Well I couldn't resist - intrigue overtook me! I moved the first of the enclosures (the only one I've really been working on) to a room where I could test-fit one of the Aurasound drivers.
I tried the speaker first in free air to compare it before it sat in the enclosure.
The difference is impressive! I was quite surprised by the definition of the low end, and like others have said, the natural and open sound they have across the entire range of the speaker.
I didn't really notice any major lack of high frequencies either - they'd definitely work for a television room application, as my wife agreed when she heard them. She was surprised too!
I did listen to each port individually, and noticed that one of them seemed to be 'dead', so I can only guess that there's a leak somewhere. Bah!
Still, my first attempt wasn't particularly accurate in terms of consistent widths of strips of foam core. The second one I'm working on had every strip cut within the same session on my table saw, so creating a seal should be easier!
I tried the speaker first in free air to compare it before it sat in the enclosure.
The difference is impressive! I was quite surprised by the definition of the low end, and like others have said, the natural and open sound they have across the entire range of the speaker.
I didn't really notice any major lack of high frequencies either - they'd definitely work for a television room application, as my wife agreed when she heard them. She was surprised too!
I did listen to each port individually, and noticed that one of them seemed to be 'dead', so I can only guess that there's a leak somewhere. Bah!
Still, my first attempt wasn't particularly accurate in terms of consistent widths of strips of foam core. The second one I'm working on had every strip cut within the same session on my table saw, so creating a seal should be easier!
As an OT post on another thread, I just found out that Gpapag made a Cornu from a pizza box a while back.
More here:
http://www.diyaudio.com/forums/full-range/247598-nautaloss-ref-monitor-2.html#post3742842
Now that is some great re-purposing - very green speakers!
More here:
http://www.diyaudio.com/forums/full-range/247598-nautaloss-ref-monitor-2.html#post3742842
Now that is some great re-purposing - very green speakers!
The 125 is rather bass heavy. It required more stuffing in the throats than other drivers and even so, some might want a tweeter with it. The next one I do, I think I will use the an old Foster 10F3. I think that box is well suited to that driver and it's clones.
George, that's very creative.
I hadn’t thought that these would attract some interest (besides, the pizza is gone )
The spiral is a slightly modified version of Dave’s first pdf (att.1).
First I modified the flare ratio at the initiation of the spirals.
Then I decided on a rigid compression chamber behind the speaker. This is made from a paper cylinder (a section from the core of kitchen paper towel) on which I cut two slits which serve as the throat of the inner spirals.
I hand drew the spirals on A4 paper and then a photocopier enlarged it to fit the size of the pizza box.
I then glued the enlarged drawing at the inner side of the box using lipstick paper glue.
I made the box less acoustically transparent by covering both sides of the paper pack with self-adhesive transparent plastic sheet.
I cut the opening and glued the speaker flange to the box with bathroom silicon. I glued around it the compression chamber.
Then I made the spirals out of packaging paper straps. I used bathroom silicon for to fix the spiral strips over the spiral drawing.
I routed the speaker wire along one of the spiral sides and glued along it’s length.
After all this silicon cured, I cut the spiral mouths at the side flappers of the box and then applying a bead of silicon on the top side of the spiral strips and around the sides of the box, I closed down the lid of the box , then the side flappers.
I trimmed the excess silicon from the sides and bundled the whole box with paper tape and put some books over the box.
Next day I removed the paper tape and let the box in open air for the silicon’s acid smell to evaporate (it takes at least two days)
The 2” speakers are taken out from some dirty cheap(8Euro) computer active speaker units having a usb powered amplifier inside.
I played the cornus with this amplifier and it is a wonder what they manage.
Kudos to xrk971 and Cal for starting and developing the Cornu idea.
George
)The spiral is a slightly modified version of Dave’s first pdf (att.1).
First I modified the flare ratio at the initiation of the spirals.
Then I decided on a rigid compression chamber behind the speaker. This is made from a paper cylinder (a section from the core of kitchen paper towel) on which I cut two slits which serve as the throat of the inner spirals.
I hand drew the spirals on A4 paper and then a photocopier enlarged it to fit the size of the pizza box.
I then glued the enlarged drawing at the inner side of the box using lipstick paper glue.
I made the box less acoustically transparent by covering both sides of the paper pack with self-adhesive transparent plastic sheet.
I cut the opening and glued the speaker flange to the box with bathroom silicon. I glued around it the compression chamber.
Then I made the spirals out of packaging paper straps. I used bathroom silicon for to fix the spiral strips over the spiral drawing.
I routed the speaker wire along one of the spiral sides and glued along it’s length.
