@gpgr4blu 💯. @audphile1 I definitely will 👍. @mulveling I totally understand that s””it happens. But the first 3 hrs or so of listening to them for the first time. Wow what a thing to happen. And I’m definitely a virgin to tube amps . And wow what a way to find out about tube arching with a REF 750 KT150. 😂
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.
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The similar thing happened to my ARC VT130. I posted about the solution here: https://forum.audiogon.com/discussions/mystery-of-red-plating I'm sorry for your loss. I know you have wanted that Ref system running for a long time now. |
Did you check to see how many hours the tubes had on them before you fired up your amp? Did you ask the previous owner if the tubes were original (ALL of them) or had been replaced and if replaced, from where were they sourced? KT 150's are problematic. They are great when they are great but the QC coming out of the New Sensor factory is terrible. Few middlemen can supply reliable matched sets of them. I apologize for being critical, but will say that as an owner of four ARC amps past and present (present are the Ref 150 SE and Ref 80S), I would have warned you that the Ref 750SE's are NOT the amps to start out with as your very first tube amps. Add the fact that they are used and your choice is even more unfortunate. The more power tubes you have, the more likely one will arc and fail. Add KT150's to the mix and well, this was not unforeseeable. I would have taken your amps to John Rutan to check out before you fired them up for the first time. If you had done this, there is a good chance (but not necessarily) that John would have seen something amiss with bias. This concerns me; "Tube bias is controlled by two KT150 tubes, each driving a bank of eight KT150 output tubes" (from the website). With my Ref 150 SE there are four KT 150's per side but there are two bias pots per side so that one KT 150 is "slaved" to the other. When an output tube is failing or faulty, it can most often be detected by checking bias on my Ref 150 SE. Perhaps with your Ref 750 SE's the best way to check all those tubes is to pull them and test them on a good tube tester. What you evidently did by unboxing them and firing them up right away is perform a stress test and the stress test failed. I am not trying to beat you up over this, nor should you beat yourself up about it-it is a good learning lesson. I truly hope John can guide you on the path of getting reliable service with 32 KT 150's running in those monsters. |
@yesiam_a_pirate Wow. That’s awesome to hear that u found a great local tech and what a great price. I am very grateful to have my ARC dealer and friend and extremely knowledgeable I have known for 30 yrs John Rutan from Audio Connection in Verona NJ. |
@fsonicsmith1 No need to apologize for being critical. I appreciate it. U made some very good points and the tubes had 660 hrs on them. All the tubes were purchased from ARC matched set. I even bought a brand new 2nd matched set from him that he also purchased from ARC. I would never buy these tubes from a middle man. I would rather pay 💰 a lot more for them from ARC knowing they will be the best out there and matched. 1 thing I did not do when they were warmed up for about an hour was check the bias on them. I did ask my seller if I needed to and he told me he checked everything out completely right before he shipped and said they should be totally fine. I also went by the meter that showed they were in normal operating range. I ordered the new KT150 with the exact number written on the tube from ARC and also new fuse and extra resistors. When John Rutan and his service tech comes to my home to do the work I will have him check everything out with them and see if they can check the tubes out and bring a tube tester also. The amps were bought from a member from here and I have spoke to him and texted each other for hours and he is extremely knowledgeable about these Ref 750s and explained everything I had questions about and many more that he brought up. Any questions I had he was always there for me. As a matter of fact he was the first person I contacted when this happened. And he was the first one who said it’s not a big issue. And told me exactly what to do and what to look for about the arching. And said it definitely does not need to be shipped to ARC for repair. As a matter of fact he boxed up all the tubes and made sure to number them and put them all back in there exact valve socket locations. And also told me to make sure there were all securely pushed down in place. I really don’t think there was nothing that he left out for me to do and explained everything I really needed to know and more. We also became friends and text all the time I know he will always be there for me also with any questions or concerns I may have. I even sent him my Straightwire Crescendo quad wired for my B&W Matrix 800s as they were Bi wired for my Krell FPB 600. He reterminated them for me. Changed and soldered the spades to Cardas to the exact size I needed for the binding posts on the REF 750s. Beautifully shrink wrapped the ends. .Custom made beautiful oak blocks that he mounted them too about a foot where they get connected to the 750s. BTW he is amd works as an audio engineer. |
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