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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
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?
fin1bxn
140 posts
 
your clipping your amp....
magfan
1,583 posts
 
First, the ribbon, in Maggiespeak, is a 'fuse protector'.
The OTHER thing about ribbons is to PROTECT them during shipment. IF you don't have them, Magnepan will sell you some 'ribbon protectors' for shipping. USE THEM. Ribbons are fairly delicate and a blast of wind can wreck 'em. The Magnepan rebuild kit has 3 new ribbons....for a pair of speakers and one to wreck during the 'learning experience'.

Fixing wire delam is less of a hassle these days if you ignore 3M77 and use DAP.
Several fix it people have had great luck. Cleaning first with Acetone is still the only way to get the old glue totally off the panel and wire.

I'd recommend reposting over on the 'planar asylum' of AA. These guys are good and there are several real pros.

IF you can't, by putting your ears near the panel, identify where the wire or ribbon may be bad, I'd find a little more juice for the panels. Bifwynne is 100% that 62 watts is on the low side.
And, though maggies are generally NOT a 'bad load', having moderate phase angles, they are low impedance which places a premium on a good amp.
Maggies and tubes? It can work, but at higher powers.

If all else fails? Get on the phone to Magnepan. Wendel will answer your questions, maybe. The don't have internet since the workforce in WhiteBear Lake is actually working, not messing with computers......like ME.
sonorous1 OP
11 posts
 
Thanks for all the responses, the more research I do I find that it must be poorly mixed recordings or mixes that don't mesh well with my particular set up. I don't think I could be clipping the amp because I don't hear it when I listen to other recordings at the same fundamental volume. Everything ARC in my set up has been gone through by ARC as of last month. Plus I know the general consensus is that magnepan would like to be mainlined to nuclear power plant if that were possible; but either way it comes down to listening volume and I don't crank. Thoughts?
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