Monitor 10B - Crossover Upgrade Parts Confirmation

d4dooley

Hi all

My speakers have only gotten worse over the last week or two since noticing some slight "cracking" on the highs. I think the "Fragile" album by Yes gave them a good working over this weekend, and they were practically un-listenable. I could notice the scratchiness from all the way outside now.

So here is my plan for the crossover upgrades to my Monitor 10B's. I am no way skilled at this stuff, and will be needing some help with the work (hopefully a buddy will be able to help me out). I hope this corrects the issue.

Polyswitch/Polycap replacement
Replacing the polyswitch w/ a Mills 0.5 ohm resister (12W non-inductive)
https://parts-express.com/mills-05-ohm-12w-non-inductive-resistor--005-.5

Components for the highs:
Dayton PMPC-12 12uF metalized poloypro capacitors
https://parts-express.com/dayton-audio-pmpc-12-12uf-250v-precision-audio-capacitor--027-246

Mills 2.0 ohm resister (12W non-inductive)
https://parts-express.com/mills-2-ohm-12w-non-inductive-resistor--005-2

Dayton DNR 2.7 10W 2.7 ohm resister
https://parts-express.com/dayton-audio-dnr-27-27-ohm-10w-precision-audio-grade-resistor--004-2.7

Capacitor for the Lows:
Dayton DMPC-33, 33uF capacitor
https://parts-express.com/dayton-audio-dmpc-33-33uf-250v-polypropylene-capacitor--027-441
Note that I am replacing a 34 uF cap w/ a 33 uF. Is this OK to do?

I have attached my schematic and notes for all of the above, that could be worth looking at as well. Cost would be around $75 total (plus shipping).

Does anyone see any fatal flaws? Have any other tips for me.

I was also wondering if there is any issue with my receiver setup and these speakers. I have an Akai AA-1135. 35 watts per channel at 8 ohms.

Heck... If anyone who knows what they're doing lives in the Denver area and would be interested in helping a newbie (me) out to do this work, it would be greatly appreciated. Beers would be provided of course! Ha.

westmassguy

They Daytons are OK for entry level, and better than what's in there now. If you want a little better, go with Clarity PX. Still entry level, but better than the Daytons. I would not mix Mills, and the Sand-Cast resistors. Go all Mills or Mundorf MOX. The Dayton Sand-Cast resistors are no better than the ones in there already.
I would not run Monitor 10s off a 35 watt receiver, vintage or not.

d4dooley

Thanks.

westmassguy wrote: »

They Daytons are OK for entry level, and better than what's in there now. If you want a little better, go with Clarity PX. Still entry level, but better than the Daytons.

I will look into these. They don't have them at parts-express though. Do you have a recommended part supplier?

westmassguy wrote: »

I would not mix Mills, and the Sand-Cast resistors. Go all Mills or Mundorf MOX. The Dayton Sand-Cast resistors are no better than the ones in there already.

10-4. Parts-express did not have an "Audio-Grade/Non-Inductive" 2.7 ohm resistor. Could I use a Mills with a different resistance? They have Mills 2.0 ohm/12 W.

westmassguy wrote: »

I would not run Monitor 10s off a 35 watt receiver, vintage or not.

Is this a "fatal" flaw of the system? The Monitor 10B manual says that lower wattages can cause problems at high volumes, but the speakers are rated 20 W-200 W. Should I just look for a different receiver/amp or add power somewhere in the system?

westmassguy

Clarity is carried by Madisound. The Mundorf MOX resistors can be found there as well. Try Soniccap for the Mills resistors, they carry all the values.
I wouldn't run 10s with less than 100-150 watt Solid State, Tube amps are a different story.

Faustin

westmassguy wrote: »

Clarity is carried by Madisound. The Mundorf MOX resistors can be found there as well. Try Soniccap for the Mills resistors, they carry all the values.
I wouldn't run 10s with less than 100-150 watt Solid State, Tube amps are a different story.

Actually the company that carries the Mills is Sonic Craft. The Mills from Parts Express are the Mexico manufactured version. Have westmassguy give you a quote on the rebuild. He does nice work and you will know it is done right. A friend of mine was using a vintage Sansui receiver and his 10b's sounded terrible. Switched them to an Adcom GFA 545 (100 watts/channel) and they sound fantastic.

cristo

I used Sonic Crafts 12 uf caps for the tweeters and Solens for the 33uf (already had
them and less critical for the lows) and Mills resistors (from Sonic Craft) and
had good results.

