Inductor Orientation

xschop

Gathering parts to build a Point-to-Point for my last set of 5Jr's. Just want to make sure the inductor positions look OK and that it is kosher to have the 0.56mH MW inductor isolated by a sleeve and captured by 1/2" diameter non-magnetic alloy?

F1nut

Looks ok.

VR3

You don't want the inductor lying flat against aluminum unless it is minimum 3/4" away

westmassguy

Keep this handy

xschop

VR3 wrote: »

You don't want the inductor lying flat against aluminum unless it is minimum 3/4" away

So, the Delrin sleeve thickness was only going to insulate it away from the alloy by 1/4" in drawing. I can lengthen it.. I was also wondering if the alloy center shaft was a problem?

Keep this handy
zbfsjld2f99k.png

There it is, I remembered #6, but couldn't remember where we previously discussed it here. Thanks WMG!

VR3

In my experience, if you run the inductor perpendicular to aluminum, it makes little too no difference.

If you run it parallel, right up on it almost cuts the value by 40%

This reduces dramatically at 5/8 to 3/4 of an inch

VR3

Alot of manufactures use brass bolts to mount inductor, I've never measured to see what effects the are and if you need to account for a change

Gardenstater

So,........if you turn WMG supplied picture 90deg to the R, what you have in your XO is exactly like #5, which is PROBLEMATIC ?

VR3

You wouldn't hear it

pitdogg2

.

xschop

Thanks Tre, I'll play it safe and move inductor to top board and large cap underneath. I'm just trying to get the height of the assembly as low as possible.
I appreciate everyone's input and experiences as always.

xschop

So mocking it up, I can get the MW inductor 1.5" away from billet plate, have perfect position to binding posts, but tweeter inductor will be only be 1/4" away from MW inductor....Or should I move tweeter inductor laterally left or right?

westmassguy

About the best you can do with what you have, is to swap the resistor and inductor location. It sucks, but you're only other option as I see it, is to do a second tier

xschop

Working on getting #6 orientation and having only 2.5" tall crossover....

xschop

Nothing like watching glue dry. I think I like this point-to-point method, you can adjust where needed and you don't have to scour for old x-over donors from that site that sells curb trash with added shipping....

Gardenstater

I think it's pretty CLEAR what you are doing here.......

VR3

Lookin good

xschop

Thanks Trey and WMG. I got it worked out finally. I can respect you guys that do this tedious work and make it look great. The solid copper tubular rivets I used worked out nicely going thru the 1/4" plexiglass with Cardas Litz 15.5g and the various capacitor and inductor lead diameters. I could have gotten it about 1/4" lower if I cut the posts down, but the suspended soundbarrier mod will still clear even the taller standing tweeter inductor. I got the tweeter resistor suspended how I needed also....

xschop

While perusing the hobby store last week for more PVA gasket donor sheets, I stumbled upon these hard expanded foam cones. Wish I knew about these when I built the custom CRS's...
I'm not sure which other Polk monitors have their X-overs directly behind a Midwoofer, but I can highly recommended doing this mod on the 5Jr's or the SDA-CRS where they do have this problem.

I tested out the Aileens and Powergrab. Neither degrades or eats at the foam material, but Powergrab is more viscous and holds everything in position immediately.

**EDIT** I didn't take a pic, but I did apply a layer or Powergrab between cone and sticky butyl mat to ensure adhesion to very porous cone material.

I cut cones to 3" length so sound barrier foam will set @ 1/4 away from tweeter inductor...
I used 5/8" open cell layer, butyl mat layer (holds the foam layers stiff/flat), 1/8" PVA foam layer, then another 5/8" open cell layer cut in @ 6.5" diameter circle...