Polk Monitor 10 no bass

YYCPolk
YYCPolk Posts: 18
edited February 2022 in Vintage Speakers

Hello all, I'm a new member and hope to get some help.
I got my hands on a set of Monitor 10 speakers, thinking this is the older original set as they have the MW6500 woofers.
Anyways, one of the speakers doesn't produce bass. Here's what I've done.

I checked the 6.5 speakers out of the box, sound great nothing wrong that I can see.
I replaced the 10" from the working speaker, no difference, both sound great in the working speaker. Both look great as do the 6.5s no damage anywhere.
I have swapped cables and receivers. So not a source issue.

What I noticed is that the left side woofer was tinkered with, the soldering looks poor and there were wire clippings in the box.

Another thing I notice is that when I push that left side 6.5 woofer in by hand, the 10 inch comes alive and starts to sound like it should or at least close. .
Again, all 6.5s and 10s look good and have good smooth movement when touched. Magnets seem in place. The left side 6.5 that I suspect may be problematic appears to have the magnet epoxied. I understand these magnets can be a problem.

Do I have a cross-over issue? Is it possible that the wires got crossed when the 6.5 inch speaker was tinkered with and can that cause no bass? The 6 5 itself seems to work just fine.

My next step is to replace the 6.5 in question with one from the working speaker, but before resoldering stuff I thought I'd check with you guys.
Also, would bad soldering cause it?Again, even with that poor soldering job the 6.5 actually sounds good.

Any other ideas?


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Comments

  • Gardenstater
    Gardenstater Posts: 4,459
    edited February 2022
    The red dot is supposed to be the positive terminal, unless they mis-marked at the factory. Black wire is supposed to be positive and white negative. That's the convention Polk used....like AC wiring (black/hot white/neutral). You need to check the wiring and polarities. If one woofer is out of phase with the other, bass is crappy. Looks like the one in your picture has the wrong color wiring. In the end wire color is not what is important but you need to trace them and compare to schematic. And both speakers need to be same. Captain obvious statement.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • Wow, thanks for this. Looks like you solved the mystery.

    This is the other speaker with black on the red dot. Where it should be.

    Thanks a bunch, I'm gonna fix that and report back.

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  • Faustin
    Faustin Posts: 1,149
    And, they are definitely in need of a crossover refresh. Age will have taken it's toll.
  • That was it, reversed the black and white and got sane sound on both speakers now. Thanks for the tip.

    Now about the crossovers. Is there a ready to buy unit or do I need to replace the individual components? Is the upgrade a significant upgrade? The speakers sound good now, but there is room for improvement.
  • Gardenstater
    Gardenstater Posts: 4,459
    edited February 2022
    You're welcome. Now you don't have noise cancelling MW's lol.

    You could start by reading this concurrent thread going on by someone who probably has the same vintage of 10's. Then you will probably have some more specific questions.

    Yes, you upgrade the resistors and capacitors and wires to better ones. Significant upgrade yes. You are just getting started and it is impossible to know how much better things can sound. Ignorance is not bliss lol although you will be poorer $$$.

    https://forum.polkaudio.com/discussion/195811/i-need-help-with-updating-the-crossover-in-my-polk-model-10-speakers/p1
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform