What, if anything, do high transconductance triodes bring to the table?

High gm helps in the S/N dept. What makes the 6GK5 impressive is the combination of high gm with high μ, along with low plate resistance.

High gm can provide resistance to slew limiting induced by a loop NFB HF error correction signal.

Eli D.

6GK5 Data Sheet

High gain and high current at the same time ..., posted on May 9, 2017 at 21:12:07

Paul Joppa
Industry Professional

Posts: 7296
Location: Seattle, WA
Joined: April 23, 2001

Those are the advantages from an engineering perspective.

There are subtleties of course. To get high transconductance, the grid must be very close to the cathode. This means distortion and greater variability unless precision geometrical construction is used - which makes it expensive. High cost gives subjectively better sound of course ... :^)

Also, to prevent cathode material from depositing on the grid and causing grid current, it is often necessary to plate the grid wires with gold - also expensive.

High transconductance also reduces high-frequency noise. This is an advantage in VHF radio service, but may not translate into low noise at audio frequencies, where 1/f noise is often predominant. That's a whole 'nuther topic ...

RE: What, if anything, do high transconductance triodes bring to the table?, posted on May 9, 2017 at 22:02:58
Donald North Manufacturer Posts: 1296 Joined: February 8, 2001	They can be low noise as gain stages and followers. I use two 6C45Pi in parallel single ended for my MC step-up.

What Paul said... all I can add is Superior resolution, from the Audiophool perspective~nT, posted on May 10, 2017 at 00:54:32
Cleantimestream Audiophile Posts: 7551 Location: Kentucky Joined: June 30, 2005	~! The Mind has No Firewall~ U.S. Army War College.

They're total garbage..., posted on May 10, 2017 at 13:13:38
PakProtector Audiophile Posts: 12364 Joined: May 14, 2002	It has been clearly demonstrated that anything over 1.7034 mA/V has no dynamics, jump factor or transfer efficiency and is not suitable for audio. cheers, Douglas Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

Always learning something new on this forum., posted on May 10, 2017 at 13:42:59
sser2 Audiophile Posts: 2571 Location: Pittsburgh USA Joined: July 30, 2003	Had no idea that 45 and 2A3 are garbage...

ahhh..., posted on May 10, 2017 at 15:20:50
PakProtector Audiophile Posts: 12364 Joined: May 14, 2002	was only referring to signal tubes, having a mu over 68.1...:) For some reason, low mu triodes are excluded from that requirement( also proven many times conclusively on this forum ). cheers, Douglas Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

I see,, posted on May 10, 2017 at 16:33:23
sser2 Audiophile Posts: 2571 Location: Pittsburgh USA Joined: July 30, 2003	that makes sense.

Let it go, please., posted on May 10, 2017 at 17:53:24
91derlust Audiophile Posts: 1101 Joined: December 25, 2014	It's difficult enough with usual protagonists in action. I'm thankful for their absence and don't relish amateur satirists trying to stoke that fire. 91. "Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

Yes, please, posted on May 10, 2017 at 19:21:17
Triode_Kingdom Audiophile Posts: 10047 Location: Central Texas Joined: September 24, 2006	Douglas, you're one of the good guys, but this is asking for trouble. I've been truly enjoying the recent lack of acrimony. Even cleaned out my garage in preparation for cutting some new chassis... :)

LOL...Like Voldemort: "he whose name must not be spoken" (nt), posted on May 10, 2017 at 21:27:11
Steve O Audiophile Posts: 12374 Location: SE MI Joined: September 6, 2001

Tube DIY Asylum

What, if anything, do high transconductance triodes bring to the table?

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