Modular as diffusor?

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, luketeaford, Joe.

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Modular as diffusor?

Post by snoop » Sat Feb 13, 2021 10:54 am

I’m currently trying to improve the sound in my home studio. Just finished the first wave of absorbers. Things improved a lot 🙂 bass is still a problem as you can see in the waterfal graph, but i’m tackling that next (i hope)

I was thinking of also making a diffusor. Now i have a big modular at my left side. Does this act somewhat as a diffusor? Probably it just messes with the sound being a metal surface??

Have anyone experience with diffusors in smal rooms (4 x 3 m)?
Attachments
7F21FC2C-47E4-4D91-ABC6-4B298BBA4BE9.jpeg

User avatar
MikeDB
Veteran Wiggler
Posts: 525
Joined: Fri Feb 08, 2019 8:28 am
Location: UK

Re: Modular as diffusor?

Post by MikeDB » Sat Feb 13, 2021 5:25 pm

I don't think the passive treatments you are thinking about will work in such a small room. Get a sub-woofer and a graphic equaliser (cheap) or automatic room equaliser (expensive) and find the best position for the speakers and woofer.

For a start face the speakers forward rather than inclined.

Oh and why do you have so much kit, but only a 2 octave keyboard ? :-)

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Sat Feb 13, 2021 5:59 pm

MikeDB wrote:
Sat Feb 13, 2021 5:25 pm
I don't think the passive treatments you are thinking about will work in such a small room. Get a sub-woofer and a graphic equaliser (cheap) or automatic room equaliser (expensive) and find the best position for the speakers and woofer.

For a start face the speakers forward rather than inclined.

Oh and why do you have so much kit, but only a 2 octave keyboard ? :-)

No, also heard diffusors don’t work well in small rooms.
Will try to make one to test

Yes, a sub is coming next week, exited to see/hear how
that turns out. May help. I have a big dip in 50-80 hz. But the sub will require more work with absorbers, i quess

What’s the ups in facing monitors forward? It’s my listening position

User avatar
MikeDB
Veteran Wiggler
Posts: 525
Joined: Fri Feb 08, 2019 8:28 am
Location: UK

Re: Modular as diffusor?

Post by MikeDB » Sat Feb 13, 2021 6:44 pm

If you angle the speakers towards each other then you'll get more phase cancellations and additions at various frequencies. You still will facing forward in such a small room but that's usually the best starting point. In fact sometimes you'll get a flatter response by turning one speaker off. Give it a go.

BTW what is that mixer below your desk to RHS ?

ashleym
Veteran Wiggler
Posts: 647
Joined: Thu Oct 22, 2009 3:34 pm

Re: Modular as diffusor?

Post by ashleym » Sat Feb 13, 2021 6:55 pm

Speakers will have to be angled for the sound to crossover on front of you to get phase cancellation problems. But because speakers aren’t beams of sound this cancellation will be slight and obviously only really affect the stuff that’s out of phase l-r. Not much in real life.

Have a think about the sub. If you’re having problems with bass and then you’re adding some more can you see the potential for a problem. Modulars are slightly rubbish resonators (usually a box of air with a metal “drum skin”) - note I said rubbish. This contribution might be slight. Is there room for bass traps in places like the corners or ceiling? You could try putting your speakers on those foam wedge supports (I’m not a fan but others like them and they might work with what you’ve got).

I can’t see the waterfall, is there much hanging around of the lower frequencies?

ashleym
Veteran Wiggler
Posts: 647
Joined: Thu Oct 22, 2009 3:34 pm

Re: Modular as diffusor?

Post by ashleym » Sat Feb 13, 2021 7:02 pm

Zooming in on the picture I see you’ve got quite a bit of sound absorbing stuff in already. Diffusing won’t help the bass. Those old Mackie monitors won’t be doing you too many favours- sorry. With this much treatment and the bass is still a problem I think you have some more fundamental problems

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Sun Feb 14, 2021 3:51 am

ashleym wrote:
Sat Feb 13, 2021 6:55 pm
Speakers will have to be angled for the sound to crossover on front of you to get phase cancellation problems. But because speakers aren’t beams of sound this cancellation will be slight and obviously only really affect the stuff that’s out of phase l-r. Not much in real life.

Have a think about the sub. If you’re having problems with bass and then you’re adding some more can you see the potential for a problem. Modulars are slightly rubbish resonators (usually a box of air with a metal “drum skin”) - note I said rubbish. This contribution might be slight. Is there room for bass traps in places like the corners or ceiling? You could try putting your speakers on those foam wedge supports (I’m not a fan but others like them and they might work with what you’ve got).

