# New Mancave Acoustics Help



## jstrouth (Aug 19, 2010)

Drawing of the mancave design below to be built in the spring.
Super chunks are in the corners. Broadband base traps designed into the walls at the early reflection points on side walls, ceiling, and behind speakers. Diffusion might be a good option behind speakers? as well as rear wall?
Anything else I can integrate into the design/ construction? ... but not be overkill?

Especially since I also will use REW to help fine tune the room. Thanks!

View attachment 25873


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## SierraMikeBravo (Jul 1, 2007)

Hi jstrouth,

Is that supposed to be an open area on the ceiling to allow sound in? Also, is this a single man's "man cave"?


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## jstrouth (Aug 19, 2010)

the open space in the ceiling is simply a bass trap. it could be boarded on the 'top' to be closed in or open to the roof truss space... that would be a question....which is better.
not a single man's man cave, but solely for that purpose. the wife wants all the equip and 'noise' out of the main house.


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## SierraMikeBravo (Jul 1, 2007)

Hi js

IMHO, I would not have an opening. Low freqs are going to pass right through your sheet rock, but the benefit of the sheet rock is that it is one more barrier for those freqs to have to pass through...attenuating the amplitude even further. Having pink stuff in the spacing will also help significantly. Plus, the flexure of the sheet rock will help to attenuate the bass freqs even further...making for a more effective bass trap. So, the moral is, drywall is a very good thing, and since the room is covered with it, the entire room itself makes for a pretty good bass trap. Hope that helps! :bigsmile:


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## jstrouth (Aug 19, 2010)

thanks Shawn.
Yes, the idea was to put 4" 503 in the cavity that is 6" deep, and make the front flush with the wall/ceiling. My understanding is that the airspace behind the fiberglass - in front of the sheetrock as you recommend - helps lower the effective frequency.

Do you think that the super chunks in the corner and integrated traps in the ceiling/wall first reflection points are enough? I don't want to over do it....but I'd like to integrate as much into the construction as I possible. 

I'm also thinking diffusion on the rear wall, but don't have lots of $$$ for it. I've seen several less expensive kinds. The ABB1,2,3 types are the cheapest, but are not QRD and I don't really know how well they work. GIK has some less expensive ones that are quasi QRD. RPG Diffracter would be nice, but not in the budget. I've considered the DIY Skyline type, but don't know if that's the way I want to go or not....heavy and lots of work...plus I'm thinking I'd like a fairly low effective frequency, which means deeper. Any thoughts?

Finally, any thoughts on IB subs? For two channel? and how to successfully integrate into the rest of the system? Goal is accuracy not thump.
Thanks!


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## SierraMikeBravo (Jul 1, 2007)

Hi js,

Yep, a few thoughts. I would be a little careful to some degree that with that 6" spacing and using dense fiberglass, that you may not creating a mold situation. Check you local code first before putting this in the rafters. They may require a different kind and installation. 

Regarding diffusors, absorbers and what not. I prefer NOT using straight broadband absorption on the sides. Your soundstage will collapse IMHO, and you'll get a very narrow sounding room. Sure, it'll help with the problems associated with the reflected mid frequencies, but it'll sound...well not to my liking. Treatment is just as much about shaping the sound as addressing the scientific issues. I prefer some combination of diffusion and absorption at the first reflection points. Center and opposing angle reflections are dealt with differently. Same goes with the rear. You want the diffuse field in the rear, but you also need to address the lower freqency reflections bouncing back at you from behind associated with the LCR. 

Bass traps, well, a whole other topic, but they do work, but I would never, ever sacrifice front speaker seperation just to get some more triangle traps in. The seperation of L/R speakers is absolutely paramount to getting a good sounding system, and no amount of triangle traps will make up for this issue. Hope this helped!


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## jstrouth (Aug 19, 2010)

Shawn, thanks.
Good point about the ceiling, but attic insul will still be above that space, so I think it'll be ok.
Your side wall absorption thoughts...this is a 2 channel room. do you still feel that way? you're advice is pretty much contrary to everything else I've read.... not sure I get it. can you elaborate?


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## SierraMikeBravo (Jul 1, 2007)

Yep, even for 2 channel. Think about this for second, what is surround sound but nothing more than an enhancement on two channel stereo? The additional channels are placed in their locations to aid in human inabilities with multiple people in a room. So, it doesn't change much for 2 channels except now we are likely only dealing with a single person. Now, we have to address whether that person is sitting in the nearfield or not. That will determine treatment strategies. Regarding the side reflections, if you sit in the farfield, take some strait up fiberglass and stick it up at these points, then take it down and listen to the bare wall. Now, don't just listen to the sound, listen for the stage width. Then tell yourself which you prefer; a wide encompassing stage, or a narrow stage with little going on along the sides. If you like the wider sound stage, you'll still have to deal with the scientific issues of stuff bouncing back at you that you don't want, but we don't want to kill the frequencies that add to our envelopment and sound stage width. There are some great new products out there that do just that. Those are what you should look at provided you are not in the nearfield which is treated differently. Hope this helped!


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## jstrouth (Aug 19, 2010)

so you would suggest diffusion as a better option for first reflection points? side walls also? what kind, since i understand angle of incidence is a factor.

my position is around 9' or so from the speakers.

also, in my current room, I'm experiencing a substantial drop off in high frequencies - about 15 db, although the speakers measure pretty flat up close (using REW and calibrated mic). i don't understand that drop.... or what i can do to help it out.


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## SierraMikeBravo (Jul 1, 2007)

Not sure what is going on in your room. Would have to see it. High freqs are very easy to kill. No, not just diffusion but BOTH diffusion and absorption in the same product. There are several companies making just this sort of device; ex. RPG and Quest AI to name two.


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## jstrouth (Aug 19, 2010)

Here's what the current room looks like. System is in the 'L' of the condo main space.
The right speaker is next to a large closet with bifold doors, the left is next to a glass slider with vertical blinds.
the system part of the room is 8' ceiling and carpeted, the rest of the area is cathedral ceiling and hardwood floors.
not an ideal space, I know...that's why I'm building the mancave...but that'll be completed a year from now.....
thanks!


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