick) in each frame and thus remaining a 10cm gap between panels and wall. Maybe I've missed mentioning it before...

Your intention having 5cm thick panels with 5cm gap is fine but better having 10cm gap (mineral- or cotton wool works more effective with a bigger gap). It should be sufficient, if not, just try with 10cm thick panels and 20cm gap.

As I have no idea about your room, above measures can be put on a minimum provided your room has normal interiors like a carpet, some sofas, curtains etc. If your floor, i.e. consiting of stone or wood/planks a carpet, in front of the speakers, would already help, not that much but some echoes/reflections would be eliminated.

Well, so far... hope some is of help. However, have fun realizing your set-up.
See ya later on this link.

Brgds
nuRoXX

edits:

A web-site with frequencies (mp3, convert to wav if required) for download (in german language).
www.hifiaktiv.at/diverses/testfrequenzen.htm

(web site and contents exclusively by David Messinger)


Depends on the frequency range of your speakers what frequencies you need but would start downloading 40 Hz and above until 200 Hz or so.

Another link detailing acoustic in small rooms for HT but of course applicable for stereo set-ups (englisch)
http://www.bilderspiele.com/de/heimkino/smallrooms.pdf

This link is showing what is meant with the 1/5 : 2/5 positioning of speakers (red dots) and the (black) listening position
http://members.chello.at/gamuerle/BlueDanube/Lautsprecher-Aufstellung2.gif

And some very basic (but useful) stuff about setting up loudspeakers
http://www.audiophysic.de/aufstellung/index_e.html
http://www.audiophysic.de/aufstellung/regeln_e.html
http://www.audiophysic.de/aufstellung/beispiel_e.html

A link for calculating resonators (Helmholtz)
http://82.95.237.142/mhsoft/Helmholtzabsorber.asp

A link for calculating diffusor (skyline diffusor)
http://82.95.237.142/mhsoft/DiffusorCalculator.html

And finally a link describing the whole story about rooms and acoustic
http://www.customaudiodesigns.co.uk/help.htm

 

[Amp_Nut]

Thanks once again, nuRoXX for answering almost all my questions, and providing extra reading info.

1. My room dimensions are : 14 feet 9 inches length x 10 feet 8 inches width x 9 feet height.

The speakers will be firing along the length of the room. The wall behind the speakers (unfortunately) has a large Glass window, 7 feet 11 inches wide, with a good sea view . I plan to have Heavy curtains while listening to music.

My plan is for 2 channel music Only - no Home Theatre, no TV in that room.

2. Thanks for the tip :

putting speakers approx. 1/5 of the room lenght from the rear wall and the listening position approx. 2/5of the room lenght (I know that your position is about 2,5 feet from the wall / door but try just to see) will eliminate modes very effectively. The distances might differ -> i.e. 1/6 : 2/6, you have to play around. That should improve already modes (provided you have some which are really disturbing the overall sound).

That would imply the speakers 5 feet from the rear wall, and the listning position only 5 feet from the speakers ?

That will sadly not work in my case.

My speakers - REVEL SALONS need the listner atleast 8 feet from the speakers for the drivers to integrate...

But ofcourse I wil try your advice.


3. Thanks for the tip on playing back test tones.

If I may, I would STRONGLY recommend the Test Tone CD ( just 3.2 MB download) from the real traps website.

I would request you to download and play this CD. It is a REVEALATION. It has test tones at 1 Hz intervals from 10 Hz to 299 Hz and plays each tone for a few seconds. It will excite your room resonances like nothing else. While I do have an SPL meter, the Test Tone CD shows up the resonances SO DRAMATICALLOY, that just listning is enough to detect Room irregularities. PLEASE TRY IT.

RealTraps - Test Tone CD

3. My intention is to use sound absorbant panels made of 2 inch thick Fibre Glass wool and have a 2 inch empty space behind the glass woll.

Do you know of any site that provides details of the ratio of Fibre wool thickness to the recommended (empty) back space ?

4. My intention is to cover ALL the walls of the room with these panels, with no wall visible at all.... except a CD Rack on one of the side walls. The CD rack will be quite large ( approx 4 feet x 4 feet, in the centre of the wall. It will also act as a diffuser, and break up the symetery of the 2 parallel side walls.

The floor is sadly Hard Granite stone, and I may cover it fully ( if necessary) with a carpet + 1 inch thick carpet backing.

As always, thanks in advance for your thoughts and suggestions.

