1992 Polk Monitor 10 Series 2 Crossover Upgrade

kennycrippen

kennycrippen

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I've been researching upgrading the crossovers in my Polk Monitor 10s for awhile. I've upgraded the tweeters to RD0-198s but have decided swapping the capacitors would also be a fun project and from what I've read will improve the sound even more.

So far I haven't been able to find a schematic that's specific to my speakers. The closest I've found is in a thread over in the Polk forum on a set from 1990: https://forum.polkaudio.com/discussion/190873/monitor-10-series-2-crossover-upgrade

As you can see from the attached photos, mine are a little different. The 27 uF and 12 uF caps are straight forward. What I'm unsure of is the yellow cap with the blue 12 uF cap on top. The yellow looks to have 14J 100V on the side but I can only see half of the numbers.

What should I be replacing the yellow cap with blue 12uF cap on top with? Other forums suggest 16uF there, and that's what the 1990 schematic suggests, I'm just not sure if my 1992 pair should take a 16uF there as well.

Also curious what the best way is to cut through the existing hot glue once I get to that step. I'm extremely new to this so please bear with me. Thanks!

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Use denatured alcohol to remove the glue. Apply with a Q-tip and keep the glue wet. After 5 minutes or so you should be able to peel the glue off.

You will then be able to read the value of the yellow cap. Add the value of the yellow to the blue cap to obtain the total value for that location.
 
Thanks F1nut, had a feeling you might show up. :banana:

Assuming the yellow one is 14, then I’ll need a 26uF cap there, which doesn’t seem to be available as far as I can tell. Would using 27 be okay?

Is the yellow cap with the 12 stacked on it the one that leads to the tweeter? If so I was thinking of getting a Sonic Craft for that one and going with cheaper caps for the other 2.
 
A method I've used to remove hot glue is by freezing it. I take a can of compressed air used for cleaning keyboards, etc. I hold the can upside down with the straw inserted in the button and spray the blob of hot glue. Once it's frozen it breaks off in pieces easily.
 
kennycrippen said:
Thanks F1nut, had a feeling you might show up. :banana:

Assuming the yellow one is 14, then I’ll need a 26uF cap there, which doesn’t seem to be available as far as I can tell. Would using 27 be okay?

Is the yellow cap with the 12 stacked on it the one that leads to the tweeter? If so I was thinking of getting a Sonic Craft for that one and going with cheaper caps for the other 2.
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It looks like it is a 27uf cap in the picture, not a 26uf?
Also RDO-198's? I used RDO-194's in my 10's. Maybe there is a different version of the 10's that will work with the 198's? Polk made so many changes on the fly.
Thats a different crossover than what's in my 10's.
 

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Lavane said:
It looks like it is a 27uf cap in the picture, not a 26uf?
Also RDO-198's? I used RDO-194's in my 10's. Maybe there is a different version of the 10's that will work with the 198's? Polk made so many changes on the fly.
Thats a different crossover than what's in my 10's.
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Mine are the later Monitor 10 Series 2 which came with the SL2500 tweeter. The RD0-198 is a direct replacement for those. The older 10s had varying tweeters which I believe the 194 is a replacement for (can't remember exact matches at the moment).

Yes, there is a 27uF cap in the photo, as well as two 12uF caps. Regarding the 26uF value, I was referring to the big yellow cap with the blue 12uF cap stacked on top of it. The yellow one appears to have a value of 14 (but I need to remove the glue to verify for sure); 14 + 12 = 26uF. F1nut suggested adding the value of those two caps and swapping in one cap with the new value.
 
Being 1uf off up or down isn't a big issue really. The electrolytic caps used back then didn't have as tight tolerances as they do today. I replaced a 34uf cap with a 33uf cap and didn't hear any difference. I've used 6.8uf in place if 7uf, etc in the past.
 
F1nut said:
I doubt that is a 14uF. More likely a 4.

The denatured alcohol proceedure is tried and true. The glue will peel right off.
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Is that yellow one the tweeter cap? I’ll get around to the glue this weekend perhaps. Not ordering anything until I verify.
 
I took apart the other speaker tonight and the value of the yellow cap was visible thankfully. :) Looks like 4.4 uF so I'll get a 16 uF cap to replace the yellow along with the blue one stacked on top of it.
 

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Resurrecting this thread here. How did everything turn out kennycrippen? I have the same speakers and would like to do the same. Where did you order your caps? It looks like I need a 27, 16, and a 12 uf cap for each speaker?
 
tfresh said:
Resurrecting this thread here. How did everything turn out kennycrippen? I have the same speakers and would like to do the same. Where did you order your caps? It looks like I need a 27, 16, and a 12 uf cap for each speaker?
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Don't forget to replace the resistors as well. Vishay-Mills are a good choice.
 
F1nut said:
Don't forget to replace the resistors as well. Vishay-Mills are a good choice.
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P.E. should have the values you need. :thumbsup:
It was much easier to find them on P.E.'s site than it was slogging through Digikey's or Mouser's site. It took me no time at all to find the resistors for my 10's crossovers.
 

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Lavane said:
P.E. should have the values you need. :thumbsup:
It was much easier to find them on P.E.'s site than it was slogging through Digikey's or Mouser's site. It took me no time at all to find the resistors for my 10's crossovers.
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Thanks guys,
Do you have a shopping list of the brands and parts I should order through parts express? I saw that sonicaps would cost about $400 if I got it through sonic craft.

And daaaang, that crossover looks crowded. Is it hard to stuff all the new components on the original board?
 
You may have to lengthen the leads. I used snipped of bits of lead or 20-22ga. wire and solder them to the leads on the caps or resistors. Then cover the exposed leads with shrink tube. You can omit the shrink tube as long as the leads aren't touching anything else. You want precision wirewound resistors, not the white brick types. You may have to unsolder one or more wires from the PCB to be able to lift it up enough to get to the back side. That's what I did. I just used an Audyn 33uf polypropylene film cap to replace the 34uf cap. It's well within the tolerances of the original cap. They're a lot cheaper than the Sonicaps. I couldn't hear any difference from the original 34uf cap. I used a Dayton for the other. You can use Solen, etc. Everyone has there go to brands of caps. I left the Blue Mylar cap that was originally there. Some replace them with polypropylene film caps.
The speakers sound good, I'm happy with them.
 
tfresh said:
Resurrecting this thread here. How did everything turn out kennycrippen? I have the same speakers and would like to do the same. Where did you order your caps? It looks like I need a 27, 16, and a 12 uf cap for each speaker?
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Just now seeing this @tfresh Wonder if my email notifications shut off when AK swapped to the new site. Anyway, yes, 27, 16, and 12 are what I’ve got. And I still haven’t gotten around to installing, so I may be the one asking you how things turned out lol. 3 small children take priority many times over my hobbies. I went with Sonicap gen 1 for the 27 and Jantzen for the others. Sounds like I should order resistors as well once I get around to this project. My Sansui will be headed to the shop soon which will be a good time to take my Polks apart. :)
 
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