Tube Break- in

[tmazz]

Well, I got my VT-200 back from the shop yesterday. (for those who hadn't heard, I put in a set of new tubes and the plates must have gotten bounced around in shipping on one of them because they shorted and blew out three bias resistors - 480V rails fight back  ) I brought it over to Scott at SG Custom Sound and he ended up having a Winged C 6550 what was an exact match for the set that was in the amp so he replaced the tube and the resistors. (Scott does great work for reasonable prices - anyone in the NYC area that needs repairs should definitely check him out, http://www.sgcustomsound.com )

I got my friend Dave to come with me to transport the amp (lifting a VT-200 is not a one person job  ) We brought it home, set it up and sat down at about 4:30 for a listen. While Dave was amazed by it, I was thoroughly underwhelmed. I couldn't put my finger on anything in particular that it was doing wrong, but the magic was just not there. Good sound, but no goosebumps. We went out to meet another college buddy of ours for dinner and came back to listen a bit more around 11 PM. Still no goosebumps. Dave left at about 12:30 and I sat down with my laptop to answer some emails. I nodded off at around 12:45 and woke up just a few minutes after 1. (even without the goosebumps the music could still chill me out.  ) The CD had ended, so I put it back to what I had last remember listening to before I fell asleep and BAM, goosebumps.
The magic was back in spades.
Now I realize the tubes were brand new and needed to break in, but this was nod a gradual break-in where things got better a little bit at a time as things warmed up. The amp had been running for 8 hours straight with no change at all and the all of a sudden in the course of 15 minutes it was like somebody flipped a switch and everything was back. 

I've given up trying to figure this stuff out. 

I'll just go with the flow and be happy it's all working.

(And it's great timing, it's down to 25 degrees today but now that the amp is back I can shut down the heat in the mancave.  )

[richidoo]

I nodded off at around 12:45 and woke up just a few minutes after 1. BAM, goosebumps. The magic was back in spades.

You just needed a little nap.

I'm glad to hear you're back in business ToM!

[AcidJazz]

Yeah...it was all in your head. 

And while you were napping, little gremlins imprinted on your subconscious "I will like the sound when I awaken...I will like the sound..."

[steve]

Hi Tmazz,

Although I cannot claim my comments for smaller tubes,  large transmitting oxide coated filaments I can. The cathodes take time to breakin. I never kept track, though, of how long the breakin took.

An example. Over and over, using reference RF power measuring equipment in the lab, over a period of many hours, the output of brand new tubes (Eimac/Amperex) actually rose approximately 50%.

Of course I never noticed this change in audio size tubes. It would be good to do some experiments sometime.


Hope this helps.

[tmazz]

Steve,

I was not surprised that tubes were subject to break-in per se, but what took me off guard was the way that it happened. The change did not ramp itself in gradually over time but rather occurred in a step function after about 8 hours of play. The amp sounded rather flat and then all of a sudden over the course of no more than about 10 minutes all the magic was back in it was sounding like its old self again. I have never seen break-in happen in this way, but like I said, I have given up trying to understand this stuff and just resigned myself to go with the flow. (I get paid to figure these type of things out at work, when I get home I want to just sit back and enjoy.)

[steve]

Hi Tmazz,

I understand what you are saying T.
A little different, years ago, I once heard a stereo start up at a friends house, and after about 30 minutes one could literally see the soundstage open up, monster size within 30 seconds. It was unbelievable. Only heard that type of "explosion" from that one stereo system.

Kinda neat how things can change when you least expect it. Since it is broken in, does it change much now, after each warmup?

Cheers.

[tmazz]

Kinda neat how things can change when you least expect it. 

One of the things that keeps the hobby interesting. 

Since it is broken in, does it change much now, after each warm-up?

I have only gotten to turn it up twice since then (between church and football there wasn't much time for audio yesterday  ), but the goosebumps are still there.

I have to tell you, in spite of what I have read and been told, my VT-200 seems to level out after only about a minute or so of warm-up, I have never really heard much difference after an hour of warm-up.

[JBryan]

Maybe the resistors needed some time to break-in....?

[tmazz]

Maybe the resistors needed some time to break-in....?

I don't doubt it, although as bias resistors they were not in the signal path, so you wouldn't think they would have a big impact on SQ , but who knows? (  sorry there I go thinking logically again  )

But again, my surprise what not on the fact that they did break in, but rather in the way that it happened, as a step function as opposed to a ramping up in SQ as the break-in occurred.

[rollo]

  Yes the Epiphany moment. It is a gas when all of a sudden  just clicks in.
   Generally it takes about 30 hours for the solder joints alone according to Gramlich. Tubes 50 hours seems to get the tonality issue out of the way. Next it opens up and the bass gets stronger. You heard change number one expect more. At 100 hours all is done. No more changes.   



charles

[jimbones]

Tom,

Congrats, you drank the Kool-aid!

[tmazz]

Tom,

Congrats, you drank the Kool-aid!

Many years ago my friend, many years ago. 


And as they said at Jonestown, "Damn, I should have had a V8!" 

[richidoo]

And as they said at Jonestown, "Damn, I should have had a V8!"