Preamp Deal of the Century

First, the Tung-Sols:

I am not an expert (far from that) on NOS tubes. Started with the stock tubes, then the Sylvanias VT-231 and now (since today!) the Tung-Sols Round Plates. The Sylvanias were airy (nice) but sounded lean and clinical in my Chardonnay. Actually, not too different from the stock tubes. But quite more expensive and microphonic. Sold them. With the Tung-Sols I had a very bad start while ago. Once I put them on the preamp they started to make some "huuummm...". When I got near them the "huuummm..." turned out to be a much louder "HUUUMMM...". Ouch! Well, I gave them a couple of minutes to settle down and the noise disapeared almost completely (!) As for the sound, it is quite the opposite of the Syls. A bit less airy (can I "fix" that with the 6F6G?...) but everything else was much better. Natural highs and lows and a palpable midrange. This is a very musical, very emotional tube. I guess I am done with 6SN7 type.

Now the 6F6G:

First of all, THANK YOU Eccletique and Bwhite! I guess I can get a pair of Sylvania Green base print 6F6G tubes. But I must confess that after my experience with the Syls VT-231 - regading sonics AND specially microphonics - I do not feel very confortable to go again with the Syls... So I ask: are these really good? How do they behave as for tight bass / sweet highs / air AND microphonics (comparing to the stock KT-66)?

Thanks guys!
Lisbon

Lisbon, The regulator tubes (6L6/6F6/KT66,etc.) will not increase the microphonics at all.

Lisbon,

My pair of JAN Sylvania VT-231's are not microphonic at all. The only tubes that I have microphonics issues with are the Ken-Rad Black Glass. I am finding that you can't label any brand of tube microphonic over another brand. You can have 2 sets of the same tube and one may be microphonic while the other is not. I have not found microphonic tubes to hurt the sound of my Syrah. Yes, when music is not playing you can hear the microphonic's, but when the music starts it sounds great.

Hi Slowhand,

I've had the line stage version of the Cortese (Sauvignon) for about 6 months now, and have just started experimenting with Tube Rolling, with vast array of information and feedback on this thread.

I've replaced the Rectifier with the Mullard GZ34 and the 6SN7's with a pair of Ken Rad Black Glass VT-231.

Initially upon replacing the Rectifier with the GZ34, the system sounded just a tad leaner with little or no loss in detail (Not much of a change after 1 week of usage).

But when I replaced the stock 6SN7 with the Ken Rad Black Glass VT-231, the improvement was immediate, extremely good bottom (Supurb Slam) with a glorious mid-range (Just put these babies in about 2 hours ago), after it's delivery by Australia Post this morning. The vocals which were once a little veiled, probably due in part to the Krell KSA-250 amplifier, is now completely brought to life. The detail is incredible, with a complete and utter transformation. I never thought changing these tubes could make such a difference. Hence the perplexation lately with some of the other comments on thread with regards to the Ken Rads (Microphonic, very little difference etc...)

Furthermore, the Sauvignon with the Ken Rads has no Microphonic qualities. I've tried tapping various parts of the Main unit and power supply, with no microphonics what so ever. Dead Quiet.

Just a question, If the bass is now very deep with an extraordinary level of detail, do you guys believe replacing the last remaining set of tubes (Regulator pair) with the 6F6G will make any more changes to it's character. Further to that, is the 6F6G a suitable replacement on the Sauvignon, I know some of the readers have replaced this component on the Syrah, but what about on the Sauvignon.

I just trying to think how the 6F6G can have any other improvements in light of the transformation that's already just taken place.

Thanks to everyone to date with their inputs. The information over the past year has been extremely informative, You guys know what you're talking about. Afterall it's not easy to purchase a piece of stereo equipment sight unseen and most importantly sound unheard.

Best Regards,
Clipsal

Clipsal you make some interesting observations and I would say that what people hear by swapping tubes must be more system dependent than anything. I wouldn't want to give the impression that different 6SN7 VT231's don't make a difference, they most certainly do but I found the differences subtle relative to each other. The Ken Rads did provide fuller bass but not better and I take issue with the fact I have tried 3 pair and haven't been satisfied, they were all too noisey. I also felt they were a tad too rich in the mids but I suppose I find this more a taste/synergy issue than anything else.

My point is I have heard much more significant differences with tubes in other designs I have owned over the years. This pre-amp is so intrinsically good that so far as the 6SN7 goes I haven't found the variety I've used to make a significant enough difference to rationalize spending the money on some of these tubes. Of all I have tried I prefer on balance the Sylvanias and National Unions with the Ken Rads my least favorite, good ones are hard to come by I suppose.

The regulator tubes I didn't find to alter the tonality so much as enhance dynamics, presence and bass. This may of course be system dependent as well. To me the 6f6g was most significant, a real eye opener. I agree that the stock tubes were not nearly as good as all the tubes I've tried but changing the regulators should provide an interesting result, you should definitely give it a try and tell us what you think.