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 Post subject: Urban Myths
PostPosted: Sun Feb 21, 2021 5:18 am 
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It is very hard to shake the inclination to move the speakers further into the room. But at typical distances this will create big SBIR nulls right in the musically vital region of 40-100Hz.
Try the speakers kissing the Front Wall. Try them nestled into your corner traps. Keep and open mind and be guided by Test Trumps Theory.

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 Post subject: Re: Urban Myths
PostPosted: Sun Feb 21, 2021 5:45 am 
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DanDan wrote:
It is very hard to shake the inclination to move the speakers further into the room. But at typical distances this will create big SBIR nulls right in the musically vital region of 40-100Hz.
Try the speakers kissing the Front Wall. Try them nestled into your corner traps. Keep and open mind and be guided by Test Trumps Theory.


This thread started out with the idea of soffit mounting after reviewing one of the small room designs. It would probably be the route I would take except for one issue. Right now I am using old passive monitors with some Hafler amps. I am hoping to treat myself to new monitors at some point. So my thinking was to sort out the room first. Soffits would require knowing what I am going to end up with.

So big traps in the back, wedges up front and use what I have to work out tuning the room. I had also read a suggestion that you could mount monitors into bass traps if they are sufficiently deep. Modify the layout I did above by building out the flat surface further into the room so that there is enough depth. I figure it wouldn't be too much work to incorporate into what would be a big front trap. I've got a lot of 6lb rigid I could use face the opening instead of plywood as one would for a soffit (only above and around the monitors) and also to create an enclosure inside the trap for the monitor (Hope that is clear enough description). If I improve things enough, perhaps this won't be necessary.

So treatment first and then cross those bridges when we get to them.


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 Post subject: Re: Old Studio Rehab.
PostPosted: Mon Feb 22, 2021 3:33 am 
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one consideration - is building your soffit to handle future speakers and build an (smaller...) frame inset to hold the current ones. so maybe you're using 8" and know that in the future you'll want 12" in the baffle, you could "speculate" on the options of 12" speakers and size the main framing to support that, and then build a smaller frame/box to house the current speakers. who knows? you might just keep the existing ones... i've had to do this on any number of projects, and sometimes to incorporate a second pair mounted in the same baffle system. a pair of 8's and a pair of 12' with their acoustic centers as close as possible so switching between them is fairly even, or sometimes it's because they're used to hype the mix to clients...

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 Post subject: Re: Old Studio Rehab.
PostPosted: Mon Feb 22, 2021 4:34 am 
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gullfo wrote:
one consideration - is building your soffit to handle future speakers and build an (smaller...) frame inset to hold the current ones. so maybe you're using 8" and know that in the future you'll want 12" in the baffle, you could "speculate" on the options of 12" speakers and size the main framing to support that, and then build a smaller frame/box to house the current speakers. who knows? you might just keep the existing ones... i've had to do this on any number of projects, and sometimes to incorporate a second pair mounted in the same baffle system. a pair of 8's and a pair of 12' with their acoustic centers as close as possible so switching between them is fairly even, or sometimes it's because they're used to hype the mix to clients...


Thanks Glenn,

You'll get a good laugh at what I've been using as a sort of midfield and it might help you understand why what is next is so up in the air. I've a couple smaller old KRK models. The smallest one, I actually like quite a bit. The other is a cheaper pair that have always been tubby in the bottom end. One day I hooked up a old pair of Bang & Olufsen (in the picture above) as I had just finished working out a cabinet buzz and wanted to test them. They are voiced very similarly to the KRK's I like, except tighter, better defined bass and being a 3 way, slightly better at mid. I paired these up with a Tannoy 15 inch sub I got for nothing and it has been what I use to check my mixes since I got rid of pretty much anything worth money years ago. So the newest thing I listen to is at least 20 years old. Shopping and comparing right now is a bit of a challenge and everyone is telling me a lot has changed. I have no idea what I want so will fix the room best I can with what I have, then move forward.

A bit longish story, sorry. I don't mind if I have to reconstruct the front of the room later. Given the shape of it and all the testing I've been doing, I really just ended back where I started with monitor placement. I'm only moving mix position back a bit and reducing all that desk surface. Oh, and adding 32 cubic ft of bass trapping.

I did an experiment last night where I unwrapped the 6lb density bundles I had in back of 1 inch and straddled 3 in each front corner. Even those tubby KRK sounded much better. I went out today and picked up insulation and some framing materials and will mock it all up and test again. At least for now, I feel like I am moving in the right direction.


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 Post subject: A quick update
PostPosted: Thu Mar 11, 2021 11:41 pm 
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A lot of reading later and I finally got around to the applied physics part (construction) of this project.

