Need some direction(s)!

Big Dog

I just recently scored a great old set of Monitor 10B's off E-bay and have been listening to them for a few weeks. I was aware that one of the Tweeters was not performing well and have a question or two for the group.
1- If I just let it go for a while will there be any damage to the rest of the components of the speaker in question?
2-When I do change the tweeter should I do both boxes at the same time?
3-And Lastly, How do I get into these things for maintenance like fuses and such? I assume (I know...) I can just pull the tweeter from the front and change it but is there more to the job than pull , solder new leads in place and screww it back together?
Thanks for any help in advance.

zingo

1- If I just let it go for a while will there be any damage to the rest of the components of the speaker in question?
No.

2-When I do change the tweeter should I do both boxes at the same time?
It depends. If you want to stick with the original tweeter, you will only need to replace the one that is bad since they are all "used". If you want to upgrade to a new silk dome replacement, do both because the new tweeter will change the sound.

3-And Lastly, How do I get into these things for maintenance like fuses and such? I assume (I know...) I can just pull the tweeter from the front and change it but is there more to the job than pull , solder new leads in place and screw it back together?

The tweeter leads will have tabs on them that match up to the x-over, so no soldering is needed. If you want to get into the cab, two good ways are either take off the passive radiator, or remove the x-over itself.

scootchu

When you say the tweeter isn't performing well what does that mean? If it drops in and out at a somewhat high volume it could be a bad thermistor which takes the place of the fuse. I am not sure if the 10B's have a fuse on the back terminal cup or not. I do know I replaced the thermistors on one set of monitors and that was the root of the problem. Then get worse and easier to trigger each time they trip.

Just something to consider.

Big Dog

Scootchu-
The tweeter in question is audible but at only say 20-25% of it's brother across the room. It seems to remain at the same diminished output even as more power is applied to them. There is no fuse at the terminal cup on these so I'm guessing it's inside.

Boywonder

I have 2 pairs of 10B's, neither have any fuses on the terminal cups.

Monitor 10B's don't have any fuses inside, just polyswitches. They are small disc-shaped parts with two leads on the crossover (sometimes tan or blue color). They are tiny, auto resetting circuit breakers that limit current to the tweeters when overdriven, by opening the circuit when they heat up beyond a set current for a given amount of time. When they cool off, they once again close the circuit, allowing your tweeters to live happily ever after. They don't age well, and can be problematic in old Polks like your 10B's. Polk will send free replacements or you can just unsolder them and replace them with a wire jumper. If you listen at high volumes regularly, it's wise to keep the polyswitches.

Of course, you may have some other problem not related to the polyswitches. The usual polyswitch symptom is tweeters cutting in and out at high volumes as mentioned by scootchu above.

scootchu

Boywonder wrote: »

I have 2 pairs of 10B's, neither have any fuses on the terminal cups.

Monitor 10B's don't have any fuses inside, just polyswitches. They are small disc-shaped parts with two leads on the crossover (sometimes tan or blue color). They are tiny, auto resetting circuit breakers that limit current to the tweeters when overdriven, by opening the circuit when they heat up beyond a set current for a given amount of time. When they cool off, they once again close the circuit, allowing your tweeters to live happily ever after. They don't age well, and can be problematic in old Polks like your 10B's. Polk will send free replacements or you can just unsolder them and replace them with a wire jumper. If you listen at high volumes regularly, it's wise to keep the polyswitches.

Of course, you may have some other problem not related to the polyswitches. The usual polyswitch symptom is tweeters cutting in and out at high volumes as mentioned by scootchu above.

Thanks for the clarification about the polyswitches. I had a brain **** and said thermistor.

Big Dog

Thanks for the help guys. I will have to decide whether to use a jumper or not. I'm just using these in my office so no really high volumes usually. I get the part about pulling the passive but how do I pull the crossover? Is it accessed through that hole or through the back where the speaker contacts are?

scootchu

Big Dog wrote: »

Thanks for the help guys. I will have to decide whether to use a jumper or not. I'm just using these in my office so no really high volumes usually. I get the part about pulling the passive but how do I pull the crossover? Is it accessed through that hole or through the back where the speaker contacts are?

The crossover is mounted on the terminal cup on the back. When Polk sent me new Polyswitches they sent directions. It's very easy to swap them out, but there is soldering involved.

If I were you I would pull the terminal cup and jumper the Polyswitch and see if it makes any difference at all in the tweeter output, then go from there. Simple enough to do and you can rule out at least the Polyswitch.

After that I may swap tweeters from speaker to speaker and if the problem follows the tweeter then it's the tweeter, if it stays with the cabinet look at the crossover as a suspect.

Boywonder

If you don't mind soldering in a cramped location you may be able to remove the terminal cup/crossover from the cabinet far enough to R&R the polyswitches without removing the PR and disconnecting the wires.

Just unscrew the 4 screws on the terminal cup and pull it out, the polyswitches are easy to spot. It's the lazy way, but it may work fine. Of course if you keep reading this forum, you'll soon want to upgrade the crossover, etc, it's a slippery slope. That will require working on the crossover on your bench/worktable.

BSUfbfan

If you are running the 10's with good, solid power and don't run them into distortion, I would highly recommend eliminating the polyswitch and installing the jumper as others have stated.