Klampy,
That is a pretty cool and innovative design. I have never seen anything like it. You have drivers facing out now so you should get some highs coming out for stereo separation. Was the main reason one set of drivers face into the box due to lack of space? Have you fired it up yet and how does it sound? Very nice work
Xrk971
That is a pretty cool and innovative design. I have never seen anything like it. You have drivers facing out now so you should get some highs coming out for stereo separation. Was the main reason one set of drivers face into the box due to lack of space? Have you fired it up yet and how does it sound? Very nice work
Xrk971
Thanks guys. Badman, it must have been unintentional because im.not sure what you mean by force cancelling. could you help me understand what that means please?
Xrk, thankyou. Yes its running atm but no lid on. It doesnt seem as loud as my first one buts i can already tell it has much more bass. Definately the reason for reversed drivers was packaging restrictions and i definately have a stereo image now. I should have used the smaller drivers in this horn coz infeel the bigger ones are less sensitive/more powerful and might need more than 3w to drive them properly.
Xrk, thankyou. Yes its running atm but no lid on. It doesnt seem as loud as my first one buts i can already tell it has much more bass. Definately the reason for reversed drivers was packaging restrictions and i definately have a stereo image now. I should have used the smaller drivers in this horn coz infeel the bigger ones are less sensitive/more powerful and might need more than 3w to drive them properly.
Klampy,
Give your drivers the juice they need, 3 Watts is so underpowered. My cheap desktop pc speakers are circa 3W - and not very loud. Why don't you get a Lepai T-amp($20) they are 20 W into 4 ohms and sound great - very low distortion and run cool. You can probably remove it from its chassis and fit it inside your box. Although you did it due to volume constraints, I think the fact that one driver faces in and another out allows the asymmetry of the drivers (movement out vs in being unequal) to self-cancel (kind of like common mode rejection). This type of back-to-front technique is used in many other fields to null-distortion: optics sometimes uses two identical lenses - the famous Gauss lens design, complementary transistor pairs, matched dual photodiodes, the list goes on.... Anyhow, you may be on to something pretty cool here.
Xrk971
Theyre running on 2x100w at the moment and still arent maxxing out.... :/ lol they are 50w drivers so it kinda figures...
Just put a cd on and straight off the cd player theyre much louder than the laptop can push via the same amp.
Now that there is a little stuffing inside and the lid is sealed they do have that deep punch ive been looking for so the do sound very warm. Not a heap of highs tho so could easily have been accompanied by a tweeter. They do sound clean tho so overall i have achieved ky goal of portable bass so ive got a win there.
Regarding the reversed driver its also wired reverse polarity so theres no cancellation. I forgot initially to reverse it and it sounded bad. but my first thought was that my ss15 subs have the magnet out and they sound epic. It was mostly so i could fit as much speaker in as possible and still give plenty of horn space. I actually had space leftover lol. But it had no positive effect on the sims to make the horn any longer than it already is.
I must say Infected Mushroom: Army of mushrooms. Sounds pretty good on my new speaker box
Just put a cd on and straight off the cd player theyre much louder than the laptop can push via the same amp.
Now that there is a little stuffing inside and the lid is sealed they do have that deep punch ive been looking for so the do sound very warm. Not a heap of highs tho so could easily have been accompanied by a tweeter. They do sound clean tho so overall i have achieved ky goal of portable bass so ive got a win there.
Regarding the reversed driver its also wired reverse polarity so theres no cancellation. I forgot initially to reverse it and it sounded bad. but my first thought was that my ss15 subs have the magnet out and they sound epic. It was mostly so i could fit as much speaker in as possible and still give plenty of horn space. I actually had space leftover lol. But it had no positive effect on the sims to make the horn any longer than it already is.
I must say Infected Mushroom: Army of mushrooms. Sounds pretty good on my new speaker box
Sounds like you have a winner there. I expected the drivers to be wired one in reverse otherwise it would cancel amplitude. I am talking about cancelling driver-inherent distortion due to unequal movements on in stroke vs out stroke. Nicely done - do you have some pics or an mp3 from a mic what it sounds like?
By having the drivers pushing against a joined panel the way they are, there's a small amount of force-cancellation- the drivers push against each other somewhat, rather than the box, thus equal but opposite forces tend to cancel.
You need a top on that- the horn won't work without a top, and the bass will all cancel as it short-circuits in the free-air above the drivers.
You need a top on that- the horn won't work without a top, and the bass will all cancel as it short-circuits in the free-air above the drivers.
I'd like to bring the discussion back to the design of the cornucopya. On page 3 of the patent in paragraph 0021 it describes the cone (5) from Fig. 1 roughly as an outward deflector of the sound waves. Perhaps that's actually important. I wonder if we could add the cone to the simulation model?
I can say that all of Scott's double-mouth horns and BVRs have a similar bit in them at the bifurcation of the horn, see attachment.
dave
Attachments
thanks for the kind words guys, dont worry badman, it has the lid tightly attatched now
XRK, ill be sure to get a short MP3 of the sound either today or tomorrow for ya, its gonna be the upload that kills me, havent exactly got a fast connection available to me at the moment...
and thanks Cal. im rather pleased with it. im even thinking about just cleaning up the glue joins and leaving it as card finish.. maybe.
