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Belles 350a reference fireworks

I turned on my Belles 350A reference yesterday, and was greeted by a flash, then a wisp of smoke coming from the right hand side of the unit. White noise emanated from my SP Tech timepiece 3.0's. I turned the amp off immediately, but needless to say I'm worried--mostly about my speakers. My 350 does NOT have the soft-start, which I'm guessing is the problem. Now i'm torn: after reading a couple of other similar stories about the amps putting out DC and frying speakers (not to mention the amp itself), I'm unsure of whether I should send the amp back to Dave Belles for repair/soft-start upgrade, or just scrap the beast and go with something more user friendly/reliable. The sound I was getting from my Belles/Modwright pre, and the SP Tech (amazing speakers, btw), was great, but I've got a case of the jitters about the 350 now. Has anyone sent theirs in for the soft-start and have an opinion? I don't want to spend the money on repair/upgrade, if there will still be reliability issues...

thanks,

david
davidm1108
sleepysurf
121 posts
 
I had a similar event last year, likewise with a Modwright Pre paired with a Belles 350A ref (WITH the soft-start circuitry). After LOTS of discussion, we suspect the problem originated with the Modwright Pre, as after checking with Dan Wright, I found my unit did NOT have the latest muting/protection circuitry to block DC surges. Turns out, David Belles uses VERY LITTLE protection circuitry in the 350A Ref, which is why it sounds so great! Dan upgraded my Pre to include the latest circuitry (as well as upgrading to the tube rectifier), and David Belles replaced my amp. Both have been singing sweetly ever since. David Belles (and Bruce Jacobs, marketing) are great to deal with and will certainly take care of you. I would also speak with Dan Wright, and have him cross-check your serial number to make sure it has the necessary protection. The power and finesse of the Belles makes it hard to give up, especially when the problem may have lied elsewhere.
avguygeorge
2,300 posts
 
I was one of those owners of the 350 ref that did what yours did. It cost me 650 which included ship/both ways. Not one incident since---(10 months later).
davidm1108 OP
17 posts
 
thanks guys--sleepysurf--i spoke to dan last year when i got the belles, and he had me send my modwright back in, so he could update it. i'll call to double-check and make sure...and yes, it would be hard to give up the belles, so here's to hping i get it sorted!
mitch2
3,717 posts
 
From the Soundstage review;
The 350A Reference is also AC coupled, while the 350A was DC coupled. The difference is essentially safety for your system. An AC-coupled amp will not pass DC to the loudspeakers, while a DC-coupled amp will if any is presented at the input. Under normal conditions, this should not be an issue, but, as we know, sometimes stuff happens. There are also sonic considerations here. AC coupling compromises the sound and may limit bass extension in the bottom octave because a capacitor has to be inserted in the signal path to block DC from passing through the amp to the outputs. Dave Belles managed to insert a capacitor that doesn’t limit the deep bass (detected by ear or by SPL meter using the DC-coupled 350A as a reference point). Thus, there’s no audible harm to the audio signal from the extra capacitor that I can detect.
davidm1108 OP
17 posts
 
thanks mitch--that makes me feel less worried about my speakers. this forum is a very cool place.
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