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HELP-Maggie IIIa's are crackling at high frequency

I have newly refurbished IIIa's. The refurbishing was done by a trusted third party tech. I noticed the high frequency once before when using my Nuera 3300pp integrated but only on ONE record so I chocked it up as a flaw in the record. But just this weekend I went up to a AR V70 power amp and an AR SP-6b pre and its more prevalent than ever. I am not a "loud" listener and I here this "crackling" on the high end of classical female vocalists the most. I have read that people push the maggies as far as to blow the fuses before they get any distortion. This amp combo sounds like it would blow me away but I can't hear past the distortion! Any advice would be awesome and much appreciated, Thank you.
sonorous1
davide256's avatar
davide256
398 posts
 
I used to have working MG-IIIa's and now have 1.7's. The ribbon tweeter is merciless on bright signal. I found tube dampers helped, I'm using the inexpensive pearls and they make an amazing difference in taming high frequency edge... supposedly they are mostly coolers but they made an immediate improvement on my CJ-PV12A. If the problem is LP specific, look to your mat and clamp system to tame, could be record isn't in tight contact. And of course, when was the last time you checked/cleaned your stylus??? If you are approaching 1,000 hrs use it may be time to replace.
sonorous1 OP
11 posts
 
Thanks for the reply David. When I hear the distortion it's during both CD and LP playback. Though I notice it more with a particular classical CD of various artists ironically. It could have been the amp/pre except it happened once before with another set up I had that included these speakers. The highs are pretty coarse distortion or not though. With the volume very low or with a mid tempo rock band it sounds perfect. I am using a broken in ultech audio CD player by the way
mofimadness's avatar
mofimadness
4,945 posts
 
You could have a bad ribbon tweeter, (or two) and/or the wires have delaminated. The repair tech might not have gotten them completely glued down. It's a major ordeal to reglue the wires, I know, I've done it several times.

You could also have a crossover problem. Lots of things to check and troubleshoot...
macdadtexas
1,794 posts
 
sounds like teh tweeters are blown. Easy to replace if you contact Magnepan.
bifwynne
2,206 posts
 
Admittedly I don't own or know anything about Maggies, so I am not adding to the advice already given. However, your OP doesn't say very much about the ARC gear other than the model numbers. I have a few thoughts about the ARC gear.

First, the V70 was first released in 1992 and actual power at clipping was 62 watts. Does the amp have enough power to drive the MG-IIIAs? That is, could you be clipping the amp? Is there an amp/speaker compatibility problem (e.g., wierd load)? Has the V70 been recently serviced? When were the tubes last replaced?

Second, the SP-6b was released in 1980, so the pre is getting up there in age. Same questions as with the V70 re: when last serviced and when were tubes last replaced?
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