Monitor 7 / Model 7 Factory 2nd's ??
Comments
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That right there's funny....what are the odds? 🤔🤣😂 -
Model 7J's... Janky🤪
Don't take experimental gene therapies from known eugenicists. -
Maybe one of Santa's pi. ssed. elves built them.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Actually the funniest part of this "defect" story is the MW with the New Years hangover date has an almost perfectly centered magnet...
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Just run 'em until you hear rubbing, then call me for rebuild/clearancing unless you can get ahold of member Kryten for the loaner MW jig.
I hear ya on that... is that your jig? I did a bit of looking at that jig and saw some instructions you posted. I get the general idea, but thinking that I'd need to pull the mag and back plate off as my alignment issue is more of a hamburger (the mag) sliding off the bun (and still functioning), whereby the bun is at or close to center/concentric with the basket. It also seemed to be fully secure (glue not compromised) Just realized a pic is the best way to show this...see pic (dimensions are approximate)
Bottom line, will I be able to re-align with the jig without taking the mag and pole plate off?
Thanks in advance and thanks to all who have responded to my questions. Much appreciated! -
If you have no coil rubbing and is functioning as it should, leave it alone, no reason to mess with it..
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If you have no coil rubbing and is functioning as it should, leave it alone, no reason to mess with it..
I may do that, but still curious as to if this situation can be remedied without taking the magnet and back plate off. -
It all depends
It may look like it is glued but that glue may have lost its bonding strength to the point where any sort of jarring will shift the pole piece. It is deceptive because the strength of the magnet seems to make the whole thing solid but you certainly don't want to test it to destruction.
I'm not sure if Rob's jig has adjustment screws for the magnet ( @xschop ). It definitely has ones for the top plate and the pole piece.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
I made a jig and have repaired some MW's that have shifted. Not saying it's impossible but it would be very difficult to center the magnet without taking everything apart.
Your jig would have to be different than the conventional jig everyone uses. The conventional jig holds the pole piece and magnet assembly that are joined as one by being glued together first, and then the screws of the jig are used to move the speaker assy. as needed to center the voice coil with the pole piece.
Your situation is that the pole piece and voice coil are already centered (no rubbing) and you are trying to center the magnet. To move the hamburger and not the bun, you would need a jig that would hold the top and bottom bun secure and screws to move the hamburger into the desired position. And that is assuming that the original glue has failed and the magnet can actually move. I agree with others that say if it ain't broke don't fix it. Definitely glue them before they shift though. -
Thanks JoeBass3 for that explanation. Based upon what you have experienced / seen, is this driver of mine (glue seems to be solid) something that was built this way or shifted during its 40+ years?
...And Gardenstater, yes I just saw your post, it may be a shift and the magnet assy is keeping it stable for now.
I may have to get a hold of a spare MW somehow and get it apart to determine what I am dealing with and create a procedure.
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Based upon what you have experienced / seen, is this driver of mine (glue seems to be solid) something that was built this way or shifted during its 40+ years?
No one can answer that question with any meaningful accuracy.
It is clear that this situation is causing you great anxiety. I advise taking the counsel of others here and letting it go (leave it alone). -
Thanks JoeBass3 for that explanation. Based upon what you have experienced / seen, is this driver of mine (glue seems to be solid) something that was built this way or shifted during its 40+ years?
Seems like it would have been assembled that way originally. Think about it. The pole piece is still centered in the voice coil and there is no rubbing. How could the magnet that is sandwiched between those two pieces shift and not allow one of them to shift too and cause binding?
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I don't what to wear out my welcome here so anyone that has an MW6500 that they are will to sell me let me know... I'll figure out how to fix my situation.
I find it funny that those to say leave it alone will go through all sorts of mods, time and $ to get incremental benefits (perceived or real) of sound quality, and not wanting to get the most fundamental part (the heart of the speaker system) "the driver" correctly adjusted to modern, or what should have been factory specifications I don't want a driver to fail, lockup, buzz, overheat, whatever down the road. I want to fix it now. If that means taking it apart, then that's what I'll do. I was just trying to figure out what the jig could do , and what it couldn't. That was the motivation, and not anxiety.