 

[nuRoXX]

Hi Amp_Nut,

wow, you have a real man's loudspeaker. Great!

And great also in its weight Have fun moving them around for the best position

Just wondering how this speakers are doing in your relatively small room, but that's why your are doing the room tunig.

Regarding the 1/5 : 2/5 positioning, probably I was not accurate enough. Distances were meant from the corresponging rear walls. 1/5 of the room lenght in your case would be around 3 feet distance between rear side loudspeaker to their rear wall and 2/5, almost 6 feet, the distance from your chair to its rear wall. You have a distance between the speakers and the chair of about 5 feet.

Well, you've said that 8 feet distance should be given. I agree here due to the size of the speakers and arrangements of chassis.

I would keep the speakers 3 feet off the rear wall (and as a minimum 1 feet (better 2) off the side walls) and yes, as you mentioned above, the listening position remains where it is, around 2,5 feet off its rear wall.

I think the window behind the speakers is not that big problem as long you can manage to put some bass absorber without destroying the nice sea view you have. More worse if you have such a large window on the side walls.

"Do you know of any site that provides details of the ratio of Fibre wool thickness to the recommended (empty) back space ?"

I've seen one in the past, let me search for. But as I remeber fibre wool (like cotton wool) requires around 150% backspace relatively to its thickness. But less backspace would do also.

BTW, what material you will be using to cover the fibre wool? I was renovating the first floor of my house a year ago incl. renewing the fibre wool. When it was uncovered the sound atmosphere was real perfect, no echoes or reflections. When it was later covered by a kind of plywood, the effect was just gone.

"4. My intention is to cover ALL the walls of the room with these panels, with no wall visible at all.... except a CD Rack on one of the side walls. The CD rack will be quite large ( approx 4 feet x 4 feet, in the centre of the wall. It will also act as a diffuser, and break up the symetery of the 2 parallel side walls."

Really Not that your room becomes an acoustical dead hole . I would rather putting first large wall panels on the side walls and behind the listening position plus some bass absorber in the corners behind the speakers before doing the entire room. You are wasting no material as you need it anyhow in case you are going for all walls.

What if you half size the CD rack having on each side wall a kind of diffusor?

"The floor is sadly Hard Granite stone, and I may cover it fully ( if necessary) with a carpet + 1 inch thick carpet backing."

Oh yes, please do!

Well, it will be intresting how you proceed and finally how it sounds (and looks, of course).

May I ask you what amp(s) is driving the Revel speaker?

And before I forget, thank you for the link to the RealTraps Test Tone. I certainly will make use of it.

So far... just keep me/us posted here

Brgds
nuRoXX

 

[Amp_Nut]

Hi nuRoXX

Cant thank you enough for the time you have spent, educating me...

Yes, the speakers are HEAVY but here in India, most homes have Hard Floors, so the speakers can be moved around MUCH easier than if obn a carpet...

Right now the speakers play in a Much Larger room, which is my living + dining room ( approx 24 ft x 12 feet 9 feet ceiling. Walls untreated, and the speakers firing into the Smaller side of the room.

The rest of the system is :
Cadras Power Cable to the CD Player
Denon 2900 Universal Player ( Due for upgrade )
LAT-2 Single Ended interconnect ( CD to Pre )
Audio Research LS 26 Pre amp with Audio Power mains cords
Gamut Balanced Cables - Pre to Power Amp(s)
Gamut M-200 Monoblock pair( 200 Watts per channel ) with PS Audio Mains Cords.
Transparent Audio Speaker Cables


Thyanks for the detailed clarification on the distance of the speaker in the room. I have observed that rules are a good starting point, but the final placement has to be done by ear... and placement makes a HUGE difference... more than change of interconnects or other cables... ofcourse, its just 2 cents of IMHO...

About the CD rack, I wanted to break any perfect symettry in the room, hence a bigger CD rack, on 1 wall only... What do ya think ?

If I do panel the walls fully, then maybe a relatively live ceiling and floor .... ?

Thanks once again for all your help...

 

[Sumit]

Hi A-Nut!!

If you are based in Bombay then maybe you can contact an acoustic expert there. he can solve all your problems. I got all my work done from him.
I don't live in Bombay. I got all my work done through email. we exchanged quite-a-few mails before it was completely done.

He sent me CAD drawings of Trap boxes and there respective locations and I got them installed accordingly. I got all the trap boxes made locally. The difference before and after was enormous.

Let me know if you are interested. Then I shall send you his contact info.

