Thanks man. nar I dont have a laptop handy.

 

besides i dont have a DSP so im limited.

28 minutes ago, genkifd said:

Thanks man. nar I dont have a laptop handy.

 

besides i dont have a DSP so im limited.

I hate the use of DSP, and even digital filters and EQ. for me REW is just to tune my room and try to make it sound better.

 

Speaking of which:

This treatment is just temporary while I wait for some quotes to have the room treatment done professionally:

These are hybrid diffuser/absorbers, I don't tend to sit this far back when listening and rather bring a chair about 1 m forward of the couch. Might have to get rid of the couch and get some other chairs.

 

 

Some panels next to the speaker, first reflection doesn't reach me on this side because of the pillar in the next photo.

 

 

 

Load bearing pole in here before you ask why I put this in my listening room

 

 

it symmetrical at least and you'll see in the measurements not the end of the world:

 

Decay

 

spikes at 200-300hz possibly a modal issue but will design treatment to try and even this out

 

 

not too bad at all. considering the windows are still not covered up!

Edited August 18, 20214 yr by Xecuter

i find that using panels that absorb / diffuse doesnt seems to be great at either. but if it works in your room i have no comments.

 

for my small room im going to use absorbers on the walls at first and then go from there. i m also trying to use as little as treatment as possible. 

 

only way i think i can adjust my system is via Jriver's equaliser. dont even know if will work.

Edited August 18, 20214 yr by genkifd

5 minutes ago, genkifd said:

i find that using panels that absorb / diffuse doesnt seems to be great at either. but if it works in your room i have no comments.

 

for my small room im going to use absorbers on the walls at first and then go from there. i m also trying to use as little as treatment as possible. 

 

only way i think i can adjust my system is via Jriver's equaliser. dont even know if will work.

 

yeh I will use straight absorbers when I do the treatment properly, this room doesn't need much absorption a part from maybe strategically for 200-300hz, and first reflection on ceiling. I'm going to be using predominately diffusion I recon.

i've used these panels before for purely absorption in another room and they were definitely better than nothing!

 

Jriver EQ does work, so does their Room DSP stuff but not my preference for correcting stuff.

 

 

i agree i would rather use the room to correct the issues but for my small room im limited what i can do.

 

cant really put thick bass traps anywhere. 

 

Ceiling probably best to put diffusers as they are generally lighter.

 

your room is looking great though.

Got the ATC sca 2 preamp. Much nicer than the rockna digital volume control. My last piece of gear I'm really chasing it the rockna wave dream NET. This streamer would let me move completely off PC for streaming.

I still would prefer to upgrade my cd-t. The cd-t in the rockna is pretty cheap and crummy but I would move all my music to local hdd on wave-net and stream to find new stuff over qobuz or something.

 

Still waiting for vector to get back to me about room treatment. I might get the GIK free room assessment and possibly see if Dennis Foley will give me an opinion but importing his diffusers would bankrupt me.

 

Hope you guys had a great week

 

Edited September 17, 20214 yr by Xecuter

I am just drooling on the ATC 150 ASLT

wow just awesome

@Xecuter - just saw this thread - lovely room build - well done!!

8 hours ago, almikel said:

@Xecuter - just saw this thread - lovely room build - well done!!

thanks mate!

Very enjoyable thread- your dedication and hard work are a gentle hobby inspiration.

and the hardwood is glorious!

Thanks David,

 

I've got a large rug in now which covers a lot of the floor but does work well to add some diffusion. I still need to add blinds and more room treatment and some other upgrades but have been very happy with the space and sound quality. I couldn't actually imagine my life without the space and spend almost every night in here!

On 08/05/2022 at 3:49 PM, Xecuter said:

I've got a large rug in now which covers a lot of the floor but does work well to add some diffusion

Hi @Xecuter, 

 

Was "diffusion" a typo or not what you meant?

 

Apologies if the rest of my post is sucking eggs, but the floor rug will have increased the room's absorption in the top end (and if you like the result, then this is obviously a good thing!), but rugs don't add diffusion...

 

Your 1st post in this thread had a picture of your dream room which has a 2D skyline diffusor and slotted diffusors on the ceiling with more slotted diffusors on the walls

You've deployed a bunch of slotted diffusors on the walls in your room

 

From a room treatment perspective, both diffusion and absorption treatments can make significant improvements to the "in room" sound, as you've discovered, but you use/deploy diffusion and absorption differently.

 

I'm very jealous of your fantastic room...

...I'm happy to continue this discussion within your thread...or leave it...

