NSB wiring and phase plugs...

[nerd of nerds]

hello! i've had a case full of those 4" pioneer buyout drivers sitting in my basement for about a month now and i decided that it was time to build some arrays!

i've been experimenting with coatings on the cones to tame that 7khz peak and i think that i have...at least i can't tell its there anymore...


but after various mods i'm left with only 28-30 woofers so i'm saving some for a PC surround system and the rest are going towards my arrays...

there will be 12 nsbs per side and i'm a little confused on how to wire it... i need it to be around 8 ohms...

also, on the parts express page it suggested drilling a 1/4" hole in the dust cap but it seems like adding phase plugs would be much easier than accidentally stabbing in the dust cap 32 times and having to order another case of these

what would the easiest method be to make about 24 phase plugs cheaply and quickly?

i had the idea of making 1 out of clay then making a mold out of it and casting some resing phase plugs filled with copper BBs so that it would magnetically atatch itself to the woofer

but i'll wait until i get some more ideas until i start on that...


thanks!

[John Sheerin]

Copper is not a ferro-magnetic material. I'd try something else if you want it stuck on there... Also, if you use something that is a magnetic material like steel, it will change the flux path around the gap. This might be good, but it would more likely be bad. Le would probably go up, BL would probably go down a little. The easiest way might be to make wooden plugs - find a dowel rod of the right size and cut a bunch of pieces off, etc. Stick them on with a dot of CA or something so you can pop them off if you decide you don't like them.

[kestrel200]

What coating did you find worked best?

[minitruck_freq]

what is the purpose of a phase plug?

[nerd of nerds]

Originally posted by John Sheerin
Copper is not a ferro-magnetic material. I'd try something else if you want it stuck on there... Also, if you use something that is a magnetic material like steel, it will change the flux path around the gap. This might be good, but it would more likely be bad. Le would probably go up, BL would probably go down a little. The easiest way might be to make wooden plugs - find a dowel rod of the right size and cut a bunch of pieces off, etc. Stick them on with a dot of CA or something so you can pop them off if you decide you don't like them.

hmmmm...then these copper BBs must not be all copper...they stick in there pretty well...i have to use pliers to gem em out...

and a "dot of CA"? please explain...

and i have just been experimenting with different ammounts of watered down elmers glue...i think that 2 coats works well...but i'd recomend that you experiment a little...

a phase plug redirects frequencies...and i would guess that unless the driver was vented it would allow for more excurstion than a dust cap...i think...



any ideas on how to MAKE the phase plug?

[RJ]

Someone on another thread made phase plugs out of a copper rod used for electrical grounding. I don't have the link. Should have saved it.
He also painted the cones and covered the back of the frame and magnet with rope caulk.
CA stands for Cyano something. Crazy Glue.

[John Sheerin]

Get a lathe and turn them. Or make friends with a machinist. Aluminum is super easy to work with on a metal lathe. Or cast them from aluminum - one step. Or like I said, carve up a dowel rod. Just cut a 4-sided pyramid with a bandsaw, maybe.

CA stands for cyanoacrylate (sp?) - super glue.

[x. onasis]

Tho' I do like the "get a machinist buddy to do it" idea...., how about using a router, table and roundover bit to "pencil sharpen" a wooden dowel, then cut it to length?

We're talking about a 5/8" dia. (I think)
Drill an appropriate sized hole in a two-by board, then rip it to a size where, when the material is removed for the cutter bit itself, it can be clamped to the router table. You can then, gently push the dowel down into the hole and "sharpen" the end. After cutting to length, insert a washer/screw to magnetically attach or glue. (I'd put a large clamp on the dowel to limit the depth of cut and give yourself a handle to slowly turn it)

For wiring, check Dr. Griffin's Figure 12, pp 22

[RJ]

Good idea about that router table and pencil sharpening dowels.
i'm going to try that.
Another web site on wiring arrays;
http://www.ratch-h.com/arrayimpedance.html

[thomas997]

Originally posted by x. onasis
Tho' I do like the "get a machinist buddy to do it" idea...., how about using a router, table and roundover bit to "pencil sharpen" a wooden dowel, then cut it to length?

Excellent idea.

Need to find some thick dowel though