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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
kenklein1
20 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.
acheung
21 posts
 
Sorry to be a little off topic,but If you replace the 6550 tube every 2000 hrs, what happens with the tube usage reader? Is that used just to measure the life of the 6h30 tubes? Also why does the audio research web page state that preamp tubes should last about 5,000 hrs? I have never used a tube product prior to my ref 5 and am still abit confused about tube life and the consequences of using a tube past its expected life.
hifigeek1
770 posts
 
Good point. Normally in say, a 610T amplifier, the timer is expressly for the output tubes and gets reset by the tech. after replacing the output tubes as you have to go inside the amp to do it. The regulator in the Ref3 does not need to be replaced every 2K hrs. unless there's an issue. It can be replaced every 5K hrs. with the small signal tubes.
sgr's avatar
sgr
689 posts
 
A concern I found with my Ref3 was that the tubes would slowly work themselves out of their sockets due to gravity and vibration. Also the pins and sockets seemed to need to be cleaned every couple of months are so to ensure the best sound. A couple of times I thought I needed to retube the unit only to find that the tubes were not fully ensconced in their sockets and needed cleaning. Once I had tuned up the preamp it sounded as good as ever. I even compared this process with a brand new set of tubes and found after a good scrubbing and repositioning one couldn't tell one set from the other.
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