I can’t see the waterfall, is there much hanging around of the lower frequencies?
Yes, Sub comes with it own sets of problems, but maybe tuning it in will solve the dip, i hope. The back wall is also not treated yet. I have bass traps in front, but building the rear wall bass traps today, and also will cover that wall with 40 cm absorbers. And then i started thinking about the diffusion part... that part is difficult. Anyone that have build one? Preferable bass trap with diffusor

Yes, putting the Genelecs on isopucks, any experience
with those?

There is long decay at 40-50 + a dip at 55-85 (decay fine) Getting the Genelec sub tomorrow 😬

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Sun Feb 14, 2021 6:27 am

Corner trap!
FEA97056-2BB4-4FD3-85A5-8B176770852E.jpeg
2995AA3E-BA71-468B-A45F-1D7C0CC6EDE9.jpeg

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Sun Feb 14, 2021 6:42 am

Before any treatment
FE364F71-5D92-4220-9ADB-8CE40A862069.jpeg
After
286E244F-A7BA-472A-8ACE-5ED222DCEDBA.jpeg
Still some issues! But huge improvement

User avatar
MikeDB
Veteran Wiggler
Posts: 525
Joined: Fri Feb 08, 2019 8:28 am
Location: UK

Re: Modular as diffusor?

Post by MikeDB » Sun Feb 14, 2021 8:48 am

I think trying two things will help see where you are :

1) Try it with just one loudspeaker, and move the speaker around the room facing in various directions. This will help identify the reflective surfaces.
2) Try the speaker in a much larger room. I suspect the bass lift at 35 Hz may be a speaker rather than room resonance.

User avatar
EATyourGUITAR
has no life
Posts: 6110
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: Modular as diffusor?

Post by EATyourGUITAR » Mon Feb 15, 2021 12:10 pm

you can also try it with the measurement mic in different areas to see where the absorption is. my low tech way of doing this is crawling under the desk like a dog while running tone sweeps on a loop. I think the only way to really fix the room is to start doing some building out in specific areas which will take away from the volume of the room. measure the dimensions of the room and use a room mode calculator. it probably matches exactly what you got in the room scan. looks like energy is now reduced at 110Hz but it is increased at 48Hz. those are related. you are making new resonant chambers. it would be better to have more absorption material in those corners so that they can actually be bass traps not bass reflex cabinets.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Mon Feb 15, 2021 1:40 pm

EATyourGUITAR wrote:
Mon Feb 15, 2021 12:10 pm
you can also try it with the measurement mic in different areas to see where the absorption is. my low tech way of doing this is crawling under the desk like a dog while running tone sweeps on a loop. I think the only way to really fix the room is to start doing some building out in specific areas which will take away from the volume of the room. measure the dimensions of the room and use a room mode calculator. it probably matches exactly what you got in the room scan. looks like energy is now reduced at 110Hz but it is increased at 48Hz. those are related. you are making new resonant chambers. it would be better to have more absorption material in those corners so that they can actually be bass traps not bass reflex cabinets.

God idea. I did it yesterday but angeling the speakers + using my ears, it seems like the problems are centered at the back wall. So i will build a massive trap at the rear this weekend (40 cm). Also getting the 10 inch SUB tomorrow, so exited to see/hear what happens

amir
Common Wiggler
Posts: 201
Joined: Thu Dec 15, 2016 12:59 pm

Re: Modular as diffusor?

Post by amir » Tue Feb 16, 2021 10:39 am

bass traps at the rear wall are ok but adding absorption anywhere else on the back wall in small room scenarios ends up causing more problems. A small diffuser on the back wall would help with that dip in the highs. Sometimes fixing that issue results in the bass frequencies fixing themselves also. There is a lot of science to acoustics but sometimes just doing minor random stuff results in unexpected outcomes as well. You could try moving some furniture like bookshelves around the back wall and see what impact they have on the sound before investing in a real diffuser as well to see how it changes the sound.

Also make sure everything is secure in the room (including your racks). In the past I've seen studios where a panel is loosely attached to a wall and you suddenly place your hand on it and the entire sound in the room changes because the panel had been vibrating and creating more issues than it was solving.

