Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders.

---

[ Follow Ups ] Thread: [ Display  All  Email ] [ Tube DIY Asylum ]

---

[ Alert Moderator ]

---

here we go again...

Posted by Allen Wright (M) on January 4, 2005 at 04:24:51

In Reply to: open wide posted by Joelt on January 3, 2005 at 18:14:37:

You make a snide response to the "nuance" word and you expect a "good" answer?

>my comments were also backed by my listening experiences which have proven to me that a cathode follower with sufficient voltage, bias, and load resistance is completely transparent<

OK, that's your experience - that's a valid experience,but that others have a different experience is NOT nonsense - OK?

>you might like to comment on the apparent disagreement you have with the designers of ultra-sensitive ultra-wideband test equipment. If "plain jane" cathode followers were bad for audio, they would surely be awful as the input to an oscilloscope, no?<

No!

First - what EXACT model of "ultra-sensitive ultra-wideband" scope uses a Miss Piggy CF at the input? And do subsequent models also - or do they enhance the CF with a CCS and/or bootstrap?

Second - a scope needs to have good flat bandwidth and good (but adjustable) sensitivity, as to make accurate measurements with it one always tries to fill the screen - as with any analog scaled instrumement. The human ear has a huge dynamic range - at least 100dB, which is VASTLY more than the visible resolution of any scope CRT. My HP 182C allows me (with x2 glasses) to just see a 0.1 div p-p sine wave (but have NO chance of accuarely measuring it) which is only 38dB with respect to the full screen of 8 divisions - and that's on it's large screen - a small screen scope (like a TEK465) will have an even lower visible "dynamic range"!

So extended dynamic range and very low distortion is NOT a vital requirement for scope electronics - as an inteligent user will always use the input atten to have the internal signal as close to full scale as possible.

The tube amp designers bible, Valley & Wallmann's "Vacuum Tube Amplifiers" goes into CF's in quite some detail, and focusses on how to make them linear WHEN DRIVING CURRENT into a load - and this is where I first read about the advantages of CCS loading and bootstrapping them. Then knowing what to look for - I found CCS loads on CF's all over the good HP & TEK tube scopes I looked at.

Good enough now?

Allen

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

Sonic Craft

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

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

---