Since claims are that these tubes sound their best after 300 hours of play time (about 12 days of constant use) I have what may be a naive question about burn-in via the MWTP: for burn-in is it enough to JUST have the MWTP and output stage turned on and music streaming through it, or do you need the preamp turned on as well to receive an output signal in order to effectively burn-in the tubes?
As a follow-up to that; to those of you who have got the tubes, how much difference was there between brand new and at X-hours of burn-in? Were the differences profound or subtle?
Very good question !
From my actual limited experience burning these in, Rachel always needs to sell mine typically with less than 20 hours on them, I did get to 300 hours once on a pair, being run though as a driver tube in our A-348 amp, so in and out was active. Not sure if the Transporter is operating in class A or not, but just having the heater on will instigate burn in, if in Class A with no signal, the tube will burn in quicker, Class A being somewhat like having your foot down on the gas pedal while in neutral or park.
My mind just won't let me break in anything to do with music though without it doing it's job of creating notes, so I would break them in with both input and output active, you can shut off downstream of the next component in the chain. But, really it is fun to hear these things go thru their changes, it is never unlistenable and with the power tubes it for me is always better than what it replaced.
I do hope that some will post what they hear as it goes thru the burn in process. What I do know is they sound very good right out of the box, the mids will be a little weird and the top and bottom extensions haven't occurred at all, but still good, likely much better than stock tubes, then it falls apart for a few hours, then around 8 hours in gets good again (probaly about 80% of what the tube can do), still tight sounding, but starts opening up and goes weird again a couple of times for a few hours until around 150 hours when I have witnessed an extra octave appears on the bottom end and soon after the air (like a mesh plate power tube) is very noticeable, at this point you are probably getting about 98% of what the tube can do.
For those that are just getting theirs, you will note the Grant Fidelity logo on the other side of the tube, this started with our last order. We have gone this route to establish what is the premium Treasure tube, with Grade A or Grade B grading, even on our latest order we had a large percentage that did not even make Grade B, these go back to the factory. The factory selects ours first from a production run based on getting as close to our spec as possible, then prints our logo.
Cheers,
Ian
