[TJHUB]

I am COMPLETELY new to tubes and I recently purchased my first DAC with a tube buffer; a Music Hall DAC 25.2.  The DAC came stock with an Electro-Harmonix 6922 tube which after about 50 hours of use sounded ok.  But without going into any deep detail, I found the highs to be decent with good decay, the midrange to be slightly grainy, and the bass is just plain muddy.  So on to some tube rolling...

What I've listened to thus far besides the EH 6922:

Telefunken E88CC 1960's:  Hate it!  Nice bass control, but the midrange is just too smooth and hollow sounding, and the highs are very dark.  The tube sounds as if a lot of the music is just gone.  Imaging is smeared, but the music is coherent.  This was a VERY expensive tube, and it's just awful!

RCA branded 6D8J/E88CC made in Holland (Amperex?):  This is a nice sounding tube overall.  The bass is bit overdone which takes away from the midbass, the midrange is very nice right between smooth and grainy (if that makes sense), and the highs are open with nice air (which will bring me to my question in a minute).  Imaging is focused, and the music is coherent.  This tube is on loan from an acquaintance from another forum.  I could live with this tube except for the overdone bass. 

Tesla E88CC NOS 1980's:  This is my tube!  Love it (so far)!  This tube sounds very balanced top to bottom.  The bass is VERY balanced like I'm used to from my solid state DAC (PS Audio DLIII) with perfect midbass, the midrange is a little smoother sounding than the RCA without being too much, the highs are nice and extended but there is little air.  Imaging is focused and the music is coherent.  The sound stage is still holographic and deep.  This is the BEST tube I've heard and this is the first tube that makes me think this DAC is a keeper and I can sell my PS Audio DAC (which I used to love).

So now my question.  Is "air" good?  Is it correct?  It sounds nice, but is the music supposed to sound airy?  I'm just looking for thoughts and opinions.  I'm certain there isn't a correct answer here.  It's just that I liked the air from the RCA tube and the Tesla doesn't really seem to have that quality.  However, both tubes sound very open in the midrange and highs.  The RCA would be the winner for me except for the overdone bass.  The Tesla is just better at everything else with very little air.

Thanks.

[JerryM]

Telefunken E88CC 1960's:  Hate it!  Nice bass control, but the midrange is just too smooth and hollow sounding, and the highs are very dark.  The tube sounds as if a lot of the music is just gone.  Imaging is smeared, but the music is coherent.  This was a VERY expensive tube, and it's just awful!

Not quite sure I have an answer to your question or not, but...

How you describe the Telefunkens is exactly what I went through with my Teles. The music being "gone" is a good description. The soundstage was flat up against the wall; zero extension. Poor musicality in the extreme. Pretty horrible stuff. However, at about 30 hours they were darned musical. At about 50 hours, pure sweetness. Not a change since; just well balanced, crisp, coherent tunes across the volume spectrum. If you have not done so, let those tube burn in. Your thoughts may change.

As for 'air'; if it belongs there, I want to hear it. If not, I don't.

Congrats on the new DAC (and valves!)! 

Have fun,
Jerry

[TJHUB]

Telefunken E88CC 1960's:  Hate it!  Nice bass control, but the midrange is just too smooth and hollow sounding, and the highs are very dark.  The tube sounds as if a lot of the music is just gone.  Imaging is smeared, but the music is coherent.  This was a VERY expensive tube, and it's just awful!

Not quite sure I have an answer to your question or not, but...

How you describe the Telefunkens is exactly what I went through with my Teles. The music being "gone" is a good description. The soundstage was flat up against the wall; zero extension. Poor musicality in the extreme. Pretty horrible stuff. However, at about 30 hours they were darned musical. At about 50 hours, pure sweetness. Not a change since; just well balanced, crisp, coherent tunes across the volume spectrum. If you have not done so, let those tube burn in. Your thoughts may change.

As for 'air'; if it belongs there, I want to hear it. If not, I don't.

Congrats on the new DAC (and valves!)! 

Have fun,
Jerry

Your comments are interesting.  When I first fired up the DAC with the new Electro-Harmonix tube, the DAC didn't sound so good.  The highs were recessed, the midrange was grainy, and the bass was terribly muddy.  Since I was new to tube gear, I hung in there for the rest of the week just to get as familiar as I could with the sound.  At about 30-40 hours, the DAC changed.  The highs sounded more extended and the midrange was smoother and more coherent.  The bass also became much more controlled, but it still isn't good or acceptable.

I purchased the Telefunken and Tesla tubes from Brendan at Tube World.  He has been very helpful and he is local to the city where I work.  It's nice to just drive over and pick the tubes up directly from him. 

Nonetheless, I emailed him today telling him what I thought of the Tele.  He basically told me to forget the Tele and try the Tesla even after I asked if I should just hang in there and break the tube in.  So that's what I did...

On the air subject, I too want to hear it if it's supposed to be there.  The question is when is it supposed to be there and when isn't it I guess.  It's just to me my PS Audio DAC may add an airy sound because it can be bright sounding.  The RCA tube didn't sound bright, but it did sound airy.  As if tubes are confusing enough...

[JerryM]

He basically told me to forget the Tele

That's exactly what I was trying not to do as I burned in the hours.    As you pointed out, nice Telefunken tubes cost a bit (for a reason).

If I were in your shoes with this quandry, I would put 55 to 60 hours on the Teslas. Then I'd roll the Telefunkens back and run them in for about the same amount of time. Then I'd roll them again (and probably again) and give a good listen to some reference songs I like.

One is bound to learn something about 'air' doing this, if not vacuum. 

Please, post your findings if you go this route.

Have fun,
Jerry