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.
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
sounds like teh tweeters are blown. Easy to replace if you contact Magnepan.
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...
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.
I didn't realize the amplification power you were using. I would say that the IIIa's need about 300w in 4 ohms to sound good, and more than that, good amplifaction, will sound even better.
A good digital switching amp form Wyred4Sound or Bel Canto, will amaze you.
Well, if the speakers really are OK.
Thanks for all the responses. I am going to go back to the drawing board with speakers. I value my amp and pre amp combo over the magnapan IIIa's.
Sonorous, have you isolated the problem to possible clipping? If not, what have you come up with?
The amp is definitely clipping. The speakers are in beautiful shape. So now I am trying to find a speaker that will best compliment my amp and preamp. I would really hate to change them at this stage. I went through a lot of trouble finding them and having them professionally gone through, let alone the time and money spent selecting tubes. The issue I am having is with the 10% percent of my music collection that is classical/opera with wide dynamic range and sustained high frequencies that easily make the amp clip. The Jazz sounds wonderful.
So now I posted a new thread to pick even more brains as to what speakers I can fuse with my amp combo and not clip the amp (if any at all) or anything else I can do to my large listening room that will make it so I needn't ask the amp for more power.
Maybe I am asking too much from one system?
Thanks for the advice thus far, learning as I go!
a pair Vandersteen X5 High pass units and a pair of Vandersteen 2WQs
this will ease the load on your main amp lower distortion
improve dynamics dramatically improving clarity and transparency of the
whole system while also retaining the intimacy you like
with your existing amp