Recapping Polk Monitor 10B crossovers

transmaster

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Just ordered the parts from Sonic Craft to rebuild a set of Polk Monitor 10B crossovers I purchased a few months ago. The replacement XO's I purchased from eBay are in much better condition than the originals were, before their rebuild, on the 10B's now. The originals had been DC blasted by a Sony receiver I once had. I know a great deal more about the subject and My service equipment is a vast improvement. This time I am going with Mundorf MCap EVO's, and Vishay Mills resistors. I am spending 1/2 the money I spent rebuilding the originals.

There may be problem with the left side XO right now. It's polarity is not right and it may be triggering my Yamaha AVR to shut down occasionally.

I am going to rebuild these crossers to 10A spec's, the only difference is I am removing and bridging the polyfuse. The polyfuse has a nominal resistance of .5 Ohms so R1 in the 10B is 2.0 Ohms. The 10A which has a 1 Amp fuse R1 is 2.5 Ohms. A 2.5 Ohm 12 watt Vishay Mills is going in. The safety circuitry in a modern audio amp is far better then anything a vintage speaker such as this set of vintage Polks ever had.

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Vishay Mills MRA series resistors.
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These standoffs are much, much better than the originals.

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I've used Mundorf MCap EVO Oils, and they had a long lead and a short lead. I 'assume' one was for the inner foil, and the other to the outer foil. I still don't know which lead was which, and if it even mattered, in a loudspeaker crossover? Hopefully, it won't matter on the Polks?

Oh yea, Parts Connexion carries Mundorf capacitors too. They're having a 25% off sale on caps, through the end of this month. Grab some more EVO's and speakers. A good time for more projects!
 
I looked at Parts Connexion and Sonic Craft is still just a little cheaper on the Mundorf EVO's Sonic Craft also had the Vishay Mills resistor values I needed. I also purchased some Cardas paste soldering flux.

On Mundorf cap's the shorter lead is supposed the foil side. There is smoldering flame war on this issue on some specialized forums. I would like input from Polkies here in this subject. Certainly the XO's schematic show no polarities on the cap's. These cap's will go in the same way just for consistency.
 
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Just read white paper on the subject from Clarity Cap's and according to their research the quality of the manufacturing is the key Clarity says it does not make any difference how they go in.
 
I looked at Parts Connexion and Sonic Craft is still just a little cheaper on the Mundorf EVO's Sonic Craft also had the Vishay Mills resistor values I needed. I also purchased some Cardas paste soldering flux.

On Mundorf cap's the shorter lead is the foil side. As I understand it the foil side goes to the output, however there is smoldering flame war on this issue on some specialized forums. I would like input from Polkies here in this subject. Certainly the XO's schematic show no polarities on the cap's. These cap's will go in the same way just for consistency.

I've used both Sonic Craft and Parts Connexion. Sonic Craft definitely has better prices on the Mundorf caps. But, PC carries some Mondorf series, that SC doesn't. Though, I can't typically afford those! I did get my Mundorf's tested and matched. I felt a little less anal, in wondering if the caps met spec or not, afterwards.

Thanks for the heads up on which lead meant what. I appreciate that. I can't tell which is which, now that the caps are installed. But, I did use the same orientation across the various crossover boards.

Also, good to know that even ClarityCap says orientation doesn't matter. I guess I'm OK then.
 
This is how the XO is going togather, as a 10A

Schematic Polk Monitor 10A
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This is the 10B, note the Polyfuse.
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Hey transmaster, please be sure to post a few photos of your completed crossover if you don't mind.
 
I wonder who's still reading these :) I love Parts Connexion - super speedy shipping and reasonable prices on a great selection, and very courteous service by email and phone. I'm going with Mills 12W resistors and Clarity Caps all around on my Monitor 10B crossovers. So far, so good with the install, but it has not been super easy as I expected. There is a ton of solder on the back of the boards. And as a 34uF cap was not available, I'm stacking a 15uF and an 18uF, and the arrangement is difficult to manage vertically with zip ties. Splicing the leads together and adding longer solid core wires for maneuverability was not fun for me - first time for everything! The 12uF cap that mounts with a resistor is also sitting pretty high, as are the other resistors, which I suppose can only be good for better heat dissipation, if there is any heat in there. I have an ultra-low temp glue gun to secure things, but with only one new cap actually contacting the board, I'm not sure if I'll bother. Does anyone know from peaking into the cabinets later whether there is any movement of components over time with these big, modern caps? I'll post photos asap. Thanks!
 
Thank you F1nut :) I’ve been doing well with a solder wick to clean the board. With a few of the components raised, I’ll have to be crafty to find a way to secure them. Putting wood or foam beneath them should be possible, but awkward. The Sonicap 34uF was pricey, hence the bundled Clarity Caps. They are not touching the board. I could get one edge of the lower cap to touch, but that would then rub the 12uF next to it. Is anyone rebuilding these or other Polk Monitor crossovers on a wood board to put in the bottom of the cabinet? That would probably allow for everything to be nicely spaced and secured.
 

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Thank you F1nut :) I’ve been doing well with a solder wick to clean the board. With a few of the components raised, I’ll have to be crafty to find a way to secure them. Putting wood or foam beneath them should be possible, but awkward. The Sonicap 34uF was pricey, hence the bundled Clarity Caps. They are not touching the board. I could get one edge of the lower cap to touch, but that would then rub the 12uF next to it. Is anyone rebuilding these or other Polk Monitor crossovers on a wood board to put in the bottom of the cabinet? That would probably allow for everything to be nicely spaced and secured.
I highly suggest you check lout the Polk Audio forum, lots of great information there from a lot of highly experienced in all things Polk inhabit, including some of the fine folks here at AudioKarma.org. :angel:
 
Thank you F1nut :) I’ve been doing well with a solder wick to clean the board. With a few of the components raised, I’ll have to be crafty to find a way to secure them. Putting wood or foam beneath them should be possible, but awkward. The Sonicap 34uF was pricey, hence the bundled Clarity Caps. They are not touching the board. I could get one edge of the lower cap to touch, but that would then rub the 12uF next to it. Is anyone rebuilding these or other Polk Monitor crossovers on a wood board to put in the bottom of the cabinet? That would probably allow for everything to be nicely spaced and secured.

My suggestion, make new boards wired point to point. I like to use FR4, but there are other good choices.
 
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