What type of fuses needed for Polk Audio Monitor 7A and 7-A? And how many Ohms?

Will2b1
Will2b1 Posts: 2
in Vintage Speakers
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I recently bought a pair of Polk Monitors, one is marked 7A (has 2 Fuses) and the other is marked 7-A (has 1 Fuse). I've only heard the 7-A work, guy I bought them from took the only good fuse off the 7A and it worked fine. What I'm needing is some new fuses for both of these, it's very difficult to read the 1 good one I have and not sure if it's the correct type,
but it says, 250v abuss agc 1a (I believe). I have not been able to find the exact specs, showing what type of fuses are needed looking online, and spent 30 min. with Polk Audio phone support yesterday, and they couldn't help me, said they'd call me back when they find the info I need... no call yet. I'm also wondering how many ohms these are. Q1 - Fuse types for both? Q2 - Ohms?
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  • tonyp063
    tonyp063 Posts: 1,083
    1. 250Volt, 1Amp fast-blow AGC fuse
    2. Fuses aren't spec'ed in ohms, so not a concern

    I just pulled one out of my 7a & it reads about 0.3 ohms on my Fluke. fwiw.

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  • Will2b1
    Will2b1 Posts: 2
    Thank you, tonyp063... And what I meant was the speakers themselves, ohms? Appreciate it!
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  • tonyp063
    tonyp063 Posts: 1,083
    8 ohms nominal
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  • Gardenstater
    Gardenstater Posts: 4,459
    Just as a matter of interest the DC cold resistance of a typical 1amp fast blow is 190mOhms (0.190 Ohms).
    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
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  • Gardenstater
    Gardenstater Posts: 4,459
    edited October 2020
    I don't know what fuse Polk specified for the MW (not tweeter) fuse in the early 7A with two fuses. I would suspect more than 1 Amp but don't go by my suspicions.

    PS: It may be that the one fuse was for the entire system, according to this photo I found:

    n1payplgasz8.png
    Post edited by Gardenstater on
    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
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  • audioluvr
    audioluvr Posts: 5,582
    These are really good ones.
    https://www.ebay.com/itm/371946656065
    Gustard X26 Pro DAC
    Belles 21A Pre modded with Mundorf Supreme caps
    B&K M200 Sonata monoblocks refreshed and upgraded
    Polk SDA 1C's modded / 1000Va Dreadnaught
    Wireworld Silver Eclipse IC's and speaker cables
    Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)

    There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus
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  • Gardenstater
    Gardenstater Posts: 4,459
    It seems they are discontinuing that particular model. I wonder what the cold DC resistance is, compared to a Littlefuse of the same amp rating and speed. They seem to be secretive regarding what's inside. They say this also:

    "NOTE: The “blow characteristics” will differ slightly (due to the different metallurgy of the fuse elements) between commercial grade and audio grade fuses. We can't guarantee that your audiophile grade fuse, won’t blow at a different in-rush current threshold, that your stock commercial fuse."
    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
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  • mhardy6647
    mhardy6647 Posts: 33,791
    edited October 2020
    Gardenstater wrote: »
    "...We can't guarantee that your audiophile grade fuse, won’t blow at a different in-rush current threshold, that your stock commercial fuse."

    Boy howdy, that's reassuring.

    :#

    Nice to know that your $10,000 audio component might give its life to protect your $30 fuse. ;)


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  • audioluvr
    audioluvr Posts: 5,582
    Not sure the M7's are valued that high. We take the poly switches out of the crossovers all the time. Now if you were sending them off for your kids first year of college?
    Gustard X26 Pro DAC
    Belles 21A Pre modded with Mundorf Supreme caps
    B&K M200 Sonata monoblocks refreshed and upgraded
    Polk SDA 1C's modded / 1000Va Dreadnaught
    Wireworld Silver Eclipse IC's and speaker cables
    Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)

    There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus
    · Share on FacebookShare on Twitter
  • Gardenstater
    Gardenstater Posts: 4,459
    Yeah in that case........DO NOT TAKE THE FUSE OUT!!!
    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
    · Share on FacebookShare on Twitter
  • Gardenstater
    Gardenstater Posts: 4,459
    Can't quite read the fuse values but it may say 1 and 1.5. Typical sloppy handwriting.

    lv79cv9q9j58.jpg
    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
    · Share on FacebookShare on Twitter