Frozen 6511 in SDA 1C's

dcmartinpc

One other quick question... Are the 6502's a suitable temporary replacement for the 6511's? I think they are the same ohm rating. My 6511 is testing at 3.2 ohms. I believe they are designed for a smaller cabinet, but I think I can find one of those readily and cheap.

Don

nooshinjohn

My 2.3TL's need the 6510's...

dcmartinpc

nooshinjohn wrote: »

My 2.3TL's need the 6510's...

No problem John... Just figured I would ask :biggrin:

Don

AudioGenics

dcmartinpc wrote: »

One other quick question... Are the 6502's a suitable temporary replacement for the 6511's?

coincidentally I have a NOS ( New Old Stock ) 6502
date May 19, 1994
with cardboard spacer ring

standing ohm measures 3.4 +/- 0.1 ohms.

dcmartinpc

AudioGenics wrote: »

coincidentally I have a NOS ( New Old Stock ) 6502
date May 19, 1994
with cardboard spacer ring

standing ohm measures 3.4 ohms.

Sending you a PM.

Don

AudioGenics

don

might want to also read this thread

http://www.polkaudio.com/forums/showthread.php?t=108982

some more information on the 6511

dcmartinpc

AudioGenics wrote: »

don

might want to also read this thread

http://www.polkaudio.com/forums/showthread.php?t=108982

some more information on the 6511

I saw that. The one thing I noted is that the 6503's are rated at 8 ohms. The 6502's are 4 ohms. I would think that the 6502's would match better than the 6503's. The 6503's might be a good match for the 6510's which are 8 ohms...

Don

dcmartinpc

nap wrote: »

Another thing to consider is if the voice coil has rubbed the metal staking ring on top of the magnet for any amount of time it may have caused some of the voice coil coating to have been rubbed away. This can cause a short at some point in the future. I have seen this happen, real hard to detect as well. As for repair, I would go down through the dust cap. Be very careful when cutting the dust cap away. A shim should be placed around the voice coil while gluing the structure back together to maintain consistent spacing within the gap. I am not sure what thickness the shim is, if you are interested I can get this info from my bud who works at Polk who does all the drivers and tweeters. Let me know. :cool:

If you have a chance, let me know the specs on the gap. Also, could you check with your buddy as to the feasibility of the 6502 being used as a replacement for the 6511? I think it is the closet match that I can find. Some have said the 6503, but the impedance seems to be off compared to the 6511...

Thanks!!!

Don

nooshinjohn

If a 6501 will work, you can have it. All I ask is that you pick up the shipping. All I need to do to it is make a "1" out of that pesky "0".:biggrin:

AudioGenics

just a tidbit of info

impedance and resistance are different measurements...

dcmartinpc

nooshinjohn wrote: »

If a 6501 will work, you can have it. All I ask is that you pick up the shipping.

Can you check the standing DC resistance on that speaker?

I would be glad to pick up shipping.

Thanks!

Don

dcmartinpc

AudioGenics wrote: »

just a tidbit of info

impedance and resistance are different measurements...

You are right, I am speaking of DC Resistance.

Don

nooshinjohn

dcmartinpc wrote: »

Can you check the standing DC resistance on that speaker?

I would be glad to pick up shipping.

Thanks!

Don

last I checked... it was 3.67, but I will check it again.

AudioGenics

my ohmmeter is a Fluke 77 so it is kinda old but trustworthy

found this http://www.audiokarma.org/forums/archive/index.php/t-65109.html
can not verify or confirm the information though


Driver: MW 6500 Driver's model #.
Brand: Polk Driver's brand name.
Fs: 31.0000 Hz (Free air resonance)
Vas: 2.6486 ft^3 (Compliance volume)
Qts: 0.2190 Total Q
Qms: 1.3000 Mechanical Q
Qes: 0.2640 Electrical Q
Sd: 0.0130 M^2 (Piston area)
Xmax: 3.1800 mm (Cone excursion, linear)
Revc: 6.5000 ohms (DC resistance)
Znom: 8.0000 ohms (Nominal impedance)
Pmax: 35.0000 watts maximum rated power


