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Pass 250.5 shuts down driving Magnepan 3.7

This is my first post so please bear with me.

My Pass labs 250.5 protection circuit shuts the amp down when I drive my new Magnepan 3.7s at high volume. I'm talking about a volme higher than I might consistently listen, but not an unbearable level.

I'm using a Cary Slp 05 preamp with long balanced ICs (25 ft,) The amp is close to the speakers with less than 6 feet of speaker wire. The system works fine at normal volumes. I've tried the same thing with a pair of Cary MB500 (750 W @ 4 ohm) and they too shut down at high volume.

I believe the maggies drop below 4 ohms and I wonder if either amp can handle the impedance drop below 4 ohms.

Has anyone experienced this issue ?

Any suggestions ?
gcoxsom

Showing 1 response by onemug

onemug
784 posts
 
Suggestions:

Call or email Pass Labs about the problem.

Thoughts:

There could be something wrong inside your Maggies.

The Pass is stable into 4 ohms and lower. It has thermo protection. You may be overdriving it causing it to run hotter than designed and therefore shutting down "as designed".

How much does needle on the Pass deflect from the idle point?
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