After all this silicon cured, I cut the spiral mouths at the side flappers of the box and then applying a bead of silicon on the top side of the spiral strips and around the sides of the box, I closed down the lid of the box , then the side flappers.
I trimmed the excess silicon from the sides and bundled the whole box with paper tape and put some books over the box.
Next day I removed the paper tape and let the box in open air for the silicon’s acid smell to evaporate (it takes at least two days)
The 2” speakers are taken out from some dirty cheap(8Euro) computer active speaker units having a usb powered amplifier inside.
I played the cornus with this amplifier and it is a wonder what they manage.
Kudos to xrk971 and Cal for starting and developing the Cornu idea.
George
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Out of curiosity, I built another pizza box project (same pizza size), this time the construction was of a closed type, the inner volume filled with pillow stuffing.
I compared the two.
Conclusion: There is no turning back.
“Pizza-box” style Cornu is a superior animal, an ideal active speaker system for a teenager’s or student’s room.
Don’t take me wrong. Cornu type speakers can be made to compete with serious speakers.
But it is the new generation that needs easy to build and decent sounding speakers, not us the old guys.
Young people need and would look for cheap, light, small, active speakers to match with their music sources -mobile phones, tablets and the likes- and speakers that take no desktop or floor space.
Cornus offer all these plus an open and balanced sound, not the screamy sound of the cheap PC speakers and flat screen TVs, they can be planned and built in a weekend and can bear the style of the one that builds them.
George
I compared the two.
Conclusion: There is no turning back.
“Pizza-box” style Cornu is a superior animal, an ideal active speaker system for a teenager’s or student’s room.
Don’t take me wrong. Cornu type speakers can be made to compete with serious speakers.
But it is the new generation that needs easy to build and decent sounding speakers, not us the old guys.
Young people need and would look for cheap, light, small, active speakers to match with their music sources -mobile phones, tablets and the likes- and speakers that take no desktop or floor space.
Cornus offer all these plus an open and balanced sound, not the screamy sound of the cheap PC speakers and flat screen TVs, they can be planned and built in a weekend and can bear the style of the one that builds them.
George
Attachments
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George,
Thanks for the detailed account of how you made it out cardboard. I may have to take up the pizza box Cornu next - those drivers you have look ideal for messing with in this application. I have similar ones on these small collapsible Bluetooth speakers. It may be good to make a BT version that wirelessly syncs with a cell phone. Mono is fine and the BT speakers have a 3 watt amp I think. Use a cheap USB to wall plug dongle to power.
What are the dimensions of your pizza box and channel depth?
Thanks for the detailed account of how you made it out cardboard. I may have to take up the pizza box Cornu next - those drivers you have look ideal for messing with in this application. I have similar ones on these small collapsible Bluetooth speakers. It may be good to make a BT version that wirelessly syncs with a cell phone. Mono is fine and the BT speakers have a 3 watt amp I think. Use a cheap USB to wall plug dongle to power.
What are the dimensions of your pizza box and channel depth?
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Internal dims:320mmx320mm, depth 35mm.
Compression chamber diameter 45mm, the two slots are each 7mmx30mm.
I haven’t used any stuffing.
The wireless idea is superb!
George
>Edit: By the way, these speaker units I used in the pizza box Cornu are ideal for diy headphones (tested!)
Compression chamber diameter 45mm, the two slots are each 7mmx30mm.
I haven’t used any stuffing.
The wireless idea is superb!
George
>Edit: By the way, these speaker units I used in the pizza box Cornu are ideal for diy headphones (tested!)
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Interesting!
Please do elaborate, if not in this thread, feel free to contact me by PM.
Thanks!
Some help please
Hi all, I'm a first time builder. I have two of these drivers lying around Dayton Audio ND65-8 2-1/2" Aluminum Cone Full-Range Driver 8 Ohm and want to put them into spiral enclosures.
I would really appreciate some help on the dimensions of the spirals. I have modelled the attached drawing rather arbitralily based on four Fibonacci spirals. I think I'll have the spirals cnc made out of plywood which would make the construction quite easy. I have tried reading up on horn theory but I have to admit its a bit over my head and I am not sure how to change it when you have four horns four throats etc.
The previous arbitrary build I did with these drivers turned out horrible and the speakers sounded worse than my tv speakers, worse than a telephone even so this time I want to do it better. I know I'm not going to get huge bass from them, but would like to get a bit of boost between 80Hz and 100 Hz where it starts to roll off.
I would really appreciate some feedback.
