I think the deflector may serve the main purpose of removing a flat reflector to reduce the reflection back to the cone, which for a 4 in deep chamber, may cause a cancellation dip around 1700 Hz? Reducing volume may or may not help depending on Qts of driver and size of chamber.
... And once you have reflected the sound onto the side walls of the chamber, where does it reflect to next? A little will go out through the horn throats, but the majority will reflect onto the parts of the cone visible through the gaps in the basket... 🙂
If the reflector is too small, it will be largely shadowed by the basket and magnet. To be effective, it would need to have 45 degree sides and be the same diameter as the back of the chamber. Take pencil and paper and draw a side view of the chamber with driver, and try to add the deflector. You'll find it will need to be truncated to allow for the magnet. Now add up the volume it takes up, you will see it considerably reduces the chamber volume which will affect the tuning. You'll probably get similar reflection reduction with less effect on the tuning by putting some stuffing in the chamber instead.
But don't think I'm trying to dissuade you. One point of foam core is that it encourages experimentation, right? It's not hard to carve a deflector cone out of a laminated stack of foam core offcuts. (You may need to cut it into "pie segments" to get it in through the driver hole.) Measure the actual frequency response with and without the reflector and see if the cancellation actually occurs and is affected by the reflector. Also check the effect on bass response.
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I'm thinking of carving up a foam ball half into a conical shap. What radius/or/diameter of ball should I start with? The Cornu is a 20"X20" one. The other test will be to see if coating the foam with PVA resin will improve how it works.
Extensive and inspirational read - so now I want to make my own Cornus Spirals 🙂
Already have a pair of 3,5" Vifa TC9FD-18-08 elements on the way in, 6mm black Depron on hand plus 4mm (3/16"-ish ) MDF panels.
The 4mm MDF panels will serve as rear/front panel while the 6mm Depron will act as the curved interiour walls.
Apprently the Vifa 3,5" fit a 51x51cm (20x20") sized cabinet with internal height = 89mm (3.5") IIRC?
Already have a pair of 3,5" Vifa TC9FD-18-08 elements on the way in, 6mm black Depron on hand plus 4mm (3/16"-ish ) MDF panels.
The 4mm MDF panels will serve as rear/front panel while the 6mm Depron will act as the curved interiour walls.
Apprently the Vifa 3,5" fit a 51x51cm (20x20") sized cabinet with internal height = 89mm (3.5") IIRC?
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Halair,
Yes, the 20x20x3.5 inch size works well for the Vifa. You can go as thin as 2.38 inches and it still sounds nice - in case you are looking for low profile wall mounts. What is Depron?
X
Yes, the 20x20x3.5 inch size works well for the Vifa. You can go as thin as 2.38 inches and it still sounds nice - in case you are looking for low profile wall mounts. What is Depron?
X
So the depth of the speaker can vary from 2,4" and up to 3.5?
Pardon my ignorance but what are the pro/con of small vs fat beside form factor?
Pardon my ignorance but what are the pro/con of small vs fat beside form factor?
More bass and mid bass volume with more depth. Bass freq extension doesn't change, just volume. It is not lacking 2.4 in IMO.
Master X- What do you think would be the best height for the channels using the Vifa ne65w-04.
cheers
cheers
Use the Force Luke. 🙂
Get me the TS params and I will run a sim for you to make sure the depth is good.
Get me the TS params and I will run a sim for you to make sure the depth is good.
Prezeden,
The NE65W can work in a 24 in x 1.75 in deep Cornu. The shallow depth is to balance the bass with the lower efficiency of the treble. Even so, you will have about 9 dB of gain in the bass down to 70 Hz and you will need some stuffing to reduce it to match the mids and treble of 86 dB. You will have to watch the excursion because even at 1 watt, xmax is already getting pushed at 70 Hz. Although for average listening, a couple of watts is more than enough. The driver may also have a larger physical xmax limit vs the low distortion xmax.
The NE65W can work in a 24 in x 1.75 in deep Cornu. The shallow depth is to balance the bass with the lower efficiency of the treble. Even so, you will have about 9 dB of gain in the bass down to 70 Hz and you will need some stuffing to reduce it to match the mids and treble of 86 dB. You will have to watch the excursion because even at 1 watt, xmax is already getting pushed at 70 Hz. Although for average listening, a couple of watts is more than enough. The driver may also have a larger physical xmax limit vs the low distortion xmax.
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With a 15month old toddler and a 4 week old boy in the house I dont get a lot of "me-time", despite that I have been able to cut the 20x20" rear/front plates and internal baffles. No ink on the home computer so wasnt able to print the plan for baffle positions. The Vifa's should arrive some time this week 🙂
All parts prepared for the weekend, kids will be with their grandparents so I will have some time to glue these together. Front/rear plates cut to shape and the spiral patterns scribed in place. Hot glue gun in hand saturday... 🙂 Drivers not here yet though....!
Thanks X- It sounds like the NE65W may not be the best driver for this project if I'm understanding you correctly. Can you or anyone else recommend anything else that will work in a 12" Cornu,
Didn't you have great success with the W4 Bamboo from Tang Band in a 24 in Cornu?
Are you looking for a 2 or 3 in driver in a 24in?