I need help with updating the crossover in my Polk model 10 speakers.

tomthomas20

I have a pair of Polk model 10 speakers that I am replacing the vinyl veneer with wood veneer. I would also like to up date the crossover.

- I need a schematic.
- Opinions on which brand of capacitors to use where.
- Does everyone agree on Mills resistors for replacements ?

I attached a picture of the crossover, tweeter, and the back of one of the speakers. I think it is great that the knowledgeable people on the site take the time to answer questions of newcomers to the Polk community. Thank you in advance.

Gardenstater

The veneer looks fantastic! Nice continuation as it wraps around.

Do those fuse blocks also have hidden wire attachment points on the mounting surface side?

Personally, I would wait until @xschop semi rings are available for your MWs rather than installing hurricane nuts at those locations. I would only use them at the passive radiator (use all 8 holes) and the tweeter (why not?). I know there is a brace in the center but I wouldn't be surprised if you got a pretty substantial SQ benefit in the bass, slam-wise.

Gardenstater

No worries. You just won't have the hidden wires look anymore. At least if the attachments corrode you can fix it easily. Who looks at the back of the speaker?

StantonZ

tomthomas20 wrote: »

I need a .2 ohm resistor to replace the fuse. Is there a certain wattage I should get? Or should I order a different resistor that is .2 ohms greater to put in the crossover (like I should have done in the first place)? If so, which resistor do I change? The 2.7 ohm or the 2.5 ohm?

These guys are giving you fantastic guidance, but I wanted to add something about the fuse.
If you decide to replace it, use a separate .2 Ohm (at least 5W) resister; in other words, don't modify/increase the amounts of the other resistors (they are doing different things, electrically speaking). As a reference, I replaced the poly-switch (re-settable fuse) in my 10B's with a .5 Ohm resistor with good results. And I used SoniCaps for all capacitors.

Faustin

I would suggest getting the dacron fill up above the passive radiator. Roll up each "leg" and staple/tack it in place so it will not fall back down. And, nice job bringing the speakers back to life.

Gardenstater

Wow. 7 months earlier production date than mine but mine are 7B's. The answers will most likely by Sonicap capacitors, Vishay-Mills 12W resistors, eliminate the fuse if you have an amp that you trust with sufficient power to never get close to clipping, up the tweeter resistor by 0.2 Ohms if you remove the fuse to compensate for the cold resistance rating of 190 mOhms of the littlefuse fuse. I'd go with Cardas Binding posts if I did it again, as well as Cardas Litz and Neotech UPOCC solid for my MW's with gold plated brass fastons for the driver connections. Your best bet is to snip the tweeter wires to a length of 1" or so to avoid damaging them by desoldering, unless you are very confident with a heat sink clip and can work quickly. Even still it is hard to remove the traces of solder. I put male fastons on the short 1" leads.

PS: Your magnet seems off center relative to the pole piece. Check for voice coil rubbing. Something *may* have shifted.

Navy_Goat

Crossover schematics are in a sticky at the top of this section.

https://forum.polkaudio.com/discussion/38755/polk-audio-speaker-wiring-schematics-amp-more-all-models-except-sda#latest

Gardenstater

Earliest schematic is Nov 1984 IIRC. OP has different tweeters and MW's and everything is different.

tomthomas20

Thank you for all that good info Gardenstater. I will take a closer look at those speakers.

F1nut

tomthomas20 wrote: »

I have a pair of Polk model 10 speakers that I am replacing the vinyl veneer with wood veneer. I would also like to up date the crossover.

- I need a schematic.
- Opinions on which brand of capacitors to use where.
- Does everyone agree on Mills resistors for replacements ?

I attached a picture of the crossover, tweeter, and the back of one of the speakers. I think it is great that the knowledgeable people on the site take the time to answer questions of newcomers to the Polk community. Thank you in advance.

The values are printed on the components. You are much better going off what is on your crossover than a schematic as Polk often changed things on the fly.

tomthomas20

I can read two of the three,12 and 34, but the 3rd has glue over the value.

