I will suggest the Faital Pro 4FE35 for $25 ea. The published freq response curve looks just as good as the bamboo and it has 91dB efficiency. Get the 4 ohm version - they give lower THD and higher power with the TPA31xx amps.
The wooden variety with double layer is how the original Cornu is built. It uses segmented pieces of thin wood and the middle layer has a slot cut in it to hold the segments in alignment. There is no acoustic benefit to having a middle layer - other than for it to force the the wave to travel down 8 horns rather than 4. The foam core method uses easily curved foam core that is held in place by hot melt glue which sets fast enough that fingers are all that is needed to hold the curve shape in place. Look at Sebastien's wooden cornu website to see how the wooden ones are built.
Three questions.
I am getting down to making the fins of the horn, can someone please remind me how far apart I need to make slits in order to curve the foamcore?
I seem to recall one side being better for making those slits. Is one side better?
I have the option of mounting the speakers against the wall. But the listener will be off axis then. So would I be better mounting flush to wall or toeing them out to face the listener?
Thanks
I am getting down to making the fins of the horn, can someone please remind me how far apart I need to make slits in order to curve the foamcore?
I seem to recall one side being better for making those slits. Is one side better?
I have the option of mounting the speakers against the wall. But the listener will be off axis then. So would I be better mounting flush to wall or toeing them out to face the listener?
Thanks
Curving the channels requires scoring cuts on the concave side. Cut deep enough to piece through top layer of paper. For right radius bends use 1 mm spacing and vary from there up to 5 mm spacing for gentle bends. Use round object with curve like a PVC pipe to form curve by pressing against strip of now scored foam on one side and palm on other side. Pre curve channels then glue section by section.
These work best flat against wall as wall helps to extend bass. Maybe make a clever angled small box where driver is to toe in driver but horns lay flat?
Good luck!
These work best flat against wall as wall helps to extend bass. Maybe make a clever angled small box where driver is to toe in driver but horns lay flat?
Good luck!
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I've just read through the thread - a bit quickly maybe but the enthusiasm is serioulsy infectious. I might just have to think about making one for my office - it would only be one speaker (i.e. mono) and I would only be playing it at low volume. So it should be small, even 3" is probably more than I need.
Has anybody looked at using a Fostex, FE83 or FE85WK - what size of box would this entail?
I tried the FE127 several years ago and found the peakiness would irritate me within 15 minutes. However, for voices it was super amazing - and I have read 'on the internet' that the FE83 and FE85WK are not irritating although they sure need help in the bass - enter the cornu....
Has anybody looked at using a Fostex, FE83 or FE85WK - what size of box would this entail?
I tried the FE127 several years ago and found the peakiness would irritate me within 15 minutes. However, for voices it was super amazing - and I have read 'on the internet' that the FE83 and FE85WK are not irritating although they sure need help in the bass - enter the cornu....
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Joined 2009
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Couldn't have said it better myself X, except that I found I didn't have to cut quite as often as you are suggesting. I used the first click on the Olfa style knife which worked out to be about 1/2 the board thickness and just did it freehand. I didn't notice if one side was better than the other to score. For the rounding, I happen to have a kitchen countertop that fit the bill.
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Thoughts on improving the sound of the Cornu
We have all been playing with the base design for some time now, with some of us willing to venture into uncharted territory. I have been thinking about how to improve the sound quality of the Cornu as it appears that a lot of mid-bass is leaking out. In a conventional BLH, the most effective way to acoustically low-pass filter this is to have a larger driver chamber with a throat. The current Cornu has a throat but a very small driver chamber volume. The ratio of the throat area to the chamber volume sets the low pass cutoff frequency. So what I think can be tried is to add a sub driver chamber either on top of the existing one in the front, or in the back next to the wall in order to expand the volume by 4x to 5x. My sims show that this will significantly reduce the mid-bass leakage and smooth out the peakiness of the main bass response. If anyone wants to try this I can post some sketches of a proposed modification to the current design. It is an easy 'after the fact' mod to your existing Cornu if you want to do some foam core surgery: cut a hole a little smaller than the existing driver chamber on the back panel, make a thin, say 1 in deep box that has 4 to 5 times the volume of the existing chamber, fill with stuffing and glue onto the back of the speaker.
We have all been playing with the base design for some time now, with some of us willing to venture into uncharted territory. I have been thinking about how to improve the sound quality of the Cornu as it appears that a lot of mid-bass is leaking out. In a conventional BLH, the most effective way to acoustically low-pass filter this is to have a larger driver chamber with a throat. The current Cornu has a throat but a very small driver chamber volume. The ratio of the throat area to the chamber volume sets the low pass cutoff frequency. So what I think can be tried is to add a sub driver chamber either on top of the existing one in the front, or in the back next to the wall in order to expand the volume by 4x to 5x. My sims show that this will significantly reduce the mid-bass leakage and smooth out the peakiness of the main bass response. If anyone wants to try this I can post some sketches of a proposed modification to the current design. It is an easy 'after the fact' mod to your existing Cornu if you want to do some foam core surgery: cut a hole a little smaller than the existing driver chamber on the back panel, make a thin, say 1 in deep box that has 4 to 5 times the volume of the existing chamber, fill with stuffing and glue onto the back of the speaker.
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For what I was hoping to use it for I can't put anything behind it inside the wall and I don't want to having anything sticking out the front - I was thinking about using more sharp bends in the spiral itself to block out the mids, just like a Nagaoka - with all-straight sides for the internal pieces it could also simplify construction.