The Job of overhaulling my Polk Monitor 10B's
transmaster
Posts: 428
I was going to plunk this in the "The Polk Monitor 10B's Live" thread but it got a little long so.........
I purchased my Polk Monitor 10B?s new in 1989 to replace a then 20 year old set of Warfedale W35's; it was a gigantic improvement in sound. The Polk gave me excellent service up until about 1992 when the right channel speaker stopped working. At the time I was switching my music system to my PC with a high end sound blaster sound card and Kilpsch Pro-Media 5.1 speakers. In the meantime the Polks which I had hung up in the corners of room where out of the way and stayed there until I was purchased the Onkyo receiver in February, 2012 and needed speakers so I decided to get the Polks going until I could get something better. It turned out I didn?t know what I had. Thanks to this forum, and The Classic Speaker Pages forum I realized I had a real classic. I listened to the advice of on this forum and the Classic Speaker pages. So here is the story.
I purchased the parts from two sources
Parts ConneXion http://www.partsconnexion.com/
Sonicraft http://www.soniccraft.com/sonicap.htm
From Parts ConneXion I Purchased 2 33uf/250VDC Axon True Cap?s for the low pass side of the cross over. The Axon?s are made by Solen in France. I also purchased the Mills resistors there, 2 each .5, 2.0, and a 2.7 Ohm 12watt. $4.95 each for a total of $29.52 the .5 Ohm resistors replaced the Polyswitches. I took the advice of the experienced restorers not to waste money on expensive caps for the low side. The schematic shows a 34uf cap for the low pass side but a 33uf is well within operating range of the circuit. The 33uf Axon True Cap?s are $6.51 each, or $13.02 for the pair, on the other hand the Sonicap Gen 1 33uf cap?s are $47.58 each, or $95.12, I saved $82.10 using the Axon?s. My order to Parts ConneXion (sans shipping) totaled $42.54. Parts ConneXion is up in Burlington, Ontario, Canada. They do not really have online ordering and it is best to call them. They have Very personal service, and it is quiet refreshing.
The rest of the parts came from Sonic Craft. 4 12uf/200VDC Sonicap Gen1 capacitors. I lucked out Sonic Craft had a sale in April going on these cap?s and I picked them up for 18.50 each, total $74.00. The regular price is $22.50, total $90.00. As you can see I saved enough on the Axon cap?s to defray the cost of the Sonicap?s.
The Crossover job was routine, in retrospect I should have purchased the 5 watt .5 ohm resistors used to replace the Polyswitch the 12 watt resistors are a bit too large I had to fit the 12 watters under the circuit board and I had to use hemostats to thread the wiring into the board. The replacement Cap?s are much, much larger than the originals but they fit nicely, again the hemostats help with threading and pulling the wires through the holes vacated by the old caps. When I got to what is the right hand speaker, the one that didn?t work, things where very interesting. The 34uf electrolytic low side cap had blown up; and had split open all of the way down one side. This was apparently caused by the failure of the right channel on the Sony receiver it was hooked to at the time. The surge that took out the low pass cap also destroyed the both to the MW-6503 drivers. It would seem the Polyswitch, which was fried, and the isolation afforded by the high pass circuitry protected the tweeter. Here is some advice, make sure your test equipment is working properly. I have all kinds of test equipment If you have read some of my other postings on this subject you will see at first I thought the 1.55mH inductor was bad, at least that is what the fancy digital VOM it was using said. Of course it turned out the speakers were roasted it took one of my 50 year old Simpson analog VOM?s to finally scope out the problem, so much for modern technology. The two replacement drivers were $48.00 each they totaled 100.80 with Wyoming sales tax. I closely examined the new MW-6503?s one big improvement is the fact braded wires coming from the audio source are no longer connected via a solder point on the speaker cone to the voice coil. Those two little bumps you see at the base of the speaker cone. instead they now have a direct connection. This removes a potential weak point on the cone and saves a tiny amount of weight as well. With the replacement drivers installed the speaker fired up and as I reported elsewhere the 10B?s sound fantastic, as the cap?s burn in and the new drivers break in they will sound even better. $217.34 cents well spent.
I purchased my Polk Monitor 10B?s new in 1989 to replace a then 20 year old set of Warfedale W35's; it was a gigantic improvement in sound. The Polk gave me excellent service up until about 1992 when the right channel speaker stopped working. At the time I was switching my music system to my PC with a high end sound blaster sound card and Kilpsch Pro-Media 5.1 speakers. In the meantime the Polks which I had hung up in the corners of room where out of the way and stayed there until I was purchased the Onkyo receiver in February, 2012 and needed speakers so I decided to get the Polks going until I could get something better. It turned out I didn?t know what I had. Thanks to this forum, and The Classic Speaker Pages forum I realized I had a real classic. I listened to the advice of on this forum and the Classic Speaker pages. So here is the story.
