Polk 7A's... are they worth fixing?

[peelerboy]

Hi everyone! First post ever here. I just came across some Polk Audio 7A's I've had sitting in my basement for quite a while and am not sure what do to with them. I only stopped using them because of the area I had for speakers in my family room was really limited and I went with some bookshelf types instead.

I hooked the 7A's up yesterday only to learn that it sounds as though one of them has a bad mid range speaker. Is this a difficult operation to repair?...or not worth the trouble? The speaker that was still functioning properly sounds fantastic, while the one with the mid range issue has a slightly scratchy sound. :frown:

Any suggestions?...advice?

Thanks in advance!
Dale

[peelerboy]

Oh, and here's a couple pix...
http://i39.photobucket.com/albums/e173/peelerboy/CIMG0787.jpg
http://i39.photobucket.com/albums/e173/peelerboy/CIMG0790.jpg

[scottyboy76]

Those are some clean looking speakers.

Im certainly not the expert around here, but im sure they are going to chime in.

so the fuses and surrounds are okay on the bad speaker, if so, i would take the bad speaker off, see if the connector is loose or bad, you know rule out the easy stuff.

Gently push in and out on the speaker, sometimes they can begin to scrape, keep track of which is the top side of speaker, sometimes, if you are lucky, on older speakers, its possible they can start sagging down and scrape, sometimes, turning them so top is bottom can help.

usually that is with larger, heavier woofers, and these arent really known for that, but it costs nothing to try.

good luck, and im sure others with more experience will chime in.

[peelerboy]

Interesting stuff, Scott! Thanks! Actually, I did very gently push on that mid speaker that sounds like it's having issues and you can definitely hear a bit of scraping coming from it. Is it purely gravity that creates this condition?... or is it something else? Because like you said, this really isn't a very large speaker. Guessing 6" or 7" diameter?

[fbm211]

well worth fixing.
You can get replacements direct from polk and mention your a member here and get a discount and free shipping.
Or you may be able to find a good used driver on ebay or right here.Make a post in the wanted section.Im not sure of the mid model number but someone else will chime in.
If you go with a new replacement from polk you should replace both mids.

[Outfitter03]

I won a single Monitor 10A on fleebay locally in October as I was looking to have a spare passive for the ones that I recently purchased. The pictures in the posting were fairly poor and I was surprised when I went to pick it up. The drivers and binding posts looked like yours.

I am relatively new to this Vintage Polk thing and I thought the Monitor 10s not 10A's looked like this. Anyway the drivers are very different on the back also, at least the ones I have are a stamped steel, not cast as in my Monitor 10As. There is not a Polk paper faceplate either, just a stamped number in red ink X,1261. In smaller red ink is 2751. The speaker itself did not have a serial number sticker. The driver has the same felt ring or whatever material it is on the outside. Maybe someone on here knows more about these drivers.

I have two of these drivers. They are in fair to good condition. The speaker wires were soldered to the posts when I removed them so I just clipped them off. I don't know if it was standard practice to solder on connectors or something one of the many previous owners did. These do not have speaker gaskets as they were mortited in place. I have not considered selling these, but tomorrow I could take a picture or two and we could see if these drivers match up to yours.

Oh, the other thing was that I removed an entire leaf sized trash bag full of sheet Polyfill out of this one speaker.:eek: Someone must have liked the stuffed sound.

[TroyD]

Well worth fixing.

I have a pair that I would NEVER part with.

BDT

[peelerboy]

Thanks for all the great feedback, guys. I would like to have run a wanted ad for the needed mids, but I don't think my newbe status will allow posting in the classifieds section yet. :frown:

I'd like to get more info on what fbm211 was saying about getting replacement parts directly from Polk. That's gotta' be the best way to go in terms of correct parts, but then again my fiddling with these speakers is something of a passing whimsy and budget to invest is a little on the light side. :rolleyes:

Just as Outfitter had mentioned, my 7A's are also chock full of that polyfill stuff. And not only was the mid gooed into place with what looks like plumber's putty, but the connections are soldered on as well. I know this is all factory original because we bought these speakers brand new decades ago and this is the first they've ever been opened.

