Problem with Ref 5SE


I recently purchased a 5se and took delivery the other day. Did not get a chance to open it up until last night. Upon installing it into system I switched it on and after it warmed up, I was very much interested in hearing how it sounded against my current 27. After listening to several tracks with the 27 I switched pre's and after a couple of minutes playing a CD I got some noise, almost a loud static sound coming from the right channel. It was not effected by changing volume controls or input selector. It went away after 10-15 seconds and then returned. At that point, as it was late, I shut everything down and figured I would take another look in the morning.

This morning I removed the top cover and pulled and reset the output tubes and then the power tubes. I fired it back up and still had the 'static' sound but now it also had a humm, like an impedance type hum and constant. I do not believe that the humm was present last night as it is quite noticeable. 

The static type load noise seemed to have abated after the unit warmed up after maybe 15-30 minutes.

Can I assume that perhaps a tube was damaged during shipping? Do you ARC guys think a new set of tubes will fix this issue or am I looking at something more severe? Any additional suggestions to try and pin this down?

I rerouted the IC going to the amps to get them further away from source IC's and no help...

I am a little bummed, as my initial impression it that it is a leap from the LS27, my current...
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Showing 5 responses by motorheadflash

I purchased a new 5 se four years ago and just recently have had a similar problem. The first thing that happened was the static noise. It came out of both channels. Then I started getting a loud pop out of the speakers, and the amp. would go into dc offset and shut off. After about 20 seconds the amp. reset and came back on. After a few minutes the pop happened again. This time the amp reset but the system would not come back on. I called my ARC dealer . He is a 30 year veteran ARC dealer. He said to bring the pre amp into his store. After taking the cover off the 5 se we discovered a burn mark about the size quarter. directly over the 6550 tube. He took the tube out and it was black inside the tube.  He had a used 6550 and installed it. The pre amp came back on but the static was still there. he put his thumb and index finger on each of the 6h30p tubes and rotated each one gently. When he did each tube gave out a loud static scratching sound through the speakers. He seemed to think there may be oxidation on tube pins or on the sockets. This pre amp was purchased new and had the original tubes still in it. The tubes had almost 4000 hours on them so we ordered a brand new set from ARC. we replaced all of the tubes as recommended. We got the same static problem. We took all the tubes back out and cleaned the tube sockets with de ox and a tiny wire brush. After putting the new tubs back in the static stopped and the pre amp sounded like new. After a short break in time my system was back to normal. While at the dealer I checked the cover of his 5 se demo model and the clear lucite cover had a burn mark directly over the 6550 tube just like mine.
 We also checked his Ref. 6 demo and it had the same thing. After talking to ARC and the dealer I find out that some people run their ref 5 and ref 6 amps with the covers off because of the heat from the tubes. One veteran repair man I know said the sockets of an amp this new should not have oxidized this soon. He also said the oxidation may have been caused by the excessive heat .
 I am worried about what will happen in the future when it comes time to install new tubes. I think that changing the 6550 tube after only 2000 hours is wise, only because it runs so hot. 
I hope this sheds some light on this subject. I would love to hear from other ref 5 and ref 6 owners and see if they have burn marks or melting marks over their 6550 tubes. Has anyone had a similar problem with the static, or the 6550 tube burning out? Thanks for all your help.
My pre amp and amp both sit on the top of a cabinet. They get plenty of ventilation. Same thing at my dealer. Both of his demos are on the top of a cabinet and not in a rack. When my pre amp has been on for an hour or so the area directly on top of the 6550 tube gets so hot you cant put your hand on it. With the brand new tubes from ARC the amp is dead quiet and sounds fantastic. It just runs hot. The demo at the dealer seems to run just as hot. The dealer has sold many ref 5 and 6's and experienced no problems created by the heat. 
I'm surprised that your 5 se has no signs of heat distortion on top of the 6550 tube. When you put your hand on top of the 6550 is it hot?
Thanks for the information. It is good to know that my heat problem may not be as bad as I thought. When I installed the new tube set it ran as hot as it did when it was new four years ago. I'm going to take your advice and order a single 6550 and have it on hand to replace at 2000 hours.
One mystery that I didn't mention before is that my ref 5SE did not come with a plastic top, it came with a metal top. I like the looks of the metal top better, but the dealer says that the plastic top sounds better. I wonder if the plastic top lets the heat out better than the metal one. The metal top has the exact same pattern of slots in it as the plastic top on the dealer demo. Thanks again for your reply . It's good to hear from another 5 SE owner

Tanks Chip
This is valuable information. I am considering ordering a plastic top for my 5SE to help with the heat. Audio Research says the plastic top actually sounds better. This was one of the upgrades from the 5 to the 5SE . I  still don't know why mine came with a metal top. 
Thanks again Chip

Would you care to jump in on this Trackman. You think the plastic top would be cooler. I'm not shure,  Anybody else got a theory?