Hi all, I'm a first time builder. I have two of these drivers lying around Dayton Audio ND65-8 2-1/2" Aluminum Cone Full-Range Driver 8 Ohm and want to put them into spiral enclosures.
I would really appreciate some help on the dimensions of the spirals. I have modelled the attached drawing rather arbitralily based on four Fibonacci spirals. I think I'll have the spirals cnc made out of plywood which would make the construction quite easy. I have tried reading up on horn theory but I have to admit its a bit over my head and I am not sure how to change it when you have four horns four throats etc.
The previous arbitrary build I did with these drivers turned out horrible and the speakers sounded worse than my tv speakers, worse than a telephone even so this time I want to do it better. I know I'm not going to get huge bass from them, but would like to get a bit of boost between 80Hz and 100 Hz where it starts to roll off.
I would really appreciate some feedback.
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It's neat that you want to try your own design. However, it's fine to experiment but I would not recommend making it out of wood as an experiment. That is too much investment for something that may not work. Use foam core and the techniques described on this thread - at least you will only lose a day of time and maybe $5 worth of foam core.
If you really want to make it from CNC wood, stick with the Cornu plan - it is proven and there are lots of happy builders out there.
Feedback on your design: what are the dimensions? You have four horns that are the same length. Cornu has two lengths to smooth out response. If you want to get estimate of effect of your horn, approximate by taking the area of the throat x 4 and the area of the mouth x 4 and the length of the path. Put that into Hornresp as a single horn with volume of driver chamber. It should be pretty close as you have simple exponential expansion. My guess is that the spiral length looks too short but can't say without dimensions. For 2.5 in driver, I would use Cornu plan scaled for 16 to 18 in x 2 in deep.
If you really want to make it from CNC wood, stick with the Cornu plan - it is proven and there are lots of happy builders out there.
Feedback on your design: what are the dimensions? You have four horns that are the same length. Cornu has two lengths to smooth out response. If you want to get estimate of effect of your horn, approximate by taking the area of the throat x 4 and the area of the mouth x 4 and the length of the path. Put that into Hornresp as a single horn with volume of driver chamber. It should be pretty close as you have simple exponential expansion. My guess is that the spiral length looks too short but can't say without dimensions. For 2.5 in driver, I would use Cornu plan scaled for 16 to 18 in x 2 in deep.
Thanks xrk971 . Will see if I can find some foam core to experiment with around these parts. The arc length from throat to mouth is 760mm (30 in). To be honest, the reason I went with Fibonacci was simply because the formula was easier to compute for modelling. Will also play a bit with hornresp to see if I can figure it out.
30 inches will not give any bass - you have a mid horn. 30 in quarter wave is 112Hz for straight pipe, with expanding mouth it goes way down - you may get 150 to 180 Hz low end. I would recommend at least double that length. Unless a mid range horn is what you want to build. Just use an exponential expansion fitted to the mouth and throat - may have to do 3 segments with an almost linear from throat to 80 % of length then two more segments with rapid expansion to the opening.
Thanks xrk. I'm struggling a bit trying to figure out what you mean by straight tube, expansion and so on. Mid horn won't do. I played a bit with the parameters for the equation and got the length up to 2538mm (100 in). The throat area is very small (1.5mm x depth of spiral (75mm)) though I'm sure I can get this up a bit without sacrificing the length. I've also attached the SPL response from hornresp (I wouldn't add to much weight to that, I'm still figuring out the program).
I'll keep on playing with hornresp, but I don't relly know what to look for. Should I try to get more length? Should I aim to get the first resonant peak as low as possible?
I'll keep on playing with hornresp, but I don't relly know what to look for. Should I try to get more length? Should I aim to get the first resonant peak as low as possible?
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This stuff. It's not the stuff used for presentations, this is cheap, flimsy and easy to work with.
Bulk Readi-Board Foam Boards at DollarTree.com
Bulk Readi-Board Foam Boards at DollarTree.com
That throat area is too small, it is tough to use an actual function. I found the same problem that it makes the throat too small. Hand draw the spiral based on your Hornresp profile. You want smooth profile with few peaks.
I'm ready to dive into the project and build a 50cm pair for my friend using the Foundtek FE85s and the TPA3116 to be driven from an iphone/laptop.
I was wondering if anyone knew offhand how long the spirals are so I can buy an appropriate amount of Foamcore.
I'm also going to use birch plywood for the front and back panels. Is this an appropriate material and would 6.5mm be too thin?
I was wondering if anyone knew offhand how long the spirals are so I can buy an appropriate amount of Foamcore.
I'm also going to use birch plywood for the front and back panels. Is this an appropriate material and would 6.5mm be too thin?