 

cheers,

Mike

Here is good,

 

Ah yes, it wasn't a typo, I always sort of thought that a rug would act more in the way of diffusing and scattering sound that would otherwise just hit the large flat area in front. But you are correct and it acts more as a absorber.

 

I do hope to do a large ceiling cloud with diffusion, I like the little block ones.

 

The vicoustic panels I have about are supposed to be both absorbing and diffusing but i think given their size and mass they would only really be effective in the upper frequencies if at all..

 

0.5 zoom makes the room look narrower than it is but gives you a good idea of the space currently.

I think next move is to cover the left window and put panels there and consider doing the cloud and trying to leave space for a motorised acoustically transparent screen?

 

Would appreciate your thoughts Mike.

 

 

 

looks great - the photo makes your room look very long.

11 hours ago, genkifd said:

looks great - the photo makes your room look very long.

Mate how did your artnovian panels go? The guys at sonic purity haven't got back to me in months about panels!

fairly easy to install and looks pretty good. best of all made a good improvement in regards to bass, soundstage and easier to hear the small details.

 

problem i found is artnovion took months to deliver the panels to the melb distributor.

On 10/05/2022 at 9:21 PM, Xecuter said:

Here is good...

...Would appreciate your thoughts Mike

I've been fascinated by diffusion for years,  but I've never actually built any, so my knowledge is purely theoretical based on research I've done rather than practical experience.

My room is very small, and one of the challenges with diffusors is they have a "minimum listening distance". If you sit closer than this you can hear "artifacts" as the diffuse sound field hasn't developed yet.

 

Of course the real reason is my lazy DIYer gene kicks in, a bit similar to my fascination with bass traps using limp mass - I've always planned to build one, but the bass in my room is "reasonably" under control, so no sawdust gets made

 

The gurus of all things diffusion are Cox and D'Antonio, the founders of RPG.

They invented the Quadratic Residue Diffusor (QRD) based on their development of a Reflection Phase Grating diffusor (hence the name of their company RPG), and named it the Schroeder Diffusor after Manfred Schroeder, one of the pioneers of Acoustic Engineering.

 

On 10/05/2022 at 9:21 PM, Xecuter said:

I like the little block ones

I do also - they're very cool 👍

They're called a Skyline based on how they look (ie a city skyline) - technically they're a finless 2D (ie diffuse in 2 dimensions - horizontally and vertically) Quadratic Residue Diffuser (QRD). Finless because the original 2D QRD designed by RPG had thin "fins" separating each well like this:

 

The 1D QRD (diffuses in only 1 direction) looks like a cutlery drawer

Each well depth is different and calculated to create a different phase shift in the reflected sound to generate a "diffuse" sound field.

Note that the 1D diffuser above has 7 wells and the 2D has 7x7 wells - this is important.

To generate actual diffusion rather than just scattering, the number of wells needs to be a prime number, in this case 7, or in diffuser speak it's called N7.

 

Many commercial designs of QRD diffusers aren't based on prime numbers, likely because RPG own the patent on the design, and the average punter would think an 8x8 QRD has to be better than a 7x7 QRD right?

 

The fins between wells improve the diffusion performance, and if DIYing a 1D QRD diffuser, it's definitely recommended to keep the fins.

For 2D QRDs, you're diffusing in both directions, so although you get improved diffusion by keeping the fins, going "finless" - ie the classic "skyline" diffuser, is a reasonable compromise to make from a complexity/cost/weight perspective - regardless of whether building your own or purchasing commercial designs.

 

Cox and D'antonio recommend a minimum listening distance of 3 x the lowest wavelength diffused for QRDs. 

 

If you want to DIY 1D or 2D Quadratic Residue Diffusers you need Collo's QRDude:

https://www.subwoofer-builder.com/qrdude.htm

IMHO QRDude is up there with other amazing free tools such as REW, Hornresp, WinISD, MultiSubOptimizer (MSO)...

...hats off to the people that develop these great tools...I'm forever in their debt...

...anyhow...even if you never build a QRD diffuser, mucking with QRDude can teach you a lot about QRD diffusers, eg lower and upper diffusion frequencies, minimum listening distance, etc

 

On 10/05/2022 at 9:21 PM, Xecuter said:

The vicoustic panels I have about are supposed to be both absorbing and diffusing but i think given their size and mass they would only really be effective in the upper frequencies if at all..

They're a different design but operate on a similar principle as the Binary Amplitude Diffsorber (BAD) panel from RPG - the combination of reflective areas and absorptive areas generates diffusion in the reflected sound field.

