HELP: vintage Model 10 Problem

vootieman

Hi,

I just bought a pair of Polk Model 10s from Ebay and there's something wrong with the performance. The sound is tinny, no bass response at all.

The tweeter and the two medium-size woofers are producing sound and vibration.

I'm not sure if there is supposed to be any sound or vibrations from the large passive radiator, but they are producing neither sounds nor vibrations. I don't know if this is related to the problem of zero bass.

Previously, I owned a pair of Model 10 Polks before this pair I just got and I know how great they should sound.

Any ideas what could be wrong? Please e-mail any responses to me at:

jbentley@volny.cz

Thanks, I appreciate any help.

Sincerely,

JIM BENTLEY

dorokusai

It sounds as tho' you have frozen drivers. IOW, voice coil locked onto the magnet structure. It is not uncommon after shipping....but may have been an existing condition.

If you push on the cone, and it is not smooth....but rubs, and makes a scraping sound, they are non-working.

The drivers should move OUT, when you press IN on the passive radiator.

Test that if you have time, and let us know what you find.

RuSsMaN

Note:

There is an implied 'very gently and evenly' to all this pushing and pressing Dorokoputz is speaking of.

Cheers,
Russ

dorokusai

Russman is correct, I figured it was a given, but be gentle on the speaker. You aren't re-enacting a search and seizure on Cops.

gidrah

Also, double check that both woofer are in phase with each other. If not, one will cancel the other and bass will suffer accordingly.

vootieman

Thanks for the suggestions. And glad to be in touch with is clearly a fun group.

I'm not experienced with speakers, so please be patient if I use any incorrect terminology.

I tried pushing (gently!) the center flat area of the two passive radiators, one in each speaker cabinet. Each one moved back and forth smoothly without any scraping or rubbing sounds. Did I do this correctly?

What next? Should I bring the boxes to a speaker repair shop or is there something else I can try?

Another reply suggested checking that both woofers are in phase with each other. Is it likely that both cabinets would have this same problem? (I am assuming it would have been caused by faulty hook-up of the speakers.) Should I check this myself? And how?

Thanks so much for all the suggestions - I sincerely appreciate it.

JIM
jbentley@volny.cz

dorokusai

Push on the PR, and watch the woofers, they should move OUT....when you press IN on the PR. You can also press on the woofers, and "feel" for scrapes or rubbing.

The PR has no voice coil, so you won't have scraping or rubbing. Yes, you have the right idea.

vootieman

Thanks.

Okay, I have pushed in and out on the PRs. This does not cause any perceptible movement on the woofers.

I then gently tried to push the woofers, which felt "tight," that is, they didn't move. I did not apply any more pressure than I felt was safe. Are the woofers supposed to have some play in them, that is, to move back and forth a little, like the PR does?

Have we identified the problem here?

dorokusai

Yes they should have movement in them. I think its fairly clear, seized voice coils. I would remove them and inspect them a little closer, but it's most likely the case.

Contact Ken, kswauger@polkaudio.com for replacement drivers. Or work something out with the seller, I don't know the terms of your purchase.

It is a common theme with shipping of vintage Polk drivers, happens all the time.

vootieman

Thanks much. When I inspect the voice coils, what should I be looking for? And if I buy the replacements, can I install them myself without any special tools or skills?

dorokusai

Yes they are simple drop in replacements. If you can work a screwdriver, you can do it yourself. Four screws, and two wires.

I would just get the driver out, and push on them again, make sure it doesn't look odd on the inside. No real purpose, I just like to inspect stuff. It's probably shot, they cannot be repaired anyways.

Pay attention to how the wires are hooked up. One wire on each will go to a "red dot" on the driver. Mark that wire with tape so you connect the replacements correctly.