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ARC Ref 3 bad tube?

I recently have developed a nasty sounding sporadic crackling sound in my system. It only happens once during each listening session. The crackling also comes out of both speakers in stereo. I have an ARC Ref 3 preamp and an Arc Ref 110 amp. I believe I have a bad tube but would like some opinions to make sure. I had my amp serviced in September 2009 by Arc so I don't think there is a problem there. The tubes in the amp have 1300 hours on them. The Ref 3 has 2500 hours on it. I replaced the four rear tubes at 850 hours with 6h30p-dr super tubes. The 6h30p tube under the 6550c power tube is orginal however. I replaced the 6550c tube in the preamp at 2200 hours. This is what I think is possibly wrong.
1.) The original 6h30p tube could be bad since it must get pretty hot from the 6550c tube above it.
2.) I noticed the 6550c tube has a strange looking white residue sticking to the inside of the glass. It almost looks like fine particles resembling styrofoam. That doesn't seem right to me.
I think it would be one of these two tubes since I get the bad crackling sound in stereo and not just one channel.

Thanks in advance for any advice.
tlg
cyclonicman
693 posts
 
No matter what, the white residue indicates this tube needs to be replaced. In a perfect world, a 6550 should last for 3,000 hours, but there is no guarantee that it will. Tubes sometimes fall way short of the expected life and that is why you will never get a retailer to guarantee his 6500 tube will last for 3,000 hours.
scousepasty
106 posts
 
The power tube in my Ref 3 went pop at about 500 hrs., easy to diagnose, no power! I changed it for a NOS GE6550A that I had, with a v.near match marking and the noticeable improvement over the standard valve was in bass and a deeper soundstage. Worth trying if you can get a GE6550A with a close match.
chadnliz
3,736 posts
 
I just had my Ref 3 retubed last week, got a bad tube on Left channel but AR sent a new one out and I bet its the main tube aswell. Try Vintage tubes in Michigan, I went with stock tubes for the Ref 3 but went with a 1958 NOS RCA tube for the Aesthetix Atlas amp and the change was huge so next go around I am gonna try different tubes for the Ref3.
kenklein1
19 posts
 
Calvin and the manager of service recommended changing the 6550 in my REF5 every 2000hrs, if you wait until it fails, expect a large repair bill.
Also, having owned several tube gear in the past, I recommend paying the extra and getting them from ARC. They test each tube and warranty them. I also recommend always having a spare set of tubes on hand just in case. Also, they are now using 6550EH instead of C tubes because they think they sound better. When I have my REF5 upgraded to SE in May-June, I will have them retube including the EH tube. Happy Listening!
hifigeek1
770 posts
 
I agree on finding an ARC warranty repair station. I have seen residue in 6550's and the tube was fine. If it's only happening on one channel it's not the power supply. First just turn the amp on and leave the preamp off. That will tell you if it's the amp. My guess would be the preamp and you could have a bad tube in it. I don't remember if that preamp uses constant current sources as it could be that as well or a resistor could still have gotten noisy.
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