Anybody here has information about the 7193 /2c22 tubes family versus 6sn7gt family ? i have read some few but very clear statements about the superiority of the 7193 family.... in the past i had experience truly superior sound in upgrading to the 6 sn7 family from 12au7 for example (bugle boy and amperex )....Now i am curious about 7193 tubes.... Perhaps difficult to buy but cheap tubes..., i waited for 19 national unions tubes now .... the adapter is "en route" .... for one 6ns7 its necessary to put 2 tubes 7193 in the adapter.....high frequency tubes in world war II used in tanks communication....i will report my impression .
some observation and opinions i collected on the web about the 7193 :
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.
We won't be able to get them anyway. 