Don't lay your monitors on the side like that if they are not meant to be. That causes issues as well as now you are sending signals in the wrong directions likely causing some of the phasing issues. Last note, keep the triangle equal distant listening position setup. I have never heard that turning one speaker will have any sort of acoustic benefit. It will likely cause more issues for you. I just woke up and typed that really fast, let me know if any of it doesn't make sense :)

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Tue Feb 16, 2021 1:27 pm

I added the sub (genelec 7360) and now i’m in even bigger trouble at the same frequencies 😬

I have bought a huge stack of rockwall and will try to treat
the back wall (40 cm + air gap) to see what happens. Many people recommend that, so I’ll give it a shot.So if the bass is more controlled, i’ll look into diffusors also. Looking forward to see those measurements...

i got info that Genelec 1032 can lay like that, so i think thats ok..

Is it much benefit in flush mounting the sub?

ashleym
Veteran Wiggler
Posts: 647
Joined: Thu Oct 22, 2009 3:34 pm

Re: Modular as diffusor?

Post by ashleym » Tue Feb 16, 2021 5:54 pm

snoop wrote:
Tue Feb 16, 2021 1:27 pm
I added the sub (genelec 7360) and now i’m in even bigger trouble at the same frequencies 😬



Is it much benefit in flush mounting the sub?
NO!! most of a subs output is unipolar, ie it radiates everywhere. Flush mount it and you end up with twice the energy projecting away from the mounting surface. This is why monitors are soffit mounted, to make the best use of the output, The same way you get you voice "projected" when you talk through cupped hands.

Dont say you weren't warned!!
Last edited by ashleym on Tue Feb 16, 2021 6:00 pm, edited 1 time in total.

ashleym
Veteran Wiggler
Posts: 647
Joined: Thu Oct 22, 2009 3:34 pm

Re: Modular as diffusor?

Post by ashleym » Tue Feb 16, 2021 5:59 pm

amir wrote:
Tue Feb 16, 2021 10:39 am

Don't lay your monitors on the side like that if they are not meant to be. That causes issues as well as now you are sending signals in the wrong directions likely causing some of the phasing issues.
THe tweeters have a wave guide that looks symmetrical, ie completely round. This means the tweeter won't know which way round it is in relation to cabinet position. i would be concerned that the tweeters might fire over ones head in the listening position.

ashleym
Veteran Wiggler
Posts: 647
Joined: Thu Oct 22, 2009 3:34 pm

Re: Modular as diffusor?

Post by ashleym » Tue Feb 16, 2021 6:07 pm

MikeDB wrote:
Sun Feb 14, 2021 8:48 am
I think trying two things will help see where you are :

1) Try it with just one loudspeaker, and move the speaker around the room facing in various directions. This will help identify the reflective surfaces.
2) Try the speaker in a much larger room. I suspect the bass lift at 35 Hz may be a speaker rather than room resonance.
I would think it is a room resonance. 35Hz is fairly low for this speaker. it will be 5-6 dB down and the FR chart shows things dropping off before that. However, i would be happy to be wrong!!

I would try the roll off switches on the speaker. Best to sort the problem at source rather than fixing your room.

ashleym
Veteran Wiggler
Posts: 647
Joined: Thu Oct 22, 2009 3:34 pm

Re: Modular as diffusor?

Post by ashleym » Tue Feb 16, 2021 6:12 pm

EATyourGUITAR wrote:
Mon Feb 15, 2021 12:10 pm
you can also try it with the measurement mic in different areas to see where the absorption is. my low tech way of doing this is crawling under the desk like a dog while running tone sweeps on a loop.
A great technique. One I used a lot installing AV systems but mainly for where to install the subs people wanted. i can still hear a big old bass boom walking downstairs into my living room. is the listening position in this room in the middle of it? This applies floor to ceiling as much as distance from the walls.

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Wed Feb 17, 2021 2:44 am

ashleym wrote:
Tue Feb 16, 2021 5:54 pm
snoop wrote:
Tue Feb 16, 2021 1:27 pm
I added the sub (genelec 7360) and now i’m in even bigger trouble at the same frequencies 😬



Is it much benefit in flush mounting the sub?
NO!! most of a subs output is unipolar, ie it radiates everywhere. Flush mount it and you end up with twice the energy projecting away from the mounting surface. This is why monitors are soffit mounted, to make the best use of the output, The same way you get you voice "projected" when you talk through cupped hands.

