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High Frequency Oscillation hurt resistors in Magico A5 crossovers

Hi,I am looking for help understanding how HFO could blow crossover resistors in Magico A5 speakers. Equipment playing at the time of the incident is as follows...
Magico A5 speakersHegel H30 mono blocksHegel P30 preamp (lt and rt inputs on the Aux inputs from the laptop and Dragonfly Cobalt)
Dell laptopAudioquest Dragonfly CobaltAmazon Hi-res streaming
I was listening to Amazon music at a very moderate level when the application said there was an update available.I instinctively clicked accept while music was paying. It was only off for a few seconds to update and when complete and I restarted music the A5 tweeters were not on. These happened simultaneously and there was no audible noise what so ever indicating a potential issue. After multiple source tests and tweeter test, I was certain the tweeters were fine and it was an electronic issue. The cross overs were removed and sent to Magico and that was when I was told that HFO blew the resistors.
Can anyone explain how/why this happened so I can ideally avoid it happening again?
Thank you!
128x128howaanders8

Showing 1 response by larryi

larryi
4,152 posts
 
I have no idea why extremely high frequency energy was emitted by the download process, but, Magico's explanation of what happened to the crossover is reasonable.  There is no way it is a failure of the Magico crossover operating under normal circumstances.  A lot of high frequency energy must have gotten through in order for resistors in both speakers to be fried.

I don't know how you have tested the tweeters independently, but, you are fortunate that they survived the ordeal.  In a way, the resistors acted as fuses.

From your experience, updating software while playing the system appears to be something to avoid.  I hope your problem is confined to that situation and it is not a problem waiting to happen again.
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