If someone was to be so kind as to sell me a driver, I will let the forum know what I am doing or did , either way failure or success. -
I see one silver basket atm on eBay that isn't exactly a steal price but not terrible. There are also a couple LF14s in Carlisle PA for pickup if you are anywhere near there. I am not certain which MW are in those but they were pretty early speakers so they could be 6500s.
https://www.ebay.com/itm/325513986225
Just looked again and seller says the LF14s are indeed 6500s.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Unfortunately none of us have tested Thiele/Small parameters to determine the effect of an off center magnet that is not rubbing. The voice coil is overhung so it does extend on the order of 1/8" past the top plate and there may be stray magnetic eddy currents in that area. I don't really know. I know there must be some reason why "focus rings" are used inside the magnet to shield the voice coil and reduce distortions.
Also, the contact area between the magnet and the front plate and voice coil WILL be less on the side that the magnet is shifted towards so there should be an uneven magnetic flux in the gap on those two opposing sides. How much and what effect that has I do not know.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
If you're hell bent on fixing it, then just take it apart and do it right. No reason to take any other route or to buy one when you have what you need already. Here is everything you need to know...
https://forum.polkaudio.com/discussion/197152/diagnosing-fixing-shifted-polk-mw-drivers
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Seems like it would have been assembled that way originally. Think about it. The pole piece is still centered in the voice coil and there is no rubbing. How could the magnet that is sandwiched between those two pieces shift and not allow one of them to shift too and cause binding?
I can see what you mean Joe, and yes from my general observations it seems like the plates are in line. So that could be the case..
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If you're hell bent on fixing it, then just take it apart and do it right. No reason to take any other route or to buy one when you have what you need already. Here is everything you need to know...
https://forum.polkaudio.com/discussion/197152/diagnosing-fixing-shifted-polk-mw-drivers
Thank you Joe, that is helpful...now I have to get those holes redrilled / fixed for the MW, kind of a pain that I have to deal with that also...oh well -
If you're hell bent on fixing it, then just take it apart and do it right. No reason to take any other route or to buy one when you have what you need already. Here is everything you need to know...
https://forum.polkaudio.com/discussion/197152/diagnosing-fixing-shifted-polk-mw-drivers
Thank you Joe, that is helpful...now I have to get those holes redrilled / fixed for the MW, kind of a pain that I have to deal with that also...oh well
I'm curious. What is the diameter of the baffle circle cutout on those speakers. Did they make it too large where the screw holes missed? Should be fairly small clearance to the basket spokes and a round hole. I was sure they had used CNC machining but who knows?George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Gardenstater wrote: »If you're hell bent on fixing it, then just take it apart and do it right. No reason to take any other route or to buy one when you have what you need already. Here is everything you need to know...
https://forum.polkaudio.com/discussion/197152/diagnosing-fixing-shifted-polk-mw-drivers
Thank you Joe, that is helpful...now I have to get those holes redrilled / fixed for the MW, kind of a pain that I have to deal with that also...oh well
I'm curious. What is the diameter of the baffle circle cutout on those speakers. Did they make it too large where the screw holes missed? Should be fairly small clearance to the basket spokes and a round hole. I was sure they had used CNC machining but who knows?
I was checking that this morning George, and the cutout is 5.675" . I did a quick measurement of the basket diameter) to be about 6.675" so a 1/2" mating surface, but it looks like they could have made the cutout around 5.550". I think on one speaker baffle the drill did not go in straight as the hole edge to baffle edge were all about .160 to .180" of meat, which is kind of weak IMHO. The other one where the hole missed almost completely the opposite hole had around .210" of meat, so it looks like a registration issue on that one. -
I don't what to wear out my welcome here so anyone that has an MW6500 that they are will to sell me let me know... I'll figure out how to fix my situation.
I find it funny that those to say leave it alone will go through all sorts of mods, time and $ to get incremental benefits (perceived or real) of sound quality, and not wanting to get the most fundamental part (the heart of the speaker system) "the driver" correctly adjusted to modern, or what should have been factory specifications I don't want a driver to fail, lockup, buzz, overheat, whatever down the road. I want to fix it now. If that means taking it apart, then that's what I'll do. I was just trying to figure out what the jig could do , and what it couldn't. That was the motivation, and not anxiety.
If someone was to be so kind as to sell me a driver, I will let the forum know what I am doing or did , either way failure or success.
Because some of us are smart enough to know when and what to leave alone.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Gardenstater wrote: »If you're hell bent on fixing it, then just take it apart and do it right. No reason to take any other route or to buy one when you have what you need already. Here is everything you need to know...
https://forum.polkaudio.com/discussion/197152/diagnosing-fixing-shifted-polk-mw-drivers
Thank you Joe, that is helpful...now I have to get those holes redrilled / fixed for the MW, kind of a pain that I have to deal with that also...oh well
I'm curious. What is the diameter of the baffle circle cutout on those speakers. Did they make it too large where the screw holes missed? Should be fairly small clearance to the basket spokes and a round hole. I was sure they had used CNC machining but who knows?