Dont say you weren't warned!!
Ok 😀

Could not sleep last night, was only thinking about building a bigger room... no, I’ll
try my best to sort this out, getting as close to «flat» as i can. I’ll post the new measurements
after the back wall is treated + finding the optimal spot. This is at least interesting, but hard. 20 db dips is no fun

The beast
C3021ED9-5B8C-4D90-BDBD-B0E002F14EAE.jpeg

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Fri Feb 19, 2021 2:52 am

Building my monster bass trapp this weekend. In my quest for building the perfect one, i came over this:
91A3AC32-13D9-431B-B136-791413744737.png
Will this work 😀

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Sun Feb 21, 2021 3:36 pm

So the monster trap is finished, i should probably covered the whole wall, but...

this is just the Shell. I will build a diffusor around it
that hopefully will spread some waves and reduce
the cancelations at 60-80 hz. Don’t know if this
works??
E8FEFC59-3C75-4BBF-8B97-5D3BA90A7115.jpeg
Things did improve, but of course not as much as
i hoped.
78F30047-5937-41A1-BD7E-FCAF43E91FE3.jpeg
Still a dip at 60-80 and a peak at 45 (room mode?).
There are no celling absorbers at the back. Maybe that
is an idea?

ashleym
Veteran Wiggler
Posts: 647
Joined: Thu Oct 22, 2009 3:34 pm

Re: Modular as diffusor?

Post by ashleym » Mon Feb 22, 2021 4:45 pm

It looks like things are getting better. Well done!

Try to take the FR peaks and troughs out of your mind and have a listen. How does it sound with some your favourite music? Are you making music for fun/pro/semi-pro? how much do you need to get the FR 100% flat? How much has it got to be a room you are happy with? (focus on whatever you want, there will be a balance of making music to getting the room completely right).

Is there any problem with eves room ? (looking at the smaller door in the picture with the Moog) Some of these problems can be solved with a bit of weight, it takes more energy to get things resonating, and sealing the door edges to lessen the movement or the door and air.

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Tue Feb 23, 2021 2:40 am

Made a huge improvement today by moving the sub and changing the settings on the main monitors. Even more than the treatment of the room
Each line is 5 DB.
60A825E2-F2D3-4FCF-A63C-54A3F5F71F5F.jpeg
Starting to look good.

But a very strange sub placement 😀
C67B4E34-BF1D-4D95-8D30-CA1C8FD41B2D.jpeg
But it works. The sub is now facing the monster trap. Think i have to try adjusting the phase on the sub as it’s now moved quite a bit.

Still have a dip (now at 90) i need to sort out, but the nasty room mode is gone. I now also have some mid that are too high.

As you point out, the little door made an impact. I had to cover it with 2 x traps!

I think improving from here will be very difficult and time consuming, but i’ll try

Crossover for sub is 80, and as you can see in the waterfall the sub waves last long, don’t know if i can do something about that without the studio ending up very cluttered?
BB68A154-5FB9-403B-8969-D207EBBEB4E4.jpeg
The room is 3,5 x 2,74 x 2,4 (height). Will diffusion help me further improve things?

User avatar
listentoaheartbeat
Super Deluxe Wiggler
Posts: 2633
Joined: Sun Mar 30, 2014 7:42 am
Location: Berlin

Re: Modular as diffusor?

Post by listentoaheartbeat » Tue Feb 23, 2021 2:57 am

At this point you can also consider using digital filters to even out the room response in the sweet spot. Automatic solutions like Sonarworks and ARC have gotten pretty good in recent years and remove the pitfalls of DIY acoustic measurements. I am successfully using Sonarworks in my treated studio. I avoid the FIR filter setting due to noticeable ringing when listening to percussive sounds in isolation, but the minimum phase setting works well for me. I think both products have trial versions so you can try before buying. You can use any measurement microphone if you have the calibration file.

User avatar
snoop
Wiggling with Experience
Posts: 455
Joined: Sat Nov 21, 2009 10:43 am
Location: Oslo, Norway

Re: Modular as diffusor?

Post by snoop » Tue Feb 23, 2021 3:15 am

listentoaheartbeat wrote:
Tue Feb 23, 2021 2:57 am
At this point you can also consider using digital filters to even out the room response in the sweet spot. Automatic solutions like Sonarworks and ARC have gotten pretty good in recent years and remove the pitfalls of DIY acoustic measurements. I am successfully using Sonarworks in my treated studio. I avoid the FIR filter setting due to noticeable ringing when listening to percussive sounds in isolation, but the minimum phase setting works well for me. I think both products have trial versions so you can try before buying. You can use any measurement microphone if you have the calibration file.
Yes, i think i have to use that as the final touch, when everything else is tried. But it will not work on dips in the frequency? Only peaks? If it’s a cancelation, no filters will help with this?

If you have time, please tell more about how the filters hjelped you?

So you mix with filters on the master, then when bouncing you bypass it?

Post Reply

Return to “Music Tech DIY”