This is scary,
just chewed about it last week.
And dreamed about using some kind of wood-based
material...
If someone has a cnc mill a large block of wood could easily be hogged out to form back and channels and only baffle needs to be glued on. Overkill but it would be very precise and easy to make.
Hi: Having read this thread I put it on my ToDo list......
First made the mini's 16" with 2 3/8ths tall channels .....with the cheapest 2" speaker I had lying around,
( creative).
It convinced me to try and build a better pair.
.....So now am doing the 20" for 4" drivers, with 4" channels...
I used some 4" JBL's out of 3 way towers and there is no bass so need to order speakers.....
the ones at parts express that would fit are:
Celestion Neodymium 5" Full Range Woofer 8 Ohm 299-416
Visaton FR13-4 5" Full-Range Speaker 4 Ohm 292-518
any advice?
Thank you.
First made the mini's 16" with 2 3/8ths tall channels .....with the cheapest 2" speaker I had lying around,
( creative).
It convinced me to try and build a better pair.
.....So now am doing the 20" for 4" drivers, with 4" channels...
I used some 4" JBL's out of 3 way towers and there is no bass so need to order speakers.....
the ones at parts express that would fit are:
Celestion Neodymium 5" Full Range Woofer 8 Ohm 299-416
Visaton FR13-4 5" Full-Range Speaker 4 Ohm 292-518
any advice?
Thank you.
Attachments
Congo,
Your 20 in x 4 in deep design has a throat area of 44 sq cm. A 4 in class driver has 50 sq cm Sd typical. A 3 in driver is arond 30 to 32 sq cm, kind of small. The TC9FD is 36 sq cm. It's ok for a 50 sq cm driver to push a throat area that is 88% of driver Sd. A MA CHR70 will work very well too.
Your 20 in x 4 in deep design has a throat area of 44 sq cm. A 4 in class driver has 50 sq cm Sd typical. A 3 in driver is arond 30 to 32 sq cm, kind of small. The TC9FD is 36 sq cm. It's ok for a 50 sq cm driver to push a throat area that is 88% of driver Sd. A MA CHR70 will work very well too.
Prez,
Measure diameter from cusp or apex of surround and use formula for area of circle. A=3.1415/4×D^2
I usually published Sd. For throat area, measure gap from plan and multiply by height. If using standard pdf plan from Dave, throat gap is 1.19 in for 27.6 in size. For 20 in size scale 20/27.6×1.19 then multiply by 2 for two throats and then by depth. There are 6.45 square centimeters per square inch.
Measure diameter from cusp or apex of surround and use formula for area of circle. A=3.1415/4×D^2
I usually published Sd. For throat area, measure gap from plan and multiply by height. If using standard pdf plan from Dave, throat gap is 1.19 in for 27.6 in size. For 20 in size scale 20/27.6×1.19 then multiply by 2 for two throats and then by depth. There are 6.45 square centimeters per square inch.
New Implementation - VIFA TC9FD
Reading this Thread and thanks to all the contributors, I decided to build a new 70 cornu speaker with the Vifa TC9FD. The channel depth is 9.5 cm to match the Sd=36cm2.
I mainly followed the building suggestions from the previous post.
What can be of interest is the process to transfer the pdf cornu drawing (thanks to @endia) to the 74x74 ply plate. I used the free software PosteRazor and I created a 74x74 collage done with A4 sheets. See the picture below.
Then I transferred the drawing to the ply using carbon copy paper. That's it.
I'm waiting for the Vifas. Just ordered.
A little bit concerned on closing the speaker with the top ply plate: the internal foamcore strips are not so accurate in width and I cannot grant perfect matching. Any suggestion?
Reading this Thread and thanks to all the contributors, I decided to build a new 70 cornu speaker with the Vifa TC9FD. The channel depth is 9.5 cm to match the Sd=36cm2.
I mainly followed the building suggestions from the previous post.
What can be of interest is the process to transfer the pdf cornu drawing (thanks to @endia) to the 74x74 ply plate. I used the free software PosteRazor and I created a 74x74 collage done with A4 sheets. See the picture below.
Then I transferred the drawing to the ply using carbon copy paper. That's it.
I'm waiting for the Vifas. Just ordered.
A little bit concerned on closing the speaker with the top ply plate: the internal foamcore strips are not so accurate in width and I cannot grant perfect matching. Any suggestion?
Attachments
This is the best gap filler glue I've found. Easy to find, even supermarkets.
Nice for xo parts also.
Amazing Goop All-Purpose Household Goop, 3.7-Ounce Tube #130012 - Amazon.com
Sika makes some great products also: Sika Corporation 90618 Sikaflex Polyurethane Commercial Grade Construction Sealant, 10.1 oz Cartridge: Amazon.com: Industrial & Scientific
Nice for xo parts also.
Amazing Goop All-Purpose Household Goop, 3.7-Ounce Tube #130012 - Amazon.com
Sika makes some great products also: Sika Corporation 90618 Sikaflex Polyurethane Commercial Grade Construction Sealant, 10.1 oz Cartridge: Amazon.com: Industrial & Scientific
Hey all,
I recently resurrected my cornus and checked the in-room frequency response using fuzzmeasure. Overall they measure quite well, and are reasonably flat through their range, however they do suffer from a tremendous suckout between 100 and 200hz. Mounting the speakers closer to the floor aggravated the dip but the location remained the same, so I don't think it's floor bounce; there seems to be cancellation occurring between the various horns. My question is whether or not others have measured this, and if so, if anyone has come up with a solution.
I recently resurrected my cornus and checked the in-room frequency response using fuzzmeasure. Overall they measure quite well, and are reasonably flat through their range, however they do suffer from a tremendous suckout between 100 and 200hz. Mounting the speakers closer to the floor aggravated the dip but the location remained the same, so I don't think it's floor bounce; there seems to be cancellation occurring between the various horns. My question is whether or not others have measured this, and if so, if anyone has come up with a solution.
I was working on a curved tractrix front horn made from foam core and got side tracked. There is math but you can try quick prototypes and almost anything that slowly allows sound wave to have smoother impedance as it propagates forward will help. Maybe I will resurrect this. There are some nice horn design articles on pdf from the 1970's that someone sent me or posted within the foam core thread. It may be GM.