Speaker placement

Dear All,

This topic began as part of another topic but became so far off topic that a moderator had to move it here.

The problem was that it lacked an introduction and therefore didn't make much sense (as cyreg comments in one of the replies), so I'll have a try at post-editing it now to give it an introduction...

SPEAKER PLACEMENT

Forum member suede commented that his next step in his quest for ultimate fidelity was to obtain some better speakers. I cheekily chirped in the following...

"Ah, you'll need an preamp/amp upgrade for your new speakers....

Aria/Proprius coming soon."

The conversation then looked at his speaker positions which are on a bookshelf.

Please feel free to reply with your own speaker placement experiences.


Edited by Graham Slee - 01 Jan 2012 at 7:08am

Unfortunately I have yet to hear B&W's, surprising as that may sound.

Most speakers boom when placed quite close to walls.

Bass to mid frequency sound waves are spherical in shape (although obviously invisible) and the sphere expands as it moves away from the speaker. A close rear wall will therefore reflect the spherical energy increasing the bass output considerably, leading to boom.

Long ago, some speakers were designed for wall placement, but today I've yet to find any that aren't designed for open space, so even with a forward facing reflex port, I think you're going to get boom.

To demonstrate the effect fill a rectangular washing-up bowl with water. Disturb the surface with a droplet of water in the middle. Now do the same close to a side. The ripple from a side has the force of the side behind it. The ripple from the middle just expands in all directions. If a speaker is designed for open space, its tonal balance is based on the box front, sides, top and bottom surface areas. Put it near to a wall and the wall increases the surface area considerably - even if it's spaced away from the wall. Because lower frequencies have larger wave-fronts than higher frequencies the wall assisted hemisphere is quite large and more bass output produced than if stood away from a wall. It's even worse if the speaker is in a room corner.

I currently have our Harbeth mini monitors stood on top of the large Leak Sandwich speakers. The frontal area of the Leak's boosts lower frequencies and sometimes boom is heard, and other times cone "break-up" is heard from the Leak bass drivers.

If you go into a club that has an organist and drummer, the organ bass notes cause the drum skins to vibrate and it's clearly heard - just another example.

Hi
Yes it got a bit off topic, sorry about that! Maybe a moderator can move the last few posts including this one to a new thread or something?
But just to stick off topic for one last post.  I borrowed home a demo pair of the B&W DM685's today and I have to say they worked very well! They're REALLY fun to listen to!! The tapping feet and broad smiling kind of fun. I'm learning to love them more and more by the hour. To my delight they almost seem to handle progressive rock and rather complex music the best , or the most impressive at least. They are extremely dynamic and the bass is really deep but very well formed, and rather tight and controlled. Rhytmically they are awesome!
Apparantely they are designed so that they can be mounted onto walls so proximity to them doesn't seem to be that big an issue with this particular model although the manual do recommend 50 centimetres of free space behind them for optimal results. And still the bookshelves themselves  admittedly do give off some slight singing resonance but I can live with that snag for now, I still have the Solo Ultra Linear/Grado GS1000i for reference listening and the new speakers are SO much fun!
If anyone is looking for bookshelf speakers under £500 I strongly recommend you listen to these!

Cheers!
Johan


Edited by suede - 30 Dec 2011 at 3:15pm