No sure what happened to my first reply to this George, but I edited it and may have lost it. Speakers both have baffle cutouts 5.675" and basket is around 5.55" , so there is some room for a smaller cutout. On speaker where the hole is offset, the opposite hole has more meat to the edge (around .210") where others are approx .170:, so that looks like a registration issue. On the other speaker all hole to edge are around the same and looks like the drill went in crooked. -
I don't what to wear out my welcome here so anyone that has an MW6500 that they are will to sell me let me know... I'll figure out how to fix my situation.
I find it funny that those to say leave it alone will go through all sorts of mods, time and $ to get incremental benefits (perceived or real) of sound quality, and not wanting to get the most fundamental part (the heart of the speaker system) "the driver" correctly adjusted to modern, or what should have been factory specifications I don't want a driver to fail, lockup, buzz, overheat, whatever down the road. I want to fix it now. If that means taking it apart, then that's what I'll do. I was just trying to figure out what the jig could do , and what it couldn't. That was the motivation, and not anxiety.
If someone was to be so kind as to sell me a driver, I will let the forum know what I am doing or did , either way failure or success.
Because some of us are smart enough to know when and what to leave alone.
Being that this is my second day into this, I believe that smart has nothing to do with it...it's a matter of experience; and, being that none of my other "classic" speakers have or had any of these issues, my experience is lacking in that capacity.
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I don't what to wear out my welcome here so anyone that has an MW6500 that they are will to sell me let me know... I'll figure out how to fix my situation.
I find it funny that those to say leave it alone will go through all sorts of mods, time and $ to get incremental benefits (perceived or real) of sound quality, and not wanting to get the most fundamental part (the heart of the speaker system) "the driver" correctly adjusted to modern, or what should have been factory specifications I don't want a driver to fail, lockup, buzz, overheat, whatever down the road. I want to fix it now. If that means taking it apart, then that's what I'll do. I was just trying to figure out what the jig could do , and what it couldn't. That was the motivation, and not anxiety.
If someone was to be so kind as to sell me a driver, I will let the forum know what I am doing or did , either way failure or success.
Because some of us are smart enough to know when and what to leave alone.
Being that this is my second day into this, I believe that smart has nothing to do with it...it's a matter of experience; and, being that none of my other "classic" speakers have or had any of these issues, my experience is lacking in that capacity.
If there was ever an MW# that should have the magnets centered it is the 6500s because it appears to have the tightest radial clearance between the VC O.D. and the top plate of any of the Polk drivers that anyone here to date (Rob mainly) has reported on, @ ~0.0065" . If the voice coil was glued up cocked at all, there is even less. Then you add some uneven magnet motor force (due to uneven flux) on one side of the coil vs the other and you "could" get into trouble. You'll hear it when it happens 😯. You could test them with some low frequency test tones to cut to the chase.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Gardenstater wrote: »I don't what to wear out my welcome here so anyone that has an MW6500 that they are will to sell me let me know... I'll figure out how to fix my situation.
I find it funny that those to say leave it alone will go through all sorts of mods, time and $ to get incremental benefits (perceived or real) of sound quality, and not wanting to get the most fundamental part (the heart of the speaker system) "the driver" correctly adjusted to modern, or what should have been factory specifications I don't want a driver to fail, lockup, buzz, overheat, whatever down the road. I want to fix it now. If that means taking it apart, then that's what I'll do. I was just trying to figure out what the jig could do , and what it couldn't. That was the motivation, and not anxiety.
If someone was to be so kind as to sell me a driver, I will let the forum know what I am doing or did , either way failure or success.
Because some of us are smart enough to know when and what to leave alone.
Being that this is my second day into this, I believe that smart has nothing to do with it...it's a matter of experience; and, being that none of my other "classic" speakers have or had any of these issues, my experience is lacking in that capacity.
If there was ever an MW# that should have the magnets centered it is the 6500s because it appears to have the tightest radial clearance between the VC O.D. and the top plate of any of the Polk drivers that anyone here to date (Rob mainly) has reported on, @ ~0.0065" . If the voice coil was glued up cocked at all, there is even less. Then you add some uneven magnet motor force (due to uneven flux) on one side of the coil vs the other and you "could" get into trouble. You'll hear it when it happens 😯. You could test them with some low frequency test tones to cut to the chase.
