Diagnosing a problem with vintage Polk Monitor 7 speakers

Sprout23

I have a pair of Monitor 7s bought in 1987/1988, powered with a Denon integrated amp of the same vintage. Recently one of them has started sounding like I've blown out one or more of the individual components. I spoke with Polk's customer service line this morning. They suggested, quite sensibly, that I swap the tweeter, midrange and woofer out individually with the corresponding unit from my other speaker, which is still working fine. That way I can localize the problem and order the appropriate spare part. Finally, the person I spoke with told me that the connections would be easy to remove (i.e., a sliding connection of some sort).

I took the midrange out of the speaker enclosure this morning, but the connections look like they're permanent, not the sort one can easily disconnect and reconnect. I tried to remove them gently (not wanting to cause any further damage), but was unsuccessful. This might reflect my inexperience with this sort of electronics work, so I thought I'd ask here to see if anyone can offer some advice on how to proceed with diagnosis and repair of my speaker. What am I doing wrong? Are the connections between the various components of my old Monitor 7s permanent or not?

Thanks,
Dave

cristo

The connections on my Monitor 10a speakers from the same era were soldered.
If you're handy with a soldering iron, should be no problem.
Don't slip and burn or poke the cone or the surround with the iron, though.
You'll need to do this to replace the bad component later anyway.
Just keep track of the correct phase on the drivers so they don't go back in
out of phase (write down which color wire goes to the marked terminal on the driver).

Sprout23

I suspect mine are soldered as well, then. I'm not very handy with a soldering iron, but I have a friend who is. Sounds like a good weekend project, I guess.

Thanks, Christo!

gimpod

Dave, Welcome to Club Polk.

First before I'd start ripping apart the speakers I would suggest you do a two simple test's.

1. Check the speaker wire connections, Make sure there tight and clean. For that mater do this for all your connections.
2. Swap the speakers Left for Right and Right for Left. If the problem is in the left channel and it stays there after you swap speakers it's the amp not your speakers.

If it turns out to be your speakers cristo is right, make sure to wright down which color wire go's where, also some times the drivers and tweeters aren't marked if that's the case get yourself a felt pen or something and mark them. Usually black is positive and white is negative.

Hope this helps. ~ gimpod

HB27

The first things I check are the fuses on the old Monitors. Make sure the fuses are good and making good connection.
Second is push in on the lower passive radiator. The mid woofers should move easily in and out without making any scraping or scratchy noises. The mid woofers are notorious for the magnets slipping and freezing up the mid woofers. IF the mid woofers don't move free and silent then you know a mid woofer is bad.
That's the basics on the old Monitors with fuses and solder connections. Maybe some Polk member is close and would lend an experienced hand to you and your old monitors.
Welcome to the club btw.

Sprout23

@Gim54pod -- the first thing I did was pull the amp out of the cabinet and check all the connections (they were fine); after that, I replaced the speaker cables out of an abundance of caution. I'll definitely swap the speakers tonight to confirm that it's a speaker problem rather than an amp problem -- thanks for the suggestion.

@HB27 -- where are the fuses located? I don't recall seeing anything other than the speaker connection posts on the back of my speakers. Thanks for the additional suggestions for diagnosing the problem.

Thanks for the welcome, guys! I appreciate your helpful suggestions.

Cheers,
Dave

HB27

The fuses "IF APPLICABLE" will be right above the speaker terminals. IF no fuses they're a B model with polyswitches for tweeter protection.
I'd still make sure the mid woofers are moving free and easy. You can see them move when you push in on the lower passive radiator.
IF you pull the drivers make sure you get them sealed back into the cabinets properly or you'll lose bass response.
Good Luck,
Harry

Sprout23

@Gim54Pod, I switched the speaker connections on the amplifier and the buzzing followed the connections, so it looks like it's my old Denon integrated amplifier that's the problem, not my speakers. I'm a bit surprised, honestly -- it seems a little odd that one channel would go and not both, though I'm clearly not an expert on these things. Hopefully I'll be able to find a stereo repair shop who can take a look at it to see if it's fixable. If not, well, I guess I'm glad I shelled out for a new Outlaw RR2150 receiver earlier this year.

TrashyTrucker

Sprout23 wrote: »

... If not, well, I guess I'm glad I shelled out for a new Outlaw RR2150 receiver earlier this year.

Sorry for your bad luck Sprout23...I recently bought a vintage amplifier and paid 700 bucks for it and lost a channel that night! It is still in the shop. It depends on what you want to do with gear. If it is a keepsake then pay to fix it, if not perhaps look for another replacement. Glad you have already had a replacement already.
BTW welcome to the forum.

Matt

HB27

Sprout23 wrote: »

@Gim54Pod, I switched the speaker connections on the amplifier and the buzzing followed the connections, so it looks like it's my old Denon integrated amplifier that's the problem, not my speakers. I'm a bit surprised, honestly -- it seems a little odd that one channel would go and not both, though I'm clearly not an expert on these things. Hopefully I'll be able to find a stereo repair shop who can take a look at it to see if it's fixable. If not, well, I guess I'm glad I shelled out for a new Outlaw RR2150 receiver earlier this year.

Before you can the old denon make sure your cables are all good. Replace one at a time and you may find the culprit there. Speaker wires also. Seperate your wires away from power cords etc. Just a couple of free simple tests should ease your mind.

Sprout23

@TrashyTrucker -- Thanks, and sorry for your bad luck! I'll probably at least get an estimate on the repair cost; it's a nice older amp that I wouldn't mind hanging on to for a while longer...

@HB27 -- Thanks for the suggestion, but that's the first thing I checked: I've replaced the speaker cables and the RCA cables connecting the components, even though I'm pretty sure it's the amplifier, since I get the blown out sound after switching the speaker connections, and from both my audio CD player and my DVD player. But don't worry, I don't plan to can the Denon -- I'm going to see if I can get it fixed for a reasonable amount of money. It's a nice backup and worth hanging on to, even though I recently replaced it with a newer receiver.

Thanks, guys!
Dave