Supratek Tubes and Tube Swappin' for Everybody

I just measured my system with Tact RCS. This is in-room response and no my room is not an anocheic chamber. Previous rectifier was a gz33. The current rectifier is a bendix 6106. Output below 300hz is reduced by a few db. There is a hump in response from 3-5khz by at least 2-3db. From about 8khz on up it just climbs a mountain. I am up at least 5-6db at 20khz. I can't consciously hear anything about 17khz but somehow I can percieve a 20khz test tone.

Interesting Jazzdude, I also run the Sylvania 6SN7GT 1952 "bass kings" in my Chardonnay and I have noticed no drop in bass performance with the 6106s. Actually, to the contrary. The bass quantity hasn't increased with the 6106s over the 5AR4/GZ34s, but the bass quality has improved. The bass seems tighter and more focused. Actually, everything is more focused. There was always a very slight fuzz that I couldn't find, but with the 6106 the notes are very crisp and clean. No more fuzz.

When I first plugged the 6106s in months ago, I hated it. But with burn-in, it really transformed. Unlike the GZ33 & GZ37 which remained total dogs.

Mick gave me a GZ32 to try, but it pop and crackled from day one so I took it out immediately.

Jazzdude, a quick question. Have you compared the Tung Sol Round Plates to the '52 Sylvanias? If so, I would be really interested in your opinion of the two. I may try a pair of Tung Sols, but I am thrilled with the '52s.

Fiddler - I'll give the 6106 a week at 24/7 and see how it does. The actual articulation of the notes from start to finish is fine and this is the most important thing. There is no question that it is a very good rectifier, but at this point it hasn't destroyed the competition.

I have a dual-getter metal-base amperex bugle-boy gz34 that goes in after the 6106

The cabernet only uses a single triode out of the dual-triode 6SN7GT. The other triode used is the we101d. Which might explain a difference in bass output between my preamp and yours.

I might give the tungs-sol round-plates a place in the hot socket one day. But for now I am working on finding the best rectifier and regulator. I am trying some alternative regulator tubes including the 6f6g and we'll see how it goes. One thing I can already say based upon my experiences. That is that the higher plate dissipation of the regulator will increase the operating point on the rectifier causing the signal tubes to distort more. So for the cleanest and most natural sound and highest resolution the 6f6g is going to smoke the 7581, 5881, el-37, kt-66, el-34, 6l6gc etc. And I am not really concerned with freq response for my system although I will note it. What I am after is the best execution of the note from start to finish and including the harmonics. I want maximum resolution of the music and for the preamp to still perform without a hint of strain.

Hi Whoopadeedoo - I really don't want to argue about it so... I'll take your word for it, printing means nothing, the construction is the same, and they all sound the same and we'll leave it at that.

How many KR's have I owned? I don't remember exactly but I have owned many. As I am sure you know, the ratio of good "pre-amp" quality 6SN7's (low microphonics / quiet) to not-so-good is relatively slim. Depending on the tube manufacturer/type/vintage, its often very difficult to find a nice vintage 6SN7 which is adequate for use in a line stage...Particularly the Supratek which is quite sensitive to tube quality. Having said that, for several years, I purchased numerous KR Black Glass tubes from various sources and maybe, at best, 1 in 10 tubes were quiet enough (no squeeks, no microphonics, no crackle) to even be considered as usable. Of the KR tubes I purchased during that time span, I kept about 20 (10 pair).

Also during that time, I was cycling through various amplifiers, cables and digital components. I discovered that I could "tune" my system with the various "flavors" of the KR black glass tubes. Initiallly I didn't know they were sonically different but after swaping back and forth tubes and matching with various components, I soon realized that they were all similar but very different. Certain marked Ken Rads were totally unusable with certain component combinations while other KR's were seemingly perfect.

Using the KR's in a line stage preamp produces a much different effect than in an amplifier. So for those people who use these tubes in amps and hope to obtain various sonic results, I don't know what to say because I would expect the results to be much more subtle and possibly less noticable in that application. It is when the tubes are used in a line stage - particularly the Supratek - that the difference in sound is obvious.

The 6SN7GT marked Ken Rads are noticably dark, and rolled off. The VT231 marked tubes are the most even/neutral of the bunch, the NAVY tubes are far more extended in the highs than the other types...but still maintain the KR signature.

Well.. your descriptions of the other tubes when used in a Supratek are weird, particularly the CV181 description. I know that CV181's do not work in Chardonnay and Syrah preamps (for whatever reason).

The "midrange" on a 350B is more-or-less quite neutral. In fact, the 350B is oddly one of the least "involving" or romantic sounding tubes available when used as a regulator in the Supratek. Where it stands out and what makes it the best, is what seems to be the most brute force and blatant accuracy of all regulator tubes. Which may be why they do not float your boat -as you put it. You state you like what they did to the midrange and that makes me a bit curious as to what else is going on in your system that you'd identify the 350B as having a particular midrange quality (vs. everything else) in your system that was good.

The 350B really comes into its own when used with a Bendix 6106.

Bwhite,

You bring up a good point that new Supratek owners should take notice of. The Suprateks are ridiculously sensitive to microphony (not a good thing). I really don't know a linestage preamp that is more sensitive. You essentially need phono-grade quality tubes for line-grade application. If I had a gripe about the Supratek design, this would be it. And for this reason I hate selling 6SN7 to Supratek owners.

I agree the CV181 does not work in my preamp. I think you may have misread what I posted. It's a tube that I do not recommend (for the Supratek or for nearly all other 6SN7 applications).

I have Ken Rads with identical base prints - down to the alphanumeric date codes - but clearly different builds (tin versus copper grid posts, different mica varients, etc.). There might be audible differences as you say (I still can't hear marginal differences myself, much less "dramatic" ones). Whether you or I believe there are sonic differences or not, base print is a virtually useless criteria.

I also find the 350B midrange very neutral, which is what I love about this tube. In comparision, the EL34 and EL37 midrange is a touch bloomy and warm. The 350B sounds fast and accurate. It does not, however, sound powerful IME. There is a leaness to the presentation that (reminds me of KT66 tubes) compared to EL37 and 6L6 tubes. The 6F6 also has possesses this leaness, and it too is very fast (faster even) and "accurate" like the 350B.