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Gor a pair of MG IIIa that had been in storage for awhile. The first time I hooked them up the tweeters on both speakers made no sound at all. Called Magnepan they gave me a few things to test with my volt meter - gave them the readings and they said I needed new tweets. I ordered the ribbons got them yesterday installed them - still no highs.I have taken the external crossover apart and it appears there are no loose connections - I gotta think there are a couple of other easy checks I can make... any suggestions???? I hate to send these to Magnepan because it must me a loose connection somewhere!!!
Thanks,
Follow Ups:
Installed the jumper - thanks Al - I feel pretty stupid but the speakers sound great!!!! I guess its down the upgrade path now... More newbie questions to come!!!Thanks again everyone!!
Tim
You may eventually get to the point of bypassing the whole Magnepan panel. Until then, use some solid copper wire as jumpers. Polish and clean it. It will sound much better than the stock Magnepan jumpers, which are gold-plated steel.
Are the connections to the tweeter ends tight? These can get loose and even corroded, I suppose. On 3.5 and 3.6 these are straight blades on the tweeter and a female crimp on type job on the wire.
Just checking the tweeters with a meter will not necessarily identify the problem because there is a inductor in parallel with the tweeter and a capacitor in series. If you put a meter across the mid-treble input you will just measure the resistance of the mid driver + mid-driver series inductor, independent of the condition of the tweeter. If you put a meter across the "speaker side" of the treble fuse and the + terminal of the mid-tweeter inuput, then the reading will be approximately that of the inductor (~0.3 ohm) regardless of the condition of the tweeter.
Did you check the resistance of the old tweeters once they were removed (~2.2 ohms)? If the fuses check out ok on the meter (visual inspection can be misleading), then I would think about colder solder joints at the fuse holder. Another possiblility is a defective (open) resistor (the one in series with the speaker) although both possibilities are unlikely to have occurred in both speakers. If the series capacitors were defective they probably would be shorting and you would most likely get a signal through the drivers. Similarily if the shunt inductors were bad (open), then again you would get a signal in the ribbons.
My suggestion would be to unsolder one end of the tweeter and check the resistance across the tweeter, if it is ~2.2 ohms (and not infinity) then the problem lies elsewhere.
I may be an egoist but at least I don't talk about other people.
There is a second pair of sockets on the Mid/Tweeter section of the input panel, where a jumper should be in place. This jumper is to be replaced by a resistor if the treble output is too high. The tweeters will not work if the jumper is missing or corroded.
Pardon my ignorance - this must be my issue - do I just connect a wire from the positive terminal to the negative terminal on the attenuator jacks or do I run a wire from the negative on the tweeter/mid terminal to the negative on the attenuator jacks and the same on the Positive side?? What really gets me is I asked the Magnepan folks on the phone what the attenuator jacks were for and they said nothing about a required jumper - only the part about the taming the high frequency. Why both were not functioning now makes sense - just want to make sure I install the jumper properly!!!
Amp problem, tone controls, etc?? Can you try a different pair of speakers and/or a different amp?
Did that also - I have them set up right next to a pair of Polk 1C's - I'm kinda a retro guy.... I intend to run the maggies with a pair of Rotel 980BX's if I can get them singing properly!!
Perhaps the previous owner fried the caps(?). I'm running out of ideas. I think the next step I'd take is trying your amp (at LOW volumes) plugged directly after the xover at the tweets to see if the tweeters are indeed working. If that works (which it should, just be careful), then possibly a fried pair of caps. To prove this right, buy a cheap Ratshack cap (or both if you want), replace the existing units with these (even just clamped/twisted in place) and see what happens.
You did check the fuses, right?
Yep - Fuses checked and replaced just for good measure!!
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