Kenrad is the best and national union second.... for 7193 tubes..... its simple, all is better across the range.. soundstage is better definite and all frequencies are more vivid... and that is the same on my speakers or on my hifiman he 400...if you read on the internet you will discover many favorable reviews of people who goes from 6sn7 good tubes toward 7193 better tubes...I had not discovered one negative review on the net,( hence i bought several tubes) here is a sample of reviews from different sources:
«National Union vs RCA vs Ken-Rad 7193 tubes.
Since I have converted my Chenin to 7193s, I have been evaluating the different brands of 7193s available (in addition to enjoying the great sound!). Let me say that they are all excellent tubes, but there are some subtle differences between them, both in sound and in construction. All have black, relatively flat plates, with small boxes in the center.
National Union: The NUs have the smallest bottle of the three 7193s, and the getter is not visible from the exterior of the tubes. They have a round top and bottom mica. These were the first 7193s I ever heard, and they sound very good indeed. These are silky smooth, with a rich midrange. They are a little rolled off on the extremes compared to the other two tubes, but it is a not a huge difference.
RCA: The RCAs have a larger bottle than the NUs, with a bottom getter and round top and bottom mica. They have more extended highs and lows than the NUs, with fuller bass and a little more detail on top. Not quite as smooth as the NUs, and not quite as warm in the midrange.
Ken-Rad: The biggest bottle of the three, slightly larger than the RCA, with bottom getter and non-round top and bottom mica (looks like a round mica with a section cut out in each quadrant). The best bass of the three - the impact of kick drums is sensational, and bass lines can be felt and heard in great detail. The highs are nice and airy, with very good detail, and the midrange is very sweet as well.
So overall, in my opinion, I would rank the 7193s as follows:
Ken-Rad: best overall - it has everything
National Union: smoothest and warmest sounding, but a little less top and bottom than the others
RCA: Similar to the Ken-Rad, but not quite as smooth in the highs.»
«The ultimate 6SN7 for me wasn't a 6SN7 at all. I replaced the 6SN7s in my Supratek Chenin preamp with CCS loaded 2C22 single triodes, biased to 3.4V using (4) Cree SiC Schottky Diodes on the cathode. To say they were MUCH MUCH better is an understatement. The 2C22 is roughly equivalent to 1/2 of a 6SN7, but the anode and grid are taken out via top caps.
Bass is clearer and more defined, mids are to die for, treble is sparkling without being grating. Using the CCS I am able to replace both sections of the 6SN7 with a single 2C22 and still have plenty of gain.
What is magic is the 2C22/7193, but that's 6.6k Rp and two top caps. Mind, that's where the magic is if that's what you want and you have a high input impedence on your amp. I thank my lucky stars i came across that tube.»
«I converted my 6SN7 preamp to 2C22 and there's no going back - better high, lows, spatial rendition, tone, etc. I run them at 14.6mA, 175V, CCS on plate, Cree SiC Shottky diodes for bias,
I couldn't believe my ears when I heard the 2C22 a few years ago - it made all 6SN7s sound boring».
«I know the 2C22 stage sounds excellent - almost DHT.»
«In my experience, the 7193 is sonically superior to any 6sn7 regardless of manufacture... nos or otherwise.
Comparatively speaking: the 7193's sonic signature is a combination of the best of the 6sn7 family.
Combine the bass power and depth of the Kenrad black, the 3 dimentional midrange of the old tungsol round plate,the bloom of the Rca grey glass with the treble extention of the best nos sylvania's.
Although a little more difficult to find these days, they generally sell for a fraction of the cost of the nos 6sn7's.»