Driver: MW 6501 Driver's model #.
Brand: Polk Driver's brand name.
Fs: 31.0000 Hz (Free air resonance)
Vas: 2.7545 ft^3 (Compliance volume)
Qts: 0.2790 Total Q
Qms: 1.4700 Mechanical Q
Qes: 0.3440 Electrical Q
Sd: 0.0130 M^2 (Piston area)
Xmax: 3.1800 mm (Cone excursion, linear)
Revc: 7.7500 ohms (DC resistance)
Znom: 8.0000 ohms (Nominal impedance)
Pmax: 35.0000 watts maximum rated power


Driver: MW 6502 Driver's model #.
Brand: Polk Driver's brand name.
Fs: 44.0000 Hz (Free air resonance)
Vas: 1.2360 ft^3 (Compliance volume)
Qts: 0.2790 Total Q
Qms: 1.9700 Mechanical Q
Qes: 0.3250 Electrical Q
Sd: 0.0130 M^2 (Piston area)
Xmax: 3.1800 mm (Cone excursion, linear)
Revc: 3.5200 ohms (DC resistance)
Znom: 4.0000 ohms (Nominal impedance)
Pmax: 35.0000 watts maximum rated power


Driver: MW 6503 Driver's model #.
Brand: Polk Driver's brand name.
Fs: 29.8600 Hz (Free air resonance)
Vas: 3.0017 ft^3 (Compliance volume)
Qts: 0.3100 Total Q
Qms: 1.7680 Mechanical Q
Qes: 0.3760 Electrical Q
Sd: 0.0130 M^2 (Piston area)
Xmax: 3.1800 mm (Cone excursion, linear)
Revc: 6.5400 ohms (DC resistance)
Znom: 8.0000 ohms (Nominal impedance)
Pmax: 35.0000 watts maximum rated power

Fongolio

This is excellent info if true. I'm just wondering now if my two blown 6511's can be reserected from the dead. both still played, just really scratchy. Is there any hope?

AudioGenics

It is only my opinion to look for a new compatible replacement for long term playability

but I would defer and agree with NAP with his statement :

"...Another thing to consider is if the voice coil has rubbed the metal staking ring on top of the magnet for any amount of time it may have caused some of the voice coil coating to have been rubbed away. This can cause a short at some point in the future. I have seen this happen, real hard to detect as well...."

no harm in spending time trying a repair
it is fun to do

[Deleted User]

dcmartinpc wrote: »

If you have a chance, let me know the specs on the gap. Also, could you check with your buddy as to the feasibility of the 6502 being used as a replacement for the 6511? I think it is the closet match that I can find. Some have said the 6503, but the impedance seems to be off compared to the 6511...

Thanks!!!

Don

I would be more than happy to. Polk opens next week, I just hope he didn't extend his Thanksgiving holiday. I'll get it one way or the other. Cheers. :cool:

zarrdoss

Fongolio wrote: »

This is excellent info if true. I'm just wondering now if my two blown 6511's can be reserected from the dead. both still played, just really scratchy. Is there any hope?

your VC's got hot and probably hit the backing plate hard and dis formed the VC. short of a re-build I don't know what could be done.

[Deleted User]

zarrdoss wrote: »

your VC's got hot and probably hit the backing plate hard and dis formed the VC. short of a re-build I don't know what could be done.

I agree. Probably not much can be done. :cool:

Audioquest

dcmartinpc wrote: »

OK. I just pulled the magnet off the basket by hand..... The back plate/pole piece (Am I identifying these correctly) are still epoxied together. I am assuming that is a good thing So I think I understand this jig a little better now. Get the cone suspended with the pencils, squeeze the magnet in the pipe, then use the screws to center the basket/voice coil on the pole. I guess I could even test it while in the pipe. Then epoxy everything back together, once it all works, right?

