New member, and new vintage monitor 10a's (still in the box)

telecaster

F1nut wrote: »

Keep mind that Polk only made these like this for the WAF. Proper 4 post stands that bring the tweeters to ear height are the better choice.

Thanks f1nut!

wispolkboy

Congratulations... I miss my 10a's... My friend has them and I can't wait until he sells them back to me...
Yours look so sweet... Sonicap if can afford them... Way up in price now... Clarity are very good as well.
And JB WELD THEM! I'm sure that they are mw6500 and hard to find if you need to replace them.

plastic_avatar

I am envious of the find.

Amazing.

Well done.

telecaster

Thanks everyone. Is there a good guide for jb welding/regluing the drivers?

Where exactly am I laying the bead down?

Also What should I use to reseal the speakers to the cabinet? I have speaker sealing caulk (almost a putty rope) that I've used on dynaco a25/a35s before (recapped them for some customers). Is that acceptable for the old polks or should I use something different?

I'd like to do some studying up before diving into that job.

Thanks!

boston1450

I put a small bead on each side of the magnet. Then with gloves on I used my finger to smooth it out so it looked good. Try not to use to much. So that way it looks clean & not messy

boston1450

On all my inner cabinets I used LocTite PowerGrab & put a bead on existing seal & smoothed it out with gloves on with my finger. Came out good imo. Others may chime in with their experience.... Sorry for edits. Long day Very tired

F1nut

Also What should I use to reseal the speakers to the cabinet?

Use the original gaskets. They are supposed to be paper thin. Do NOT use Mortite or any other type of sealing caulk.

boston1450

^^^^^ that. My apologies I was thinking sealing cabinets. Like stayed above use original gaskets unless they are ripped ... Out of many SDA's & Monitor Polks I have only replaced 1op2

telecaster

Ok got it, thanks guys. I'll be careful with and re-use the original gaskets.

I'm getting ready to order my parts for the x-over refurb. Looks like the old stock USA mils 2.5ohm are still available in 5-watt versions, but the 2.7ohm resistors are unobtanium. I tried some searching, and contacted Michael Percy.
Seems folks prefer the old stock ones over the new Mexico production resistors.

Am I overthinking the resistors and should I just order 12-watt new production suckers?
Worth mixing old and new? Anyone have a line on where to get all old stuff in both values?

Thanks!

F1nut

The new ones are fine.

telecaster

F1nut wrote: »

The new ones are fine.

Thank you F1nut! Ordering now

telecaster

Ok, finally after getting all the parts and having the speakers sit for a few months ... I have time to finally repair them. Hold my beer and watch this ...

I'll take a bunch of pics and document the journey and maybe it helps others, or myself if I run into trouble and need you kind folks to bail me out .

telecaster

Well bummer . Finished all the work and I'm assembling the first cabinet. When I went to test the seal by pushing in the speakers I noticed one of them has voice coil rub when pushed far in .

What's a fella to do here? Are these replaceable?

The work all went great and I took lots of pics. I'll upload them soon.

Gardenstater

That's disappointing but pretty common. They are replaceable but you have to find them for sale on eBay and a saved search will eventually pay off. Usually they are repairable as well.

When you were inside did you find any production dates on XO's or drivers? What MW model #?

telecaster

Thanks Gardenstater,

Yeah they are MW6500, production date looks like Jan 1983. Here's a shot of the sticker:

Any recommended repair places that you can send these out to?
I'll keep an eye on Ebay in the mean time.

telecaster

Well, keep me honest folks. There's absolutely no rub when pushing in the cones slightly, only when they are pushing somewhat far in. Is this normal for these drivers or is this early signs of mis-alignment and VC rub? I notice both speakers do it in this cabinet, one happens earlier than the other though.

Gardenstater

I recently, with the help of xschop's resetting fixture, found out that my original 1979 MW6500s have crooked voice coils which will rub on the frame piece. Very hard to fix that and hopefully yours are rubbing on the pole piece and are not crooked. That is easy to fix. Search the forum for lots of info. on people making alignment jigs out of PVC pipe and adjustment screws.

The MW6500s have a tighter clearance between the voice coil O.D. and the frame piece. We think that Polk opened that up in later models because it was a problem to get everything aligned accurately enough and for them to stay that way.

I don't know if he still has time, but @lawdogg was fixing people's drivers last time I checked.

F1nut

telecaster wrote: »

Well, keep me honest folks. There's absolutely no rub when pushing in the cones slightly, only when they are pushing somewhat far in. Is this normal for these drivers or is this early signs of mis-alignment and VC rub? I notice both speakers do it in this cabinet, one happens earlier than the other though.

Chances are you are causing the cone to move slightly off center when you push them in all the way, which is a bad idea anyway.

When I went to test the seal by pushing in the speakers

That is not how you test for air leaks. Push the PR in and hold it in. The mid-drivers will pop out then start to recede before coming to rest. A good time is 3 to 5 seconds.

