Help with defective midrange

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NeilGabriel
NeilGabriel Posts: 1,487
edited May 2007 in Troubleshooting
I just got a pair of used Monitor 5s in today. Great cosmetic condition and they had been listed as tested and fully functioning. Apparently a reliable ebay seller....even though the speakers were wrapped in newspaper and burlap bags....my cat loves the burlap. I was anxious to report on the differences between a series one and series two 5, but the midrange on one of the speakers is not functioning properly. There is a small amount of sound coming from it, but not much. The tweeter seems fine (until I pulled the fuse) to make sure the mid was producing some sound.

I thought someone posted a question about fixing a mid, but I can't find any. Suggestions please. This could be my first speaker surgery.

Mike
Post edited by NeilGabriel on
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  • engtaz
    engtaz Posts: 7,654
    edited May 2007
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    H9 is my mentor. PM him
    engtaz

    I love how music can brighten up a bad day.
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  • NeilGabriel
    NeilGabriel Posts: 1,487
    edited May 2007
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    The mid is a 6502 with date of April 29, 1986. All wires appear connected. There does not appear to be any damage to outside or inside of speaker.
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  • heiney9
    heiney9 Posts: 25,092
    edited May 2007
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    Swap drivers to see if the problem follows. My best off the cuff guess is a x-over component.

    Inspect the driver for tears in the surround or cone (although that shouldn't affect output that much)

    Very lightly push the cone evenly in and release several times listening for a scrunching/rubbing/scratching sound. If you hear the aforementioned sound the driver VC is toast.

    If these 3 steps reveal nothing buy a new driver. If the driver works in the other cabinet then I'm guessing x-over. If it the same in the other cabinet the driver is no good, buy a new driver.

    I'm told they will available again from Polk in a short time as they have decided to manufacture them again.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • Polk65
    Polk65 Posts: 1,405
    edited May 2007
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    NeilGabriel wrote:
    the speakers were wrapped in newspaper and burlap bags

    Newspaper and burlap? :eek:

    Pack speakers as good as or better than you would a hard drive. Layers of bubble wrap or soft foam are good. Newspaper, shredded paper, burlap and peanuts should be avoided. Some outer protection like pieces of rigid foam or double boxing helps out a lot.
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  • engtaz
    engtaz Posts: 7,654
    edited May 2007
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    Polk65 wrote: »
    Newspaper and burlap? :eek:

    Pack speakers as good as or better than you would a hard drive. Layers of bubble wrap or soft foam are good. Newspaper, shredded paper, burlap and peanuts should be avoided. Some outer protection like pieces of rigid foam or double boxing helps out a lot.

    They best packing advice I have seen
    engtaz

    I love how music can brighten up a bad day.
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  • Polk65
    Polk65 Posts: 1,405
    edited May 2007
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    I take no credit for it. The suggestion has been posted before.
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  • NeilGabriel
    NeilGabriel Posts: 1,487
    edited May 2007
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    heiney9 wrote: »
    Swap drivers to see if the problem follows. My best off the cuff guess is a x-over component.

    Inspect the driver for tears in the surround or cone (although that shouldn't affect output that much)

    Very lightly push the cone evenly in and release several times listening for a scrunching/rubbing/scratching sound. If you hear the aforementioned sound the driver VC is toast.

    If these 3 steps reveal nothing buy a new driver. If the driver works in the other cabinet then I'm guessing x-over. If it the same in the other cabinet the driver is no good, buy a new driver.

    I'm told they will available again from Polk in a short time as they have decided to manufacture them again.

    H9


    Thanks. I will try swapping tonight. Since I use a 5 for a center, I actually have a spare...so to speak....but I would like to get this up and running. Does anyone know if there are photos posted showing the cross-over? I would be guessing as to what it is. Do you get to it through the hole from removing the mid (or passive) or do you take out the back where the binding posts are? Thanks.

    Mike

    Mike
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  • heiney9
    heiney9 Posts: 25,092
    edited May 2007
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    See this post

    http://www.polkaudio.com/forums/showthread.php?t=51420

    Depending on when the 5b was manufactured the x-overs might be a bit different (looking). If you have the peerless tweeter the x-over is quite different(parts wise).

    H9

    Taking it out from the back is the best method if you need to work on it.
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • NeilGabriel
    NeilGabriel Posts: 1,487
    edited May 2007
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    It's the driver. I put in another 6502 and it worked fine. Can these be ordered through Polk? I seem to see people advertise to get them. Anyone with a spare 6502 will be rewarded.

    Not that I will likely understand, but what in a driver goes bad? It looks perfectly healthy?
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  • engtaz
    engtaz Posts: 7,654
    edited May 2007
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    whoever sold it to you should send a replacement
    engtaz

    I love how music can brighten up a bad day.
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  • Polk65
    Polk65 Posts: 1,405
    edited May 2007
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    NeilGabriel wrote:
    what in a driver goes bad? It looks perfectly healthy?

    Pictures... http://www.polkaudio.com/forums/showthread.php?t=43823

    The rear part (pole piece) is glued to a plate. The reason for failure is the effect of being dropped or sliding loosely in a delivery truck against walls. This can cause the magnet or pole piece to stick together or even shear off. Newspaper and burlap is below average for shipping an item with moving parts.
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  • NeilGabriel
    NeilGabriel Posts: 1,487
    edited May 2007
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    Thanks for the info and that link is great. The seller is giving me a small refund. Nice enough for a small dollar purchase. I agree about the packing and advised him that it was not very secure...two speakers in a vacuum cleaner box stuffed with paper and burlap bags.
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  • engtaz
    engtaz Posts: 7,654
    edited May 2007
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    Good for you on the refund.
    engtaz

    I love how music can brighten up a bad day.
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