Original Owner Of Monitor 5JR Plus

melchionda

I’m working on the crossover. I have two questions.

1.). Im using red and white wire. Which one is positive and which one is negative?

2.). With inductors, is there a direction in which they are supposed to be hooked up? One wire seems to come from the outside and the other wire is from the inside of the coil. Is one considered “in” and the other considered “out”?

3.) I was planning on putting the crossover up in the top of the cabinet on the back wall behind the tweeter. Is that a good place to put it? It looks like the crossover panel is going to be about 5" wide and about 8" tall.

F1nut

Why in the world are you twisting the lead wires!?!

RTally

And don't bend the leads right where they come out of the capacitor body. The leads should come straight out and if they need to have a bend, it should be a short distance away from the cap body so that the sealed end of the cap is not stressed. I generally position needle-nose pliers on the lead next to the cap and then bend the lead as needed.
When laying out the leads for soldering, it is best to make the solder joint away from the component body. Caps are sensitive to heat. If the soldering point is close, use a heat sink (pliers work, metal spring-loaded clips work best) on the leads between the joint and the cap. Good soldering technique is crucial. Apply heat only long enough to form a good joint.
I prefer to assemble the components on a board first. Masonite, perf-board, or plywood will all work. Secure the caps with tie-wraps or clamps. Some will use hot glue, but did I mention heat is bad for caps? Space the resistors away from the board and other components at least 1/4" inch to avoid heat from the resistors burning the board or the other components. By laying out the components on the board first, the component positions are fixed in place before soldering. Doing what is shown in the picture, that is, connecting all the components before attaching to a board, can result in undue stress on the component leads.
There is no polarity with coils. There is no in or out. But the orientation of adjacent coils is critical to avoid cross-coupling of the coils.

xschop

I was wondering why you had the mount holes taped. How did you get this thin layer of RTV applied evenly as the flange gasket? I like this method.

melchionda

Regarding my crossover build technique I am using the same technique that Danny Richie uses at GR Research. I size my board based on the size of the resulting crossover network. It turns out to be about 5”x7 or 8”. I’ll be using zip ties. I will not be using any hot glue because zip ties are good enough. The leads on my caps are very heavy gauge and if you hold the lead with one plier while twisting with the other plier then it will not break.

PS- If anyone is willing. I’m still interested in answers to my questions posted above about potential crossover location and color code of the wires. Ie- red and white vs red and black. (I guess black and white are interchangeable?)

melchionda

xschop wrote: »

I was wondering why you had the mount holes taped. How did you get this thin layer of RTV applied evenly as the flange gasket? I like this method.

I had the holes covered because when I spread the sealant I didn’t want it to go through the holes and come out the other side. I used a “glue spreader” from Amazon:

30Pcs Glue Spreaders, Colored Polypropylene Glue Smear Sticks Applicator Easy Clean Glue Spreaders Painting Scrapers for Handmade DIY Art Leather Craft Tool https://a.co/d/7cOUohs


I spun the driver as I spread it. The original gaskets for the base drivers were totally spent and so I couldn’t reuse them. Plus the sealant acts as a damper along with the dynamat.

pitdogg2

My question to you is, Why would you use RED for anything BUT positive? Seriously I'm dumbfounded that you have a schematic right in the picture with +RED .....

I realize Polk used black for positive and white for negative, so obviously you would use the WHITE for the negative. In the real world of wiring both red and black used 99.8% for POSITIVE.

So yea I would use white for the positive ...... no question!

joebass3

...

melchionda

pitdogg2 wrote: »

My question to you is, Why would you use RED for anything BUT positive? Seriously I'm dumbfounded that you have a schematic right in the picture with +RED .....

I realize Polk used black for positive and white for negative, so obviously you would use the WHITE for the negative. In the real world of wiring both red and black used 99.8% for POSITIVE.

So yea I would use white for the positive ...... no question!

Because in some wiring scenarios (like in Romex) the wires are Black and White. I'm just wanting to make sure as this is the first time I am doing this. Thanks for your help!

Gardenstater

The convention for AC wiring is Black = Hot and White = Neutral. Polk used Black for + and White for - in all the non SDA speakers (which had blue and green wires also). It is like they were following AC convention, which audio signals are, more or less.

melchionda

pitdogg2 wrote: »

So yea I would use white for the positive ...... no question!

Wait... so white is positive?

pitdogg2

melchionda wrote: »

pitdogg2 wrote: »

My question to you is, Why would you use RED for anything BUT positive? Seriously I'm dumbfounded that you have a schematic right in the picture with +RED .....

I realize Polk used black for positive and white for negative, so obviously you would use the WHITE for the negative. In the real world of wiring both red and black used 99.8% for POSITIVE.