Gardenstater

Another test is to play a series of low frequency tones, like say 30, 40, 50 Hz, through the drivers and listen for distortion. That is where the problems usually become apparent. This test will reveal minor intermittent rubbing of the voice coil. Vary the volume as well. Obviously the problems are more likely to reveal at higher.

xschop

6500's are a problem with very tight VC to base plate clearance as Gstater pointed out. After time, the suspension relaxes and then it's a crap-shoot if they rub or not. Try turning the drivers up-side-down and play them to listen for rubbing. F1 is also right that you're probably pushing them out of alignment at the bottom of the stroke.

Just my opinion, but if they still rub, I'd replace them with 6510's. Their VC to baseplates have more clearance and TS parameters are close IIRC. Polk probably manufactured the 6510's as their replacement. Ive dissected both and the 6510's are physically same, but with more VC clearance.

Gardenstater

UH OH. we got an LOLer again

telecaster

Well, I decided to stop fussing with them and just try them out (besides rotating all the drivers 180 degrees). And holy crap, these things sound amazing . I'm listening to songs I've heard my whole life but never like this. Just super detailed and great lows, highs, balance. Just wow.

And this is through a crappy Yamaha RX-V485 receiver.

Time to restore the Dynaco ST70 & PAS3 that have been sitting in my garage waiting for me for 3 years.

Ok pics and details of my work are coming next. Let me just grab my Norah Jones CD first ...

telecaster

Here's some details of what I did. Hopefully this is helpful for others going down this journey for the first time in the future. And of course please critique anything that looks off or wrong.

Materials list:

---

(4) 12uF Sonicap gen1
(2) 34uF Solen caps
(2) 2.5 ohm 1% tolerance 12 watt Mills Wire-wound resistors
(2) 2.7 ohm 1% tolerance 12 watt Mills Wire-wound resistors
(1) tube of loctit power grab ultimate to re-glue the magnets
(1) tube of Dow DOWSIL 737 Neutral Cure Sealant (for holding everything together on the crossover PCB)
(1) can of Caig Deoxit 5 to clean all the terminals/contacts/fuse and holder etc

Step 1: Remove all the speakers, crossovers, and tweeters from the cabinets. I labelled all the holes and speakers so I knew exactly where they came from when putting it all back together. I also kept the screws for each cabinet in their own magnetic tray (and guess what, they used different sizes in the two cabinets ... no joke).







Step 2: I made a jig to hold the drivers while I was glueing them so the cones and guts weren't compressed or getting screwed up on my bench.







Step3: Lay a bead of Loctite on both sides of each magnet, and smooth em out with your gloved finger (like you would a bead of caulk around your tub). Clean up any spill/mess quickly.







Step4: Set those freshly glued drivers aside to set overnight:




Step5: Time to mess with the crossovers. The new crap is like 40 times larger than the old. This should be an interesting exercise in spatial reasoning ...




Step6: Take lots of pictures for reference, and then remove the top PCB from the plastic crossover housing (you need to de-solder and remove the two binding post wires and the inductor wire from the board prior to doing this. Take pics and label them so you put them back in the same place afterwards.





Step7: Remove all of the old components we'll be re-placing. I clipped the leads and left a little length to make it easier to grab them and put them out when de-soldering them. Remove all the old solder and leads and clean up the board to get it ready for the shiny new stuff. Oh and drink lots of red wine while you do this. All good soldering/repair work is done while intoxicated.





Step8: Install the new resistors first, and then the caps. Carefully find placements for these so they will all fit when re-installing the crossover back into the cabinet. Also, make sure the caps are well seated against each other and the other components on the board. After soldering everything, apply copious amounts of Dowsil 737 neutral cure silicon sealant to create good solid bond holding the caps, resistors, and other components to the board and against each other.

They look like ****, but they all fit back inside and after curing overnight were structurally/mechanically very solid. No worries of vibrating caps breaking off the leads overtime etc.






Step9: Clean all of the speaker terminals, spade connectors, binding posts, fuses and fuse holders with deoxit. And then re-assemble everything.




<Corrected> Thanks to the fellas on this forum ... test the seals by pushing in the reactive speaker on the bottom and make sure the drivers pop out and don't re-seat for 3-5 seconds or longer.

telecaster

Weird. I did a real long write up of my work with lots of explanations and pictures. I was editing it to fix a typo and it just disappeared on me. I'm not sure if I screwed something up, or if the original post got removed for some reason. Anyone know if there is a moderator that can help retrieve it? I spent a good deal of time writing it up .

Thanks!

JayCee

Afraid it's lost. I've been bitten by the same thing and learned to use Word to compose long write-ups and then paste when ready to post. At the very least, if I do start typing in Vanilla, I'll do the reverse and copy as I go into a text editor. Vanilla does have a "Save Draft" function and it seems to work...when I remember to do so, but a stand alone editor is still my preference.