I purchased the parts from two sources
Parts ConneXion http://www.partsconnexion.com/
Sonicraft http://www.soniccraft.com/sonicap.htm
From Parts ConneXion I Purchased 2 33uf/250VDC Axon True Cap?s for the low pass side of the cross over. The Axon?s are made by Solen in France. I also purchased the Mills resistors there, 2 each .5, 2.0, and a 2.7 Ohm 12watt. $4.95 each for a total of $29.52 the .5 Ohm resistors replaced the Polyswitches. I took the advice of the experienced restorers not to waste money on expensive caps for the low side. The schematic shows a 34uf cap for the low pass side but a 33uf is well within operating range of the circuit. The 33uf Axon True Cap?s are $6.51 each, or $13.02 for the pair, on the other hand the Sonicap Gen 1 33uf cap?s are $47.58 each, or $95.12, I saved $82.10 using the Axon?s. My order to Parts ConneXion (sans shipping) totaled $42.54. Parts ConneXion is up in Burlington, Ontario, Canada. They do not really have online ordering and it is best to call them. They have Very personal service, and it is quiet refreshing.
The rest of the parts came from Sonic Craft. 4 12uf/200VDC Sonicap Gen1 capacitors. I lucked out Sonic Craft had a sale in April going on these cap?s and I picked them up for 18.50 each, total $74.00. The regular price is $22.50, total $90.00. As you can see I saved enough on the Axon cap?s to defray the cost of the Sonicap?s.
The Crossover job was routine, in retrospect I should have purchased the 5 watt .5 ohm resistors used to replace the Polyswitch the 12 watt resistors are a bit too large I had to fit the 12 watters under the circuit board and I had to use hemostats to thread the wiring into the board. The replacement Cap?s are much, much larger than the originals but they fit nicely, again the hemostats help with threading and pulling the wires through the holes vacated by the old caps. When I got to what is the right hand speaker, the one that didn?t work, things where very interesting. The 34uf electrolytic low side cap had blown up; and had split open all of the way down one side. This was apparently caused by the failure of the right channel on the Sony receiver it was hooked to at the time. The surge that took out the low pass cap also destroyed the both to the MW-6503 drivers. It would seem the Polyswitch, which was fried, and the isolation afforded by the high pass circuitry protected the tweeter. Here is some advice, make sure your test equipment is working properly. I have all kinds of test equipment If you have read some of my other postings on this subject you will see at first I thought the 1.55mH inductor was bad, at least that is what the fancy digital VOM it was using said. Of course it turned out the speakers were roasted it took one of my 50 year old Simpson analog VOM?s to finally scope out the problem, so much for modern technology. The two replacement drivers were $48.00 each they totaled 100.80 with Wyoming sales tax. I closely examined the new MW-6503?s one big improvement is the fact braded wires coming from the audio source are no longer connected via a solder point on the speaker cone to the voice coil. Those two little bumps you see at the base of the speaker cone. instead they now have a direct connection. This removes a potential weak point on the cone and saves a tiny amount of weight as well. With the replacement drivers installed the speaker fired up and as I reported elsewhere the 10B?s sound fantastic, as the cap?s burn in and the new drivers break in they will sound even better. $217.34 cents well spent.
Radio Station W7ITC
Post edited by transmaster on
Comments
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Congrats on your repair/refresh. The amount of performance that can be unleashed in these older Polk speakers is surprising.
IMHO doing these kinds of mods/tweaks is $ well spent. I keep thinking I'd like to get a pair of M10's, but I have no place to put 'em!"Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer -
transmaster wrote: »
I purchased my Polk Monitor 10B?s new in 1989....
Let me guess...that stereo store that used to be in Frontier Mall, right? That's where my first 5B's came from. What was the name of that place, anyway? I can't remember.
G~Polk SDA SRS 2
Polk RTA 15tl
Polk Monitor 7C
Polk Lsi9
Infinity RS-II (modded)
Infinity RS-IIIa (modded)
Infinity RS 2.5 x 2
Magnepan 1.6QR (modded)
System: http://forum.audiogon.com/cgi-bin/fr.pl?vevol&1290711373 -
Let me guess...that stereo store that used to be in Frontier Mall, right? That's where my first 5B's came from. What was the name of that place, anyway? I can't remember.
G~
The store in question at the Frontier Mall had delusions of being a mondo audiophile destination, it wasn't. I don't remember the name I was only in the store a couple of times. I purchased My 10B's from the base exchange at Warren, AFB and saved a whole bunch of money.Radio Station W7ITC