XRK, ill be sure to get a short MP3 of the sound either today or tomorrow for ya, its gonna be the upload that kills me, havent exactly got a fast connection available to me at the moment...
and thanks Cal. im rather pleased with it. im even thinking about just cleaning up the glue joins and leaving it as card finish.. maybe.
In the spirit of this thread... If I take an arc shaped strip of foam core and score it radially outwards from the inner edge of the arc to the outer edge of the arc, the carefully bend it and close it on itself, then fasten it with hot melt... I might be able to build a cone. Hot melt that into place and check it out. Another idea is to use the plastic nose cone from a model airplane propeller. Any other ideas where to find an easy cone to try? My problem is that my Cornu is rather shallow and may not allow much room compared to the 4.5 to 5 in deep ones that seem to come with the full size ones.
Iko, are you well versed with Akabak? I believe the cone will improve efficiency, but I don't think it will have much of an effect on the horn resonances, peaks and dips, that Don Hills pointed out in his sims. Interesting to see how it works though. How do you plan to implement the cone in the script?
The horn of a rear-loaded horn speaker is mostly for bass reinforcement - you don't want HF coming out of the horn. The cone-shaped deflector will tend to make the HF problem worse by reflecting more HF into the horn mouths. It won't help the bass at all because the wavelengths are too long compared to the dimensions of the cone. Also, the cone will reduce the volume of the back chamber. This will have to be factored into the rear chamber dimensions.
No, I've never seen akabak before in my life. That's probably why the simulation results don't make sense to me. The script uses conical horn elements. I don't know if in akabak a cone is a real cone, meaning that it is a circle in cross section. The real horn of the cornu is not a real cone. It's a pyramid. I can't really comment until I learn akabak.
That cone at the back of the driver, if it's not there, you can obviously see that the sound waves hit the opposite wall and some will come straight back to the driver, no? To me it makes common sense to have that cone in there. Is my common sense so far off?
That cone at the back of the driver, if it's not there, you can obviously see that the sound waves hit the opposite wall and some will come straight back to the driver, no? To me it makes common sense to have that cone in there. Is my common sense so far off?
"Conical" in AkAbak means that the area increases as the square of the length. It doesn't matter if the cross-section shape is circular, elliptical, square, rectangular, octagonal etc, provided that the longest dimension across the cross-section is significantly less than 1/4 wavelength at the frequencies of interest.
Flat-walled horn with 4 straight walls, all diverging = conical profile.
Flat-walled horn with 4 straight walls, 2 diverging, 2 parallel = parabolic profile.
For horns with small rates of divergence (taper), such as the Cornu near its centre, the profiles are almost identical. They differ more at the mouth, where the divergence increases rapidly.
Actually, a true Cornu / Euler spiral curve horn built as a spiral between 2 parallel plates more closely follows a conical area rule than a parabolic area rule. If you imagine it "unrolled" into a straight horn, the walls are not straight - they curve away from each other.
Regarding the cone behind the driver, if common sense was (common), the world wouldn't be in the mess it is. Look at it this way: Most of the HF reflection through the cone occurs from the driver frame/magnet and spider. A cone behind the driver would only be useful if there was nothing between the back of the driver's diaphragm and the cone. Because of the shadowing effect of the driver's rear parts, the cone would also have to be significantly larger diameter at its base than the driver in order to have any effect. Finally, if you did have a cone, the reflected energy would just bounce off the chamber walls, back off the cone and up through the driver. Replacing the cone with an equivalent volume of stuffing would be more effective.
Flat-walled horn with 4 straight walls, all diverging = conical profile.
Flat-walled horn with 4 straight walls, 2 diverging, 2 parallel = parabolic profile.
For horns with small rates of divergence (taper), such as the Cornu near its centre, the profiles are almost identical. They differ more at the mouth, where the divergence increases rapidly.
Actually, a true Cornu / Euler spiral curve horn built as a spiral between 2 parallel plates more closely follows a conical area rule than a parabolic area rule. If you imagine it "unrolled" into a straight horn, the walls are not straight - they curve away from each other.
Regarding the cone behind the driver, if common sense was (common), the world wouldn't be in the mess it is.
Look at it this way: Most of the HF reflection through the cone occurs from the driver frame/magnet and spider. A cone behind the driver would only be useful if there was nothing between the back of the driver's diaphragm and the cone. Because of the shadowing effect of the driver's rear parts, the cone would also have to be significantly larger diameter at its base than the driver in order to have any effect. Finally, if you did have a cone, the reflected energy would just bounce off the chamber walls, back off the cone and up through the driver. Replacing the cone with an equivalent volume of stuffing would be more effective.
First, a thanks to Don Hill for all his input. I don't have to understand it all to know how valuable his input is here.
You saw how easy it was to dress it up with a little veneer, trim pieces and grill cloth. Go for it.
All of this make sense. I am am glad someone in the know said it.