Congrats on enjoying the speakers and I'm sure they'd be very happy w/the ST70/PAS3 combo. Looking forward to seeing your progress on them, too. Realize you've been on CP since Feb but just want to say welcome to the forum.

Gardenstater

I was in the process of "liking" your post when an error message popped up. When I refreshed, your post was no longer there.

I thought you were clever in making that fixture to hold the MW drivers steady and with clearance to the surround, for gluing.

What was the neutral cure silicone like as I have never tried that? I'm assuming no acetic acid cure smell was emitted?

Your speakers may just sound better and better as the XOs breakin. I know it sounds crazy but that's what I experienced. You may want to do internal wiring and binding posts in the future. I did everything I have done in increments and it was fun that way.

I'm glad yours are playing OK at the moment in the upside down configuration. I hope they aren't like mine and you end up hearing "funny stuff" when playing difficult bass material with prolonged tones. 99.9% of the time mine were fine but when I finally got around to disassembling I found that the voice coils were either assembled crooked or the spiders didn't age well but they would just barely rub the frame piece and you could see the scuff marks on the coating on the wires.

odcics2

OP mentioned some potential VC rubbing. Perhaps that’s why they look so new; they had that issue and were put away.

telecaster

Oiy, Ok lesson learned on long posts. Here's attempt #2 (probably a shorter version than the original .

I'm writing down and documenting my driver re-glue & crossover refurbish project in the hopes that it helps others starting down this journey for the first time. Thanks to everyone for the education leading up to this point. Please feel free to critique anything you see wrong (or that could have been done in a better way). Thanks!

List of materials:

(4) 12uF Sonicap gen1
(2) 34uF Solen caps
(2) 2.5 ohm 1% tolerance 12 watt Mills Wire-wound resistors
(2) 2.7 ohm 1% tolerance 12 watt Mills Wire-wound resistors
(1) tube of loctit power grab ultimate to re-glue the magnets
(1) tube of Dow DOWSIL 737 Neutral Cure Sealant (for holding everything together on the crossover PCB)
(1) can of Caig Deoxit 5 (for cleaning all speaker terminals, spades, fuses, fuse holders etc).

<Note, I had the dioxin and 737 sealant on hand and only had to order the caps, resistors, & loctite>.

OK Step1: Remove all the drivers, crossovers, and tweeters from the cabinets.
I labelled all the locations and parts so I could put everything back in the same order when done (note though I ended up swapping the left/right drivers in each cab and rotating them 180 degrees based on some good advice here. This fights the effect gravity has had on the VC and such over the years).

I put all the screws in separate magnetic trays and labelled them as well. Believe it or not, each cab used a different size wood screw. On set had a thicker diameter and needed to go back into the same holes.




Step2: I made a jig that would hold the drivers while I glued them up. This was to prevent the cone/surround from getting compressed or screwed up against my bench while I worked on things.






Step3: Lay a bead of Loctite ultimate power grab on both sides of the magnet. Use a gloved finger to smooth the beads out (like you would caulking your tub). Clean up any mess/spillage quickly afterwards.






Step4: Let the drivers sit overnight so everything hardens.




Step5: Get everything prepped and ready for the crossover work. The new components are like 540x larger than the old ones. This should be an interesting exercise in spatial reasoning …




Step6: Remove the top PCB boards from the crossovers. Note you have to remove the two wires from the binding posts, and the wire for the large inductor. Desolder them and take pics and label the wires so you put everything back together in exactly the same spots.




Step7: Take lots of pics for later reference, then remove all of the old components. I clipped the leads but left a little length to help with removing them when desoldering the board. Next I desoldered everything and cleaned up the PCB (soldering wick, and then ISO alcohol and q-tips).




Step8: Took a short break, and then cleaned all of the binding posts, fuses, fuse sockets, and speaker terminals/spades with deoxit.




Step9: Plan out your layout, and insert the resistors first, then the capacitors. I was careful to place everything in such a way that would allow me to insert the crossovers back into the holes in the cabinet, but also so they sat against the board, each other, and other components. This allowed me to use copious amounts of the 737 neutral cure sealant to bond everything to the board and to each other. It looks like sheeit, but after drying everything was structurally and mechanically very solid. No worries of loose vibrating capacitors breaking off their leads over time and such.

Re-solder the binding post and inductor wires, and then re-insert the PCB’s back onto their standoffs.





Step10: Install everything back into the cabs. When done, push on the passive lower radiator and make sure the drivers pop and stay out for 3-5ish seconds before settling back down (thanks F1nut!).




And then … plug the bad boys in, sit back, and listen to some good music!

pitdogg2

3M high bond double sided tape MUCH more desirable and for whatever reason should you need to go back in no need to fight silicone caulk. Yes you're correct it looks terrible.

xschop

Good work. I don't know what the name of the mod is called, but you could try Westmassguy's driver isolation procedure and eliminate any comb filtering. JAT