PrimaLuna Dialogue Premium Preamplifier. DESTROYS SPEAKERS!!

For clarity, this is not a large coupling cap that failed in George's preamp.  It's a high-frequency snubber, which is why the suspicion about outside causes.  

So...the amp got DC not through the coupling cap but through some shunting circuit between signal and ground???

This makes even less sense. I don't doubt you, @upscaleaudio  I'm just more and more confused. If a snubber failed... I'd more expect HF oscillation to occur, which definitely could be damaging. << shrug >> but without seeing some sort of design, I certainly cannot be an arm-chair critic. I'm just expressing my cross eyed lack of understanding.

Best,

E

So help me out. This snubber is before or after the DC blocking cap?

Best,

E

Good Doctors,

I wouldn’t be so arrogant and rushed to blame the patient for his misfortune. Yes, maybe OP had his ML power supplies covered with warranty But spending good money buying brand new product directly from a Dealer TWICE for the same component with the same defect that almost catastrophically ruined $30,000 speakers for which  he could be compensated a mere $50 that faulty and defective capacitors are worth does make me uneasy.

 

But maybe that’s because this happened to me, (twice.)  My initiation into the high end twenty years ago began with a brand new CAT Signature pre-amp, Krell MDA 300 monoblocks driving Apogee Duetta’s. They had a magical synergy and sound for a brief 6 weeks, until too many sparks kept flying and one night the “light reflections” I was told I was seeing actually burned through the large thick aluminum woofer ribbon. The separate dealers that sold the CAT and Krell as well as CAT designer and owner  himself Ken Steven’s felt it impossible that their particular product could be at fault or ever pass DC and none took any initiative nor responsibility to troubleshoot or even offer to check their product and left me on my own, even though by now finally acknowledged I wasn’t hallucinating all those late night sparks after all. So while paying to repair and shipping the 150 lb. Duetta across the country, and since others thought perhaps the tubed CAT preamp may have passed some intermittent DC or had low frequency oscillations trying to drive the difficult Duetta’s load, I had some back up speakers to use.   Within days, 2 of 4 midrange Seas drivers were promptly blown in a 3 way Rauna Balder speakers. The two supposedly reputable dealers I just paid about $10,000 to (20 yrs ago) for the CAT and the Krell pointed fingers at each other as did each manufacturer;  Ken Stevens of CAT, and representatives of Krell – would not even offer to check their equipment, and finally one dealer “graciously” offered to buy back the equipment at a used 50% markdown, about 6 weeks after I had just paid him full retail and tax.

 

The CAT, Krell, and Duetta’s had a glorious sound, and the magic, much I suspect coming from the CAT and ribbons; but after many calls to more straight talking technicians and engineers, all agreed it best to keep tube preamp with tube amps to avoid any potential or intermittent bleed of DC current which the solid state amps may pass on through. But the CAT I had in house needed to go, and I needed muscle and magic to drive a pair of Apogee Duetta’s, once repaired. I just lost a third of the entire budget for the system with nobody seeming to care. Worse I almost lost my passion and enthusiasm in the discouragement in dealing with many callous, arrogant, misinformed people that profess to know so much when they guess and shoot from the hip. (a lot of comments and denigrating in these posts is bringing  back those memories).

 

I was lucky to find a godsend in a great Dealer, advisor, and friend 20 years ago. Victor Goldstein convinced me I would be more than pleased with the Jadis JPL and Defy Monoblocks to replace the CAT and Krell. Not just an understatement, but an essentially trouble free investment over 20 years; while I’ve had expensive Magnan Vi cables terminations disintegrate; early MSB DAC problems recur; and a variety of other high end depreciation over 20 years,  as everyone does. I don’t think anyone would usually blame these on the user, or say the cables should be more expensive to match the systems or else you deserve defective equipment and the damage it causes........

 

More germane though, this year I bought a new integrated high end amplifier. Upon connecting a Metronome DAC with the amp and to the 93Db sensitive Reference 3A speakers, and in a mere 20 minutes out of the box the amp overheated, blew out 2 of 2 woofer and 2 of 4 midrange voice coils of the right speaker and caused various internal damage in the amp. Since repair of the amp itself, all seems to be working fine with no DC output or problems of any kind and no design issues reported with many other units of its kind.