StantonZ

westmassguy wrote: »

I would not run Monitor 10s off a 35 watt receiver, vintage or not.

That caught my eye; I'm not even sure that's not part of your problem. Nearly all vintage Polks benefit from an XO upgrade, but at the very least you can get that PS out of there (I replaced my with a 0.5 Ohm Mills also). I used SoniCaps (bought everything from Sonic Craft) when I did my upgrade, but westmassguy knows more about this stuff than most of us. Good luck.

TennMan

westmasguy will do a fantastic job on your crossovers at a reasonable price. Check with him before you buy SoniCaps or Mills.

Mystery

Do you have another pair of speakers to see if it's not the receiver?

While 35 watts is low for them, I've used similar receivers against many Polk monitors and they are fine for low/normal volume but yes, you can't crank them and they do sound better with 100wpc or more.

voltz

I did the crossovers in my Monitor 4's but I was not up to doing my Monitor 10's, so I got Dave ( westmassguy ) to do them and now they are nice and burned in and they are Rock-N the house!
here is a pic of them

d4dooley

Thanks for the comments all.

I will make a decision on the work and look into upgrading my amp/receiver as well.
Looks to be a tough market for 70s classic integrated amp/receivers in the 100 Watt/channel range. Not much to choose from.

I must admit that I did "crank up" the volume a few times when showing off the speakers to a couple of buddies. That's probably what caused the issue.

RandyWilliamson

To be honest the amp probably started clipping and offed your tweeters. Why don't u hold off on the upgrade and buy a man's amp? I promise you...you will not regret it and will get more from your money...with that amp you are liable to repeat the error next drunk night or girlfriend comes over. Ask me how I know. Save a little more...replace the tweets and buy an amp. Then go to westmassguy ..he's the master.
You will love your polkies even more.

At some point I was looking at good value for priced harmon kardons right off ebay i think either new or refurbished look into maybe they are still around....but then I fell in love with Adcom and I may never "upgrade" as im happy...and I am proud my entire setup is USA bred mostly. Not sure if your on a budget or not.

here's one 200 bux so far....and 100 watts per...id want more but hey...
http://www.ebay.com/itm/Harman-Kardon-hk870-Power-Amp-/201201220875?pt=LH_DefaultDomain_0&hash=item2ed886fd0b

Intergrated is not so cool dude they tend to be wimpy transformers inside them but im sure there are some exceptions to that. I used to be a sony fan...ask me how i know.

d4dooley

RandyWilliamson wrote: »

To be honest the amp probably started clipping and offed your tweeters. Why don't u hold off on the upgrade and buy a man's amp? I promise you...you will not regret it and will get more from your money...with that amp you are liable to repeat the error next drunk night or girlfriend comes over. Ask me how I know. Save a little more...replace the tweets and buy an amp. Then go to westmassguy ..he's the master. You will love your polkies even more.

Randy... This is the type of wisdom I was seeking. Yes, both the girlfriend night and drunk night have happened, and will most definitely happen again. Ha.

I think replacing the tweets will be the first step, along with an amp with a little more muscle and a new receiver with a Pre-Out (mine doesn't have one). The new Polk RD tweeters are supposed to sound nice from what I am reading anyway. (Around $100 or so?). Then proceed I'll with the X-over upgrade. May have to wait on tax returns in a few months, but hey, I can listen to David Grisman on my current setup , and it sounds really nice still. I'll just lay off of the Yes and Janis Joplin.

Should I go ahead and replace the polyswitch though if I replace the tweeters?

Mystery

You can bring 10B's at my place and use my amp to see how it performs.

d4dooley

Mystery wrote: »

You can bring 10B's at my place and use my amp to see how it performs.

Thanks, Mystery. If you are in the Denver area, I would definitely take you up on that.

Mystery

d4dooley wrote: »

Mystery wrote: »

You can bring 10B's at my place and use my amp to see how it performs.

Thanks, Mystery. If you are in the Denver area, I would definitely take you up on that.

Of course I am.
We've been emailing back and forth remember.

d4dooley

Mystery wrote: »

Of course I am.
We've been emailing back and forth remember.

Ha. OK. Gotcha. I'll shoot you another email off-forum. Thanks, man!

