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In Reply to: RE: MGIIIa tweeter question posted by Davy on August 12, 2014 at 13:27:36
Dave,
You can look at www.shackman.deReiner Rφmer does the new Mylar. The re-wiring is done by a friend of mine.
Prices are higher than at Magnepan but no problem with customs as it is within EU. In the end cost is similar to sending them to Magnepan. I visit Germany regulary (my wife is german) and that make shipping easier.
Tympani I - IV, Bass, new film and wire panel 300.0
Tympani I - IV, MT/MHT, new film and wire panel 200.00
MG I/II. Bass/MHT, new film and wire pair 790.00
MMG/SMG, non quasi ribbon, new film and wire pair 650.00
MG 0.5 - 12 pair 286.00
MG3.x Series, Bass, MHT, new film and wire pair 1250.00
Sheila at Magnepan wrote:"The 40" and 60" are 2 ohm and the 60.6" is 3 ohm
I don't know about a 3 ohm for the T4a, they use a 60" tweeter."I think even a 3 ohm ribbon would work in the older ribbon cage. Could not be all that important if the gap between the magnets is a bit wide, it is a matter of about 1 mm each side of the ribbon.
Edits: 08/13/14 08/13/14 08/13/14Follow Ups:
Thanks for the info. Well its great to know someone can replace the mylar with the same spec and tension for a cost. I can rewire myself but it's a bit of a slow process so rewiring as well is welcome. Seen many different Tympanis before for sale with broken mylar. If this had been available then....
I think you are right it's actually well worth trying an narrow 3 ohm ribbon foil in an older wide cage. The gap is wider but not vastly. I thought about it before but was put off as it's is very important to get those adhesive dots down to secure the ribbon and I didn't think it would be possible (discussed it with Satie). If it however viable to put those dots in (might be a bit tricky because of the extra space) then it might work just fine. I might try it soon in my MGIIIa tweeters cages, as like I say, that narrow ribbon sounds a lot better than the 2 ohm wide type.
I'd still bet on your Tympanis having the older discontinued 3 ohm wide ribbons in them though, as there are no resistors in the crossover. It's still a good tweeter, just not exactly replaceable if it breaks. Its a very thin material so I'd be careful moving them around.
Its a bit weird that Shelia is not aware of the older 3 ohm wide tweeter that is 60" long. It's likely a common issue that comes up with people break their MGIIIa ribbon as both the wide 3 ohm and 2 ohm ribbon was used in that tweeter, and if supplying a new 2 ohm ribbon to someone that had an early MGIIIa (with the 3 ohm ribbon) they need to be told to install 1 ohm resistor in the crossover. Info about that is written in the MGIIIa manual. The Tympani IVa obviously also used both types of ribbon too throughout its manufacture.
Magnepan is clear on when to install a resistor in series with the ribbon. They just do not mention why. My T-IVa are early ones, serial no. is 020838. They can have 3 ohm ribbons as there are no resistors.
http://www.forumbilder.se/DDN94/60-inch-ribon.jpgNext step will be to investigate the ribbons on the 3.6 to see if they really have different ribbon cages.
Edits: 08/13/14
Thanks for the link. That confirms the TIVa (like the MGIIIa) also used both types of wide ribbon during it's manufacture. Those instructions are for installing the current 2 ohm wide ribbon, - which is why they are saying you need to install a 1 ohm resistor in the earlier models (as it was not present already because the theearlier speaker used the 3 ohm wide ribbon).
Yes from your serial no (and lack of resistors) I'd almost bet my life on your TIVa ribbons being the discontinued wide, very thin 3 ohm versions. Why did you buy more ribbon foils?, just for backup/spares?
Let me know what you see when you have a look at the 3.6 ribbon vs the IVa ribbon. The channel the ribbon goes in is definitely a different size between the two (newer version is narrower). If you take them out I would also be interested two know whether the cage is the same width (the part that hides in the speaker) or different (I think the newer cage is likely a less wide, but I could be wrong). I could look in my two pairs but no time at the moment.
At some stage I might buy some of the new thinner 3 ohm ribbon foils and try installing in the older wide cage. It might be a bit tricky but still possible to glue the foil down with the necessary adhesive dots. If the magnet gap is also different between the two cages it might not quite work as intended though, - perhaps it might affect the output a bit?.
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