A random pattern of absorption/reflection is required to generate diffusion.

Just like QRDs, BAD panels can be 1D (ie diffuse in a single plane) or 2D (ie diffuse in 2 planes).

A 1D BAD panel looks like this - a random sequence of slats/gaps mounted over absorption:

 

A 2D BAD panel looks like this - a random sequence of panel/hole mounted over absorption:

 

BAD diffusers don't provide as much diffusion as QRD diffusers...the upside is because BADs don't provide as much diffusion, they don't have the same rules as QRDs from a minimum listening distance perspective.

I've been unable to find design tools for BAD panels like QRDude for QRD's.

I created this thread on BAD panel diffuser design in an attempt to quantify some design criteria...

It didn't...

 

My conclusions on BAD diffusers are:

• they provide an excellent solution for bringing treble back into your room (with the added benefit of some diffusion) if during the process of adding sufficient absorption to your room to manage the room's bass, you've absorbed too much top end - just add BAD masks over the absorption to bring treble back
• don't bother trying to determine where diffusion starts/stops when adding BAD masks over absorption - just accept that you're reflecting treble back into your room to make it "less dead", but with the bonus of some amount of diffusion added

It's very easy to add slats over absorption in a 1D BAD pattern - by far this is the easiest diffuser to DIY.

• Let's say you have multiple absorption traps 1000mm wide in your room straddling corners doing their job absorbing bass, but unfortunately soaking up too much top end
• Choose a slat width that's easily/cheaply available - let's say 50mm wide slats are readily available at reasonable cost
• 1000mm/50mm = 20 "positions" are required for the 1D BAD pattern for a single 1000mm wide corner trap
• You need a random sequence to determine slat vs gap for the BAD sequence
• I like the uniqueness of tossing a coin a 100 times or so and choosing any contiguous run of 20 coin tosses to determine the sequence - heads=slat, tails=gap
• If you prefer, select a different contiguous run of 20 coin tosses to determine the BAD sequence to overlay the other bass traps
• This will provide BAD panels with 50% absorption and 50% reflection
• if more reflection of top end is required just add slats at 90 degrees which creates a 2D BAD pattern with 25% absorption and 75% reflection

cheers

Mike

Oh man this is GOLD! I think building custom diffusers based off the measurements is the way to go.

I too don't like to DIY much and don't have the tools or space but I do have some very handy carpenter friends.

 

I'll have a look at seeing if I can do the measurements and calculations this weekend!

So let's assume you're going to build a 2D Skyline diffuser for your ceiling - as hey, what's cooler than that!

 

For a ceiling mounted 2D Skyline, you should target lighter materials - pine or MDF will be very heavy for a large diffuser.

Expanded Polystyrene (EPS) foam is used in many commercial designs - seek out the denser stuff - like 30kg/m^3.

Balsa wood could also be an option.

Ages ago I remember seeing a thread on GearSpace where they used Polyurethane, but I can't find it.

 

For a Skyline diffuser - from a lazy DIYers' perspective, you source long pieces of the material in the square profile size you want your "buildings" to be - that way you only need to cut the long pieces into the correct "building" heights...

 

Eg - here is balsa wood in 35mm x 35mm (they say 70mm long but I assume 700mm long)

Balsa 1014 Block Pack 35 x 35 x 70mm 1pc | Hobbyco

...so each "well" of the Skyline will be 35mm x 35mm...

...preferably you source material in longer lengths than this example.

 

Some random googleweb searches found these sources of EPS and polyurethane in Australia

Polystyrene (EPS) Cut to Size - The Foam Company

Polynyl Plastics | Polyurethane Products

 

If cutting EPS with a hot wire cutter - do it outside as the fumes are toxic.

For gluing or painting of EPS or urethane, take note of manufacturer guidance - some paints/glues eat EPS.

 

As a lazy DIYer, I'm happy to go overboard on the time I spend on the design of anything I build, but anything I actually build has got to work 1st time...I don't make sawdust if there's prototyping involved...

...Skyline QRDs are very well understood, and from a DIY perspective, there's only a bit more additional construction effort in building say an N23 (or higher) skyline diffuser compared to repeats of say an N7 pattern (an N23 requires more "different height" buildings than an N7).

 

That said, a modular DIY design based on N7, N11 or N13 will work fine, especially if you rotate a panel or two 90 degrees (which reduces the "periodicity" effects of multiple "same" diffuser panels).

 

It's been ages since I mucked with QRDude - but I'm happy to assist.

 

cheers

Mike

if i may suggest, choose only 1 type of diffuser so you can predict how u can control it.