Navy_Goat

Both the original and rev1 M10 schematics call for 2x12uf and 1x34uf so what you can see checks with both versions. I definitely agree that assuming they are unmolested (which seem to be the case) you would be best served to replace with exactly what is on the board.

F1nut

tomthomas20 wrote: »

I can read two of the three,12 and 34, but the 3rd has glue over the value.

So, remove the glue!!!

Gardenstater

Maybe they later paired the MW6501's with the SL1000 whereas in his earlier models they had the MW6500's paired with the Peerless and this was done without making any XO changes. That would be interesting.

tomthomas20

I didn't think I could remove the glue without making the value underneath it unreadable, but it worked, It is 12uF. Are the two 12uF capacitors different types (the yellow and long black one) and if so what is the best replacement for them?

Gardenstater

The yellow one is a mylar film type and the black one is an electrolytic. People are going to probably advise Sonicaps or maybe Clarity Cap CSA. You'll save a lot with the Clarity Caps and they might be as good or better. No personal experience. You can't get a 34 in the Clarity Cap, only 33. Sonicaps have gotten pretty sky high in price.

F1nut

tomthomas20 wrote: »

I didn't think I could remove the glue without making the value underneath it unreadable, but it worked, It is 12uF. Are the two 12uF capacitors different types (the yellow and long black one) and if so what is the best replacement for them?

I wouldn't steer you wrong.

Sonicap Gen I or Clarity CSA for the caps. Vishay-Mills for the resistors. Sonicap has the exact values for vintage Polk speakers, Clarity doesn't. Your choice.

tomthomas20

Thank you very much I will start ordering parts.

Gardenstater

tomthomas20 wrote: »

Thank you very much I will start ordering parts.

Cool! Try to keep the voltage ratings for the caps at 200 or 250V because those are going to be large enough! You'll see.

So, just to be clear you are saying that your speakers have the same resistors (as well as capacitors) as in that 11/26/84 schematic with different drivers, right?

Whatever resistor is inline with the the tweeter fuse, electrically, you don't want to forget to up that value by 0.2 Ohms if you are removing the fuse blocks so it doesn't sound too bright.

tomthomas20

The 1984 schematic looks like the crossover I have. (same values)

I think I would like to keep the fuse in the circuit just
to be on the safe side.

I ordered the capacitors this morning and I believe they are rated at 250v.

I will post pictures as I go I am working on the wood veneer till the parts come in. I may need some advice with mounting the parts for the crossover.

F1nut

The wire to the fuses could look like this. Not good.

Gardenstater

You might want to get a 0.2 Ohm resistor to replace the fuseblock rather than upping the value of the resistor in the contour network, which might mess up that for you. @westmassguy ?

They do have them but it will add $16 to your build.

https://www.soniccraft.com/product_info.php/020-ohm-mills-mra-12-p-4468?osCsid=944a4d0f6cd08eb5bc5ea69220a7a886

tomthomas20

I removed the crossover circuit board so I could get a good look at the back of the fuse block and attached the picture. It looks pretty good to me and this is without me doing any cleaning with deoxit. What do you guys think?

tomthomas20

tomthomas20

Clipdat

I would just remove that fuse altogether.

Gardenstater

tomthomas20 wrote: »

I removed the crossover circuit board so I could get a good look at the back of the fuse block and attached the picture. It looks pretty good to me and this is without me doing any cleaning with deoxit. What do you guys think?

Well......ummm......to be completely and brutally (😂) honest it looks like it is much more tarnished than mine ever was. Nothing a nice cleaning with some 1500 grit sandpaper or crocus cloth won't cure! The fuse ends should be nice and shiny. The brass is very bad.

Your walnut veneer is looking great so far!

I've never seen anyone solder on the speaker wires. Did your Dad lose his binding post nuts? Solder has a lot more resistance than copper or brass does, even nickel plated brass. Better to use bare wires than do that but I would go with some nice spades or even ring terminals or bananas.