Speaking of which, here's a couple pix I just snapped-
http://i39.photobucket.com/albums/e173/peelerboy/CIMG0793.jpg
http://i39.photobucket.com/albums/e173/peelerboy/CIMG0792.jpg

The numbers on the magnet weren't entirely clear, but what I could make out was a black ink stamping of "6KU ..." and then directly beneath it "557 732"
Then obviously in red marker it said "23" and either "M" or "W".

Any thoughts as to how to properly identify what I need here?

[Outfitter03]

Here are three pictures of the drivers that I have. You can see that the speaker connectors are different and Polk was using black and white hookup wire. Otherwise they look very similar.
http://img255.imageshack.us/img255/2825/monitor10drivers002.th.jpg (http://img255.imageshack.us/i/monitor10drivers002.jpg/)

http://http://img255.imageshack.us/img255/2825/monitor10drivers002.th.jpg (http://img255.imageshack.us/i/monitor10drivers002.jpg/) http://img225.imageshack.us/img225/7288/monitor10drivers008.th.jpg (http://img225.imageshack.us/i/monitor10drivers008.jpg/) http://img832.imageshack.us/img832/9490/monitor10drivers012.th.jpg (http://img832.imageshack.us/i/monitor10drivers012.jpg/)

Part numbers labels are different though.

[comfortablycurt]

Definitely worth fixing. I've got a pair of 7A's myself(though mine are later production examples than yours), and I'll never part with them. Truly an excellent sounding pair of speakers.

The only real way to fix them would be to replace the faulty driver. Your best bet would be to track down an original, rather than getting a newer production replacement. The new ones are very similar to the originals, but there's still a slight difference in tonality.

[gdb]

Are you at all handy at tinkering with "stuff"? If so, you might get that driver operating again if you re-center the magnet. After that's done, I'd suggest putting JB Weld on the other one to prevent shifting magnet syndrome on it as well.:wink: Link Below:

http://www.polkaudio.com/forums/showthread.php?t=79649&highlight=magnet

[peelerboy]

Are you at all handy at tinkering with "stuff"? If so, you might get that driver operating again if you re-center the magnet. After that's done, I'd suggest putting JB Weld on the other one to prevent shifting magnet syndrome on it as well.:wink: Link Below:

http://www.polkaudio.com/forums/showthread.php?t=79649&highlight=magnet

Thanks, gdb! I'm definitely pretty handy and do love to tinker with stuff. I'll keep you guys posted if I manage to successfully re-center the magnet! :cool:

[gdb]

You go boy !!!:biggrin:

[nadams]

These look like very early 7a's... I've never seen a set with soldered wires. And could the "plumbers putty" be the Mortite that Matt Polk supposedly tinkered with vs the foam gaskets?

[peelerboy]

Update: Bad news... I somehow managed to prior off the magnet's backing plate with the magnet! :eek: :frown: I'm really losing motivation on this project fast and not sure where to turn next. I was originally going to repair the one bad mid driver and give them back to my brother as a surprise, but now completely need another driver as this one is messed up. D'oh!

Any suggestions? Or, anyone want a great pair of 7A's for dirt cheap just needing one driver? :redface:

[Tour2ma]

Well worth fixing.

I have a pair that I would NEVER part with.

BDT
How many autographs are on them now?

peelerboy,
What he said... and please get the exact, original MW replacement. Troy's 7A's may be historical, but all 7A's are a piece of audio history.

I don't think WTB posts are restricted. 100 post requirement is for the sell side.

[geppy1]

Those are early 6500 drivers. They pop up on ebay and here once in awhile I would find them before i would get the one fits all replacements. they do not sound the same.

[peelerboy]

How many autographs are on them now?

peelerboy,
What he said... and please get the exact, original MW replacement. Troy's 7A's may be historical, but all 7A's are a piece of audio history.

I don't think WTB posts are restricted. 100 post requirement is for the sell side.

Thanks for the heads up. I think I read that somewhere regarding the classifieds...that I wouldn't be able to post in there until I had a hundred posts or somesuch. But to post a WTB ad may be different? That'd be cool. :cool:


Those are early 6500 drivers. They pop up on ebay and here once in awhile I would find them before i would get the one fits all replacements. they do not sound the same.

You guys have me gaining hope & superior attitude again. :smile: geppy- are you confident of your assessment of what drivers I need? Because I really don't know enough about them to be able to identify one from another. If I were to go hunting here, eBay or elsewhere...what sort of part number or name should I use in my searching to make sure I get the right one?

