HELP-Maggie IIIa's are crackling at high frequency

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?

your clipping your amp....

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.

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?

Sonorous1: If you think the Maggies are ok, then I still suspect the amp may be clipping. I am dubious that 62 watts at clipping is enough power for the Maggies. I suggest that you borrow a high power SS amp from a friend or a friendly dealer and try it out. Crank up the volume and see if Maggies still crackle. If not, then you solved the puzzle.

Good luck and let us know how you make out.