[TubeNewb]

I have been a low end audiophile for years (basic integrated, monitor speakers, etc), but recently got the bug to try tubes.  I now have a DAC with 6922  tubes in the output stage. How long do the tubes takes to burn in, and what changes in sound can I expect? 

[TheChairGuy]

I've found about 10 hours they're 'in'...sometimes a wee longer (depending on tube types and other factors)

[Steve]

Hi John,

     Good to be back here.

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Hi Tubenewb,

I am wondering what tubes came with the dac? Might want to tube role if chinese or Sovtek are used.

Another interesting idea is to install a second set of output jacks, and bypass the tube altogether. You would still have the original output jacks available. Gain will be slightly lower, approx 6-9db from what I have found. PM me if you have a tech nearby and want to try it. Just a thought.   

Hope this helps.

[JLM]

Tubes go through a "warm up" where the entire filament reaches design temperature.  Some say 30 minutes, but it'd be tube dependent with most of the effect happening initially.

Tubes also "age" as the filaments breakdown and finally fail.  During this process their sound changes.

[TubeNewb]

The DAC in question is the LiTe DAC 62 from Pacific Valve (a variant of the DAC 60, designed and made for Pacific by LiTe).   I have the stock tubes (not sure the brand), JJ Tesla, and JAN Philips.  I gave each set of tubes a quick listen, and am now breaking in the JJ Tesla tubes.  Next up will be the JAN Phillips, and then the stock tubes (might not bother with these, and keep only as back up tubes). 

I think Chair Guy is spot on - all day Sunday on shuffle seems to have resulted in a huge improvement in the JJ Teslas.  I originally hated these tubes - they were noisy and distorted on the top end - although they had a very airy sound, which I found pleasing (I assume this is why people love tubes).  They are now greatly improved - highs are nice and clean, noise is gone, but so is that airy sound - they almost sound solid state.  I should note that the entire unit is still breaking in as well, so there are lots of variables (including my ears).

Overall, this unit sounds great (fed from an Oppo 971).  However, the case design does not make tub rolling very easy.  Also, my rack set up is also not good for tube rolling - I have to completely unplug the unit, remove it from the rack, remove 8 screws, pull the top off, swap the tubes, and then reverse the process. 

I look forward to breaking in the JAN Phillips later this week (have to travel for business mid-week - dang it).  Based on the initial sounds, I expect that these will be my favorite.  I am very curious to see how these end up in relation to the Teslas. 

As for bypassing the tube stage - interesting idea, but  I don't have a local tech (and I am not so inclined).  I will keep this in mind.  It would be a fun A/B for sure. 


More questions to follow. 

Thanks.   

[TheChairGuy]

Enjoy it all, TubeNewb 

Steve - 'tis true, you've not been heard from in these parts for a while....welcome back or welcome home (?)

John

[Steve]

Thanks John. Just been busy and checking out some things that did not turn out very well. 

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Yep, the sound does change as it breaks in. Might also try demagnetizing the tubes as during the manufacturing process, induction heating is used and sudden induction shut down leaves the plates etc magnetized. This will cause some gritty/harsh highs. Hopefully will help some. I know it does the power tubes. (Use a hair dryer and hold the dryer near the tubes. Slowly take away the dryer and when about 3 feet or farther away, shut off the dryer. Again, hopefully this will help some.)

"As for bypassing the tube stage - interesting idea, but  I don't have a local tech (and I am not so inclined).  I will keep this in mind.  It would be a fun A/B for sure."

Yes, it was pretty interesting, and surprising when I tried it awhile back. (I don't do CD player mods.) The space is physically too small to properly design a good stage, especially tube. And I have yet to hear an excellent ss design as well. That is why I suggested bypassing that stage. It is probably the weakest stage in a good system. I see it is not be possible for you due to circumstances. Just a thought, maybe keep in the back of your mind.

Take care.