[cporada]

Hi everyone
We are currently considering the idea of finishing off our third-car garage and I am wondering if it might be suitable as a more-or-less dedicated listening room.  Since it’s the “garage”, acoustic treatments would be simpler than in our family room, which is where my current set up “lives”.  The room is 222” long, 146” wide, and has an 11’ ceiling throughout.  Would this be a suitable listening room for the ACI Alpha Limited with the right treatments, or would this be too small for them to really "sing"?  If it is acceptable, would using the Cardas Golden Ratio for speaker placement be OK, at least as a starting point?
Thanks so much
Chris

[JLM]

OK, what's an ACI Alpha?

The Cardias site shows an ideal room is a "Golden Trapagon":

http://www.cardas.com/content.php?area=insights&content_id=36&pagestring=Room+Setup+10

Doesn't look like your room is wide enough (to keep 8 foot ceilings) by his formulas, but don't sweat the exact numbers.  Just having a dedicated room is huge.  (Listen when you want, to what you want, and at what volume you want.)

The Cardias ideal speaker (nearfield) setup is found here:

http://www.cardas.com/content.php?area=insights&content_id=26&pagestring=Room+Setup

IME nearfield only works with small monitors.  Spreading the midrange/treble drivers out quickly loses coherency.  I have a dedicated room following the Cardias "Golden Cuboid" and recommended nearfield setup with single driver speakers and love it.  First timers are blown away when they hear "real stereo" for the first time.  I'm sure you'll be pleased.

I'd use 5/8 drywall, insulated/flexible ductwork, and dedicated audio circuit.  If there is living space above, suspend a ceiling or use Green Glue with a 2nd layer of drywall.

[cporada]

Hi JLM
Thanks for the helpful response.  ACI Alpha limiteds were a DIY kit offered by ACI/Dzurko Acoustics back in 1995 or so.  They are pictured next to my name on each of my posts.  Each speaker consists of two AC5 mids, two AC10 woofers, and a Vifa H26TG-35-06 tweeter for a sensitivity of around 93db.  My concern is that these move a pretty good amount of air and I though it possible they may overload a room that size, but I don't know enough to ascertain whether this is a reasonable concern or not.  It's been suggested that I slope the ceiling from 8 feet over the speakers to the full 11 feet at the back of the room, which I guess sounds reasonable but, again, I don;t know enough about these things to make a sensible decision without advice.
Thanks so much again
Chris

[JLM]

Chris,

The Cardias "Golden Trapagon" does slope ceiling and side walls, but I'd imagine that such a room looks quite weird and dis-orienting.  The primary advantage of a rectangular room is that its a known situation (and that it's not a cube or sphere which would have standing waves like crazy).

The Cardias "secret" (that is accepted by many) is in the ratio of room dimensions, that aren't even ratios to each other, so as to avoid echos happening say up/down and left/right at the same time.  With your restrictions I'd just use an 8 foot ceiling height with the full width/length.

Getting the "right" room size/shape is the primary step in acheiving proper room response.  Second is speaker/listener layout (which you can play with all day in a dedicated room, so that's taken care of).  Third is room treatments.  In my room (about the size your's will be) with the Cardias prescribed layout and single driver speakers that beam over 4,000 Hz room treatments don't do much.  But I do have a very nearly ideal setup for minimizing any remaining room interaction to start with.  Fourth is tweaking with equalization.  Keep in mind that EQ should only be used as the last step, its a band-aid, not the surgery itself.

Those are some pretty meaty speakers for a room this size.  Four 10 inch woofers should be able to load up that room very nicely.  Frankly this is where going the typical ACI route, with separate powered subs really shine where you buy enough sub for the room/material/taste and adjust levels independent of the main speakers.  But there is free software (if you're running computer based audio) that can do the same (you'll need a microphone to use it).  Or add a equalizer, like a Behringer DEQ 2496 ($400 with mike).  This will tweak the room, and ensure that those woofers aren't overloading the room.

[bpape]

Your room will be fine.  You can try the Cardas setup if you want or you can set it up more normally.  The room is large enough to allow a variety of good options.  The big benefits are plenty of length and a nice high ceiling.  I'd kill for an 11' ceiling

Bryan

[Joe_K]

I'd use 5/8 drywall, insulated/flexible ductwork, and dedicated audio circuit.  If there is living space above, suspend a ceiling or use Green Glue with a 2nd layer of drywall.

I'm wondering why flexible ductwork is recommended so often? I may know the answer, but would like to know others thoughts/comments on this.

Thanks,
Joe

[bpape]

Flex duct will not transmit sound into or out of the room as effectively as typical tin ductwork.  At mid to high frequencies, it almost amplifies it.  At lower frequencies, if poorly put together, it can rattle and buzz like crazy.

Bryan

[Joe_K]

Thanks Bryan,

Makes sense, not to mention some energy savings of non-metallic ductwork.
Is there any relatively easy fixes for metal ductwork that rattles when the floor is stomped on? Or someone walks heavy on it?

Thanks,
Joe

[bpape]

If you can get at it, you can damp it with a variety of materials.  How best to deal with it really depends on WHY it's rattling.  Is it just the flexing of the individual sides?  Is it loose with regards to the brackets holding it?  If it's just flexing, it can be as simple as tying a rope tightly around it to keep it in a tensioned state.  If it's the brackets, try some weatherstripping  between the brackets and the duct itself.

Bryan