You may check out the trap boxes of cinema on this post:

http://www.hifivision.com/my-audio-video-setup/1167-showcase-your-audio-video-setup-here-10.html

Bye the way guys- Nuroxx and Amp-Nut > Awesome equipment

Sumit

 

[nuRoXX]

Hi Amp_Nut,

always welcome...

Yes, real nice equipment you are having, the amps (mono blocks) are very fine and certainly needed to drive the speaker properly, at least when it comes to low frequencies. Yep, cool stuff

I have observed that rules are a good starting point, but the final placement has to be done by ear

I agree, a good starting point. I am also away from rules and basics if I just look at my present listening position -> nada zero with 2/5. Realizing this I would sit in a nice bass hole... but more because of the design of my room as it is not an rectangular but has some of a "L".

About the CD rack, I wanted to break any perfect symettry in the room, hence a bigger CD rack, on 1 wall only... What do ya think ?

For optical reasons, I do agree but for acoustical matters symettry, in respect of absorber and/or diffusor, is best what you can do. Just imaging that the CD rack has a great affect on one side only...

... and placement makes a HUGE difference... more than change of interconnects or other cables...

I am sorry for soundsgreat if he should read here but you are so right

If I do panel the walls fully, then maybe a relatively live ceiling and floor .... ?

Yes, probably a good idea. A certain diffuse sound should exist having not that dead and clinical sound.

Tjodi, looking forward that you are doing the right thing with your room. Will you start soon?

Mounting all these panels will certainly take a lot time and hopefully wont create that much headache on you

BTW, what music you are listening to?

Brgds
nuRoXX

 

[Amp_Nut]

Hi Sumit,

Many Thanks for your offer.

Do send me the contact details and the (approx) fee charged by the consultant.

You can pm me, if you prefer.

P.S: How large is your room ? Setup details if you dont mind ? Thanks

 

[Amp_Nut]

Hi Sumit,

Just saw your HT setup .... BEAUTIFUL !

Love the colours... refreashinly different. neat yet cosy.

CONGRATS !

 

[Amp_Nut]

nuRoXX said :

Mounting all these panels will certainly take a lot time and hopefully wont create that much headache on you

Manpower is cheap in India. Infact once the panels are made, mounting should be easy as wall paper ?

BTW, what music you are listening to?

Mainly Classic Rock, Fleetwood Mac, Floyd, Pop like Tina Turner, Lobo, Paul Anka... etc etc as well as ...

Audiophile recordinds, and a touch of Jazz, ( as an audiophile tool ... )

I tend to be less adventurous to what I listen to ... and am repeatedly drawn to the known and familiar, in each category..

 

[nuRoXX]

Hi,

Bye the way guys- Nuroxx and Amp-Nut > Awesome equipment

Thanks Sumit, have seen your HT and was impressed -> great job done

Your suggestion consulting an acoustic expert of course is the easiest and probably the most effective way.

But, to be honest, getting the knowledge how to built traps and for what frequency a trap is needed i.e. is not that difficult, just a bit math and the rest can be done by a local carpenter.

Minimizing early reflections and diffuse sound, which has a great affect on sound, can be done just by placing some wall panels...

Well, finally I did consider optimizing my room by myself as part of my hobby and had a lot fun. Ok, if somebody cannot spend time on that, yes, get the help of experts, definitively.

Brgds
nuRoXX

 

[nuRoXX]

Hi Amp_Nut,

any news from your side?

Have you asked the acoustic people Sumit suggested or have you made any progress yet?

Don't forget to keep us posted please

 

[Amp_Nut]

Hi nuRoXX & Sumit,

Thanks to Sumit, for his very prompt feedback to me regarding the specialist's contact details.

I did write to him, and he responded the next day. However, he is away for this entire wek, and I am waiting for his return.

On the other hand, I have tentatively moved away from covering All my walls with glasswool panels. Instead, I plan to cover only Half the ceiling with Glass wool ( part of the aesthetic design ).

Also, while I will probably cover the entire Back wall with Glass wool panels, only a couple of panels on the side wall.

Also one side wall, will have a fairly large CD rack... breaking the symettry... I am concerned about that....

Will probably post a drawing here tomorrow ....

Wish me luck !

 

[Sumit]

Hey Amp-Nut!!

You are welcome!!

I suggest you let the expert handle the acoustics. You can give him your suggestions also.

All the best.

 

[Sumit]

And guys...I recommend to continue the discussion under the appropriate thread. WE are still under the introduction thread.

Sumit