2. amps-preamps
  3. 188604-150037

JJ preamp tubes - repeated problems

I purchased an amplifier that came with stock tubes made by JJ.  There were problems with the amplifier so I replaced some tubes and then figured out it was the pre-amplifier tubes and small tubes. The manufacturer in this case who is McIntosh did send me replacement tubes and they worked for a month or so and then began to crackle. Now I have to figure out which of the six small tubes is creating a problem. 

I'm curious to know if manufacturers test the tubes that they use in the amplifiers before they ship them out? Maybe they test fine and then go bad within a month. I'm very suspicious they don't bother testing their tubes.

Judging by the process to test individual tubes and when you have 24 tubes on an amplifier I can understand them not giving them much attention during the manufacturing process. Maybe they expect people to replace all the tubes just like the power cords they send out.

 .Many replace the stock tubes immediately with gold lions which seems like an easy choice. Maybe manufactures do test their tubes and they're just using a poor manufacturer. 

Do others have tube problems with McIntosh amplifiers?

emergingsoul

Showing 5 responses by immatthewj

immatthewj
2,668 posts
 

I recently had a relatively new (about few dozen hours) JJ 6922 gold pin in my preamp went "pop!" then died with the glass badly cracked near the base.

Wow--sounds like an epidemic!  Pics?

immatthewj
2,668 posts
 

I had a preamp JJ 6922 go bad at about 100 hours.  Heard a crackling and then the left channel went silent. Popped the top on the preamp and the top of the tube was completely burned out.  When I went to pull the tube the glass completely disintegrated. 

@samzx12  , that is interesting.  I've had power tubes actually short out before and all that ever happened was that a fuse in the amp blew . . . you are saying that a fuse in your preamp practically caught fire (almost) and no circuit protection device tripped? 

immatthewj
2,668 posts
 

Popped the top on the preamp and the top of the tube was completely burned out.  When I went to pull the tube the glass completely disintegrated. 

I had a pair of 6550 (output) tubes (in an amp) redplate for way longer than I ever should have let them, and nothing like that happened.  I'd like to see that 6922, @samzx12  , pics?

immatthewj
2,668 posts
 

I have used JJ tubes for the past 7 years, in my case re-branded tubes with the McIntosh logo on them.  The 12ax7 tubes are quieter than the 2 Gold Lion 12ax7 tubes I am using in the line stage.  This weekend I will swap out the Gold Lions for 2 McIntosh (JJ) tubes.  I have no such problems with them and never have.

@stereo5  , I am using a quad of JJ (first time with JJs for me) 6SN7s in a SLP05, and the reason I went with JJs was because a friend of mine related basically the same as you did.  So far I have no problem with them.

immatthewj
2,668 posts
 

Popped the top on the preamp and the top of the tube was completely burned out.

Sorry if I misinterpreted that, @samzx12 , when I initially read that  it just sounded almost catastrophic was all, and I was thinking that it must have been a lot of current to do something like that. No biggy though--I was just curious.

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