Preamp Deal of the Century

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.

Tubegroover, I am excited about your discovery of the 6F6g and much of your experience with tube rolling seems to mirror mine with the exception of the Ken Rads. But I think your comment about taste and synergy is often grossly overlooked. I personally believe this whole journey is about taste and synergy, otherwise we would all be listening to the same thing. I applaud your comments.

Regarding the 6F6g, help me overcome my jitters about this tube. I would love to find another regulator as good as the WE 350B, especially at 1/10 the price!

However, when I looked up the 6F6g online I couldn't find anywhere that it is a drop-in replacement for the regulator tubes. I didn't take the time to research the operating specs, but I didn't see it mentioned anywhere as a replacement for any of the usual Supratek regulators. I have great respect for your help and experience here and I am foaming at the mouth to try the 6F6g. I just need a little reassurance that the tube will perform within acceptable operating points for the Supratek!

I apologize if this has been addressed in an earlier post as I have not read all of the posts lately.... realizing this thread continues to be the "Mother of All Audiogon Threads".

In fact, we should all agree to a virtual toast to Slowhand for making us aware of the Supratek to begin with and also for establishing an Audiogon record that will probably never be broken!

Here's to you and yours
And to mine and ours.
And if mine and ours
Ever come across you and yours,
I hope you and yours will do
As much for mine and ours
As mine and ours have done
For you and yours!

Fiddler has a point. Did some research on 6F6G and also found nothing saying that these could replace the 5881/KT-66/(...). Also the supratek "manual" does not mention the 6F6G as a possible substitute for the stock tubes (while other types are referred). As Fiddfler "I am foaming at the mouth to try the 6F6g. I just need a little reassurance that the tube will perform within acceptable operating points for the Supratek!" In the meantime, anyone asked Mich about this?

Fiddler,

Thanks for the toast! I am wondering why the views of this thread is stuck at 48. I know we were over 10,000 views. We must have broke something at Audiogon, or they got tired of keeping track. Be careful guys, when we hit 1,000 posts smoke may start pouring out of our computers.