Home » Sponsored » Pi Speakers » 7 or 4, room shape, cabinet materials, etc.
7 or 4, room shape, cabinet materials, etc. [message #63406] Fri, 16 July 2010 09:24 Go to next message
mfaughn is currently offline  mfaughn
Messages: 2
Registered: April 2010
Esquire
Hello,

New here. I've just got some 2226H on the way. Now I'm trying to decide what to do with them, 7pi or 4pi. Here are a couple of questions I have so far...

1) MDF or plywood? Does it matter much? Appearance doesn't matter a whole lot...might even have them painted as I've got some very talented artists at my disposal.

2) What is a good corner? I understand that both or these work well in corners but that the 4pi can also manage against a wall too. My room is 20x24 and there is a very good chance that the speakers would need to be placed in the corners 24' apart. Also, there is likely to be two 4x8 glass windows between them on this wall if that matters. It seems like the 7pi is the better speaker if one has the right space for it but that the 4pi is more versatile in placement options. I suppose I could build the 4pi and then work on the cabinets for the 7pi and transfer the drivers.

Thanks,
Michael
Re: 7 or 4, room shape, cabinet materials, etc. [message #63409 is a reply to message #63406] Fri, 16 July 2010 15:30 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18783
Registered: January 2001
Illuminati (33rd Degree)

"What is a good corner?" That's a good question.

The biggest thing (other than the obvious, no rattling furniture or windowpanes, etc.) is the corners shouldn't be too far apart. When you have a rectangular room with a long wall and a short wall, this approach only really works well if the corners are unobstructed and they are at each end of a short wall. The reason you want that is you want to be able to sit behind the point where the forward axes cross.

The spectral balance is good everywhere in the room, but the channel balance is only good if you're sitting between the speakers, equidistant from each one, except for the special case where you're behind the crossing of the forward axes. In that area, you can move side to side a fair amount and still have good channel balance. This is because movement away from a speaker simultaneously moves you closer to being on-axis with it. This has a self-balancing effect. See the posts in the link below, especially the ones on placement and toe-in:
As for the cabinet material, I prefer MDF for its acoustic properties but Baltic Birch for its architectural properties. MDF is non-resonant because it's really just a bunch of sawdust held together with white glue. But it turns to mush in the presence of moisture, and even humidity can make it swell. Sometimes, after a while, in humid environments, you can see the seams underneath veneer where MDF is glued together. Baltic birch is much more durable. But like any other plywood, if there are voids, then there can be debris in the void that will buzz. Baltic birch seems to me much better than other plys in this regard, but it is always a concern. Even if the wood doesn't buzz when a cabinet is first built, if there are internal voids, some debris can break loose over time and a cabinet can develop a buzz.

Re: 7 or 4, room shape, cabinet materials, etc. [message #63410 is a reply to message #63409] Fri, 16 July 2010 16:51 Go to previous messageGo to next message
mfaughn is currently offline  mfaughn
Messages: 2
Registered: April 2010
Esquire
Thanks very much for the speedy reply.

I'm not too concerned about rattling since I rarely get to listen to anything at concert volume these days (wife, baby, 4yo). Even still, the forty or so guitars occupying the same room do need to be damped or it gets a bit odd sounding.

I'll probably go MDF even though I live in the (damp) mountains or NC. I don't have time for fancy these days and will probably want to build pretty cabs in a few years anyway if they work out like I hope.

It occurs to me that I might do well to first build the 4pi and play with them in terms of placement -- maybe build the 7pi later. I am extrapolating a bit from what I'm reading here but if the 4pi works in the corners of my room I might expect that the 7pi would also work, yes?

Might I please have the plans for the 4pi?

I'm hoping to get these built before classes start...not much chance after that whirlwind starts.

Cheers,
Michael
Re: 7 or 4, room shape, cabinet materials, etc. [message #63415 is a reply to message #63410] Fri, 16 July 2010 21:21 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18783
Registered: January 2001
Illuminati (33rd Degree)

You've got mail!

Previous Topic: Strange three-way
Next Topic: X-over Cap Voltage rating
Goto Forum:
  


Current Time: Tue Nov 05 14:55:14 CST 2024

Sponsoring Organizations

DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Miller Audio
Miller Audio
Tubes For Amps
TubesForAmps.com

Lone Star Audiofest