No baffle for tweeter?

[enigmaticEntity.]

I'm playing around with ideas at the moment, and was wondering if it is worth pursuing "mounting" a tweeter on no baffle to improve imaging. This would either mean I need a small face-plateless tweeter or I'll have to get one where the face-plate can be removed.

Is this idea worth pursuing? (Comments and/or suggestions...)

[thadman]

I believe Linkwitz explores the concept in his Pluto design.

However, you still have to deal with significant reflections contributed by the enclosure.

[mavric]

what kind of tweeter? or manufacture? from your drawing, it looks like you could posistion the tweeter up down left or right for imaging. that is just my idea by looking at your pic. As a note, you typiclly want the voice coil of the driver and tweeter alighned and on the same plane, other words, you dont want to have the tweeter out in front or behind the driver, what your pic suggests is a big co-axial. Have fun!

[s3tup]

It depends.

The Morel mdt33 i have tested without and with baffle sounded completely different and on the harsh side wihout baffle support. In opposite, Vifa xt25 haven't noticely changed it's behaviour with addition of baffle.

I guess the difference comes from the shape of tweeter's flange - vifa has kind of acoustic lens/horn surrounding the dome, that limits the angle of waves propagation.

You can check it yourself by attaching a masking tape in the shape of baffle to the tweeter's flange.

[Hjalmar]

You can try the HiVi tweeter with pod. It will give you a speaker that looks like the B&W's or Tannoys's with supertweeter.
In my recollection it is not very expensive.

One thing you will keep without the baffle is reflection from the woofer speakerbox below it. If you want to avoid this, why not mount the tweeter facing upward and mount a cone above it to make it omni-directional.
At the Visaton site Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories you can find a design like this.

Hope this helps,

Hjalmar Dijkstra

[domtw]

I have done something in the same style.




I am no expert but the directivity of the final speaker is not bad.
Here is a graph at 0,20 & 40°



What Hjalmar said about the reflection from the woofer speaker cabinet is true.
In my design, I didn't totally understand it but I could see some effects from some test measurements...
I regret not to have a deeper study to bring to the subject...

[enigmaticEntity.]

Originally Posted by Hjalmar

You can try the HiVi tweeter with pod. It will give you a speaker that looks like the B&W's or Tannoys's with supertweeter.
In my recollection it is not very expensive.

One thing you will keep without the baffle is reflection from the woofer speakerbox below it. If you want to avoid this, why not mount the tweeter facing upward and mount a cone above it to make it omni-directional.
At the Visaton site Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories you can find a design like this.

Hope this helps,

Hjalmar Dijkstra

I'm not too keen on the Hi-Vi, as it didn't measure too well (Zaph). The cone idea is interesting, except for the thought of making the cone...

Originally Posted by domtw

I have done something in the same style.

[IMG]img691.imageshack.us/img691/5213/mini008.jpg[/IMG]


I am no expert but the directivity of the final speaker is not bad.
Here is a graph at 0,20 & 40°

[IMG]img691.imageshack.us/img691/7482/directivity02040.jpg[/IMG]

What Hjalmar said about the reflection from the woofer speaker cabinet is true.
In my design, I didn't totally understand it but I could see some effects from some test measurements...
I regret not to have a deeper study to bring to the subject...

I may need to put lots of dampening material on the top surface, while trying to maintain a clean look.

If I do go with a baffle, I will have the woofer out about 1/2'' to align the acoustic centres. The baffle will need to slope back before it gets to the tweeter.

Has anyone had any experience with omni-directional tweeters?
How do you make sure the right amount (level and flat FR) of sound is reflected along the line of the woofer's motion?

e.E.

[Hjalmar]

Originally Posted by domtw

I have done something in the same style.




I am no expert but the directivity of the final speaker is not bad.
Here is a graph at 0,20 & 40°



What Hjalmar said about the reflection from the woofer speaker cabinet is true.
In my design, I didn't totally understand it but I could see some effects from some test measurements...
I regret not to have a deeper study to bring to the subject...

Congratulations on the design of your speakers, they look really nice!!

Some of the disturbances on your graph will be due to reflection from the edges around the woofer and below the tweeter.
Ideally the speakers should be flush with the front of the box. However surrounds are always around and will give their presence ....

Be aware with most speakers at some frequencies you actually need a baffle in order to get a decent output.

Regards,

Hjalmar Dijkstra

[Patrick Bateman]

Originally Posted by enigmaticEntity.

I'm playing around with ideas at the moment, and was wondering if it is worth pursuing "mounting" a tweeter on no baffle to improve imaging. This would either mean I need a small face-plateless tweeter or I'll have to get one where the face-plate can be removed.

Is this idea worth pursuing? (Comments and/or suggestions...)

Go listen to some of the speakers that use enclosures that reduce diffraction. You'll quickly realize that diffraction is *very* audible, and that controlling it will improve your imaging.

The problem with taking a tweeter and mounting it outside of the enclosure is that it simply pushes the diffraction effects further up in frequency, where the effect is less audible. (Due to Fletcher Munson curves.)

[dry martini]

Home. Believe me, I get guff from DIY guys almost exclusively. Nature of the beast, I suppose. Having right or near right angle cabinets, visable to waveforms, is incompatible with 3D imagery and breadth of space as it exists in good recordings. If that weren't enough, late arriving diffracted waveforms sum in to create disturbance in the frequency domain, let alone time. You can and should neutralize that interaction I don't care if any so called state of the art box speakers that cost 25k and are adorned by magazines dining on their contributions ignore or compensate for it otherwise. Somebody gonna tell me that reducing the output where this is most pervasive is a good thing?