Don

This is a really common occurance. I've owned quite a few different vintage Polk speakers over the years, and nearly every one of them has a driver issue at some point. What I do now is as soon as I bring them home, test to ensure they are working and out come the drivers. I run a nice heavy bead of PL Premium (Home Depot) around the 3 magnet/structure joints, then smear it nice and smooth. This encases the entire assembly, and once dry it can never move. PL is moisture resistant and doesn't dry rock hard but close and will never come off. Never had a problem with a driver magnet shifting since doing this.

inspiredsports

For those of you with broken drivers, I'd reccommend contacting http://www.midwestspeaker.com (no afilliation). They do work on Polk drivers (as well as hundreds of other brands) and ressurrected a 6509 for me in the past.

Speaking of 6509's, I bought 4 replacements directly from Polk in 2008 that I later sold when I found original vintage 1986 6509's. My opinion is that the bass response was better with the originals. Maybe a break in thing as I only had 200 hours on the new ones, but just my 2 cents worth.

dcmartinpc

OK... Polk has both the 6511's and the 6510's. So I feel a bit better. But now here comes my dilemma. Should I go ahead and replace all 8 drivers? Both the 6511's and the 6510's? Would it be worth it? I would like them to match, but I do listen most of the time with the grills on with little ones running around...


Suggestions or Opinions?

Thanks!

Don

AudioGenics

I would replace what is only broken
as long as Polk CS can supply replacements you can always order more
And know they are fresh, unused, and come with some warranty.

IMO... speakers will not perfectly match.
There is always variations.
Some that you might hear or think you hear.
Visually....well...keep the grills on. Out of Sight and Protected from little curious pokers

dcmartinpc

Mostly, I am concerned about the drivers disappearing... If they run out, I could be up against a wall if something happens. It is a big difference in price obviously. I hate these kind of decisions!

Don

smglbrth

If it is really a concern for you just go ahead and purchase all new ones. That way you can keep the good ones "on hand". That's what I did years ago and don't regret it. Besides the crossovers there's really nothing else to go wrong at that point. No worries, just kicking back enjoying your 1C's!

AudioGenics

Thats a question for POLK Customer service
Call and ask how long they expect to supply the drivers
and then determine how long do you expect to keep your speakers
would you ever upgrade or change.

just a little bit of contingency planning.

It would be one thing if they were really rare but not really

In any event ...you have plenty of time to decide

inspiredsports

dcmartinpc wrote: »

OK... Polk has both the 6511's and the 6510's. So I feel a bit better. But now here comes my dilemma. Should I go ahead and replace all 8 drivers? Both the 6511's and the 6510's? Would it be worth it? I would like them to match, but I do listen most of the time with the grills on with little ones running around...


Suggestions or Opinions?

Thanks!

Don

If you choose to replace selectively, I would replace them "symmetrically", meaning using the new drivers as the SDA effect drivers and originals as the stereo drives. Personally, I would seek out vintage replacements as it is my opinion they sound different (better).

dcmartinpc

inspiredsports wrote: »

If you choose to replace selectively, I would replace them "symmetrically", meaning using the new drivers as the SDA effect drivers and originals as the stereo drives.

Unfortunately, in the 1C's, they are different drivers....

Don

inspiredsports

dcmartinpc wrote: »

Unfortunately, in the 1C's, they are different drivers....

Don

Correct. Still, I suggest you replace whatever is bad symmetrically.

In each SDA 1C cabinet, the inside pair of "stacked" MW-6511's are your stereo drivers, and the outside stacked pair of MW-6510's are your dimensional drivers. That's why Polk's are clearly labeled as "Left" and "Right".

For example, if you replace your inside top 6511 on the left cabinet with 2010 new stock, you would "mirror" the replacement of the right cabinet's inside top 6511 with the 2010 version, and so on.

I would still suggest being patient and finding originals as I believe the bass response is better.

nooshinjohn

I would still lean towards vintage drivers. I have ZERO experience with the replacements, but others have commented that the just are not the same.