Infinity Quantum Midrange repair with pictures !

Need advice-Infinity Quantum Mid repair

I followed the directions. I am still reading open. If I take yet another winding off, will that create a problem? The other side is reading 8.8. So, is 8.8 too high?
 
I have to do both sides, one side is done, the other is a problem. I can't find the end of the coil on the side with the split in the ring. Is it fed under all the windings? Any advice finding the wire on this side so I can take a winding off to feed through the dome?
 
Update-Well, I am 3 for 3 on repairs of the midranges. Taking an additional winding does not affect anything. Readings around 6.9 are fine (I have a 7.2 and can not hear any difference). The other wire IS hard to find. The biggest issue I have is seeing the thin wire. I am still looking for a jewelers magnifying glass. I have been using a loop, which is not fun. After I glue down, I use black nail polish to hide the wire, and any glue snot remaining. I have been using speaker foam glue. May not be the best, but is working thus far.

Thank you for laying this out so nicely. I followed it, and it works!
 
I too have repaired 6 of these now, 4 on the qls1 and both in my q4 with this great method. One thing needs to be noted if not already done so is to mark face plate and magnet so they go back together the same way they came apart.

After having my qls1 together for a few months I noticed some distortion in the midrange. Sort of in and out on some recordings then I wouldn't notice it. Finally I played a passage over and over where there was distortion and it was two mids I repaired. They sounded just fine 99% of the time. The coil was not centered perfect. If you very gentle pinch the dome and push it in a little bit and let it come out on its own sometimes I could feel a tiny bit of rub in both of them. Now I played music thru these when I was putting them back together, did a frequency sweep and could not hear any problems when I first put them back in the speakers after my repair. Only thing I can think of was they were put together with the holes lined up differently as I did not mark them. I switched them 90 degrees and snugged them back up and pushed on the dome and centered it until it was perfect then tightened. No distortion on any recording after a year now...QLS still my favorite speaker and best I ever heard.
Jim
 
Thanks to this thread I was able to fix the bigdome midrange of my Dahlquist DQ 10. I had to replace the tinsel wire and solder it (link to the thread). I noticed that aligning the voice coil in the magnet is very hard, especially when I am inserting the screws. Some other people mentioned it repeteadly here. The issue is that even when the midrange is fixed and installed back in the speaker, it seems that the high notes never sound perfect and there is some kind of distortion after the "repair" because the voice coil is not perfectly placed. Here is an example of the distortion:


It is difficult because when one tries to insert the screws, any vibration will move the allignment. Here is another example:


I decided to contact a person on the bay that repairs these kind of soft domes, and, very kindly, he shared a trick with me:
Sometimes a little silicon lubricant paste like vassoline petroleum jelly can help as well.

After using it, the midrange dome sounded way better, and I don't notice any distortion now:


Well, that is all, folks! Rubbing a little bit of vaseline on the voice coil seems to help.

Hopefully this little piece of information will be helpful if any of you deal with the same issue I had.
 
I forgot to mention on my previous post that if I ever need to repair a midrange soft dome like this one again, I would NOT open it. Instead, I would cut most of the tinsel wire (but not the portion near the dome), replace it with a hair of speaker wire, solder it and see if it works with a multimeter (like in the image below). Unless it is extrictly necessary I would avoid opening it. This way you are certain you have not messed the voice coil nor need to deal with alligning it.

IMG_20191211_194927 - Copy.jpg
 
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i'm attempting my own midrange repair adventure as well! I don't think my repair was possible without opening up the unit and unwinding some of the voice coil. Has anybody run into an issue where when unwinding the wire, there's a drop of adhesive or lacquer in the way?

I am trying to unwind half a revolution of coil for the + and - side, but for one of these I can only unwind a quarter turn before I hit this drop of adhesive...

I'm thinking about just pulling this wire through the dome where it is now, and then add wire to get to the solder terminal... it will look ugly but better than breaking the voice coil wire!

Where I’m pointing at is where the wire runs into this glob of an anchor.

upload_2023-5-28_23-36-43.jpeg
 
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i'm attempting my own midrange repair adventure as well! I don't think my repair was possible without opening up the unit and unwinding some of the voice coil. Has anybody run into an issue where when unwinding the wire, there's a drop of adhesive or lacquer in the way?

I am trying to unwind half a revolution of coil for the + and - side, but for one of these I can only unwind a quarter turn before I hit this drop of adhesive...

I'm thinking about just pulling this wire through the dome where it is now, and then add wire to get to the solder terminal... it will look ugly but better than breaking the voice coil wire!

Where I’m pointing at is where the wire runs into this glob of an anchor.

View attachment 2898162

I see they have some new OEM style speakers now on the auction site to replace any that are bad. Not the cheapest fix but they are brand new and look fairly close to the originals.

About ten years ago a speaker company had a close out deal on those mid ranges, I got enough brand new ones to replace all my mids in both pairs of my QLS-1's and for a couple pairs of my Q2's
 
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