Back wall is simply picture framed in at a 2ft depth and loaded with batts of R38. I've covered it with light poly batting and will cover with fabric once I make some color choices.

Front wall are 2ftx2ft freestanding in the corners. These can be moved into the other room later if I decide to build the soffit. Will engage someone then to do the design.

Ceiling cloud I kept super simple. 8ftx8ft drop tile grid with light fiberglass acoustic tiles and R30 above. Grid is in place but will install last as it is still a bit of a work area and don't want to damage the delicate tiles. I didn't go full width of the room with the grid as it would be in the way of the window plug.

Still figuring out some of the challenges for the wall treatment. I have a baseboard heater to contend with along with an outside window, studio window and a door. May need pressure traps so also want to leave some space if so. I'll probably have some questions when I get there but still reading and studying this topic.

Attachment:
backcovered.jpg


Attachment:
roomfront.jpg


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 Post subject: Re: Old Studio Rehab.
PostPosted: Fri Mar 12, 2021 1:57 am 
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nice workmanship. just wondering if you testing it yet. i think i would have simple spanned the entire wall - like the opposing wall.

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 Post subject: Re: Old Studio Rehab.
PostPosted: Fri Mar 12, 2021 4:39 am 
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gullfo wrote:
nice workmanship. just wondering if you testing it yet. i think i would have simple spanned the entire wall - like the opposing wall.

First, thank you. Pretty simple carpentry.

Next a question.

I kept reading you don't want to put monitors up against treatment and want them up against the boundary wall. Was why I started my first post here about soffits. I'm clearly missing something in your suggestion. Does a full span bass trap become the new boundary?


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 Post subject: Re: Old Studio Rehab.
PostPosted: Fri Mar 12, 2021 5:27 am 
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it doesn't become a new boundary unless you add a hard surface to it, and not all speakers work well against the wall without some baffle step compensation (reduce the bass level to compensate for boundary effects). and you should have absorption there to counter reflections off your desk/console etc.

so one option - build your front wall same as opposing wall, except - place 3ft wide 3/4" thick panels behind your speakers placement. this drives a boundary effect but leaves the bulks of the wall for absorption. you could leave the corner units and simply add the additional (say 8-12") absorption between them. you could make these as standalone absorbers as well and if you find the SBIR really cannot be solved without pressing them against the wall, you can move them out to use as other absorption including gobos (nice in front of an amp or drum kit).


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 Post subject: Re: Old Studio Rehab.
PostPosted: Fri Mar 12, 2021 7:53 am 
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gullfo wrote:
it doesn't become a new boundary unless you add a hard surface to it, and not all speakers work well against the wall without some baffle step compensation (reduce the bass level to compensate for boundary effects). and you should have absorption there to counter reflections off your desk/console etc.

so one option - build your front wall same as opposing wall, except - place 3ft wide 3/4" thick panels behind your speakers placement. this drives a boundary effect but leaves the bulks of the wall for absorption. you could leave the corner units and simply add the additional (say 8-12") absorption between them. you could make these as standalone absorbers as well and if you find the SBIR really cannot be solved without pressing them against the wall, you can move them out to use as other absorption including gobos (nice in front of an amp or drum kit).


Thanks,

This all came about as a question about treating the adjacent room for recording. When the studio was built, I was mixing live recordings from when I operated my sound company. Somehow I ended up tearing apart the control room first. I need to purchase a new pair of monitors but it will be a while before I can really audition them anywhere. When I get the chance, I am hoping to hear the Neumann 3 ways. It's a bit out of my budget right now but I'm hoping my main business which is commercial AV picks up in a couple months. It is also why soffits don't make sense till I pick something. So I can certainly build more boxes to fill the front but there will still be questions unanswered but I don't need the answers today. That is the advantage of building the front modular. What make the idea so intriguing is that it would push me further into the room which is what I wanted in the first place. So build something now and then later after I have a pair of monitors I like, perhaps build soffits if I feel the need.

Note: I did run a test of both channels today with the room empty. I needed to quickly dig out a 20 year old ProTools projects for someone which will halt progress for a day or so. I also have some tests I did before I tore it all out. I just need to gather them all together. Some were done on my Mac Mini the rest on my laptop.

Interesting enough, the other room has ceilings just like the control room. So I need to build a lot of treatment as the other room is double the size. So nothing I build would go to waste. It just made sense to me to treat the control room first before doing much else. Also, it has been 20+ years and it needed paint.