RTally

tomthomas20 wrote: »

That fuse and fuse holder look nasty. More importantly, you don't show the back side connections to the fuse holder.

I agree with Clipdat. Just remove the fuse and holder from the circuit.

Gardenstater

I rewired my fuse blocks with Cardas because I was nervous about my old, probably unserviced amp. Just temporary until I do get a nicer and newer amp some day. I was concerned that the plastic would melt some and the rivets would loosen but they didn't. However, I started fresh with some identical fuseblocks I found on eBay that were not ever used for speakers and the rivets were never soldered to. I had to spot drill them for the end of the wire but then they soldered up very easily. In your case you would have to desolder (with flux) and clean up and flux and resolder. More time to possibly melt something.

Because their tendency in the shop was to gob everything up with beige colored hot melt glue, there is nothing to see on the inside without removing all of that stuff with a small chisel, or the like. Once you have done all that it doesn't make sense to not rewire it or remove it. The solder will be intact and that joint will be electrically sound. You will probably see some green tarnish on the strands but mine was really not very bad to be honest and I saw none. I just wanted better quality larger gage wire.

tomthomas20

I need a .2 ohm resistor to replace the fuse. Is there a certain wattage I should get? Or should I order a different resistor that is .2 ohms greater to put in the crossover (like I should have done in the first place)? If so, which resistor do I change? The 2.7 ohm or the 2.5 ohm?
Which Cardas Binding post should I get? I don't know who soldered the binding post. I assumed it was original.
Thanks for all the input, even if it is brutally honest.

Gardenstater

Same fuse I posted above, 12W to keep the thermal noise level down. Like I was saying, I *think* on second thought that you don't want to up the resistor that is in parallel with the capacitor because those two form what is called a contour network and changing either of them throws that off.
https://forum.polkaudio.com/home/leaving?allowTrusted=1&target=https://www.soniccraft.com/product_info.php/020-ohm-mills-mra-12-p-4468?osCsid=944a4d0f6cd08eb5bc5ea69220a7a886

Well that is weird that they soldered to the binding posts on the inside like that! On mine they at least used ring terminals with another nut and washers above and below, with oodles of hot melt of course.

Gardenstater

I would suggest making things easy on yourself and get the Cardas Long Binding Posts and then you can just use the mounting block they supply and the teflon washers as well. They probably still supply only one nut per post but I believe, since I chewed them out, they are now made out of tellurium copper instead of brass lol. If you use the short binding post it can be a pain because the plastic of the Polk XO and binding post cup is very thick. I had to eliminate their thick teflon washer and used a brass washer, fiber washer, ring terminal, their gold plated brass nut, in that order. I didn't want the current going through the brass washer. I was pissed that I had to use a brass nut on such expensive posts, even if it was gold plated but it was what it was....... I would not have had room for a 2nd nut. What I would've preferred is to use one nut to secure the post and to sandwich the ring terminal between the 2 nuts (gold plated copper nuts!).

Gardenstater

Confession - when I saw your first picture with the wires soldered onto the binding posts I was thinking that was the *outside* of the XO/binding post cup because I didn't see the fuse lol. Just to clear up any non sequiturs 🤣

I think I would get these binding posts. I know(!) they are expensive. At least they have 2 nuts now, but they are not saying if they are copper or brass. Correction - still 2 nuts per assy....cheap bastids!

https://www.soniccraft.com/product_info.php/cardas-ccrr-binding-post-p-1669

PS: I sawed and filed off the bosses on the glass filled nylon mounting blocks so it wouldn't stick out so much and look crummy and I did NOT want to have to drill out the XO cup to the size necessary for those bosses to be inside the hole and be recessed. Kind of stupid on their part I guess but I suppose they are allowing for metal panel installations.

tomthomas20

I'll look up those items tomorrow. Thanks

tomthomas20

Does anyone have recommendations on how to safety clean the speaker cones. I am also considering changing the grill cloth to a light color like old Klipsch or AR speakers. What kind of adhesive should I use ?