thanks mate
means alot heres a shot from inside the mouth. its getting covered in a black velvet material, and running blue thin pile carpet on the inside, leaving the walls red.
Planet10,
Your assumption is that all flow paths or air columns are combined and modeled as one, when in fact it is the channel walls separating them that makes them independent. Even with symmetry, there are still two separate horns as the lengths are unequal. I am not sure how to model two separate exit terminii at different lengths in the model. In fact, I am not sure what happens when you take a trumpet and add two bells to it at different lengths. I think the waves will establish in one or the other rather than split they may oscillate back and forth but this is the nature of fluid dynamics. In this sense I think the solution is to superimpose the two different length solutions. If you use MJK's models, the location of the terminus for each case is different (two vertical, and two horizontal) and this affects the final SPL calculation in the simulated room.
Regards,
Xrk971
Your assumption is that all flow paths or air columns are combined and modeled as one, when in fact it is the channel walls separating them that makes them independent. Even with symmetry, there are still two separate horns as the lengths are unequal. I am not sure how to model two separate exit terminii at different lengths in the model. In fact, I am not sure what happens when you take a trumpet and add two bells to it at different lengths. I think the waves will establish in one or the other rather than split they may oscillate back and forth but this is the nature of fluid dynamics. In this sense I think the solution is to superimpose the two different length solutions. If you use MJK's models, the location of the terminus for each case is different (two vertical, and two horizontal) and this affects the final SPL calculation in the simulated room.
Regards,
Xrk971
thanks mate
heres a shot from inside the mouth. its getting covered in a black velvet material, and running blue thin pile carpet on the inside, leaving the walls red.
Looks very cool. How does it sound?
Double you get any stereo imaging?
thanks XRK, as far as "stereo imaging" no.. its a single sound source, but i do get the left/right sounds, and i also do plan to fit a reflector infront of the outermost drivers to try and aim some of the higher frequencies out of the mouth better.
the closer i get to having a sealed box, the better it is sounding, and also the more i listen to it, the better its sounding to me. ive been playing with the Dolby software on my laptop with it, and i can crank up the 30-100hz sliders on the EQ and it does sound much much better, but ultimately i lose volume when i do so for running out of excursion on the drivers.
back to the shunting of the drivers, i was considering mounting a tweeter on each of the front faces of the box, and then lowpassing the rear/innermost drivers to act more like subwoofers.
i tried just holding the cones of the front most drivers still to assess if less drivers made better or worse, and volume dropped considerably when i cut two out of the equation. so definately winning with the Quad setup.
how much bass/rumble to you guys get from your spiral horns?
the closer i get to having a sealed box, the better it is sounding, and also the more i listen to it, the better its sounding to me. ive been playing with the Dolby software on my laptop with it, and i can crank up the 30-100hz sliders on the EQ and it does sound much much better, but ultimately i lose volume when i do so for running out of excursion on the drivers.
back to the shunting of the drivers, i was considering mounting a tweeter on each of the front faces of the box, and then lowpassing the rear/innermost drivers to act more like subwoofers.
i tried just holding the cones of the front most drivers still to assess if less drivers made better or worse, and volume dropped considerably when i cut two out of the equation. so definately winning with the Quad setup.
how much bass/rumble to you guys get from your spiral horns?
It is the same technique Martin used to model Sachiko.
The horn is square, the path lengths should be the same.
dave
heres the little amp thats going into it
being class D, i presume that if i run it at 4ohm, its probably not going to like it, but at this sort of power i doubt its going to be an issue... lol
would i be correct to assume its rated to 8hm and that running it at 4 will approximately double the output power to roughly 6w?
being class D, i presume that if i run it at 4ohm, its probably not going to like it, but at this sort of power i doubt its going to be an issue... lol
would i be correct to assume its rated to 8hm and that running it at 4 will approximately double the output power to roughly 6w?
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A quick question on the Cornu spiral - Is there any reason why the spiral pattern can't be taken larger? I.E., make the baffle 3'x3'? (Or bigger?)
I will be buying a bunch of foam core monday, and proceeding with this fantastic project. SHMBO actually likes the idea!
One, well, kinda small thing... I don't have a suitable driver. Any suggestions? FE126En? A Markaudio?
I will be buying a bunch of foam core monday, and proceeding with this fantastic project. SHMBO actually likes the idea!
One, well, kinda small thing... I don't have a suitable driver. Any suggestions? FE126En? A Markaudio?
3 ft square will give you a bigger mouth and expansion ratio, so the volume would go up and you may get way too much bass. Cal is already noticing that the bass is larger than mids, also path would be longer and tuning frequency will go below what the driver can handle - unless you model it, hard to tell. The 70 cm size already goes down to 38 Hz based on the 2.24 m path of the longer horn. I think the driver selection does not seem to be critical. The original Cornu uses several different types of drivers (Monacor, Lowther DX, Fostex) with the Fostex FE108ez being the main. Personally , I would pick one with more xmax. The one Cal is using seems to work well too. I am using a much smaller 3.5 inch high Qts driver and it works fine. Just size the throat area to match the driver piston area Sd. I personally, would pick the MA CHR70 for my next one given the combination of performance and price. One thing that I noticed with the Cornu is that it is a very efficient and loud speaker that works very well even at lower volumes. The richness and depth of the bass is still there even at low volumes. This means that even lower efficiency drivers will sound loud, and high efficiency drivers will be even louder. If you matched this up with a 98 dB driver and a SET or a Pass Labs d'lite, it would be really special.
