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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
Post removed 
chadeffect
586 posts
 
I had a problem at high volume using tube ARC monos.

I think the amp is seeing something it doesn't like impedance wise.

Are the bass panels rattling at these volumes? Are you playing very dynamic music? Things with sudden big bass hits?
brownsfan
1,508 posts
 
I suspect there is a problem with the speakers. My Cary 500 MB's have never shut down driving my 3.7's. Do both channels of the Cary shut down?
ozzy's avatar
ozzy
7,459 posts
 
I had a problem with the Cary SP-05 driving my Pass Labs Amp X350.5. The result was Low bass and Highs.
With your long interconnects that can't help.
I moved to a Pass Labs Preamp XP-10 and all is fine.
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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