6sn7 vs 6cg7 in cornet2

rotcoddam · « **on:** 28 Mar 2005, 05:25 am »

After running the 6cg7 for a few weeks and rolling several types I settled on a 1951 RCA blackplate d getter. Very nice upgrade from the 12au7, and this tube easily beat out 6 others, but I'm never one to be satisfied so I built a tube adapter for the 6sn7. (pain in the arse) Anyway, so far the first sn7 I tried easily beat out the rca. Much fuller, great bass, more realistic strings, voices and cymbols, better highs, and way smooth. Cornet is singing now. Glad I didn't stop at the cg7. Next I'll permanantly install the octal socket in the chassis. Happy days.

SHIF · « **Reply #1 on:** 28 Mar 2005, 07:07 pm »

I’m a big fan of the 6CG7 tube and use them in my Cary preamp and also in my new DIY headphone amp (an OTL design from Headwize.com). I understand it to be electronically the same as the 6SN7 but in a 9-pin envelope. I’m expecting delivery this week of some Russian 6N1P tubes to try in my headamp, replacing the 6CG7. Have you considered this option?

How well is the power supply in your Cornet handling the increased heater current requirement of the 6CG7? What transformer are you using?

I like the idea of a socket adapter to test octal tubes in the Cornet’s 9-pin sockets.

-S

coffeedj · « **Reply #2 on:** 29 Mar 2005, 02:59 am »

I've noticed a huge difference in sound depending on which 'u7 is used. I wonder if there the octals are superior, or is it just tube dependent.

I'm currently using a bugleboy AU7 which really signs in comparison to the Philips, RCA, GE, and Sylvania NOS (all 1950's).

rotcoddam · « **Reply #3 on:** 29 Mar 2005, 01:48 pm »

Although I really like the 6cg7, (I use them in my Heathkit w5-m's), The sn7 really was the clear winner here. It could just be a matter of tube selection. (Sylvania 6sn7wgt red base). I have 9 other tubes to try, Sylvanias , RCA's, Raytheon's, GE, Tungsol and others, so I'll post later on these.
I built the adapter with the base of a cg7 broken off, wired to an octal socket. Then held together with Goop. This isn't easy as the tiny tube wires are stiff and two broke off at the glass. I was able to solder them back on finally. Couldn't believe it worked after all the hassle. Anybody have a better idea?

coffeedj · « **Reply #4 on:** 29 Mar 2005, 06:06 pm »

You can desolder the old wires out of the socket pins (from the adapter male 9 pin, and resolder new, heavy duty wires directly in with pigtails to connect to the octal female socket sitting right on top of the adapter 9 pin socket. I've done this technique several times and it works quite well-including useing it to create a power adapter coming into the coronet when I took the power off board and added DC heater voltage. Fill the void with expoxy and you are done.