Tubes Asylum Questions about tubes and gear that glows. FAQ

---

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

---

[ Alert Moderator ] [ Edit ] [ Delete ]

---

Practical upper limit of grid-stopper resistance on pentode amps? - Can large stopper 'soften' clipping?

Posted by freddyi on November 25, 2000 at 21:59:51

Dear group

suppose you have a pentode amp being driven by a split-load phase-inverter and you know at some point near Ec=0 that the output tubes will stsart pulling grid current, which if asymmetrical can cause the splti-load to amplify in the plate section , what value of grid stopper would you choose when you are up against several constraints:

(1) finite input capacitance which will introduce a HF rolloff if the stopper is 'too large'
(2) desire to 'soften' the clipping

My Eico HF-87 which employs a 6SN7 as a cathode-couple inverter does some nasty clipping near the 30 watt mark.

Grid stoppers on output tubes are generally 1K - how far upward have you taken this without sonic degradation in hi-fi or musical instrument tube amps?

thanks

Freddy

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

Schiit Audio

---

[ 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 ]

---