Thanks for your help and encouragment, guys!

[geppy1]

Yes i am. That is a very early one. 1977 to 1978 The next year or so they had a label on the back then in 1981 they were all balck and did not have the grey stuff anymore.

[ben62670]

Don't toss the old driver. I have one in GA that needs the paper ring. Bad news is that I will not be there till April.

[geppy1]

Would I lie to you Look what we have here. Notice this pair had one of each. The one on the right is slightly newer.
http://cgi.ebay.com/Polk-Audio-Monitor-7-series-Speakers-Woofers-parts-/130481207259?pt=Speakers_Subwoofers&hash=item1e614937db

[geppy1]

I mean the black one is slightly newer

[peelerboy]

Don't toss the old driver. I have one in GA that needs the paper ring. Bad news is that I will not be there till April.

Hey Ben... you're totally welcome to this one. If you can't swing by the Dirty-D (Detroit) to pick it up, I'd only ask that you cover shipping costs and this one is yours. :cool:



Would I lie to you Look what we have here. Notice this pair had one of each. The one on the right is slightly newer.
http://cgi.ebay.com/Polk-Audio-Monitor-7-series-Speakers-Woofers-parts-/130481207259?pt=Speakers_Subwoofers&hash=item1e614937db

Thanks for the heads up, geppy! Is it okay to just replace the one that's bad?...and would either of these fit properly for my 7A's specs and application?

[ben62670]

All I would need is just the paper ring. I am not going to use it, but I would like to be able to help a Polkie out in the future. The older ones are getting harder to find.

[peelerboy]

All I would need is just the paper ring. I am not going to use it, but I would like to be able to help a Polkie out in the future. The older ones are getting harder to find.

you'd have to tell me in explicit detail how to properly remove it. I already did a number on the magnet mounting plate, so I'd hate to mess the ring up. :eek: I'm a newb! :redface:

[peelerboy]

Well guys... I really really appreciate all the help and advice you've provided, but I'm wimping out and throwing in the proverbial towel. :(

I've decided to part ways with these speakers and would like to ask how much you think the pair is worth with one of them having a messed up driver. I just don't have the time to fool with them any longer and need the space.

Any thoughts as to their value or how to best advertise/sell them?

Thanks again,
Dale

[Conradicles]

Well I have these now! Small world huh?

Anyway I pulled the crossovers and they have:

12uf cap
33uf cap
2.7 res
4.7 res

These must be some really early model 7A's.
Sweetness.

[peelerboy]

Well I have these now! Small world huh?

Anyway I pulled the crossovers and they have:

12uf cap
33uf cap
2.7 res
4.7 res

These must be some really early model 7A's.
Sweetness.

Very cool. So, did you buy these from Travis?

[Conradicles]

Sure did. I'll take good care of them:smile:

[TNHNDYMAN]

They were nice Peelerboy and I enjoyed them this summer but wanted to put some $ towards either a preamp or upgrading the crossovers in my other pair of 7's. You gave me a good deal on them and I tried to be fair w/ Eric. He scored a pair of stands the same day and I hope he enjoys them and does the crossover upgrade. I did my part driving them to Asheville so they could stay in the family :biggrin:

[Conradicles]

Here are the crossovers before the modification:
(Note these are very early models, maybe around 1978 and they used a bit different values than newer versions)

[Conradicles]

For this upgrade I wanted to keep costs as low as possible since these are going to be garage monitors. Jantzen had the exact value caps, and Mundorf resistors fit the bill. Also replaced the internal speaker wire and fuses.

They are breaking in now.:smile:

[michael1947]

Yes. Fix 'em. Use them in the garage or pass them along to someone in need.

[TNHNDYMAN]

Eric,

Looking great man! Hope they sound even better than before. Offer on 6500 mid still applies if you need it let me know.
Travis

[gdb]

"Yes. Fix 'em. Use them in the garage or pass them along to someone in need."

Wowzer, thats profound.:smile:

[Oldfatdogs]

Conradicles, I have a question for you. On your caps 33uf it says 400v on TrashyTrucker post for his cap are 200 vdc can you tell me what the difference is?

[Conradicles]

Conradicles, I have a question for you. On your caps 33uf it says 400v on TrashyTrucker post for his cap are 200 vdc can you tell me what the difference is?

