2. amps-preamps
  3. 177110-5705

Tube or Amp Problem? Please help.

I have a Melody El34 Integrated Amp that I use with 2 pairs of Shuguang Treasure 6CA7-z. Last week I was listening to music when everything went all horrible sounding and one of the tubes lit up like blue fireworks. I turned off the amp and looked at it the next day. To my, admittedly untrained eye, the tube looks fine but when I checked the bias it was at .32 (the amp says to set to .40) so I tried to set it to .40 but it would only go to .34. All of the other tubes I can set to .40. I have never had this issue with this amp. Is it the tube or did something happen to the amp? If it's just the tube will it be ok to have one set to .34 and the other .4 or should I set both tubes to .34, all 4? I would buy a new pair but they were expensive and on top of that don't seem to be offered anymore.

128x128jkontuly
jkontuly's avatar
jkontuly OP
59 posts
 

Thanks russ69. I don't have that many hours on the tubes, had them for maybe 2 years but only probably use 5-10 hours of week due to busy schedule. if I keep the 2 shuguang treasures on 1 side will it sound bad if I replace the 2 on the side w/ the bad tube with something else? As I mentioned don't think I can find these tubes now and even if I could they are very pricey.

russ69's avatar
russ69
3,360 posts
 

will it sound bad if I replace the 2 on the side w/ the bad tube with something else? 

Probably not but it might sound different on each side. I saw on the web that those tubes might not be very robust and you have around 1000 hours on them. You can change just a pair but if it was me I'd get a matched quad and start fresh. When you bring the bias to spec and everything adjusts normally, chances are the amp is fine. 

russ69's avatar
russ69
3,360 posts
 

Ref: Upscale has Gold Lions for $92.95 each and Electro Harmonix for $45.95 each, no charge for matched quads.

lowrider57's avatar
lowrider57
5,393 posts
 

Do you have a spare EL34? You really need to see if a tube will bias in that slot. It's possible you'll need a new resistor. Better to find out before buying a new quad and not being able to play them.

jkontuly's avatar
jkontuly OP
59 posts
 

lowrider57, I am not home now but I will check. If I do I will definitely try it out. Hope I do but unfortunately I don't think so.

russ69, thanks for all of your helpful comments.

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