Chill-Baffle speaker (L-baffle design)

[fedde]

Hi folks,

I created a webpage about my new L-baffle experiment:
http://www.fedde.nu/audio/chill-baffle.html

The idea is to combine the advantages of an open-baffle and an U-baffle. I have never seen a L-baffle speaker before nor have I done a thorough theoretic evaluation. Still, the concept seems to work very well...

The L-baffle configuration in my humble opinion has the following advantages:
- The baffle width is reduced
- The appearance is symmetric...
- ...but the baffle is not (thus less deep frequency peaks/dips)
- The baffle gets more rigid due to the side panel
- The construction is quite stable due to 3 connecting panels
- It is very easy and cheap to build! (the construction, not the drivers)

What do you think about this concept?

Fedde

[fedde]

And here is the construction plan...

Fedde

[fedde]

BTW: I used the 8" Supravox 215 Signature Bicone driver. No passive filtering was done, but some equalization was done in the PC (optional).

Fedde

[Bigun]

looks interesting. I wonder if it makes a difference which way around you have the speakers in terms of Left vs Right.

[Rudolf]

Yes, a L-baffle is a valid solution.

I've looked into baffles with wings at my German home page. My very rough rule of thumb is, that below ~300 Hz the complete added width of all parts of the baffle counts. Above 300 Hz the central baffle width is dominant, if wings are folded back sufficiently.

Your setup looks like the driver axes are meeting behind your head. You may test to toe in the baffles until the driver axes meet 40-60 cm in front of your head. I found that to be more satisfying, but the result could depend much on the room layout. Anyway, it should be worth a try.

Rudolf

[norman bates]

needing 7db of boost at 280hz, you see that you need a wider baffle.

I like the idea of an L-open baffle.
It can help you get to 1 : 1.618 ratio for the distance from the front of the driver to the back. The golden question is how deep should the L be?

Here is a neat article on open baffle offset.
Open baffle study,

I'm thinking of making a L shaped open baffle for some Alpair drivers.

I know that for a 24" x 24" front baffle, 19" deep (open in the back) gave a somewhat chesty sound, even with the opening covered in 3" foam. Covering the inside should help. It had very good bass (midbass) needing no baffle step. It had flatter bass than a 2' wide speaker enclosure.

To me, the bass will still roll off at the shortest distance from front of the driver to the back. If the baffle width is 2', then if the driver is infinitely small, you'd have a dip near 560hz (front wave 1/2 wavelength out of phase 1129/2'), Feq you'll have a peak around 280hz (front is 90 degrees out of phase thusly adding), then it will roll off.

Naturally, a driver will roll off (open baffle or infinite baffle) at Fs/qts.

If I remember, the wings can be 1/4 deep compared to the width.

Here was my open baffle focused array.


I recommend covering the back of the driver with a 3-4" thick foam box.
Some people don't like the large reflective surface of a large open baffle.

Norman

[wjlamp]

Originally Posted by fedde

Hi folks,

I created a webpage about my new L-baffle experiment:
http://www.fedde.nu/audio/chill-baffle.html

The idea is to combine the advantages of an open-baffle and an U-baffle. I have never seen a L-baffle speaker before nor have I done a thorough theoretic evaluation. Still, the concept seems to work very well...

The L-baffle configuration in my humble opinion has the following advantages:
- The baffle width is reduced
- The appearance is symmetric...
- ...but the baffle is not (thus less deep frequency peaks/dips)
- The baffle gets more rigid due to the side panel
- The construction is quite stable due to 3 connecting panels
- It is very easy and cheap to build! (the construction, not the drivers)

What do you think about this concept?

Fedde

Hi Fedde,
It's interesting,but..What do you think???

How does it compare to a U baffle,or a plain dipole one? Your opinion and impressions would have more substance if you mount the driver on a baffle with no wings,and listen,measure.
Symmetry is no evil in loudspeakers,au contraire..
The environment of a given listening space,has so many non symmetrical values,that it is futile to design asymmetries in a loudspeaker.Placement of a speaker in space ,always in relation to the listening spot ,is the most important parameter,all else being equal.

Just for the record...

I do open baffles since 1998. My main speakers are open back line arrays of a symmetric WWWWTWWWW kind.Height of the baffle is 180 cm.The 30cm wooden baffle that has the speakers mounted upon,is flanked by 25 cm glass wings 15mm thick, on each side.The wings were sturdily mounted in wooden frames
Day one,it was 7th heaven,not a step lower.After some more listening sessions,some problems were raring their ugly ears.Too much low bass and uneven low mids,Despair.Solution,was to move them into the room,fixing some,but creating other irregularities.The project went on,for almost a year.The solution once more,was the flash thought,to remove the glass wings,thus halving the baffle area,and possible sympathetic vibrations.Needless to say that ,in my listening room,and in some others,of relatively equal proportions but wildly different acoustically,that I tried them,they sound as planned.Coherent from top to bottom,as I like them.Comments, from fellow nutheads, are positive.most of the time.

It would be nice to try the iterations,since you are in a good starting point,and let us know more.


B.L

[fedde]

Hi everybody,

Thanks for all the responses! I was already thinking about covering the back of the speaker with foam or something similar. I think that this is a good idea. Regarding the width: this was tailored for the space I have in my room.

I would have preferred to get them 50 cm wide instead 45 cm. The depth was calculated to be the same distance from the back of the speaker to the right of the speaker as a 65 cm baffle.

I never tried U-baffles because many people told me they sound not so good. I have a flat baffle upstairs that I can compare it with. I'll try this later (problem is that it does not fit well in my room). Also, I plan to do some measurements lateron. Furthermore, I was thinking about mounting some strips (e.g. 5 cm wide) to the side of the panel to measure the effect.

Regarding the 7 dB bass boost. This is for a large part taste wise. Maybe some people prefer less bass. I like it when the bass is a bit fat (but tight!). 3 or 4 dB is sufficient and even without EQ the bass is more than most monitor speakers (I used 7 dB also on my Tannoy SGM-12x). I also add a few dB at 40 Hz (to get more output between 30-50 Hz).
The 7 dB treble boost could be reduced if I angled the speaker a bit upwards.

Fedde