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My Logans just fried my Pathos Logos amp

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paulo m

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As usual, I left my system playing relatively loud when I went out this past Sunday, to continue the break-in process of my Vantages (got them some 3 months ago). I made different CDs with sounds in various regions of the spectrum to exercise either the woofer, the panel or both. My last CD has a continuous 15 kHz sine tone with some minor and slow modulation of a few Hz and some harmonics for variety. I have left this CD playing on some three occasions now.

On that fateful day, I left the system going with that CD at a volume squarely in the middle. After we came back, some two hours later, no sound was coming out: The power supply fuse had blown. No matter, just replace it and off we go for a nice relaxing listening session, I thought. Replace, switch the amp on, nothing. The new fuse also blew. Hmmm was it defective? Let's try another one. Blown again.

I think the low impedance of the speakers at such a high frequency coupled with the relatively loud volume (I get 90 dB SPL with the volume at about a third, using typical CDs, even though some play at a somewhat lower intensity) over the extended period just fried some internal component in my amp. I opened it and gave a thorough look, nothing seemed burnt or melted, however, although on the previous two occasions it ran considerably hot, which I figured is normal for an amp in class A operation.

I am taking it this Saturday to the shop. I am coming out with a loaner if repairs are not obvious or trivial, so at least then I will be able to listen to some music again.

Oh well. Maybe I should start looking for an amp that handles 2 ohm and lower loads more nimbly.

//p
 

miljac

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paulo m said:
Oh well. Maybe I should start looking for an amp that handles 2 ohm and lower loads more nimbly.

//p
Oops. Sorry it happened. Just reminded me that I saw the Logos in the shop where I bought my Ascents and wanted to treade in my McIntosh amp for it - they talked me out of it saying that although the power was similar it cannot drive the MLs, at least not as good as Mac. This seems to confirm their opinion from 3 yrs ago.
Still, it's a pity. Logos is a fine looking and fine sounding amp (heard it with Sonus Faber speakers).

I would say - change. Make sure the amp delivers at least 80% nominal voltage output at 1 or 2 ohms w/o phase-induced drop of power output. That should cover for it.

I do know that at least McIntosh integrated solid-state amps (6500, 6900) drive Ascents like charm. Other members can help with other suggestions, I guess.

HTH & good luck

miljac
 
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