RandyWilliamson

d4dooley wrote: »

I think replacing the tweets will be the first step, along with an amp with a little more muscle and a new receiver with a Pre-Out (mine doesn't have one). The new Polk RD tweeters are supposed to sound nice from what I am reading anyway. (Around $100 or so?). Then proceed I'll with the X-over upgrade. May have to wait on tax returns in a few months, but hey, I can listen to David Grisman on my current setup , and it sounds really nice still. I'll just lay off of the Yes and Janis Joplin.

Should I go ahead and replace the polyswitch though if I replace the tweeters?

For me personally I would not remove safeguards like polyswitches I would probably put in new ones of same rating or whatever matches the RD tweeters you plan to buy. I believe the RD0198s came with Monitor 12's so aim for same polyswitch rating as monitor 12s. I dont know which model had RDO194's. Reason being is if you sometimes get loud they will save your tweeter. I left my fuses in line because I know how I can be. So they have saved me more than once already. I also dont believe in or have a desire for any home theater crap 5.1 or 7.1 or 9.1 lmao...I run my movies stereo too...and a few movies go loud without warning and zap goes the fuse. No big deal I got a stack.

But I really don't know if the fellas here have seen a true detriment with the polys...but if it's just for a small advantage in sound quality which is why some bypass the fuses. I wouldn't do it. Though I understand the devotees that do and my hats off to them for their great self control. Now if the difference is night and day then you just may have to learn some self control unless your willing to retro fuses in.

When you have a proper amp you will not be killing tweeters or switches/fuses often. You will learn where to stop before degradation and you may never even need to go that far more than half the time. The amp will be passing the signal cleaner and with ease rather than struggling and degrading sooner like now, before your ears are satisfied.

Focus on the amp..maybe even stock replacement tweeters used if found cheap and stock replacement new polys to go with that. Or do RD0198s and their matching polys and find the .27mh .5ohm inductors...and then revisit the caps and resistors in a couple months after.

westmassguy

RandyWilliamson wrote: »

d4dooley wrote: »

I think replacing the tweets will be the first step, along with an amp with a little more muscle and a new receiver with a Pre-Out (mine doesn't have one). The new Polk RD tweeters are supposed to sound nice from what I am reading anyway. (Around $100 or so?). Then proceed I'll with the X-over upgrade. May have to wait on tax returns in a few months, but hey, I can listen to David Grisman on my current setup , and it sounds really nice still. I'll just lay off of the Yes and Janis Joplin.

Should I go ahead and replace the polyswitch though if I replace the tweeters?

For me personally I would not remove safeguards like polyswitches I would probably put in new ones of same rating or whatever matches the RD tweeters you plan to buy. I believe the RD0198s came with Monitor 12's so aim for same polyswitch rating as monitor 12s. I dont know which model had RDO194's. Reason being is if you sometimes get loud they will save your tweeter. I left my fuses in line because I know how I can be. So they have saved me more than once already. I also dont believe in or have a desire for any home theater crap 5.1 or 7.1 or 9.1 lmao...I run my movies stereo too...and a few movies go loud without warning and zap goes the fuse. No big deal I got a stack.

But I really don't know if the fellas here have seen a true detriment with the polys...but if it's just for a small advantage in sound quality which is why some bypass the fuses. I wouldn't do it. Though I understand the devotees that do and my hats off to them for their great self control. Now if the difference is night and day then you just may have to learn some self control unless your willing to retro fuses in.

When you have a proper amp you will not be killing tweeters or switches/fuses often. You will learn where to stop before degradation and you may never even need to go that far more than half the time. The amp will be passing the signal cleaner and with ease rather than struggling and degrading sooner like now, before your ears are satisfied.

Focus on the amp..maybe even stock replacement tweeters used if found cheap and stock replacement new polys to go with that. Or do RD0198s and their matching polys and find the .27mh .5ohm inductors...and then revisit the caps and resistors in a couple months after.

The last versions of the Monitor 4, 5, 7, and 10, AKA Model 2s, all came with SL2500s. Polk eliminated the Polyswitches on all of them, including the last RTA TL Series. Polk always had problems with Polyswitches. Their initial resistance varied, they add distortion, their resistance changes over time, and they become more sensitive the more they're tripped. Polk even tried pre-conditioning them, so they left the factory with a uniform resistance. They're nasty little devices. Neither fuses or Polyswitches will protect your tweeters from damage due to Amplifier Clipping, or DC. They only protect against excessive current.
The RDO-194-1 and 198-1 came out over a decade after the Monitors, RTAs, and SDAs were discontinued.

