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 2 responses by atmasphere

Funny with the amount of tube amplifiers I see at shows I hardly see this as the product being in it’s twilight. JJ tubes maybe of questionable quality, or filaments maybe getting damaged in shipping?

@audio_is_subjective I used that phrase because there are class D amps out there that rival tubes in every way except grace at clipping. The guitar market is the primary market of tube producers; high end audio is a tiny portion of their market. These days many guitar players rely on their effects pedals to get their ’sound’ so the amp only has to be smooth enough (not grating) and otherwise similar limited bandwidth of conventional guitar amps (unless one is talking about a Marshall Major or Ampeg V4, which are built on hifi standards).

Tube guitar amps weigh a lot! At 3:AM in the morning after playing a gig, it makes a difference if the amp weighs 85 pounds or only 15. Now that there are musical class D guitar amps out there its simply a matter of time that they will invade the market more and more since they are more reliable with no change to the ’sound’ that players are looking for. So in ten years the guitar market will look quite different. That means that the major market of tube producers is shrinking and nothing to do with the war in Ukraine or what high end audio is up to.

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.

@emergingsoul They definitely test them! But there is not a good way to really know how long a tube will last, especially now in the twilight era of tube amplifiers.

Usually a tube amp producer will have a warranty on the tubes, which is usually 90 days. We do a year but that's unusual. So if you've had this amp less than 90 days I'd simply get a replacement tubes. If you own a tube amplifier its a good idea to have spares on hand. You can use a spare to help you sort out which tube is giving you trouble.