JJ preamp tubes - repeated problems

JJ's are mediocre tubes at best. For best sound and reliability, get some nos from a reputable dealer.

Repeated problem: I am highly suspicious of the AMP, not the tubes.

TUBES: A simple tube tester puts you in control, without one, it’s a confusing mess.

test single and matched sets you buy, test periodically, test when problems occur.

Have Spares, but they should last many thousands of hours.

Many are on eBay etc.

Keep your eye out for a decent tester that seller says works, and accepts returns.

I have the smaller model 157, I would get this model 257 if I did not have one. I got a 257 for a friend, he loves it.

seller: 100% positive rating: 30 day returns:

read full description and ’watch video’

Until you get your amp checked out by a reputable technician, all these comments are guesses at best. Blaming the JJ tubes might be correct, or not.  As many have noted, poor shipping, handling, and such can damage any tube, even NOS. 

JJ tubes are treated roughly in guitar amps and don't fail very quickly. I have used them in a Schiit headphone amp to good effect (6922). Sure, NOS might sound better, but if we want this hobby to continue with vacuum tubes or "valves" as they are called in Europe, then we have to be looking at new production tubes because the supply of vintage tubes will run out one day. What do you do then, move to Class D with Hypex or PuriFi chips? 

Perhaps replace the JJ tubes with something else and see if they too get fried. If not, then you'll sort of know it might have been "something unquantifiable" with the JJ. But if they too get fried early on, then you definitely should get the amp looked at. Nothing made by humans is 100% perfect or as intended 100% of the time. Just the reality of manufactured goods. 

in my new mac gear the JJ's were the first to go they sound flat, bright, toneless  compared to better tubes, specially some nice NOS tubes. first thing is to upgrade those small signal tubes asap. yup I get it I also have a mac preamp and power amp all tubes and yup there is a lot of them. start with the small signal tubes.

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.