RandyWilliamson

Great to learn that West....looks like the polys have a lot of cons against them. Those are great reasons to remove them entirely as they are not the safeguards you're looking for.....move along. The fuses have worked for me and shouldn't be difficult to put in place if you think you will need them. A good amp will make it less necessary. But like I said I do movies and such and I'd be ticked if I had to replace my tweeters for all the times they would have gave up by now. So a safeguard is something to consider in my opinion especially if you like loud volumes. Where there's a will there's a way. Wether you do it just like the factory or other form it's up to you. You could also pickup entire used xo's off ebay with the fuse cage in place and inline.

dbp

So if I decide to change out my 10B tweeters (SL2000) for RDO194s, should I take out the Polyswitch? And replace it with what? I am not yet ready to do a rebuild of the crossover.

I purchased my 10Bs on April 3, 1987, and my Instruction Manual had a sheet inserted in it that explained the new SafetyGuard Tweeter Protection. Interestingly, the date on the Polk Audio schematic is May 17, 1989 and the date by the "Approved" stamp is June 12, 1989. Perhaps there was an earlier schematic with the Polyswitch?

westmassguy

dbp wrote: »

So if I decide to change out my 10B tweeters (SL2000) for RDO194s, should I take out the Polyswitch? And replace it with what? I am not yet ready to do a rebuild of the crossover.

I purchased my 10Bs on April 3, 1987, and my Instruction Manual had a sheet inserted in it that explained the new SafetyGuard Tweeter Protection. Interestingly, the date on the Polk Audio schematic is May 17, 1989 and the date by the "Approved" stamp is June 12, 1989. Perhaps there was an earlier schematic with the Polyswitch?

This thread is about upgrading the crossover. If all you want to do is change the tweeters, buy the RDO-194-1s, and put them in.

Faustin

]So if I decide to change out my 10B tweeters (SL2000) for RDO194s, should I take out the Polyswitch? And replace it with what? I am not yet ready to do a rebuild of the crossover.


This thread is about upgrading the crossover. If all you want to do is change the tweeters, buy the RDO-194-1s, and put them in.

^^^This. In other words, the RDO-194's are a drop in replacement. You do not have to rebuild your crossovers. Easy upgrade......buy the 194's, remove the 2000's, and put the new 194's in.

Mystery

d4dooley wrote: »

Mystery wrote: »

Of course I am.
We've been emailing back and forth remember.

Ha. OK. Gotcha. I'll shoot you another email off-forum. Thanks, man!

So how's it coming?

d4dooley

Mystery wrote: »

So how's it coming?

So Mystery and I figured out that it is not the speakers/tweeters that are the issue. It's probably not my receiver either (though I do need more power). They sounded good at his place though his equipment and got plenty loud without any noise. Pretty clean overall.

He got me into a Luxman receiver with Pre-out, and a 125 wpc Kenwood amp. So I have the power now, but I still definitely have crackling on the tweets when running my turntable. Frustrating! There must be an issue with my TT somewhere, but I need to add a different source to fully confirm that the TT is the issue, and if it is, then it's off to try and figure out how to correct that.

We also think that my 10Bs could benefit from a x-over upgrade, as they do sound a little too bright and the lows are not quite where they should be. We compared them to several different HiFi speakers including Monitor 7Cs. Thanks for the time, knowledge, and equipment sale Mystery! The rabbit-hole continues...

Mystery

You are welcome.

If the crackling only happens with turntable and not other sources, it's is the TT.
They sounded fine with my TT.
You may want to get a cheap TT to test.

Faustin

Most members here are more than happy to help you spend your money as you travel down the infamous rabbit hole.

JesseS

Hey folks: Has anyone rebuilt with a new wood board to mount in the bottom of the cabinets? That would allow all components to be well spaced and secured. I'm working on the crossovers to my Monitor 10B speakers now. The caps are too large for the board, and securing them will not be easy. I might try foam or wood blocks underneath them, then low-temp hot glue. (The double is a 15uF and an 18uF - Clarity PX).

pitdogg2

yes it has been done. Small piece of wood with the extended leads run back to the XO. Most will screw the wood to the bottom and use hi bond double sided tape to hold the caps.

westmassguy

You can do and over/under with a supplemental board

JesseS

westmassguy - Those look great! What are the plastic joints called, and are they available at retail? Also, is that foam tape around the edge for a better seal? Thanks!