Tubes Asylum Questions about tubes and gear that glows. FAQ

---

[ Follow Ups ] Thread: [ Display  All  Email ] [ Tubes Asylum ]

---

[ Alert Moderator ] [ Edit ] [ Delete ]

---

Actually, I did not say that

67.85.67.224

Posted by j rodney on June 24, 2006 at 22:13:34

In Reply to: Re: Curious in what amp are you using the KT77's? posted by MIchael Samra on June 24, 2006 at 19:06:39:

I prefer the 350B to either tube. A year or two ago I did a bunch of tube rolling in in some 2 stage SE amps with a seperate feedback winding in the output transformer (pentode). I would rank my conclusions as 350B, XF1 EL34's, 6L6G's, 6L6GC, KT66, all the rest. It was actually pretty close overall, but they all sounded different. Hence I could someone prefering one in a particular setting. I did a similiar test in a two stage differential amplifier and several vintage designs. I would say that it depends. Some designs are limitted in filament supply, B+, ect, and you are limitted to the tubes you can use.

This issue gets more complicated as 6L6s and EL34s are entirely different types of tubes, one a beam tetrode, one a pentode. Their curves do look different, but I would be hard pressed to say one looks better (in tetrode/ pentode). I am sure one could find a sweet spot for either. Moreover, I remember the 6L6 curves looking a bit better than the GC's.

As for the 807's, well they were a crowd favorite in the late 1940's and 1950's. They were very cheap as the military used them in transmitters. Anyway, the 807 is awkward for audio use as it has a low screen voltage rating compared to the plate rating. But back in the day many considered it an excellent tube in triode. If you look at the triode curves you will see why. Also compare these to the 6L6GC. The tubes may be very similiar in some ways, but...

Of course all of this is mute as none of these curves are as nice as a 2A3, 71A or other power triodes. So if curves are your concern, it is time to cut the grid and get some real tubes ;>)

Seriously, there are a number of considerations, not the least of which is power required, and front end design. Back in the day, one could not drive a 2A3 or 300B to max output with a single triode driver stage, but today one can. Of course that may not matter if you need 30 or 40 watts...

Take care,

Rodney

This post is made possible by the generous support of people like you and our sponsors:

Parts Connexion

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---