How to repair a tear of a Magnepan 1.7

[PCR]

Hello everyone. One of my Magnepan 1.7 speakers has a tear on the innermost line of its tweeter section. It is approx. a 5 mm tear. How can I fix this? When I make a hearing test from top to bottom, high frequencies seem homogeneous throughout. Although I may try a fix if possible. Thank you in advance.
Kind regards.

 

[Spkrdctr]

If it has no sound difference than the other one than you don't have to do anything. Just enjoy them. Nothing to worry about. Good Luck!

 

[somebodyelse]

In the absence of a recommendation from Magnepan I'd be tempted to patch it with a high quality tape like Scotch Magic to try to stop the tear growing.

 

[amper42]

Those speakers make fantastic kitty scratching posts.

 

[PCR]

Thank you for the reply. Sound pressure on the damaged speaker seems low to me, if not completely gone. I can balance the sound with the balance knob. However, some sources report that if at some point in the tweeter foil it breaks, the tweeter shuts off. I am trying to understand this. Can the tweeter work partially if some point in the tweeter foil is damaged?

 

[PCR]

Those speakers make fantastic kitty scratching posts.

This wouldn't upset me I love them. However, it happened most likely during transportation.

 

[somebodyelse]

Thank you for the reply. Sound pressure on the damaged speaker seems low to me, if not completely gone. I can balance the sound with the balance knob. However, some sources report that if at some point in the tweeter foil it breaks, the tweeter shuts off. I am trying to understand this. Can the tweeter work partially if some point in the tweeter foil is damaged?

Possibly, depending on the conductive element, but it seems unlikely. I've only seen the SMGa and that was a long time ago, but IIRC it had a wire bonded to the back of the membrane. I'm thinking that might be what I'm seeing through the hole in the picture, but it seems a bit different to what I remember. With the wire I think it's unlikely to be partially cut, so a reduction in sensitivity seems unlikely. If it's something more like a foil or PCB track then a partial cut is more plausible, but I'd still be surprised if it made a significant change to sensitivity as it would only affect a small section of a long track. Maybe you can test the DC resistance on left and right to see if they're still the same?

 

[PCR]

No, I couldn't check the DC resistance since the conductive aluminum foil is on the backside, and the backside is covered by a wood frame, so I can't reach it. It looks like the aluminum foil is discontinued by the damage; however, I agree with you, and as my research results are saying, the tweeter is continuous, just one piece from beginning to the end. Thus, if at some point it discontinues, then it is an open circuit and shuts off completely. However, it is working. Probably another component aside from the speaker creates the drop of sound pressure. I encountered this situation many times.

 

[Plan9]

In the absence of a recommendation from Magnepan I'd be tempted to patch it with a high quality tape like Scotch Magic to try to stop the tear growing.

I used that method for my MMG's and so far so good after about a year of casual listening from the proverbial sweet spot.

 

[bargainguy]

Having rewired a pair of MG-1 tweeters in the 80's, I can verify it's one continuous wire.

I bought those MG-1s knowing that the tweeter wires were blown and I'd have to redo them myself.

I sent off to White Bear Lake for a $13 kit that included a spool of nichrome wire and some green glue to hold the wire to the Mylar.

I had to scrape off the old wire and glue without damaging the Mylar underneath. No small feat.

Then I had to run nichrome wire across the Mylar and glue it in place in long runs that were 1/4" apart, looping at each end.

First time I tried one speaker and let the glue set, no sound whatsoever.

Had to completely remove glue and wire and start all over.

Luckily, the second try produced sound and I had just enough wire and glue to repair the remaining speaker.

Had those MG-1s for a decade before I sold them and moved on to MG-2s.

Never would have taken on that project if I knew how difficult it was.

 

[PCR]

The photos in my first post are taken facing front, from the listener side. When I look to the photo below I see the aluminum foil which is marked with red triangle. I can see the grey arch like shapes behind, suggesting they are magnets. However I am confused. I am searching for a long time and couldn't understand. To where does the the foil faces? To the back (magnet side), or to the fron (listener side). I wrote to Magnepan but I couldn't understand the replies. Thank you in advance.
Kind regards.

 

[somebodyelse]

If you could post Magnepan's replies maybe we'll be able to interpret them. From your picture it looks like the tracks (foil, wire or whatever) are on the other side, which I take to be the magnet side and away from the listener from your description. I've had a quick look for photos of how the 1.7 is constructed, but couldn't find any. It seems like it might have changed since I saw the SMGa without a cover though - or my memory is faulty!

 

[DonH56]

If the foil trace is separated the tweeter will not sound. The traces used to be on the side opposite the magnets for most speakers (the 20 and 30 series have magnets on both sides). In the past I repaired small tears like that using silver (conductive) epoxy. Last time I bought from DigiKey but here is some from Parts Express: https://www.parts-express.com/CAIG-...d-Membrane-Repair-Kit-1.0g-341-290?quantity=1 You have to clean/scrape the coating away to get good contact to the conductor (foil); that was usually the hardest part (easy to rip the foil whilst removing the adhesive coating).

HTH - Don