Now I remember why I own so many Valvo Hamburg 12AX7 tubes!!

headrott

I promised some people on the DIYAudio site that I would roll some tubes in my DAC I built a few months back. The original tubes I had in there were some early 1960's Telefunken ECC88 (or 6DJ8) tubes. They sounded good, but this piece of gear is the only one I have used them in so far. I had used them in the DAC for about 3 1/2 to 4 months so I knew the sound of them pretty well.

Yesterday, I decided to put some Valvo Hamburg 45 degree halo getter 12AX7 (or ECC83) tubes in the DAC and did some comparisons. I have owned the Valvo Hamburg 12AX7 tubes for about 8 years and have previously used them in my tubed CD player and my previous pre-amp. I have not used them for a while now (about 1 1/2 years) as I have been using other tubes/types instead to try them out. I installed them with the Herbie's Unltrasonic Rx-9 tube dampners (which were of course, also on the Telefunkens). I let the rig warm up for about 1 1/2 hours. Here are the results.

The first song I played was "Rain" by Madonna. This is a pretty nice sounding song (from a fidelity point of view). Not the absolute best, but pretty nice. The first thing i noticed was the gain increase due to using 12AX7's instead of 6DJ8's. I can adjust the gain output on the DAC with a gain controler I installed, but also with the pre-amp as well. I the output on the DAC at maximum as this is typically what sounds best, so long as there is no distortion. There was not. The second thing I noticed was the increase in bass. There was both an increase in the attack and extension! If you have heard "Rain" on a good system you know what I am talking about. I thought that the bass was not as clear as the Telefunken's, but after playing a few more tracks found that it is actually the bass in the recording itself that is not as solid as I thought (more on that in a little bit). The third thing I noticed was the high end frequency extension and clarity. The highs from the Telefunken's was good, don't get me wrong but the Valvo's was phenominally extended, clear and accurate. The fourth thing I noticed was how much more revealing the Valvo's are compared to the Telefunken's. If it is a bad recording (or parts of the recording are bad) the Valvo's reveal them more than the Telefunken's do. The width of the soundstage was the same as the Telefunken's, which is pretty wide. Not as wide as some Amperex tubes, but very nice. The hight and depth of the Valvo tubes increased by a little (I would guestimate 15%).

The second song I played was "Let's Dance" by David Bowie. This was from the AU20 Ryko 20 bit 24K gold ChangesBowie CD. This is a very nicely mastered CD!! The bass on this recording was solid and acurate and the Valvo's made it shine!! Again, the highs were excellent and I now also heard the midrange come through very nicely from the Valvo's.

The third song was Robert Plant's "I'm In the Mood" from the remastered boxed set version of "The Priciple of Moments". Again, I was blown away by the bass attack compared to any other time I've heard this song. This is not the best recording ever, but is not bad either. The Valvo's put out everything there was to be heard (both good and bad ) from this recording. But, it did it so much better than the Telefunken's it is crazy!!

The fourth song I played was Depeche Mode's "Enjoy The Silence" from the unremastered "Violator" disc. This mastering is, overall better than the remastered version that came out IMO. Again, the bass is amazing from these tubes! Very revealing and clear sound coming out if the speakers!

Last I played Sade's "Your Love Is King". If you have ever listened to just about any Sade song on a good system, you know how well these are recorded. Absolutely everything on this song was amazing coming through the Valvo's. The bass, the highs, the midrange, the soundstage depth and hight were all absolutly outstanding on this song!! This song showed why the Valvo tubes absolutely kicked the a$$ of the Telefunken's in every aspect.

Conclusion: If you have not heard the Valvo Hamburg 12AX7 tubes and you own a piece of gear that can use them, get some!! I do not see how you could be disappointed. I now remember why I bought 6 pairs of them:biggrin:

I will post some more tube rolling findings in the DAC when I have finished. I will try some early 1960's Siemens CCa's with the grey shield, some early 1960's Brimar 13D5 tubes and some early 1960's Amperex 7316 tubes as well.

Greg

RuSsMaN

How are you interchanging 6DJ8 and 12AX7? They aren't even close to being compatible.

thsmith

Op must of meant 13d5. I think the 6dj8 are more like 6922(?)

Op was is your DAC?

heiney9

Valvo Hamburg tubes in both the ECC81 and ECC83 variety are S-U-P-E-R-B. My favorite tube. I have a lot of pairs as well.

H9

heiney9

The 12AX7 and 6DJ8 aren't compatible one runs on a 12v heater the other runs on a 6v heater and the pin outs are different.

H9

thsmith

Greg, what DAC are you using?

headrott

RuSsMaN wrote: »

How are you interchanging 6DJ8 and 12AX7? They aren't even close to being compatible.

Sorry, I didn't remember that I didn't mention it in my original post regarding the DAC I made here: http://www.polkaudio.com/forums/showthread.php?t=119264&highlight=Tube-I-Zator+DAC

but, the "Tube-I-Zator" SRPP I/V output stage boards have a heater switch capable of switching the voltage plate voltage between 6.3V and 12.6V. Therefore, it is possible to use a very wide variety of tubes in this SRPP I/V output stage. Thanks for bringing that up Russ, as I totally forgot to. That would have actually been a very important thing to bring up and talk about(as you pointed out I didn't really give a review in the thread above).

Anyway, thank you Russ for bringing it up here as that is absolutely a very important thing to talk about.

I just put the Siemen's CCa tubes in in place of the Valvo's (so I switched the heater current switch to allow this). I will give people my impressions of these tubes vurses the Valvo Hamburg and Telefunken tubes.

Greg

headrott

thsmith wrote: »

Op must of meant 13d5. I think the 6dj8 are more like 6922(?)

Op was is your DAC?

Yes, you are correct. The 6dj8 and 6922 have the same heater voltage I mean. As do the 13d5 and the 12ax7 tubes, respectively.

The DAC I am using is located here: http://www.polkaudio.com/forums/showthread.php?t=119264&highlight=Tube-I-Zator+DAC

It is one I built using boards I bought and assembled and custom built R-core transformers. It is a great sounding DAC. Although, I cannot compare it to say the W4S DAC (although it's not a tubed DAC either) as I have never heard it before.

Greg