12AU7's

[bpape]

And there are as many opinions on caps as there are on tubes - maybe more. Charles just told of a couple options. In MY preamp, Ven Haus Teflons for coupling caps and OIMP's for output caps does the trick.

YMMV

[rpf]

link=topic=4766.msg61952#msg61952 date=1380563629]

  Ah to tube or not to tube is the question. When tubing remember that the caps used will influence the tube used. IMO that is the synergy we go after.
    For example when V-caps are used as output caps the RCA brand works wonders. When Duelund CAST is used the GE tubes are better.
    Just keep trying all ya can. Have fun amigo.


charles

Charles is on point here: it's very true.

Also caps, IME, make at least as much difference as tubes, and often more.

[BobM]

So do power cords ... and interconnects ... and speaker cables ... and footers ... and salt lamps in the room (well maybe not so much). I think most of us have experienced how just about anything can influence the sound. And blending all these things into a sound that YOU like and appreciate can go through quite a few iterations and configurations, and may not ever get "perfect".

That being said - can we get back on 12UA7 topic and tubes that you have experience with and like?

[Response Audio]

I want to add one more thing that I find influences our systems that many don't take into consideration. Being in the North East where our weather and humidity changes by the hour, we find that the sound of our systems can change quickly with different humidity levels. (thicker air). A hot humid or rainy damp day causes the sound to be muffled and dull unless our listening room is temperature controlled with an air conditioner.

If you don't beleive me, leave your air off on the next hot humid day (if we see any more days like that)

That being said - can we get back on 12UA7 topic and tubes that you have experience with and like?

[mlee]

My new PrimaLuna Dialogue Premium preamp uses these...
Anyone know what stock 12AU7 they use ???
It sounds fine to me out of the box..but I may want to experiment with different ones when its time to re-tube.

Dick Olsher said in his review of the PrimaLuna DiaLogue Premium Integrated Amp in the Absolute Sound (May/June 2013) that the stock 12AU7 is a good-sounding tube but found a weakness later, an assertive upper mid-range.

If you find that to be the case, then a warmer sounding tube may be needed.

The DiaLogue Premium preamp uses 6 12AU7s.  Note that you need not use 6 tubes of the same make or model, but can mix and match 12AU7s of different manufacturers.

Jason/

[BobM]

It is rare that you find a reviewer who will roll tubes during a review. Generally they are supposed to test and evaluate the equipment just as it comes from the manufacturer. What we can know from that, is if they like it stock, then it likely can be improved with a little judicious tube rolling.

[GT Audio Works]

D.O. is reviewing the integrated amp not the preamp...I do not notice an assertive upper mid-range in my system.
I find this preamp is adept at dynamic changes without getting aggressive.  Of course its all system dependent your results may vary.
 When the time comes to replace tubes I am interested in improving on it's virtues if possible.
Speaking of replacement, the manual indicates a tube life of 5,000 to 10,000 hrs. sounds a bit optimistic to me.
                                                        Greg

[Response Audio]

Speaking of replacement, the manual indicates a tube life of 5,000 to 10,000 hrs. sounds a bit optimistic to me.

This does not have to be too far out of reach. It is very possible to design a preamp circuit that allows this kind of tube life. Our Musica Bella preamp circuit is also design in such a way that we rate tube life as high as 10,000 hrs.

I have one of my original preamps that is almost 10 years old that still has the original tubes in it. Not sure of the hours but I would guess over 5k-6k hours.

[GT Audio Works]

Speaking of replacement, the manual indicates a tube life of 5,000 to 10,000 hrs. sounds a bit optimistic to me.

This does not have to be too far out of reach. It is very possible to design a preamp circuit that allows this kind of tube life. Our Musica Bella preamp circuit is also design in such a way that we rate tube life as high as 10,000 hrs.

I have one of my original preamps that is almost 10 years old that still has the original tubes in it. Not sure of the hours but I would guess over 5k-6k hours.

Well if that's the case, I will not feel so bad about leaving it on the better part of the day.

[Response Audio]

I leave my preamps on 24/7 for a few days at a time. Unless there are real expensive tubes in it or if it has a tube power supply. Same for my hybrid amps as the tube input stage is a low voltage design. I do turn the output stage off but leave its power supply on all the time. (A benefit of Class D)

[JBryan]

Greg said..."Speaking of replacement, the manual indicates a tube life of 5,000 to 10,000 hrs. sounds a bit optimistic to me."

Tube life is very dependent on the circuit and varies greatly by the manufacturer - both the unit's and tube's. I have a Scott 222c in a 2nd system that has been used almost daily for over 15 years and it still has the original tubes that were installed in 1961. I have no idea how much the original owner used it but by my calculations, I have put about 15-16K hours on these Telefunkens (12AX7 and 7189) and last I checked (actually Terry DeWick checked 'em) they still test strong.

I also have a DAC with tube output stage and the Tele 12AX7's I installed back in 2002 have been either 'On' or in 'Standby' ever since and they show no signs of wear yet. Of course, now that I've said this, they'll all catastrophically fail this afternoon....

[Response Audio]

I guess a couple reasons you are getting so long life with your Scott. One..... NOS tubes were built much more rugged than today's tubes. Two.... The older gear does not stress tubes like much of today's equipment does. Combine these two together and you may never have to replace those tubes again.