George, your scarin' me...I just had just started to test both drivers on a 50hz generator and doing some A B testing amongst other manufacturers drivers. BTW did you see my baffle cutout dimensions? Are they in spec? -
Gardenstater wrote: »I don't what to wear out my welcome here so anyone that has an MW6500 that they are will to sell me let me know... I'll figure out how to fix my situation.
I find it funny that those to say leave it alone will go through all sorts of mods, time and $ to get incremental benefits (perceived or real) of sound quality, and not wanting to get the most fundamental part (the heart of the speaker system) "the driver" correctly adjusted to modern, or what should have been factory specifications I don't want a driver to fail, lockup, buzz, overheat, whatever down the road. I want to fix it now. If that means taking it apart, then that's what I'll do. I was just trying to figure out what the jig could do , and what it couldn't. That was the motivation, and not anxiety.
If someone was to be so kind as to sell me a driver, I will let the forum know what I am doing or did , either way failure or success.
Because some of us are smart enough to know when and what to leave alone.
Being that this is my second day into this, I believe that smart has nothing to do with it...it's a matter of experience; and, being that none of my other "classic" speakers have or had any of these issues, my experience is lacking in that capacity.
If there was ever an MW# that should have the magnets centered it is the 6500s because it appears to have the tightest radial clearance between the VC O.D. and the top plate of any of the Polk drivers that anyone here to date (Rob mainly) has reported on, @ ~0.0065" . If the voice coil was glued up cocked at all, there is even less. Then you add some uneven magnet motor force (due to uneven flux) on one side of the coil vs the other and you "could" get into trouble. You'll hear it when it happens 😯. You could test them with some low frequency test tones to cut to the chase.
George, your scarin' me...I just had just started to test both drivers on a 50hz generator and doing some A B testing amongst other manufacturers drivers. BTW did you see my baffle cutout dimensions? Are they in spec?
Sorry don't stress! You will just hear some subtle distortion, and go.....what was that?....and it may not do it the next time. For me the first thing I noticed it on my original drivers was "Tubular Bells" by Michael Oldfield lol. But using the test tones will tell you quickly what's what. May want to go to 35, 40.
I don't want to disturb my setup right now it is sounding so good. Superstition lol. But I plan to do the 8 hole mod on my MW's in the not too distant future and will report back on that measurement, which I never made because mine are all good in that regard.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
I don't what to wear out my welcome here so anyone that has an MW6500 that they are will to sell me let me know... I'll figure out how to fix my situation.
I find it funny that those to say leave it alone will go through all sorts of mods, time and $ to get incremental benefits (perceived or real) of sound quality, and not wanting to get the most fundamental part (the heart of the speaker system) "the driver" correctly adjusted to modern, or what should have been factory specifications I don't want a driver to fail, lockup, buzz, overheat, whatever down the road. I want to fix it now. If that means taking it apart, then that's what I'll do. I was just trying to figure out what the jig could do , and what it couldn't. That was the motivation, and not anxiety.
If someone was to be so kind as to sell me a driver, I will let the forum know what I am doing or did , either way failure or success.
Because some of us are smart enough to know when and what to leave alone.
Being that this is my second day into this, I believe that smart has nothing to do with it...it's a matter of experience; and, being that none of my other "classic" speakers have or had any of these issues, my experience is lacking in that capacity.
Ok, some of us are smart about vintage Polk speakers due to our lengthy experience.
Post edited by F1nut onPolitical Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Here is one that the magnet is way off center. No rubbing and sounds fine. I betcha it was that way since new.
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Gardenstater wrote: »Unfortunately none of us have tested Thiele/Small parameters to determine the effect of an off center magnet that is not rubbing. The voice coil is overhung so it does extend on the order of 1/8" past the top plate and there may be stray magnetic eddy currents in that area. I don't really know. I know there must be some reason why "focus rings" are used inside the magnet to shield the voice coil and reduce distortions.
Also, the contact area between the magnet and the front plate and voice coil WILL be less on the side that the magnet is shifted towards so there should be an uneven magnetic flux in the gap on those two opposing sides. How much and what effect that has I do not know.
From taking many of these apart, I can say that the ones that were VC rubbing, either had shifted magnets from factory or a build-up of galvanic corrosion in the VC gap.Don't take experimental gene therapies from known eugenicists. -
Here is one that the magnet is way off center. No rubbing and sounds fine. I betcha it was that way since new.
Yep, my pic may not have been as clear as yours but that's almost exactly what my magnet offset looks like.
