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I went round to my mate's place yesterday, to see whether I could get the T1-Ds going - in the meantime, after picking them up on Monday, he had removed all the staples and taken the socks off the 6 panels.
The tweeter panels (magnets both sides) are fine - and running some warble tones through them from 1KHz to 16KHz (which we couldn't hear! :-)) ) didn't reveal any buzzing.
All 4 bass panels have been patched with Miloxane - so there's no delam but, unfortunately, the 2 panels on one side don't produce any sound ... and I can't get a resistive reading from either driver. I can see some white spots on the wires in a couple of places - so maybe some corrosion has broken continuity?
So these 2 panels will have to be sent to the Oz Maggie importer, for a strip & re-lay. But I was able to get the remaining panels working - a tweeter panel plus a bass panel each side. (I am calling these a 'T1-d', rather than a 'T1-D' ... given there is only 1 bass panel per side! :-)) But the bass is entirely satisfactory - given it's the same as what I have on my Frankenpans.)
Next task, while we're waiting for these panels to come back, is get some braced stands made - to allow the panels to be arranged in an arc.
But I have one question for you guys: the tweeter panel is only 3/4 length - currently the top of the tweeter is the same level as the top of the (full-length) bass panels ... which means there is no sound source for the bottom 2'.
Now Maggies sound best when you are sitting down, so that your ears are at approximately the centre of the drivers. This says to me that when we ultimately replace the chipboard frames (yes, the frames are chipboard - not MDF - they're so old!), the tweeter panels should be located lower, so that the listener's ears are at the middle of the tweeter panel?
Your input would be appreciated.
Thanks,
Andy
Follow Ups:
An update for any interested parties - and not all good news!! :-((
Well, initially, the 2 tweeter panels worked and 2 of the 4 bass panels. So we sent off the 2 non-working bass panels to the Oz Maggie importer, for re-wiring. He had to bring in some thicker wire from the factory (thicker than what he uses on 3.X series) and that only just arrived.
So he will start the re-wire of the failed bass panels in a few days. Meanwhile, one of the other 2 bass panels has also succumbed to corrosion - so they need to be sent off, too. And just yesterday, one of the tweeter panels (double-sided magnets) failed - and it's not the fuse! :-((
So they will have to be shipped off as well.
So it will be a couple of months until poor old David can get his T1-Ds working properly. :-(( They should sound great, though, as the 6 braced stands have been made - see pic of 1 of the bass panels fixed to its braced stand:
Regards,
Andy
Sad to hear corrosion got all the panels. But not really surprising as if the conditions to create corrosion damage on one panel were present, then the other panels should be expected to be exposed the same way.and fail in quick succession.
And at least the guy got to hear them initially (with 1 bass panel per side), so he could see they were worth spending the money on. :-))
Andy
Andy wrote:
"Well, initially, the 2 tweeter panels worked and 2 of the 4 bass panels. So we sent off the 2 non-working bass panels to the Oz Maggie importer, for re-wiring. He had to bring in some thicker wire from the factory (thicker than what he uses on 3.X series) and that only just arrived."
According to Magnepan they use AWG 25 on the Tympani I-D basses and AWG 22 the 3-series. Maybe the importer ment the midrange wire of the 3-series where AWG 31 and 32 as been used?
I have no idea, Roger - the Maggie importer is 1,000kms away from me - so I can't just drop in and have a chat.
I just have to send them up and let him deal with them.
Andy
Andy,
Do you know how much he want to rewire each driver? Just curious...
No, I don't know yet.
Andy
Recliner sits on 5" thick concrete blocks
An extra cushion is on the seat raises ears to middle of the midrange and just above the middle for the rest of the drivers
Yes those white spots are an aluminum oxide--in my experience these "nodules" may suggest breaks in the voice coil. I used a continuity tester to locate the two breaks in the wires in my "silent" MG-IIa. I repaired those breaks and the speakers still play sweetly two years later. I stripped off and replaced the tweeter wires--easy job.
If you are seeing voice coil corrosion in all the panels why not replace all the wire while the speakers are apart? From your posting I got the impression that only the dead panels were being sent out. Maybe I misread that.
Regarding tweeter height... In the old days we would put Decca or Sequerra ribbons way up on top of the tweeter panels and it sounded great. These days I would try a pair of Linaeum tweeters crossed at ~6Khz for fun. Time to dust off that Dahlquist DQ-LP1.
My T-1C and all the T-1D I recall had "L" bracket feet that facilitated any alignment of the panels.
...j
... why not replace all the wire while the speakers are apart? From your posting I got the impression that only the dead panels were being sent out. Maybe I misread that.
You read correctly - the first thought was to just send off the dead panels. But I am seeing my mate on Sunday, so will ask him whether he wants to send them all off - rather than 2 now ... and the other 2 in 'X' years time, when they inevitably fail.
There are 2 advantages with proceeding with the current plan, though:
1. he still gets to listen to some great speakers while he waits for 2 failed panels to come back from the refurb. :-))
2. 2 bass panels fit inside the ply 'coffins' that I made for my own Frankenpan bass panels (for shipping protection) - 4 bass panels won't.
My T-1C and all the T-1D I recall had "L" bracket feet that facilitated any alignment of the panels.
These panels have some chrome 'mushrooms' (about 1"D) nailed to their bases - not the usual T-feet. They were removed when the burlap socks were stripped off - and won't be needed with the braced stands.
Regards,
Andy
Actually the tweeter height matters less in this case since the tweeter covers from 1khz so most of the height localization is with it. It would be better to do as you plan and have the driver centers aligned at the same height at listening height. .
.
Tweeter height matters, slightly. The tweeter of my Tympani IIIA shown above, is partly split into two sections by the silicon dots 1/3 from the top. The upper section is probably not going as low as the lower one. The main listening axis is at about half way up on the lower section. The upper section has a lower moving mass and maybe reproduces higher frequencies better?
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