[Housteau]

I am considering adding about 180 square ft. to the current footprint of my dedicated listening room.  It will make my current long wall at 21.5 ft. the new short wall and add 10 feet behind my listening chair to the back wall.  This will allow me to be set up on a short wall and still have the width and space from the speakers to the side walls that I like.  The new footprint will be 21.5 X 25 ft.  The Room Mode Calculator shows this to be a good ratio and very similar to my current room at 21.5 X 15.2 ft.

For me I think the main benefits will be the added free space behind my listening position and a smoother low frequency response from changing over from a long wall to a short wall set up.  This won't be an easy project and will have to be done in stages, but if I pull the trigger and move forward passed the preliminary prep stages that I am in right now, it should be rewarding.  At least I hope it will be with all the chaos I will have to create first before making it to that point .

[JLM]

Bigger is always better (never say never and never say always).  Not familiar with 'Room Mode Calculator', but realize that while rectangles are practical (and so are also familiar) they are one of worst room/speaker shapes for acoustics that you can come up with (sphere and cubes being the worst).  Consider cutting down the shorter dimension a bit with skewed walls to reduce standing waves.

Recommend you also:

1. Sound insulate (staggered stud walls, suspended drywall using gauge metal Z channels)
2. Use an insulated fiberglass exterior door with weatherstripping (available in a variety of styles, woodgrain can be stained/painted)
3. Use lined/flexible/fiberglass ductwork (won't hear the furnace)
4. Wire the room for everything you can think of (for orientation in both directions)

Realize too that below the Schroeder (transition) frequency (guessing to be about refer to Floyd Toole's 'Sound Reproduction') in-room bass is omni-directional (versus 'rays') and best produced from multiple/separated sources.  Assuming 8 ft ceiling height and reverb time of 0.4 seconds your Schroeder frequency would go from 147 Hz to 115 Hz.

[bpape]

While skewing the walls can certainly help, not sure he wants to lose that much width. To effectively counter standing waves in the low frequencies, you would need to taper the walls 1" per foot of length per side.  So, effectively losing 50" of width in the front in a 25' long room.  Less taper will still help with reflections and some standing waves, just not in the low frequencies where we really want to deal with them.

It can certainly be done and will still leave over 17' of width in the front.  Just saying....

Bryan

[Housteau]

Thank you for your suggestions.  Here is the Room Mode Calculator http://www.bobgolds.com/Mode/RoomModes.htm It is a really nice tool to help show what is mathematically going on in rooms with parallel walls.  My room is actually part of a small separate structure that is not attached to my main house.  So, sound isolation for me is in the prevention of external sounds getting in.  My room has the door JLM suggested as well as the insulated low noise AC system and special wiring.  There are some photos in the gallery, those older and a few newer.

This room extension will be creating new square footage all behind my listening position and the walls will not be effected in my present room.  I think my current listening position will be able to move back about 2 feet from where it is now leaving 10 feet of space to the back wall.  It will be off-set just a bit at 18.5 ft. wide instead of the 21.5, but I am planning on keeping parallel walls since the space will be behind me.  My ceiling is a cathedral peak that is treated.  This is my one non-parallel surface.  However, the room extension will have a standard 8 ft. ceiling, but once again that will be behind me.  Some say that cathedral ceilings are bad for listening rooms.  I have found this to be true only if left untreated.  Once controlled I feel they can have a lot to offer.

All rooms have issues.  Even those with ideal ratios, which my current one nearly has.  But, I agree with JLM that with all other things being equal that a larger dedicated room is often better than a smaller one. 

[Big Red Machine]

I have not fully evaluated this yet, but going from a room where the back wall is 5 feet behind me to one where the back wall is 16+ feet behind me seems to make the soundstage deeper away from my listening position.  Most likely due to reflections/room constraints?  You might experience a very nice surprise in adding more depth behind you.

[Ethan Winer]

will add 10 feet behind my listening chair to the back wall.

Yes, do it!

going from a room where the back wall is 5 feet behind me to one where the back wall is 16+ feet behind me seems to make the soundstage deeper away from my listening position.

With no treatment on the rear wall behind you, increasing the distance makes those "early" reflections much later and thus less damaging. It also reduces their strength due simply to the increased distance. Even with treatment on that wall the improvement should be audible and show up in measurements.

--Ethan

[Housteau]

My room project has been moving forward with the completion of several of the preliminary steps that I needed to finish before the actual walls begin to expand.  I still have a few more of those to go.

As a part of my finished room I want to raise the floor by around 6 inches.  The current foundation is cement.  I can pour new cement over the existing floor, or build up a sub-floor using wood.  I remember reading somewhere that a wooden framed floor can act as a membrane type of bass trap.  Are there any benefits to having a framed wooden floor over a solid concrete one?

