Tweeter Placement

[ocho]

I'm currently in a speaker design course, and have a question about tweeter placement. So far, I've noticed that tweeters are usually placed in-line with the other speakers or "mirrored". When "mirrored", the outside diameter is usually flush to the outside diameter of the mid or woofer.

So my question is what advantages does the mirrored configuration provide and why is the tweeter's outside diameter flush with other speakers (in other words, why isn't it just offset some other amount)?

[ThomasW]

These are design tools you can use to answer the question

http://www.tolvan.com/edge/

http://www.pvconsultants.com/audio/diffraction/downloadbds.htm

[ocho]

thomas, thanks a lot. i'll definitely use those when I start designing my speaker.

on another note, does everyone go through an extensive testing process when making their speakers (ie: placing the tweeter in line and testing placement all the way to the edge) ?

[alias2]

Vertical placing means you only have to tool one baffle layout.

For mirrrored a typical spacing is ~0.6 for the tweeter centre,
though as you allude to, may be lined up to an aesthetic point.

Regarding your last question, I would say no. You would use
some ratios to set the tweeter point, say ~ 0.6:1:1.6 to the
three nearest baffle edges.

/alias2.

[ThomasW]

does everyone go through an extensive testing process when making their speakers (ie: placing the tweeter in line and testing placement all the way to the edge) ?

They don't build numerous test baffles, that's what the software is for. It's of course a good idea to verify the model with measurements takes from the real thing

The idea is to create a lobing pattern desired for the application..

[Xander]

Often the width of the box is at a minimum to fit the size of the woofer, so the woofer is inherently centered.

Centering the tweeter will cause equal distances between the tweeter and the two edges, exaggerating any diffraction effects at the frequency related to the wavelength between the tweeter and edge of the baffle. Placing the tweeter off-center will spread the diffraction out over the frequency spectrum.

[Quwiksilver]

I'm currently in a speaker design course, and have a question...

Out of curiosity, where are you taking your speaker design course?

[ocho]

Thanks to everyone's responses. I'm definitely gonna have to play with speaker placement quite a bit on my project. Thanks.

Quick:
University of Southern California

I now have another, similar question (if you don't mind)...

Does vertical placement make any difference?

Example, will this placement:
T
.
.
.
M

sound any different than :
T
.
.
M


Lets say that a . represents 1 cm. I'm assuming that it may cause the listener to be off axis if they're very far apart, but do slight changes also make a difference?

[alias2]

Slight changes make slight differences unless its unimportant in the first place.

http://www.rjbaudio.com/Audiofiles/FRDtools.html

http://www.zaphaudio.com/

http://www.rjbaudio.com/projects.html

http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm

https://htguide.com/forum/forumdisplay.php?f=39

http://www.humblehomemadehifi.com/

The above links illustrate simulation and measurement based techniques.

Speaker placement in a design is usually a given and not very flexible.

/alias2.

[dlneubec]

Thanks to everyone's responses. I'm definitely gonna have to play with speaker placement quite a bit on my project. Thanks.

Quick:
University of Southern California

I now have another, similar question (if you don't mind)...

Does vertical placement make any difference?

Example, will this placement:
T
.
.
.
M

sound any different than :
T
.
.
M


Lets say that a . represents 1 cm. I'm assuming that it may cause the listener to be off axis if they're very far apart, but do slight changes also make a difference?

The main difference from chaning the driver center to center distance will be in the vertical polar response. The higher your crossover point in frequency, the more exagerrated this effect will be.

For example, the graph below illustrates the vertical polar response of the design I'm currently finishing up. The outside curve (dark red) represents the lobing at the crossove point of about 2.5khz. Each succeeding curve to the inside, indicating a narrower vertical lobe as a result of moving the tweeter and mid 1cm further apart, with the black line representing an increase of 3cm between the drivers. On each side of the main lobe is a null area. What that means is that as your ear height moves vertically, you will move toward the null area and the speaker will sound different. The narrower the main lobe, the quicker you will hear a difference as you move vertically. Where the lobe and null areas are pointed can also effect how the speaker sounds due to floor and ceiling reflections and the resulting cancellations that can occur.

[ocho]

Thanks everyone for their response. I've just started on design of my loudspeaker now that I have a better idea of what's going on. I might end up posting some of my ideas here as I design/build, and I will definitely post everything once the project is done.