[Ant_222]

Hello all!

At this site
http://members.myactv.net/~je205d/monob.htm
is presented an OB design wherein on top of the baffle, right over the speaker and perpendicular to the baffle is placed a small plate which is said to have the following effect:

"My initial listening was done without the 7" x 13" top plate and the sound was congested in the midrange and lacking in definition in the bass"

Do you have any ideas as to how this plate works?

Anton

[opnly bafld]

I can't comment on the change in the sound, but the top plate causes the driver to act like it is in a taller baffle, but without blocking the reflection of the backwave as much.
Personally I like the sound of a tall, narrow baffle better.

Lin

[mcgsxr]

I run one of those horizontal pieces on the rear of my baffles too, to increase the size of the effective baffle, without changing the height.

Pics are in the gallery somewhere...

[Ant_222]

Thanks for the comments!

I run one of those horizontal pieces on the rear of my baffles too, to increase the size of the effective baffle, without changing the height

Do you understand the physics of this effect? Baffle is used to increase the length that airwaves have to travel from the rear side of the speaker to the frontal side, thus shifting the cancellation effect to lower frequencies. And the addition of such a tiny (compared to baffle size) piece just can't increase the length of this path distinctly. I must be missing something...

Personally I like the sound of a tall, narrow baffle better.

And this is another phenomena that I don't understand. If we take two baffles equal in width, but one significally taller than the other (30"x40" and 30"x60"), what will be the difference in LF response? I suppose that it shouldn't be big because most of the cancellation will still happen along the shortest path, i.e. around the left and right sides. Could you please explain it?

Anton

[Bob in St. Louis]

Please don't ask me the physics behind it, but a very wise man once told me that the shortest length for the rear wave to reach the front should never be over the top of the baffle.

Bob

[mcgsxr]

The reason I used that piece of horizontal rear baffle, is to help alleviate the fact that otherwise, the shortest path would be over the top of the baffle.

The only other thing I could do, would be to use a much taller baffle, and I am not looking to do so, as they are already 42 inches at the highest point.

[opnly bafld]

Anton,

By narrow and taller I mean not wider than it is tall like the one you linked (42"w x 36"h).
I like less than 20"w with the wide range driver higher and then a helper woofer can be placed lower.
The helper woofer benefits from the floor gain.
IMO the imaging is much better this way.

Lin