Supratek Preamp. and 6SN7's impressions


I have had a Chardonnay for over a year now and have enjoyed it immensely. I used to drive a Plinius P8 amplifier with it, which was an overkill (200 w/c) for my Reference 3a MM Decapo's. It was a fairly musical combination, though.

Recently I sold the Plinius and bought a First Watt F4 stereo amplifier. It is a class A, 25 w/c buffer type amplifier,(designed and built by Nelson Pass)which means it does not amplify voltage, it is a current amp. You need to have a high gain preamp to drive it, and the Supratek is perfect in that respect.

This also means that the characteristics of the preamplifier are passed thru the amplifier without any gain or editing -or at least minimal editing-. So, I thought this would be a perfect combination to study the effects of the 6SN7 tubes in the Chardonnay.

I have used the following tubes: EH, NOS Tungsols, RCA's, Sylvania's. Verdict: The EH came on top. More natural sounding in both tone, pace and in soundstaging. More vocal and instrumental body. The others seem to have more energy in the highs -brighter- and do not throw a soundstage as natural and effortless as the EH's do.

Also the same conclusion was obtained with the 6106 rectifier that some raved about in this forum.. It does not really function as well as a GZ34 or GZ37. It gives the impression of more dynamics but at the end makes the preamp sound more "hifi". Soundstage is also constrained compared to the GZ34's. Not recommended if you want your Supratek to work as intended. Mick had informed in an email that the 6106 does strange things to the circuit's operating voltages.

So, what would this seem to indicate, in my opinion, is that Mick apparently voiced his preamps. around this tube (EH and GZ34, etc.)to make it as musical as he intended. That works very well.

Sources: Shigaraki CD transport and DA with 47 Labs Dumpty power supply. Supratek Chardonnay preamp. Interconnects and speaker cables: Jena Labs. Power Conditioning and power cables: Jena Labs
manolo
Which RCA, Sylvania, and Tung-Sol 6SN7s did you use? Take RCA as an example. Did you use clear glass 6SN7GTB or smoke glass 6SN7GT or VT-231?
I recently went through similar 6SN7 rolling comparing early 1951 Sylvania WGT, RCA Gray Glass GT, Raytheon GT, Russian 1578/6N8S, and recent production EH. EH was only surpassed by Russian and Raytheon, and not by much. EH is very good indeed.
RCA with clear glass 6SN7GTB from 1956 sold to me by Tube World. A small bottle with black base. Sounds smooth. I know it is not the best RCA there is.

The Sylvanias were also small bottle, chrome top cryod,1960's. Sold them.

The Tungsols where lent by a friend they were NOS, do not have them.

But my theory or point is that we tweakers do not realize sometimes the voicing process in the design of electronics. The better designers listen to their products and optimize them for the parts and or tubes they use.

Sometimes we go ahead and start swapping caps, tubes, resistors... and because it sounds different we think it is better. Sometimes that happens but not always.
I stopped tube rolling when I replaced my Syrah with the Cortese. You hit it right on the head. Mick voices the preamps very well for the stock tubes he puts in them. I would much rather enjoy the music than constantly switch tubes. That being said, I am going to try the adaptor that Ait described on the Supratek thread. When completed, I will be able to go from using 6sn7's to using 7193's which many feel sound better than any of the 6sn7's and have no micro phonics to them.
I have a Sauvignon with upgraded V-caps. I agree with you the GZ34 double D getter was the best IMS.

The 6sn7 tubes are a different story. I like the NOS tubes better. The best all around tube in my set-up is the 52 Sylvania (Bad Boys)it has a very nice midrange,extended smooth highs, and deep tight bass.

The regulators I use are either GEC KT-66 or Sylvania 6F6g they are both nice. Sylvania has more bass and the KT-66 are little more extended and airier.