"What does the Voltage Rating on a Capacitor Mean?


The voltage rating on a capacitor is the maximum amount of voltage that a capacitor can safely store.

Remember that capacitors are storage devices. The main thing you need to know about capacitors is that they store X charge at X voltage; meaning, they hold a certain size charge (1?F, 100?F, 1000?F, etc.) at a certain voltage (10V, 25V, 50V, etc.). So when choosing a capacitor you just need to know what size charge you want and at which voltage.

Why does a capacitor come in different voltage ratings? Because you may need different voltages for a circuit depending on what circuit you're dealing with. Remember, capacitors supply voltage to a circuit just like a battery does. The only difference is a capacitor discharges its voltage much quicker than a battery, but it's the same concept in how they both supply voltage to a circuit. A circuit designer wouldn't just use any voltage for a circuit but a specific voltage which is needed for the circuit. For one circuit, 12 volts may be needed. A capacitor with a 12V rating or higher would be used in this case. In another, 50 volts may be needed. A capacitor with a 50V rating or higher would be used. This is why capacitors come in different voltage ratings, so that they can supply circuits with different voltages, fitting the power (voltage) needs of the circuit.



Take note that a capacitor's voltage rating is not the voltage that the capacitor will charge up to, but only the maximum amount of voltage that a capacitor should be exposed to and can store safely. For the capacitor to charge up to the desired voltage, the circuit designer must design the circuit specificially for the capacitor to charge up to that voltage. A capacitor may have a 50-volt rating but it will not charge up to 50 volts unless it is fed 50 volts from a DC power source. The voltage rating is only the maximum voltage that a capacitor should be exposed to, not the voltage that the capacitor will charge up to. A capacitor will only charge to a specific voltage level if fed that level of voltage from a DC power source.

Keep in mind that a good rule for choosing the voltage ratings for capacitors is not to choose the exact voltage rating that the power supply will supply it. It is normally recommended to give a good amount of room when choosing the voltage rating of a capacitor. Meaning, if you want a capacitor to hold 25 volts, don't choose exactly a 25 volt-rated capacitor. Leave some room for a safety margin just in case the power supply voltage ever increased due to any reasons. If you measured the voltage of a 9V battery supply, you would notice that it reads above 9 volts when it's new and has full life. If you used an exact 9-volt rated capacitor, it would be exposed to a higher voltage than the maximum specified voltage (the voltage rating). Usually, in a case such as this, it shouldn't be a problem, but nevertheless, it's a good safety margin and engineering practice to do this. You can't really go wrong choosing a higher voltage-rated capacitor than the voltage that the power supply will supply it, but you can definitely go wrong choosing a lower voltage-rated capacitor than the voltage that it will be exposed to. If you charge up a capacitor with a lower voltage rating than the voltage that the power supply will supply it, you risk the chance of the capacitor exploding and becoming defective and unusable. So don't expose a capacitor to a higher voltage than its voltage rating. The voltage rating is the maximum voltage that a capacitor is meant to be exposed to and can store. Some say a good engineering practice is to choose a capacitor that has double the voltage rating than the power supply voltage you will use to charge it. So if a capacitor is going to be exposed to 25 volts, to be on the safe side, it's best to use a 50 volt-rated capacitor."

[Oldfatdogs]

Thank you sir.

[Conradicles]

These things sound soooooo much better with the crossover upgrade. They mate very well with the NAD components. I moved them out a bit further than they were in the pictures. Amazing speakers.:cool:

[chandler9a]

awesome set up man. My father had his 1.2TL xovers done with Jantenz caps, Im sure there are better but they sound very nice so far...

Not a bad garage set up at all.

[TNHNDYMAN]

Glad you got them upgraded. Now you need to get a set of 10's :)

[Tour2ma]

Not a bad garage set up at all.
LOL... May be the only garage rig I've ever seen with acoustic treatments...

[Conradicles]

LOL... May be the only garage rig I've ever seen with acoustic treatments...

I actually put up egg crate style foam (I get it free from work) all over the whole garage. It looks like a huge anechoic chamber.:eek:

[Tour2ma]

... and it looks like a great place to sip a cool one on a warm, Spring afternoon... with an egg-salad sandwich... :cheesygrin: