between the speakers and on the wall !!

Hi MPW,

As always heuristics rules. If you want to pay for my flights I volunteer to stand between the speakers and hold up the rug while you do some listening tests!

I suspect you'll have someone closer to home.

M

Yesterday I was in the weekend apartment my in-laws own in a lake area, and had to build an Ikea Hemnes shoe cabinet to put in a short corridor where there's nothing. When I finished assembling the main frame, even without the drawers, I took it to the corridor and placed it against the wall to check the effect.

The corridor is short, has 4 doors and an opening on a sideways small entrance, has a tiled floor and almost bare walls; it resonates audibly. As soon as I placed the shoe cabinet, the resonance immediately diminished, the 'sound' of the space became more normal, all got better. It was enough to place the wooden irregular structure against the wall to scatter and diffract the waves, with an immediate benefit.

Hope it helps.

M. 

Massimo Bertola posted:

Yesterday I was in the weekend apartment my in-laws own in a lake area, and had to build an Ikea Hemnes shoe cabinet to put in a short corridor where there's nothing. When I finished assembling the main frame, even without the drawers, I took it to the corridor and placed it against the wall to check the effect.

The corridor is short, has 4 doors and an opening on a sideways small entrance, has a tiled floor and almost bare walls; it resonates audibly. As soon as I placed the shoe cabinet, the resonance immediately diminished, the 'sound' of the space became more normal, all got better. It was enough to place the wooden irregular structure against the wall to scatter and diffract the waves, with an immediate benefit.

Hope it helps.

M. 

If you look up Quadratic Residue Diffuser, or QRD, online you will find many fancier versions of your shoe cabinet, and the maths behind them. Widely used in studios I believe, often on rear walls and ceilings, for diffusion - both in control rooms and recording spaces.  Can be very badly approximated to by taking a bookcase and mixing up small and big books.

thanks very much - the QRD  is interesting but i understand there is a science behind it and to get something readymade is not likely whilst getting something custom - made will be costly.

A book shelf is a nice idea but that would mean that i shift my wooden rack to one side.. which may not be so visually appealing..

would appreciate if you could pics of your setups with whats in-between the speakers..

regards

Hi MPW,

A QRD is still a possibility if you have some spare time, there are a number of DIY recipes on the net, and construction is very simple.

It mainly needs a saw that you can use to cut a lot of straight lines (typically about 18 or 30 as I recall) , and somewhere between about a hundred and about four hundred little wooden blocks.  Then you just glue them together and paint them.  It's definitely the right thing to put between speakers.

While you're about it have you considered whether you'd benefit from bass traps for the corners of the room?  (With the Merlins, this depends on the room dimensions.)

Huge,

thanks

In my room, there is 1 corner - other sides are open

I do have plenty of time and there will be quite some carpentry going on ( sofas and chairs ) and i might slip a corner bass trap & QRD in as well 

There are some calculations involved in the length, width and depth and placement of the wooden blocks... a trying to get a rough idea of these things..

regards

mpw posted:

would appreciate if you could pics of your setups with whats in-between the speakers..

Here:

that was when I still had a system.

Best

Max

mpw posted:

thanks very much - the QRD  is interesting but i understand there is a science behind it and to get something readymade is not likely whilst getting something custom - made will be costly.

A book shelf is a nice idea but that would mean that i shift my wooden rack to one side.. which may not be so visually appealing..

would appreciate if you could pics of your setups with whats in-between the speakers..

regards

 

 

Just have a look in the System Pics thread.

mpw posted:

Huge,

thanks

In my room, there is 1 corner - other sides are open

 

...

Doesn't that get drafty?  How do you keep the heat in in the winter? 

You only need bass traps in relatively small enclosed spaces - if the minimum dimension is more than 10m then they won't achieve anything useful.

HH

My request for photos were specific to the QRD's ( or its versions used ) and i thought it would be more focused and gainful for the thread readers and myself.

thanks

huge

let me try and attach a pic of my system as it was before it i dismantled it. Maybe you and fellow readers will get a better idea.

From the seating position - the speakers are about 17 ft away and from the seated potition, the only corner is the ceiling left hand corner at about 10 ft height. The main left stereo speaker distance from the side curtain is about 2.5 meters

The right side ( from the seating position ) is completely open )

regards

system pics 2015 - page 22 is my system

mpw posted:

HH

My request for photos were specific to the QRD's ( or its versions used ) and i thought it would be more focused and gainful for the thread readers and myself.

thanks

Ah, ok, that wasn't clear. 

Looking at your photo, I would have thought a sub, sandwiched that close between rack and speakers, might cause problems, especially as your rack doesn't look like it has any form of isolation, spiked feet etc. Mine lives behind the sofa, well out of the way, although this does make cable runs more difficult. Maybe your refurb plans allow for this?

hi chris

surprisingly - i encounter no problems with the subwoofer ( sealed type ) and i make sure the cross over and amplitude are set to match the main stereo speakers. 

What you suggest could be a possibility but i prefer the subwoofer up front - i think it looks better too. Besides i take hi-level signals from the rear speaker posts of the NaimNait 5i-2 and i prefer the signal travel distance to be as short as possible.

