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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
1,886 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.

Ag insider logo xs@2x
samzx12
1,220 posts
 

@immatthewj I didn't take a picture after pulling out the tube. 

audioman58's avatar
audioman58
4,134 posts
 

Those are crappy cheap tubes, buy a quality New Old Stockthe real deal 

call either vintage tube services ,brent Jesse recording 

the original tubes last longer and sound better 

brent Jesse ever offers for a $30-40 extra a two year. Warranty peach brand sounds different , nos tubes were built to a much higher standard.

yoyoyaya's avatar
yoyoyaya
737 posts
 

There's nothing particularly bad about JJs - they are extensively used in the front end of guitar amplifiers that get a much harder life than hi fi. It's relatively unusual for small signal tubes to fail early in their life, but it does occasionally happen.

@OP - it's not guaranteed that it's the tubes that are at fault. It could be a dry joint on a tube base, for example.

dinov's avatar
dinov
833 posts
 

Yes they do test them but current tubes aren’t what they used to be quality wise. McIntosh is very easy on tubes, so the problem is definitely the JJs. That’s why I use NOS. I use Amprex Medical 12 ax7 s in my C2300 and have well over 10000 hours. I would look into those or NOS Telefunkens. I think you’d be very happy both quality wise and sonically.

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