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Audio Research REF 750 pre July 4 FIRE WORKS. TUBE ARC.

Well I just had time to finally hook up my new Audio Ref 6 se for the first time as I got it back from AR last week. So I waited patiently for my night off from work last night and was also very excited to finally hear that for the first my Audio Research REF 750s. that came with the KT 150s with 660 hrs on them. I was really enjoying the beautiful sound of these phenomenal amps for a few hours and called my wife up to hear how amazing Barbra Streisand sounded playing The way we were. I had all the lights off in my listening room and we were lost in the sound quality as my B&W matrix 800 speakers disappeared and melted also to the beautiful sound of her voice and when all of a sudden there was an explosion as I had first thought. The middle of the top KT150s there was a loud SIZZLE a FIREBALL and a loud POP !!!! And WHITE SMOKE and then cut off. We immediately jumped up and my heart sank as I yelled OMG. I jumped up and ran to my L amp and I pulled the plug while the R amp and speaker was still playing. I said WTF happened?? My heart sank in my stomach as the first thing I thought was now after all the anticipation of that night to finally arrive I was now devastated as I had no idea WTF just happened. I was numb. I finally calmed down some looked over the amp on top. Didn’t see no damage and texted my guy that I bought them from and he told me it sounds like a tube arc. He then told me to take all the top tubes out but u can leave the 2 inside ones in. He then said to carefully take off the top cover as I did. I turned the cover over and saw black underneath as I then turned it over I saw it was V10. He said now look at the resistors by V10 socket. Sure enough the wire leads were gone. He said your V10 tube is shot and u will need to replace the resistors by V10 socket. I said does it have to be sent to ARC ? As I just got delivered the REF 6SE that had been upgraded and just got it back from ARC on Tuesday. I couldn’t think now about packing up the Left Ch REF 750 and shipping it back to ARC. He said nope no need to. Just have the Resistors replaced and get a new V10 tube with the same number on it from ARC. And call your ARC dealer here in NJ to see if his technician can come to my home and replace and solder the new resistors back on. Put the new KT 150 in and you will be back in business. So now I am waiting for my ARC dealer to open this morning and hopefully he will tell me some good news. Just don’t understand how or why this happened? Has anyone else had a similar experience? Wow I will tell ya that it was a very scary thing.BTW I never owned a tube amp except for my REF6 SE pre so this is still very new to me.

128x128Ag insider logo xs@2xtattooedtrackman
4afsanakhan
134 posts
 

My apologies. LoL! I have to laugh at the timing of you tube arc fireworks!

I recently took on a job myself, repairing my single ended triode amp. I heard a pop, splurt and puff of acrid smoke accompanied by the smell of burning cap. Opening the bottom plate, i located the failed part. Not sure if the wirewound Dale / Vishay RH-25 25w 220ohm resistor had gone too, i decided to replace also. The cap was a Philips HP LL 330ohm electrolytic cap. These older caps at exact value are hard to find. I eventually located both and soldered them in. Worked great. Then the opposite side gave out in the same manner. Fortunately i had ordered multiple replacements. I also picked up a quad of nos Mullard (Blackburn factory X3) EL34, along with an old and fantastic nos RCA 5V4G rectifier. A ‘potato masher’ Ratheon had been put in by someone so i just returned the unit to correct spec. Sound is much MUCH improved. Fingers crossed no more fireworks : )

carlsbad2's avatar
carlsbad2
1,602 posts
 

I can't imagine a life where I can't do my own repairs.  I blew a resistor a couple monts ago.  went to my shop and didn't have the right value.  Ordered it from amazon and was listening to music less than 24 hours later without a single post on the internet.  

I know I'm the exception but think others should consider being a bit more self sufficient.

Jerry

gpgr4blu
1,081 posts
 

John Rutan  (Audio Connection) really does care about customer service. a great dealer 

audphile1's avatar
audphile1
4,906 posts
 

@tattooedtrackman along with amp tubes, keep an eye on the power tubes in your Ref 6SE. Check with ARC on their lifespan and drop in a fresh set ahead of time. Signal tubes will live longer and die more gracefully do nothing much to be concerned about there. 

mulveling's avatar
mulveling
1,892 posts
 

Yes, I had similar happen in 2010. I know it sucks. It was an EH KT90 in one of my Rogue Apollo monoblocks. They're no lightweights at six KT88/90/120 per side, but still nothing like your 750! Anyways, yeah a few seconds of fireworks and then a pillar of smoke. No big BANG, fortunately.

The tube (presumably it shorted out) and its resistor (a big blue metal oxide one) were toast. It also singled the board under the resistor, stripping the green mask off and exposing 1cm of bright copper trace. It would've been OK to just replace the resistor and tube, but since the amp was only a few months old at that point, I sent it in and got the full audio board replaced. It didn't put me off tubes - sh*t happens. I swapped to KT120 shortly after this incident. 13 years later and I've never had another tube incident. 

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