Suprabaffle Testing
I've done some initial testing with and without a Styrofoam suprabaffle. It is ~11.5 X 11.5 inches. This time the speaker is about one foot from back wall and two feet from side wall. I've also put a little polyester stuffing about halfway in the horn path. This gives me flatter response but still plenty of base.
The difference with and without the baffle is fairly subtle. I think I like it better with but I'm not sure it's worth the lower WAF.
I've done some initial testing with and without a Styrofoam suprabaffle. It is ~11.5 X 11.5 inches. This time the speaker is about one foot from back wall and two feet from side wall. I've also put a little polyester stuffing about halfway in the horn path. This gives me flatter response but still plenty of base.
The difference with and without the baffle is fairly subtle. I think I like it better with but I'm not sure it's worth the lower WAF.
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I'm getting better with the tools. On this graph I show with and without the suprabaffle. The baffle increases output mostly a db or two but with one dip of ~ 3db at 2k. I think the dip may be due diffraction off the edge of the suprabaffle since 2Khz = wavelength of 6" = spacing from center of speaker to suprabaffle edge. I may try playing around with other shapes/sizes.
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Here is the second speaker ready to have the mouth painted. You can see that I've added a "V" shaped support in the mouth. I could feel the sides vibrating there while the top half of the speaker had very little. I'm planning to add .5 or .75" of MDF on the sides but I decided to add the support anyway while I have the speaker open. I'll post updated plans later.
I've cut back the foam block in the CC a couple of inches. I've broken the piece I cut out into little pieces and am adding them back in to tune the volume. Right now I'm at about 1.8 liter and will probably stay there. I've also added .5 inch adhesive back foam (grey in the picture) to a couple of bends and to the bottom and one wall of the CC
I've cut back the foam block in the CC a couple of inches. I've broken the piece I cut out into little pieces and am adding them back in to tune the volume. Right now I'm at about 1.8 liter and will probably stay there. I've also added .5 inch adhesive back foam (grey in the picture) to a couple of bends and to the bottom and one wall of the CC
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Great job, I've really enjoyed following this thread. It's nice to see someone having the courage to post measurements of their horn design, it's not something that we see often. The large hump in response ~ 180 Hz may in part be due to a room node, or the CC may be a bit too small letting midrange energy out into the horn section. You also might want to consider experimenting with a baffle step filter to tame that rising response. You'll be able to shape your response very effectively and have high WAF without a humongeous baffle. Once again great job and keep up the good work.
Thanks for the encouragement. I've been able to tame the base bump by moving the speaker out of the corner and I have also increased the CC a bit. I will look into filters. If not for the baffle step (I'm thinking on going with a removable suprabaffle) then perhaps for the rising high end of the driver.
dhenryp said:
The above is from post 37 regarding a previous design. I'm now in the position to answer my own question. Since I'm all set up to take measurements I've plotted to responses; 1) with the mouth of the current bugelhorn on the floor and 2) with the horn elevated 17" on a handy bench. In both cases the horn is 18" from the back wall and 24" from the side wall. The mic position wasn't changed.; at driver height when the speaker is on floor and about 2 meters from speaker.
FWIW: The answer for 17" is about 3db, using ~the values at 120hz as convenient corresponding peaks. Ignore the differences at the upper frequencies as I believe these are a function of the mic height relative to the driver.
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jemraid said:Perhaps I'm a bit daft not being any sort of expert but merely interested in the this thread, I would have thought that the mouth would be 17" larger since it was that much further up the wall, so to speak
The floor acts as a mirror (as does the corner)... at the floor in the corner you magnify the apparent mouth size by 8x, lift it up it becomes 4x.
dave
ruerose said:
I'm only using it to take up space in the CC so I'm depending on it to not absorb anything. If it did absorb, I think it would tend to increase the effective CC size (as fiberglass insulation would).
Jem - The closer the mouth is to the fllor/wall boundary the better it reinforces the low frequencies.
Andrewbee said:
Looking Good!
A suggestion if I may. Do not add any damping material that you cannot easily remove
Horns can be very sensitive, sometimes a little damping in the wrong place kills them.
Thanks. I can get to all but one of the bends from the outside. Maybe I'll remove it before I seal it up.
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