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 Post subject: Re: Old Studio Rehab.
PostPosted: Sat Mar 13, 2021 4:55 am 
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gullfo wrote:
it doesn't become a new boundary unless you add a hard surface to it, and not all speakers work well against the wall without some baffle step compensation (reduce the bass level to compensate for boundary effects). and you should have absorption there to counter reflections off your desk/console etc.

so one option - build your front wall same as opposing wall, except - place 3ft wide 3/4" thick panels behind your speakers placement. this drives a boundary effect but leaves the bulks of the wall for absorption. you could leave the corner units and simply add the additional (say 8-12") absorption between them. you could make these as standalone absorbers as well and if you find the SBIR really cannot be solved without pressing them against the wall, you can move them out to use as other absorption including gobos (nice in front of an amp or drum kit).


Ok, I re-read this a couple times. I had to set up a quick edit for someone so I decided to just mock this up after I was done. I also got a chance to download your drawing and have a better look. From the screen shot, it looked somewhat flat.

So 2ft out isn't quite the right spot. Thinking of building some 16inch deep absorbers. I currently have some R38 and a ton of 703 panels so will mock this up tonight when I have a chance. The middle between the quad outlets I may leave open below with enough space behind the absorbers to vent. I have the powered sub and a small rack that I could place there which would solve another problem of where to put a couple things. The sub only gets used for casual listening and occasionally when mixing so not a critical part of the system. Above the sub and rack would match along the surface of the 16 inch traps.

I do have a question. I see you have the slats in a various width pattern. If the absorbers are built as just an open frame, does this serve any particular purpose?

Attachment:
MockUp.jpg


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 Post subject: Re: Old Studio Rehab.
PostPosted: Sat Mar 13, 2021 6:36 am 
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the slats aren't needed in the speaker positions but can add a bit if using moveable absorbers as gobos. plus it looks cool esp if you have the just off the absorber slightly and run some led lighting behind them :twisted: in my drawing i was think about 8-10" behind the speakers with the big ones on the corners. then a 4" (or so) "cloud-like" absorber on the front of the sloped wall.

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 Post subject: Re: Old Studio Rehab.
PostPosted: Sun Mar 14, 2021 3:21 am 
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gullfo wrote:
the slats aren't needed in the speaker positions but can add a bit if using moveable absorbers as gobos. plus it looks cool esp if you have the just off the absorber slightly and run some led lighting behind them :twisted: in my drawing i was think about 8-10" behind the speakers with the big ones on the corners. then a 4" (or so) "cloud-like" absorber on the front of the sloped wall.


I set up testing at various distances using OC703 and R38 and two 2'x4' 1/2" plywood. Results are kind of interesting. The room currently is the bass traps front and back and I completed the cloud last night. The side walls and angled ceilings still need to be treated.

So surely there must be some rules of best practice to follow. You mentioned 3ft wide 3/4". What do I gain vs lose with size of baffle? Is there an optimum ratio for size of monitor? 3ft x 3ft work for dual monitors (small and medium size)? Or even 2ftx4ft sideways?

Tried to enclose the REW file but it is too large. Here are a couple of screen shots while I figure out a file share service.

Attachment:
23inch-Distance.jpg


Highlighted is flush with the corner bass trap.

Attachment:
Monitor-Distances.jpg


Attachment:
16inchDistance.jpg


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 Post subject: Re: Old Studio Rehab.
PostPosted: Sun Mar 14, 2021 4:33 am 
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I find it reassuring and encouraging to fire up some old school tech now and then. A Sine Gennie..... light up a mode and listen to it's hotspots. Or Pink Noise and a Spectrum or RTA, immediately view the trouble zones.

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 Post subject: Re: Old Studio Rehab.
PostPosted: Sun Mar 14, 2021 5:16 am 
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DanDan wrote:
I find it reassuring and encouraging to fire up some old school tech now and then. A Sine Gennie..... light up a mode and listen to it's hotspots. Or Pink Noise and a Spectrum or RTA, immediately view the trouble zones.


If there is one thing I am not short on is old school test gear. Got a B&K precision audio test generator and even a couple O-Scopes. Still not sure it will answer my questions about baffle sizes and boundaries.

Glen had suggested I continue the bass trap treatment fully across the front as I had in the rear. Even was kind enough to draw it up. So I mocked it up this morning at various depths and and took measurements. Fundamentally I am trying to understand the whole idea of creating a new boundary before committing to the idea. The more I know, the better I'll be able to adapt it to new monitors.


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 Post subject: Re: Old Studio Rehab.
PostPosted: Sun Mar 14, 2021 5:38 am 
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Soffit or Flush Mounting is common in the higher echelon of studios. It completely eliminates Front Wall BIR and Speaker Cabinet Edge Diffraction. It creates an up to 6dB LF boost, which is benign, often welcome, and easily controlled by the simplest Eq. Result more and extended LF, headroom.
Downside- the modes are driven most efficiently at this pressure zone.

For less than full boundary flush, I suggest googling loudspeakers and open baffle, infinite baffle, etc. etc.

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