New pair Monitor 50s: one SIGNIFICANTLY lower volume than the other.

Scoobmaster

Hi there.

I just purchased a pair of Monitor 50s last month as part of a new living room 5.1 theater setup that includes a CS-10 center, Monitor 30 surrounds, and a PSW-505 subwoofer. All these are driven by a newly purchased Harman Kardon AVR 2600 receiver. The PSW-505 was the last purchase and I just received it yesterday and swapped out my old JVC "HTIB" subwoofer I was temporarily using. Once the new sub was in place, I re-ran the Harman Kardon's EQ procedure to set my speaker levels with the new sub. Every time the left front Monitor 50 was being tested, the "white noise" test tone had a different pitch and sound level to it from all the other speakers. I let it finish then started playing content from my DirecTV receiver.

Something didn't sound "right" and I noticed that moving my head directly in front of the left Monitor 50 revealed a MUCH diminished and muted sound level compared to the right side speaker. I checked the levels in the H/K receiver and they were slightly different, so I made them equal - that made no difference. I tried different channels and even switched sources to my PS3, but still the left speaker is not "up to par". I have disconnected and reconnected the speaker wire (it is new as I ran all new wire last month when I got these) and double-checked the polarity (it is correct). My next step when I get home from work tonight will be to swap the Monitor 50s to see if the problem follows the speaker to the right side.

If it DOES, obviously the problem is in the speaker. Could it be a bad driver? If the problem stays on the left side I assume the issue is in the receiver and I should take my issue up with Harman Kardon at that point, right?

Any other suggestions or ideas for things to test, try, examine, etc...?

Thanks.

BeefJerky

Make sure both of the jumpers are on the speaker. If not, you will only be getting sound from either the woofers or the tweeters. In addition, even if the jumpers are there, try a piece of speaker wire in the place of the jumpers. Sometimes the jumpers just don't make a good connection.

PerfectCreature

Is your sub on the left side? Maybe having it to close to your speaker during calibration messed with the settings...
Try re-wiring everything. I know I mixed up the +/- one time and that happened to me as well.

Scoobmaster

Thanks for the replies.

Beef: Where are the jumpers you are referring to? Inside the speaker cabinet?

PC: The subwoofer is on the RIGHT side, far away from the left Monitor 50. I did re-check my speaker wire polarity (it was the first thing I thought of).

Swapping the speakers should identify this as a speaker or AVR problem definitively - I just didn't have time to do that last night.

BeefJerky

They're on the back of the speaker. You should have two sets of binding posts on the back of each speaker. For normal use with a single set of wires, you need to have jumpers connecting the two reds and the two blacks.

Scoobmaster

Well I found out the problem. It is definitely the speaker and it was so glaringly obvious as to be laughable. I'll let the pictures speak:

My setup with the covers off, notice anything?


Let's examine the tweeters. First the GOOD working speaker:


And now the bad one:


Oh my, what have we here? WHERE is my tweeter cone? I couldn't believe it. just a hole there where the dome SHOULD be?! I peeked inside and could not find any trace of it. I have only had these for about 40 days and have never taken the covers off, I wonder if they were like that from day one? Anyway - a call to Polk and a new tweeter id on its way!

Thanks for your help. I feel pretty dumb for not taking the covers off first

Echosphere

lol That was a good one! You are a good man to admit that omission!

This reminds me of the line from the move The Lawnmower Man:
I checked the carb, spark, filter, lines, pulley..
"Did you check to see if it has gas in it?"

Btw, before you call, did you check inside the cab to see if the tweet had fallen in?

PerfectCreature

Wow, that is just way to odd.
I'm glad I wasn't missing one. Mine were just sort of defective.
Glad you fixed your problem

yepimonfire

LOL oops, looks like someone forgot to put the driver into the tweeter!