I've been admiring your site and your generous engagement with the community over a few months.

Now I'm interested in replacing my very inefficient Thiel CS3.6 speakers with a pair of your Pi Fours or Pi Sevens (and moving to smaller amps - possibly Bottlehead Paramour II eventually, but my Music Reference RM 9 initially). My living room is populated with built-in bookcases and a grand piano, as well as couch etc.

It seems from other posts that the Pi Fours are more flexible with respect to room location, but that the sevens will yield better sound if they can be made to work in my room. Am I right in that conclusion? Or is the seven mostly about increased efficiency?

My dilemma stems from the fact that my only available corners currently have built-in bookcases on one side each, and a baby grand piano arranged between those two corners with seating opposite. Is it reasonable for one side of the horn to be up against the bookcases, or would I need to build a mini-wall to complete the horn loading? If so, how big? This placement would put the horns back with the piano sort of sticking out between. The wall is about 15' wide (the speaker wall) and about 18' deep. Ceilings are high - about 10-15 feet (sloping).

Or should I just stick with the Pi Fours and give myself more choices?

Thanks for your help,

tim

The cornerhorn arrangement is about sound quality as much as about efficiency. By placing a horn into a corner, sound radiates into eight-space. This increases the effective mouth area of the horn and smoothes its response. It also increases SPL by focusing the sound in a smaller area, and enforces a 90° radiating angle, set by the walls. When all horns (bass, midrange and treble) have the same 90° dispersion angle, the sound field is uniform through the room. You can walk anywhere in the room and hear the same tonal balance, not just in the "sweet spot." Since sounds are reflected within the room, off-axis tonal balance is important, making a uniform reverberent field. So the cornerhorn arrangement improves quality of sound by providing a better acoustic load for the horns and by generating a uniform reverberent field, in addition to increasing efficiency, dynamic range and SPL.

With the more uniform sound field should I expect more or less "imaging" than I would have with a more traditional out-in-the-room arrangement?

Next question: It seems that all the 7 Pi speakers are identical except for the woofer - is this right? If so, are the sound quality differences between them relatively smaller than between the two-ways where the woofer is crossed over higher? I'm trying to think through the economic tradeoff... I like to listen at moderate levels with headroom for the climaxes, but I'm not often looking for the levels of SPL your systems seem capable of.

Finally, could you send me a copy of the 7 pi plans, please?

I appreciate your help,

tim

Imaging is such a subjective term. It is also affected by music source as much or more than any other thing. But one thing can be said for sure of constant directivity speakers, the imaging is more uniform across the listening field. You don't have to be exactly in one spot for things to "click in" like speakers with non-uniform directivity. Imaging is great over a larger listening area.

I think I can make this work after preliminary discussions with my very tolerant wife. (Her suggestion was to mount them upside down at ceiling level - probably won't happen!

The good news is that the Thiels are already huge and sit out in the room taking up space - even the not-insignificant sevens will be less obtrusive.

I'll scan the forum for construction tips and pictures.

tim

• Cabinet bracing and other exciting information
  
• Rubber Ball Brace

I'm working on layout on 4x8 sheets of 3/4" birch ply...It looks as though I can get one bass horn onto a single sheet and the whole project I'm hoping will fit onto three with mitered joints for the cabinets.

I've ordered an EZ Smart cutting system to help with the construction for this and other woodworking projects. My last furniture project was done on the table saw and I don't want to wrestle with full size sheets that way again!

That does raise another point - the birch ply sold by Home Depot does seem to have some voids. They are never more than a single layer thick, and seem to be relatively small - a few inches long. Is this a big problem? The more expensive alternative is 5x5 baltic birch which I believe is void free.

I haven't yet found any photos of π sevens, so if you can point me to any I'd be grateful.

Thanks again,

tim

seven π cornerhorn

The ply I've been using has a lot more than 5 layers - but it's not completely void free, so I'll look for the better quality.

At Southern Lumber this morning they offered me 4'x8'x3/4" Baltic Birch ply for $220 a sheet! But it's clearly a better product...

Here's a picture of what I've been using for my other projects - this is a layup of two thicknesses of 3/4" for a shoe rack.