Preamp Deal of the Century

Hello Gang. RE: The use of 6F6g as regulators. Fiddler and Lisbon,I can certainly understand your apprehension and anxiety here.Consulting tube substitution guides and doing net searches will give you imformation that is simply not applicable here regarding our application in the supratek. Firstly...The 5881, and the 6L6 tubes employed in the supratek are are actually output tubes[beam tetrodes]. They were never really designed for use as a regulator tube.These tubes were originally designed for amplification duty only, re: output stages for amplifiers,radios and TV's. Just like many other common output tube types such as the KT-66,el-34,kt-88,6550,kt-90 etc to name a few . When one referrs to any tube subsitution guide or manual,the manual will give you direct substitions for that one particular tube type that would have similiar voltage curves[among other parameters] for the tube being substitued."IE" for voltage,amperage,bias and output power[wattage]etc. These paramaters are really not applicable here as they are not employed as an output stage tube in the supratek.The duty of these tubes in the supratek were specifically designed and employed as regulator tubes, whereby their application in the supratek are specifically used to smooth the ripple of the rectifier, "not" as an output tube per say. A tube substitution guide will tell you absolutely nothing when referred to in this context. Consulting any tube substitution manual will only tell you what tube can be substituted as an output tube . Example: A typical substition for a 6L6 found in any given manual, would be a 5881,7581,5932,Kt-66,6L6G,6L6ga,6L6gb,6L6gc etc.In actual fact, there are many relatively common power tubes[power tetrodes,power pentodes,beam power tubes] that can be substituted for the 5881/6L6 in the supratek. The 6F6 is a small power pentode and is perfectly safe and suitable for use as regulation duty in the supratek. I personally use the western electric 350b in my supratek only because I've had a pair in my stash for many years.I have also tried nos 5881's, all of the 6L6 itterations, as well as 7581's,5932's,kt-66's,6v6g's and of the 6f6g's. The legendary WE 350b beamer is the "King of the Castle" for regulation duty in my rig and in my humble opinion, the 6F6g [round plate] is the next best thing to it.If I didn't have a pair of 350b's, than the 6f6g would be "THE" tube of choice. I ran a pair of these in my syrah for more than a month. Try em, they are terrific.

I've learnt a lot from this thread, and certainly appreciate the sharing of info re the 6F6. For what it's worth, I did ask Mick about this about a week ago. He simply said "No;" he would not recommend it. He did not elaborate. Mick's take is of course valuable, but it is not necessarily a trump card, and Ecclectique your experiences with it are a great contribution to this thread. Thank you.

Re the Ken-Rad VT-231 black glass, they made an immediate and noticeable improvement in my system (tube CDP, Chardonnay, SS amp, Hales speakers: a greater tube "bloom" and deeper bass; no unreasonable microphonics). Clearly, system dependency cannot be ignored.

Thank you for your kind words Rabelais. I can certainly appreciate Mick's take on using different tubes. For what it's worth,I did asked Mick that very same question the week I received my Syrah. I had a few pairs of the WE 350b,s in my stash and was curious about rolling out the stock 6L6's. His answer was the same. I also asked him the same question regarding swapping out the stock 6sn7s for euro eqivalents like the Mullards,his answer was no to swapping them as well. I have used the we 350b as my regulator choice[ an exact equivalent by the way] for well over a year now and they will "stay" in my Syrah until the day I sell it. My posts regarding tube choices in this thread are simply my observations with respect to how they sound in my system.They are not recommendations per say. Your mileage may vary of course.

Thank you Eccletique for sharing some more tecnhnical information with us. I do feel safer now and I will try a pair 6F6G in my Chardonnay.

For those who already tried the 6F6G I would like to know a bit more as for sound. How do they compare with (1) stock KT-66 and (2) Tung-Sol 5881 as for:

tight bass (less boomy)
sweet highs (less sibilant)
emotional presentation (instead of clinical)
air

Thanks once more.

Hi,

With some reluctance I make this post to ask a question about the sound of a Supratek Cortese preamp. I know by asking this question I will be breaking the current flow of the conversation almost like a complete stranger coming late to a party in which he doesn't know anyone except the plant in the corner.

I have read about half of the postings here which span about 300 pages when printed out. I had planned to read it all before asking my question, but I guess I couldn't wait.

My questions is this: I am having a little trouble getting a handle on the sound of the Cortese, the preamp I am most interested in buying. Can anyone help? What does it sound like?

I am looking for a romantic sounding preamp, but not one that is overly lush or one that obscures too much detail and transparency.

The Conrad-Johnson Premier 17LS, EAR 864, and Sunfire Classic Vacuum Tube Preamp fall to this more romantic camp. Not too many preamps these days do.

Does the Cortese have any warmth, or would you say it's a very neutral, clear, present, dynamic, and natural sounding preamp? Would you describe it as having yin or yang energy, or do these terms even apply?

The C-J unit mentioned above has some warmth, sweetness, nice harmonic layering, ease, decent texturing, and a suaveness to it that makes that preamp easy to listen to. I would not call it overly dynamic and it does not have gobs of immediacy.

Would you say the Cortese is closer in sound to, let's say, the First Sound Presence Deluxe or to either the EAR 864 or Conrad-Johnson?

Todd Warnke at SoundStage! described the First Sound this way:

"Utmost clarity, jaw-cracking dynamics, intense and deep bass, and newfound layers of nuance," but a "complete lack of mechanical sound" too; "of all the sonic skills, detail retrieval was the most astounding"; "the preamp for those who want a passive but need the facilities of an active."

Does any of this apply to the Cortese? Is the Cortese ruthlessly revealing?

I know I am asking far too many questions, and I do apologize for that.

Waiting 6 months or more will not be a problem for me, even if I have to wait a year. What troubles me, though, is the possibility that after I receive the Cortese I either won't like the way it sounds or it will be too noisy for my tastes.

Thanks in advance for your help.

Artar1