[bpape]

Just more 'feel' is about it.  Plus it would help to provide a tad more isolation. You'd be surprised how sound can flank through a concrete floor into structural walls tied to the rest of the house.  If you want the feel, you can also just use Dri-Cor http://www.homedepot.com/p/DRIcore-7-8-in-x-2-ft-x-2-ft-Aspen-Subfloor-Panel-CDGNUS750024024/202268752#.UqTh4-KneLw  that gives you a bit of feel, a place for spikes to dig into, etc. without losing as much height.

Bryan

[Housteau]

without losing as much height.

The added elevation is actually my goal.  I live in Louisiana where slab home foundations are the norm.  Although I have never had water in my home, I have always feared it as a possibility having come very close a few years ago.  My listening room is separate from my main house and when I had it built I made it 6 inches higher in elevation.  This room expansion project allows a perfect opportunity for me to raise it up another 6 inches or so.  The extra cost is worth it to me just to have a better feeling about it.  I think of it as a proactive step, a just in case sort of thing.  The room has a tall cathedral peak and so the slight loss of space will not be noticed. 

A framed floor may be my easier choice and I just wanted to be sure I wouldn't be taking steps backwards by going that way.

[MaxCast]

Would you be raising the floor with in the present walls or raising all walls on the higher floor?

[Housteau]

Would you be raising the floor with in the present walls or raising all walls on the higher floor?

The present walls will stay as they are and the floor will be raised within them.  All baseboards will be removed as will the the lower Sheetrock and insulation, then reinstalled at the newly raised level.  The floor area just inside of the one entrance door will remain at the present elevation creating a step up into the room.  If I do this as a raised wooden floor then I will build in a simple drainage system and clean-outs in the event water would get in under the new floors pressure treated framework.

I know people that have gotten water into their homes around here and just a few inches can ruin everything.  When they rebuilt I asked what did they do different and not one did anything.  They just rebuilt similar to what they had as if it would never happen again, which makes no sense to me at all.  I have been in this house for 26 years and have had the listening room for nearly 20 without any issues, but I always plan all changes and renovations as if there will be, with rising water on the top of that list.     

[Housteau]

I wanted to post an update on my progress.  In order to do what I want I needed to do a lot of preliminary work first.  All of that has been done.  These are the main things I have been working on:  For insurance purposes and changes in my policy I needed to build a new covered walkway connecting my detached listening room to the house.  The two car garage which is part of that structure is what I will be building into and so I needed to convert the 16 ft wide door over to 9 ft.  Since I will be loosing all of that storage space and a place for a car I needed to build a carport for the car and set up storage space elsewhere.  For storage I bought one of those prebuilt buildings by Derksen and tied it into my back pool deck.  It is of the style they call a lofted barn which allowed me to create a workshop and have a lot of space for storage.  That has all been done.  As you can see I have been pretty busy.

Next comes the hard part, empting out my listening room.  I want to wait until the last moment to do this.  This will not be easy and I will be without for some time once I start.  Those bass towers weigh around 300 lbs each.  I believe go time will be in about three weeks.  I have decided to go with cement as fill for my newly raised floor and the new addition.  The AC folks are designing a new system for me now and I am currently planning the new dedicated electrical service to the gear using an industrial isolation transformer.

[Housteau]

The room has been gutted, the load bearing wall removed and the cement is due be poured on Tuesday.  Following that will be the framing up of the new section, the wiring and the final finishing work.

I am also mapping out and building up new room treatments concentrating on all the room corners including the cathedral ceiling peak and other wall/ceiling junctions.  They will be much more substantial then before.   

[Housteau]

The project has been going very well and is ahead of schedule.  The cement was poured on Monday, the new walls framed and the electrical run (except the audio circuit) on Tuesday, the new AC system installation stated on Wednesday, the sheetrock hung on Thursday and they started floating the walls today.  The walls should be finished on Sunday where I can begin painting.  The isolation transformer is due in on Monday where I can finish up the dedicated audio circuit.  The tile work is set for Wednesday and the carpet the following Saturday.

I will post some photos once things begin to look more like a listening room. 

[Housteau]

Here are some early pictures as the room begins to take shape.  The carpet still needs to be installed and the only acoustic treatments I have built and mounted are the ones off of the floor in the area of what was my original room.  Once the carpet is down all the vertical corners will also be fully treated.  There are five of them.  Amazingly I have enough rigid fiberglass to do all of this repurposed from my original set up.  The front part was the original room which is pretty much the same except for being raised up 5.5 inches.  I now have a step up from the entrance.  That area has just been tiled.













These here show the new addition.  That space is approximately 10 x 17.  This will all be behind my listening position.  It is offset to the one side to allow the original garage entrance door access to the garage from the outside.  That is where the fifth vertical corner comes from.  That back area will be filled with music storage along the back wall.









This last photo was taken back in the new section looking the length of the new room.