Monitor 10B Crossover problems?

Blacksoldier

Hi guys, I restored a set of monitor 10B's a while back and now I seem to be having issues with the sound coming from one of them. The sound is not as full and solid as the other one. I checked the speakers and all seem to be working fine. Could it be the crossover? All caps etc. were replaced so I don't know what the problem could be. I looked at the connections and all seem to be soldered correctly. Any suggestions please? Thanks in advance for all your help.

TennMan

Did you replace the polyswitches when you did the crossovers? If not when they get old they can develop resistance that will cause the problem you describe.

Blacksoldier

Yes, I actually removed the switches since I do not play my music loud anyway, and it was recommended by some others on this site. Could the wiring be the problem as well, do I need to change out the wiring?

Easy Runnin

Air leak?

drumminman

Is this a new problem, that is, did the speaker in question work normally for a while after the rebuild and did the problem just occur?

canadianicon25

could be the amp. do you have another pair of speakers you could hook up and see if they too have the same problem?

Blacksoldier

drumminman wrote: »

Is this a new problem, that is, did the speaker in question work normally for a while after the rebuild and did the problem just occur?

While I was putting everything together after to restoration, I did notice the problem and came to the conclusion that one of the drivers was bad. I therefore replaced it and thought that it was ok but not exactly the way it should be. I figured the driver was also bad since it was one that I had to fix because of a shifted magnet. Once I got another good driver however and installed it the problem continued and was more discernible.

I hooked it up to various amps and noticed the same situation.

F1nut

You're going to have start swapping stuff from one cabinet to the other. Start with the tweeter, then one mid-driver, etc. If you still haven't found the problem, swap the PR's. If at that point you haven't found the problem, swap the crossovers.

Also check that black or blue wires are connected to positive and white or green are negative. Check the binding posts, red (+) should be on the left.

Blacksoldier

Thanks for the info F1nut, I will start on that tomorrow after work. I will let you all know what I find out during this process.

westmassguy

In addition to polarity as F1 suggests, make sure the drivers are in phase with each other. When you replaced the one driver, did you use the same model MW65** as the other three? I've seen 10s with 6500s, 6501s, and 6503s. As suggested, check for airtightness. When they're buttoned up tight, press in and hold the Passive Radiator. Both woofers should pop out, and stay out for at least 4-5 seconds, and then slowly return to their normal position. If they pop out, then immediately begin to fall back, you have a leak somewhere. Leakage will interfere with the "fluid" coupling between the woofers and the PR, and bass response will suffer.

StantonZ

I'm going to follow this thread because I had a similar problem (thin sound in one speaker) when I rebuilt my XO's, and it was a bad solder joint (only discovered it through Ohm'ing everything out). Assuming it's not something obvious like a bad driver or seal, I really think it's SOMETHING to do with the XO.

Blacksoldier

Thanks for all the info guys, I will start to check as much as I can today after work. All the drivers are MW6503's which is what they came with. Also F1Nut, when I rebuilt the crossover and put everything back together, I used white for Pos(+) and black for Neg(-). It is the same for both cabinets and it is consistent throughout. I dont think this is the problem because if I am correct, both cabinets would sound funny. As far as pinpointing a bad solder joint, are you saying that I have to check resistance between everything? Thanks again for all the good information guys. I will eport back after trying everything you all suggested. I am also going to swith between sources as well to make sure that is not the problem.

westmassguy

Polk internal wiring for that period is Black= Positive or +, and White= - or Negative/Ground
Your Speakers are wired incorrectly

rromeo923

"Until, from the midst of this darkness, a sudden light broke in upon me -- a light so brilliant and wondrous, and yet so simple! Change the poles from plus to minus and from minus to plus!".

Blacksoldier

Hi again guys, well I disassembled both cabs and re installed them again with the right polarity. I also used Mortite caulk to seal both cabinets completely. I tested them, and they work perfectly!! Thanks guys, you were all a lot of help as always. I did find out however that part of the problem was my little Ming Da MC-84-c tube amp. The right channel seems to be bad. It is much lower than the left at times, and other times it sounds ok. Does anyone have an idea what it could be? Thanks again guys, I really appreciate all your kind help. I am back in business with my Monitor 10's.

F1nut

Bad tube(s).

Blacksoldier

Ok, I guess I need to get some tubes. I never changed them, I got them off someone on CL sometime about march. Is parts express a good place to find the tubes? Also, would I need to change all of them or at? If not all, how would I know which ones need changing? Thanks again for all your responses.

F1nut

Is your tube amp manual bias or auto bias? What are the tube types?

Blacksoldier

As far as I know, it is auto bias. It uses 4 EL84 and 2 12AX7 Tubes.

F1nut

Well, you better find out for sure.

Blacksoldier

I have been searching online but have not been able to find out anything definite. From what I can gather, it is supposed to be auto bias.