2. amps-preamps
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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
immatthewj
1,870 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? 

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samzx12
1,220 posts
 

@immatthewj no I didn’t say it practically caught fire. The tube went bad and the top of the tube was very discolored and when i went to pull it out the glass crumbled. I sent you a PM.

I replaced both tubes left and right channels and preamp plays just fine.  

immatthewj
1,870 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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samzx12
1,220 posts
 

No worries at all 👍 

yoyoyaya's avatar
yoyoyaya
734 posts
 

@atmasphere - it's even worse than that because guitarists are switching to modelling systems which include cab simulation so that they can ditch their amps altogether.

As far as I'm concerned these systems and class D amp's are very far away from the real thing but, as you say, convenience is driving the market and it will undoubtedly affect tube sales.

I can't see us running out of 12AX7s, EL84/34s or equivalent any time soon but non guitar amp tubes could get scarce.

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