 

Well, a second identical amp had already been sent even before the repair of the first amp. Since the Reference 3 systems was out for repair with exotic and expensive drivers needing ordered from France and being handmade from Reference 3A now in Canada, it was unboxed and put in a second system. There was no single component aside from the housewire that was common: Lector Digitube DAC with the Amp with Martin Logan Quest Z. The amp was turned on low volume to warm up and for background music with some trepidation, and 15-20 minutes and loud pitched siren screaming started and a half second I had it all shut down. Again one speaker of the ML Quest Z had the 12 inch woofer voice coil blown, and later Tech repair shows internal damage with all 4/4 transistors shorted, and many other parts damaged still to be determined and analyzed.

 

Whether there were a few bad capacitors bunched in the packs of hundreds that get installed randomly in “our” units that cause all this grief will be anyone’s guess; but parts are parts and they are not and never will be perfect, not even for NASA.  Now when you go put them in a complex system with more parts, potential for problems compound.

 

I read through these forums because I want to learn, but it makes rough reading with so many trite, negative and uninformative attacks. Reproducing music is an amazing and fascinating hobby. Yet, I always try to remind myself that it’s the people that make the music, and all people deserve my respect and passion as well.  

 

I thank you Almorg, Atmasphere and others for all along being civil and informative-it kept me engaged and learning.

 

And Mr. Dean for actually being responsive, on vacation and since, and for  whatever offers that you could offer. What else to do—no good answers are easy—perhaps a letter to alert purchasers of the preamp of xxx units before the defective ones—everyone knows there were not just 2 bad capacitors—but obviously there weren’t hundreds because you would have heard or notice that number. But there are likely other LONE CUSTOMERS not in the know or OUT IN THE COLD being turned back by other dealers like I was 20 years ago to fend for themselves,(which you graciously did not do).

Thorloki-OP—I sure understand and feel where you’re at, but also glad you have gotten responses, at least to some good degree. I’m feel your anger when something comes and puts your “babies” at risk- but it does no good and like you I have to let go. Sad to see all the immature attacks; and with the  post of other defective PL-- if this is a cluster of something bigger no one will ever know unless it gets tracked or PL or others are open and honest about quality control. Mr. Dean sure seems to be willing and trying—not what I experienced 20 years ago. I’d rather be a customer of an honest, supportive Dealer that’s had a few defective products than a defective Dealer that has “perfect products forever”.

(I may feel your pain, but enjoy the tubes and stats moreJ)

Awwww geez louise where does the madness end? This "lbocquin" has come here with his very first post and splintered English and confirmed we do indeed have a sea of defective products out there just waiting to combust our draperies and homes. But now the problem is not of Chinese origin but a high-end problem from diverse artisanal producers. The answer is clear-don't buy high-end gear and instead limit your purchases to Best Buy offerings! Be forewarned! The parts manufacturers have dropped the ball-that's the answer. 

I agree with Ilocquin. Why is it so diffifult to believe with all the hundreds of thousand components manufactured yearly that some are of poor quality or design? I guess the logic is? if it was not "me" that bought some defective gear it must not exist? Also why is it hard to understand that with so many products made in hundreds of factories in China that QC can fail? If a company has moved manufacturing to China, is it not to cut costs to improve profit? Is it not possible to believe that a supply of cheaper parts are chosen over another more expensive load? What about the influx of counterfeit parts in China? Why do so many people believe manufacturing CEOs are always honest and always want to do the right thing? Cmon use your brain, not every single audio component made is made correctly and not every audio brand exec is honest and does the right thing. BTW I don’t think Primaluna sales will suffer from this post! I am sure all the fans of PL don’t have to worry that the company will fold.
I think that most audio forums actually serve an important function to INCREASE sales of many brands. But I think since this is a forum to exchange ideas, experiences, and the glory of musical enjoyment...we also can (and should) talk about the bad or ugly that has happened. If we don’t do that, it really is not an open forum. The forum appears to be more like brand advertisement, not a healthy exchange of ideas and experiences.