The rack is a teak wood rack and i havent tried any isolation etc... as i havent felt the need for any ( not even under my turntable )

please post a pic of your setup

regards

ChrisSU posted:

Looking at your photo, I would have thought a sub, sandwiched that close between rack and speakers, might cause problems, especially as your rack doesn't look like it has any form of isolation, spiked feet etc. Mine lives behind the sofa, well out of the way, although this does make cable runs more difficult. Maybe your refurb plans allow for this?

When I ran a sub, I found that (in spite of advice) it sounded wonky (asymmetric, un-integrated and phasey) if it wasn't in between the speakers. The TT sitting there looks sub-optimal, though. That's what I'd look to move.

HI winky

My room is quite large as you will see from the photo posted and i made the sub to cover the lower frequencies which my Merlin TSM does not. It was an experiment and this is a semi- DiY effort ( with Hypex DS4 plate amp + Dayton RS series 10 inch bass driver )

I get good results with the sub and i find that much depends on the ideal placement. Whilst i dont claim the sub is ideally located now but its an acceptable compromise for me.

The TT will remaim there on the rack but i may experiment with further isolation for it.

I am very pleased with the sound i get and any hardware change will be only doe to boredom ( and to try something new ) and nothing else.

With the proposed removal of the TV and addition of some form of QRD ( QRD / bookshelf / thick rug ) - i have a feeling the sound will get even better and thats why this thread - i am looking for ideas for QRD ( looks good sounds good costs less and i am not interested in perfection - even if it does 85% of the job - i am good )

regards

mpw posted:

thanks very much - the QRD  is interesting but i understand there is a science behind it and to get something readymade is not likely whilst getting something custom - made will be costly.

A book shelf is a nice idea but that would mean that i shift my wooden rack to one side.. which may not be so visually appealing..

would appreciate if you could pics of your setups with whats in-between the speakers..

regards

 

 

In my experience, the effects of proper aftermarket diffusers are much more significant or tangible than racks filled with books/records/CDs. I have tried using racks filled with CDs and books and they don't do much to the sound. On the other hand, with the RPG wood diffusers, the effects are very much appreciable. Even by shifting the panels in small increments relative to speaker placement, the sound will change accordingly.

This is a photo showing the placement of diffusers in my system. They are on the front wall between the speakers.

ryder

thank you for your reply.

what was the selection criteria for the diffusr ? did the RPG guys take some measurements ? 

regards

mpw posted:

ryder

thank you for your reply.

what was the selection criteria for the diffusr ? did the RPG guys take some measurements ? 

regards

 

 

No problem MPW. No particular criteria when I chose the RPG Omnifussors. I just wanted to try them out and it's on a trial and error basis. I shipped them, no measurements taken. Apart from the Omnifussors, I tried RPG Skylines as well but preferred the effects of the Omnifussors more than the Skylines. Got them about 7 or 8 years ago.

Changes or improvements with these panels include a more organic, live and 3-D like presentation with the elimination of certain hardness in the sound.

I had experimented a lot with room treatment panels several years ago when the system was in a dedicated room. I (always) prefer diffusion over absorption when tackling the mid and high frequencies although a combination of both will usually yield good results.

mpw posted:

Hi,

I will be without music now for about 5 to 6 months - my home  us under renovation and for the moment i am trying to make do with a pair of Audioengine A2's till i put back my main rig.

My system is a CD5XS + Naim Nait 5i-2 + Merlin TSM ( this is all wrapped up now temporarily )

This time i plan to shift the 46 inch TV between the speakers ( on the wall ) to a different location altogether and i wanted to know if :-

a. I could leave the wall between the speakers bare

b. hand up a thick rug or a painting ??

Having an LP rack or book shelf is unlikely  due to dust & accessibility reasons

Open to suggestions which would improve aesthetics, sound and not be too expensive as well.

regards

mpw

Mumbai

Between option a and b, I suppose you would do fine with either one. You might or might not obtain an appreciable change in sound by hanging a rug or painting on the front wall. If there is a change in sound, I would expect it to be minor. A bare wall would be fine if the system sounds good as it is, with the bare wall. If you intend to place a canvas painting or nice (thick) rug on the wall for aesthetics reasons with a small boost in sound quality, it might be a worthwhile attempt though. A nice painting will definitely look much better than the unsightly looks of aftermarket treatment panels. Much higher WAF.

Thanks ryder..

There are QRD's available here ( 2 ft by 4 ft size ) for about 550 USD - but they say the operating frequencies are 300 Hz to 14Khz.

I dont now how to digest this information - if i believe it or not 

Let me ask them if they would allow a home trial for me to feel the difference.

One other option for me is to get my carpenter on the job - there will be carpentry work anyway but i will have to look for the science behind this - the overall dimensions, the dimensions of the slots / blocks, the spacing.. etc..

Hope to find something on google / youtube..

regards

MPW

http://downloads.bbc.co.uk/rd/.../reports/1990-15.pdf

But for use on walls mostly only 1D diffusion is required

http://arqen.com/sound-diffusers/  (Arquen are a commercial acoustics company, so a direct link is contrary to AUP, but this is a free design for DIY use)

Huge thanks ! 

Hi MPW,

I'd be interested to know how you get on if you do buy or build a diffuser.
I do appreciate it may be a little time before serious music starts to happen again though!