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Length of the newer (3 ohm) ribbon cage

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Posted on August 30, 2020 at 22:22:47
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000
Can anyone do me a favour and tell me the length of the 3 ohm ribbon cage?

I have just blown one of my T-IVa ribbons - which are 2 ohm - so am taking this opportunity to migrate to the newer ribbons, rather than just getting my ribbon repaired.

The new ribbons will require me to lengthen the slot which my current ribbons fit into. As I can't realistically listen to music with a blown ribbon, I can do this work whilst waiting for the new ribbons to arrive ... if I have their length measurement.

Then I expect a mate of mine will seize the opportunity to add a (relatively) cheap pair of old ribbons to his T-1Ds! :-))

Thanks,
Andy

 

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RE: Length of the newer (3 ohm) ribbon cage, posted on August 30, 2020 at 23:18:16
Roger Gustavsson
Audiophile

Posts: 1766
Location: Huskvarna
Joined: February 12, 2010
As I have both, the ribbon cages are the same. Both measures 60" (1524 mm). The magnets are thicker and the ribbon itself is narrower in the newer ones. The attachment of the ribbon element is different, not sure how. I will have to check.

I have three pairs of ribbon tweeters. The very first one with the extremely thin ribbon (3 Ohm), one of them broken but I have the 2 Ohm replacement. Then two pairs of the newer narrower ones.

 

RE: Thanks very much, Roger! ..., posted on August 30, 2020 at 23:28:23
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000
I'm delighted to hear they are the same length - I had read the newer ones were 1/2" longer (although I could never understand why Magnepan would've bothered to change the physical dimensions of the ribbon cage!).

Now, you say "The attachment of the ribbon element is different, not sure how. I will have to check. ". I presume you mean the way the ribbon is suspended between the magnets?

If so - that is not a concern to me - however, it will be annoying if the flange screw holes are not located in the same places.

Andy

 

RE: Thanks very much, Roger! ..., posted on August 31, 2020 at 02:53:55
Roger Gustavsson
Audiophile

Posts: 1766
Location: Huskvarna
Joined: February 12, 2010
The ribbon is suspended in the same way between the magnets but I think the termination at the ends is different and need a bit more space. I have measured the Cages and they are the same for T-IVa and MG 3.6. These are of two different generations of the Magnepan ribbon tweeter. The third pair is also of the second generations (still in use today) but it is still in its container.

 

RE: Thanks very much, Roger! ..., posted on August 31, 2020 at 04:31:23
Roger Gustavsson
Audiophile

Posts: 1766
Location: Huskvarna
Joined: February 12, 2010
Magnepan Ribbon Tweeter





 

RE: Thanks very much, Roger! ..., posted on August 31, 2020 at 08:14:54
Roger Gustavsson
Audiophile

Posts: 1766
Location: Huskvarna
Joined: February 12, 2010
Above and below the cage, there need to be some space for the connections. Here is a picture showing the MG 3.6 upper connection.





Here a spare set I have.





Here the ones of the T-IVa (hardly visible in my storage baffle).





Magnepan and others use to say the new ones are taller/longer. Both cages measures 60"/1524 mm. The ribbon itself is slightly shorter in the wide version.

 

no ribbons no problem, posted on August 31, 2020 at 09:21:53
farfetched
Audiophile

Posts: 819
Location: Cleveland!
Joined: October 13, 2010
"I can't realistically listen to music with a blown ribbon, I can do this work whilst waiting for the new ribbons to arrive"

Recording technology is hard-limited on freq. response till the mid 40's. You can listen to Bix Beiderbeck. You can listen to Louis Armstrong and his Hot Five. You and listen to the fabulous songbird Erna Berger on the Lebende Vergangenheit label.

You can listen to Flagstadt, Ponselle. You can listen to Friedrich Schoor sing some excellent Wagner. You can listen to early Furtwangler and Mengelberg. You can hear some strange, strange opera singing and listen to Fernando de Lucia on the Pearl label.

You can listen to Benny Goodman's famous Carnegie Hall concert. You can listen to Cortot play Chopin. You can listen to Casal's groundbreaking Bach cello suites.

There are decades of music to listen to. And unless you needed the sizzle and hiss, you are missing none of the music w/o tweeters because the the recording technology did not cover what we now call the tweeter range.


/ optimally proportioned triangles are our friends


 

RE: Length of the newer (3 ohm) ribbon cage, posted on August 31, 2020 at 10:47:17
emailtim
Audiophile

Posts: 2135
Joined: July 2, 2017
My 3.6 and 20.1 measure 60.75" inches tall, but that includes the Magnepan top and bottom name plates. The top and bottom connectors make it slightly longer.

The width of both are 2 1/16" wide.

Good luck with your repairs.

 

RE: Length of the newer (3 ohm) ribbon cage, posted on August 31, 2020 at 15:02:31
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000
Thanks, Tim,

Are you able to just take a measurement of the length between the top & bottom ends of the ribbon cage flanges?

From the rear, if the name plates are hiding them on the front?


Thanks,
Andy

 

RE: Length of the newer (3 ohm) ribbon cage, posted on August 31, 2020 at 15:41:55
emailtim
Audiophile

Posts: 2135
Joined: July 2, 2017
I pealed off the back nameplates and remeasured at 60 5/8". The name plates were mounted with a little overhang.

I can not measure the cages without taking off the socks.

The inside width of the metal cage is 0.7" wide according to my Starrett calipers.

 

RE: Great - thanks, Tim ..., posted on August 31, 2020 at 16:54:34
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000
Mine are exactly 60". So I have to extend my slot by 5/8" = 16mm.