So yea I would use white for the positive ...... no question!

Because in some wiring scenarios (like in Romex) the wires Black and White. I'm just wanting to make sure as this is the first time I am doing this. Thanks for your help!

In your same scenario using 12/3 with ground you have black and red, both being designated hot or positive.

F1nut

The original gaskets for the base drivers were totally spent and so I couldn’t reuse them. Plus the sealant acts as a damper along with the dynamat.

The original gaskets are supposed to be paper thin. Using something that creates a damper/cushion between the basket rim and the bezel is the exact opposite of what you want.

I don't care who does it, twisting the leads is a lazy/bad idea.

xschop

What Sean did here was a great job.
I wanted to have gaskets this thick stamped out but the shop wanted a minimum 1000 part order, so I just glued the 2mm PVA foam to my baskets. This renders them more inert and has positive sealing and most importantly, re-usable...and EASY to install too lol

Gardenstater

Looks like "just a schmear" 👍

MrGeology

melchionda wrote: »

Wait... so white is positive?

Yes. I didn't realize Polk used the AC wiring standard until actually rebuilt one of the crossovers either.
Having been a member of IBEW since the early 90's though, it made sense when I realized what they were doing.

melchionda

F1nut wrote: »

The original gaskets for the base drivers were totally spent and so I couldn’t reuse them. Plus the sealant acts as a damper along with the dynamat.

The original gaskets are supposed to be paper thin. Using something that creates a damper/cushion between the basket rim and the bezel is the exact opposite of what you want.

Interesting. What is the point of the gasket? I thought it was to seal the enclosure. The original gaskets didnt hold up very well and are difficult to install even for the Polk factory workers. I know this because I’m the original owner of these speakers and when I removed the drivers (for the first time) two of the gaskets were not seated properly and one was broken.

xschop

Black or Billet?

melchionda

Nice! I’m going to go with the black for both. I can’t wait to hear how these sound!

xschop

Ill have a fresh set of RDO plates done and painted Sunday.
Looking forward to completed pics as well.

F1nut

melchionda wrote: »

F1nut wrote: »

The original gaskets for the base drivers were totally spent and so I couldn’t reuse them. Plus the sealant acts as a damper along with the dynamat.

The original gaskets are supposed to be paper thin. Using something that creates a damper/cushion between the basket rim and the bezel is the exact opposite of what you want.

Interesting. What is the point of the gasket? I thought it was to seal the enclosure. The original gaskets didnt hold up very well and are difficult to install even for the Polk factory workers. I know this because I’m the original owner of these speakers and when I removed the drivers (for the first time) two of the gaskets were not seated properly and one was broken.

It doesn't take much to seal the driver/cabinet, hence the paper thin original gaskets. The idea is to make the basket rim one with the bezel. When there is a cushion between the two it causes a smearing of the mids.

I've opened countless vintage Polk speakers over the years and have never seen an improperly seated or broken gasket.

xschop

The durometer of what he used is spot on for sealing and no "cushion" in between.

When I pull the 5Bs back out of storage for their focus rings, I'll be making a set of gaskets with this durometer to accompany the pre-loaded tension rods I have designed.

melchionda

Is there a typo on this crossover diagram? Look at the tweeter. Shouldn’t the positive and negative symbols at the tweeter be the opposite of what they are?

Gardenstater

It looks like 1st order low pass for the woofer (-45deg at the crossover point) and 2nd order high pass for the tweeter (+90deg at the crossover point). They must have decided that it sounded better that way because of the phase of each driver at the crossover point.

https://download.phoenixphorum.com/TechSupport/X-Over Chart.pdf

xschop

The 5Jr's I built were like that too.

pitdogg2

In some XO 's the phase shifts 180°, to remedy that the tweeter is then hooked out of phase to bring it back into phase with the drivers.
The RTA 12's are well known for this.

xschop

Got a few sets ready yesterday with 3 coats flat-black and a sun-bake...

pitdogg2

xschop wrote: »

Got a few sets ready yesterday with 3 coats flat-black and a sun-bake...

Damn those look great Rob!

F1nut

They do look good

melchionda

Instead of using the plastic clips to secure the speaker grill to the front baffle I decided to go with Neodymium magnets. I purchased and installed 5/16" x 5/16" magnets into the existing holes on the front baffle and the speaker grill. The magnets do a great job of securing the speaker grill.

The Neodymium magnets are nickIe plated and are super shiny, so I wanted to cover them. To do this I pushed the magnets into the particle board just a little deeper than the surface. I then used a hole punch on the walnut veneer scraps to create small circular patches to cover the magnets. Obviously its not perfect, but from a few feet away the small walnut circular patches do a good job of hiding the magnets.