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Yes, it seems like it is the same but if you lay string down for the paths they are quite different. Also, when you build it, you know from how long the channel strips that you have cut and are using. The different path lengths were supposed to help smooth out the resonance peaks, this is where a model would help. Why not 3 different pathlengths? Would that be smoother? In any case, I think this is what gives these speakers their 'character' good or bad.... That is what the 6 moons reviewer noted.
Thanks for this Planet10! Did you make it? This will really help out folks starting on this project.
Looks really nice, I like how the long and short paths are color coded.
You are owed them and even even more. You helped me scratch a long standing itch.
To possibly include a silkscreen cover over the drivers.
WHAT? I CAN'T HEAR YOU, I HAVE TO GO TURN THE BASS DOWN.
There, does that simplify it?
Wow, what an inspiring thread. So much so that I went out and got a bunch of foam boards, 30x20 inches each, and a whole bunch of hot glue. I'll probably get the plywood faces tomorrow.
I'm a total beginner at speaker building, so I do have a question. I got a couple of Visaton B200 drivers in an OB that I don't like. Is it possible to use the Visaton B200 for this project?
Here's the data from the manufacturer:
Rated power 40 W
Maximum power 70 W
Nominal impedance Z 6 Ohm
Frequency response fu–18000 Hz
(fu: Lower cut-off frequency depending on cabinet) .
Mean sound pressure level 96 dB (2,83 V/1 m)
Opening angle (-6 dB) 48°/4000 Hz
Maximum linear displacement +/−3,5 mm
Resonance frequency fs 40 Hz
Magnetic induction 1,2 T
Magnetic flux 755 µWb
Height of front pole-plate 8 mm
Voice coil diameter 25 mm
Height of winding 4 mm
Cutout diameter 190 mm
Net weight 2,16 kg
D.C. resistance Rdc 5,0 Ohm
Mechanical Q factor Qms 8,39
Electrical Q factor Qes 0,83
Total Q factor Qts 0,75
Equivalent volume Vas 102 l
Effective piston area Sd 214 cm²
Dynamically moved mass Mms 9,7 g
Force factor Bxl 3,9 Tm
Inductance of the voice coil L 0,5 mH
I'm a total beginner at speaker building, so I do have a question. I got a couple of Visaton B200 drivers in an OB that I don't like. Is it possible to use the Visaton B200 for this project?
Here's the data from the manufacturer:
Rated power 40 W
Maximum power 70 W
Nominal impedance Z 6 Ohm
Frequency response fu–18000 Hz
(fu: Lower cut-off frequency depending on cabinet) .
Mean sound pressure level 96 dB (2,83 V/1 m)
Opening angle (-6 dB) 48°/4000 Hz
Maximum linear displacement +/−3,5 mm
Resonance frequency fs 40 Hz
Magnetic induction 1,2 T
Magnetic flux 755 µWb
Height of front pole-plate 8 mm
Voice coil diameter 25 mm
Height of winding 4 mm
Cutout diameter 190 mm
Net weight 2,16 kg
D.C. resistance Rdc 5,0 Ohm
Mechanical Q factor Qms 8,39
Electrical Q factor Qes 0,83
Total Q factor Qts 0,75
Equivalent volume Vas 102 l
Effective piston area Sd 214 cm²
Dynamically moved mass Mms 9,7 g
Force factor Bxl 3,9 Tm
Inductance of the voice coil L 0,5 mH
Yes, that's all I can say at the moment. Tomorrow I will move them. Right now they are wedged in and around TV, chest of drawers and an armoire or two so they are bound to be bassy.I was actually encouraged when Cal said it had strong bass.
May as well make the front and back something nice as you can hide the sides later if you feel the need to.
Mark, Is Flexy ply the MDF with Kerf cuts? If so not recommended. Bendy-Ply would work but is in IMHO unnecessary. Plus unless you dado the board, it wouldn't be as easy to use as foam board. It's well past my bedtime right now but maybe I can explain later.
No need to go beyond that at this point. I know it seems counterintuitive but again, later. I see there's lots of posts to repsond to.
Yes.
Not the foam core I have. It is XPS so the density doesn't change. At that thickness it is extremely flexible but as you pointed out, you have to score the inside of the facer. The outside will expand a very little, but the facer on the inside won't compress, it just buckles, so what you are doing by scoring it, is to relieve that buckling as you bend it. The outside facer helps to control the compression of the inside so you end up with a nice dense material at the curves even though you have scored it. Nice trick BTW, xrk.
Ya, no sheep dip.