Andy

 

RE: Great - thanks, Tim ..., posted on August 31, 2020 at 23:35:06
Roger Gustavsson
Audiophile

Posts: 1766
Location: Huskvarna
Joined: February 12, 2010
This is strange. Last time I measured them the were same length, T-IVa amd MG 3.6. I will have to check once more.

 

RE: Yes, it is (strange) ..., posted on September 1, 2020 at 00:01:19
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000
... Roger! :-))

I had always thought that the new ribbon was a bit longer.

Andy

 

RE: Yes, it is (strange) ..., posted on September 1, 2020 at 07:19:58
Roger Gustavsson
Audiophile

Posts: 1766
Location: Huskvarna
Joined: February 12, 2010
Embarrassing .... being a pro in measuring. The old cages are 1524, the later ones are 1540 mm. I took for granted the later ones had the covers over the edge of the cage to cover the connections.

 

RE: Thanks - it's settled then! ..., posted on September 1, 2020 at 15:31:58
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000
1540 it is!

Andy

 

Audiophiles want clear high frequencies!, posted on September 6, 2020 at 07:04:06
GreatSound
Audiophile

Posts: 18
Joined: August 23, 2020
You must listen to, and have old mono recordings!

Have you heard of stereo!

 

Did the tweeter fuse blow ?, posted on September 10, 2020 at 14:04:44
emailtim
Audiophile

Posts: 2135
Joined: July 2, 2017
Did the tweeter fuse blow ?

 

RE: Did the tweeter fuse blow ?, posted on September 10, 2020 at 14:55:40
Norman M
Audiophile

Posts: 1321
Location: NYC Suburb
Joined: December 9, 2012
I believe andyr has removed both fuse holders and fuses.

 

RE: No, Tim - as Norman posted ..., posted on September 10, 2020 at 15:12:48
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000
I have removed both fuses & fuse-holders.

The ribbon blew because the amp was pumping out positive-only square waves; unfortunately, my testing was not sufficient (before connecting it up to my Maggies).

Andy

 

RE: For reference - for others swapping 2ohm for 3ohm ribbons ..., posted on September 11, 2020 at 22:03:51
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000


The above is a pic of the top end of my mid/ribbon frames, showing the extra length I had to extend by ribbon slot by. This was made a bit harder in my case because there is a rebate either side of the slot for the ribbon cage flanges to fit into - these rebates also had to be extended.

(In contrast to a stock Maggie, I have my ribbons 'back to front ' and mounted on the front of my hardwood frames - so that the sound from the ribbons is not diffracted by the horizontal bars of the ribbon cage. The rebate is there to put the ribbon in the same vertical plane as the mylar of the adjacent T-IVa mid panels.)

Roger kindly measured his 3ohm ribbons and determined that, as the ribbon cage is 5/8" (16mm) longer than the older 2ohm ribbon cage - and the screw holes are positioned the same as with the 2ohm ribbon cage - the length extension required is 5/16" (8mm), each end.

Regards,
Andy

 

RE: For reference - for others swapping 2ohm for 3ohm ribbons ..., posted on September 11, 2020 at 22:44:35
emailtim
Audiophile

Posts: 2135
Joined: July 2, 2017
I like the idea of reversing the tweeters.

Were you able to hear any differences by doing this ?

 

RE: Were you able to hear any differences by doing this ? ..., posted on September 12, 2020 at 00:52:47
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000
Can't say that I did, Tim - because I didn't try them both ways. I designed my hardwood frames to have rebates on the front - and that's how the furniture-maker built them.

It just seemed more logical not to have the horizontal bars of the cage impacting the ribbon's output.

(This does reverse the polarity of the ribbon, though - so now the top is the -ve (black) end. :-)) )

Andy

 

RE: Were you able to hear any differences by doing this ? ..., posted on September 13, 2020 at 06:52:11
Roger Gustavsson
Audiophile

Posts: 1766
Location: Huskvarna
Joined: February 12, 2010
There is a difference in response from the front and the rear, maybe even more so in the original baffle. The cavity in front of the ribbon does influence the response and there are two layers of cloth in front as well. This is the response front vs. rear of my 3.6, close to the ribbon. It is more even from the front (orange).





 

RE: Very interesting - thanks, Roger nt, posted on September 13, 2020 at 15:41:18
andyr
Manufacturer

Posts: 12062
Location: Melbourne
Joined: September 2, 2000
.

 

RE: Very interesting - thanks, Roger nt, posted on September 14, 2020 at 00:58:58
Roger Gustavsson
Audiophile

Posts: 1766
Location: Huskvarna
Joined: February 12, 2010
My swedish friend, who did a complete modifaction of his 3.6 , also made a measurement of the ribbon tweeters both ways. His baffles have a less deep cavity in front of the ribbon, 6 mm or so where the original baffle is about 20 mm. (My measurement above had the ribbon in situ, there is no cavity on the back of the baffle)



 

RE: Maggie Tweeter, posted on September 14, 2020 at 18:17:11
shumi
Audiophile

Posts: 97
Location: Virginia
Joined: January 11, 2020



OCDhifi Mike uses Reynold Wrap for his Maggie tweeters.....

https://www.youtube.com/watch?v=OeeSsMMvt2A


 

WOW, posted on September 14, 2020 at 22:01:57
emailtim
Audiophile

Posts: 2135
Joined: July 2, 2017
WOW, that is nuts !!!

Would love to see some measurements of the DIY tweeter response.

 

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