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Replacement of a tweeter

Discussion in 'Speakers' started by bmwuk, May 15, 2018.

  1. bmwuk

    bmwuk Well-Known Member

    I had noticed recently that my Paradigm Monitor 9s had one tweeter on the left speaker out. After looking online it looks like this was a common issue with the v2 series.

    What I remembered was that I had a pair of ADP dipole surrounds with the matching tweeter that I was no longer using. I took out the bad tweeter and a tweeter from the ADPs. The part number was slightly different on them. The ADP part number shared the same part number as the mini monitors but not the Monitor 9s.

    So after some discussions offline with a fellow Texan forum member, it was advised to invest in a multimeter to see if the Ohms matched. Thanks to Amazon, I had one ordered and delivered in two days.

    I ran the Ohm setting on the multimeter and the ADP tweeter read 4.8ohm. I took out the good tweeter from the monitor 9 and got 4.9. With that, I swapped out the bad tweeter . My suspicions were that the part number difference was the wave guide sizing. The mini monitor and ADPs have a 6.5" mid driver and the Monitor 9 has an 8" driver. So the wave guide for the two are different in sizing, hence the part number difference.

    I hooked up everything back up and audio happiness again. I'm hoping to upgrade them soon but at least I can enjoy my system while I wait for the upgrade
     
  2. rammisframmis

    rammisframmis Well-Known Member

    The resistance in Ohms which you read on a speaker is almost meaningless, and I certainly wouldn't use that alone to determine anything about a speaker. Its just the DC resistance of the wire in the voice coil - doesn't mean much at all. Doesn't necessarily mean the speaker driver "won't work", but there might be other differences besides the waveguide.
     
  3. Flint

    Flint "Do you know who I am?" Superstar

    There were many other factors involved in the decision to rely on the resistance measurement as one verification point of compatibility. It was really a gut check to ensure that the claims lacking strong credence on the internet might be true.
     
  4. rammisframmis

    rammisframmis Well-Known Member

    When measuring low resistances with a multimeter, I doubt many people realize that unless compensated for, the resistance of the test leads themselves can make the measurement off by as much as .5 Ohm. Just short the two leads together to prove it to yourself; the result will not be zero, assuming the meter is good enough to read less than one Ohm accurately. Most meters have some mechanism to cancel this lead resistance out. So if someone on the internet says something should be "4.9 Ohms", nobody knows if that includes lead resistance or not. Just something to keep in mind.
     
    Last edited: May 15, 2018
  5. Flint

    Flint "Do you know who I am?" Superstar

    Good advice.

    In this instance, since one tweeter came from a standard speaker with a single tweeter rated at 8 ohms and the replacement came from a dipole speaker with two tweeters rated for 8 ohms, the concern was that the tweeters may not have the same voice coils despite being from the same "line" and claiming to have identical "voicing" and technologies. One might be designed to be double the impedance of the other to accomplish a rated 8ohm load for the speaker system. The resistance check confirms they are of the same general impedance, if not identicle.
     
  6. bmwuk

    bmwuk Well-Known Member

    Yes apologies for not representing the discussion well. I am a novice in this area so me repeating everything in the conversation wasn't going to happen.

    The multimeter was the last check
     
  7. malsackj

    malsackj Well-Known Member

    I disagree with the meter being the last check, How did the swap sound and did you hear a difference between L / R.
     
  8. bmwuk

    bmwuk Well-Known Member

    It went great. The right and left sound good.
     
  9. JeffMackwood

    JeffMackwood Maxi-Me

    Congrats!

    Out of curiosity did you measure the resistance of the "bad" tweeter and if so what did you get? (In other words were you able to confirm that the problem is absolutely with this tweeter? I've seen cases where the act of changing out a tweeter was enough to make things right, even though there was nothing wrong with the tweeter itself to begin with - but rather with something else like a loose connection.)

    Jeff
     
  10. bmwuk

    bmwuk Well-Known Member

    The tweeter backside had the below copper ring that was pulled apart from the magnet. It was busted
     

    Attached Files:

  11. rammisframmis

    rammisframmis Well-Known Member

    The copper thing is the voice coil, and it appears it has become detached from the dome of the tweeter (assuming you didn't pull it apart). The tweeter might have failed from clipping of your power amplifier, thus overheating the voice coil. That is something which is relatively easy to do with a signal source like a movie.
     
  12. bmwuk

    bmwuk Well-Known Member

    Chicken or the egg... The tweeter wasn't properly working. When removing the wave guide the tweeter pulled a bit from the magnet, pulling the voice coil. However, I believe it was already messed up
     

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