Why Use Standby

Questions and Answers

From mgarvi--(at)--anix.com Wed Oct 18 12:32:54 CDT 1995
From: mgarvi--(at)--anix.com (Mark Garvin)
Newsgroups: rec.audio.tubes
Subject: Another reason to use STANDBY switch
Date: 18 Oct 1995 12:33:07 -0400

I just posted this to a.g.amps but realized it may be relevant here
as well. Pardon the dual post.

=====================================================================

Cathode stripping occurs when current gets pulled thru the tube
before the tube is warmed up. Most techs know this.

But consider what else happens. Tubes that are not warmed up will
draw appreciably less current. This means that there will be very
little voltage drop across resistors in the power supply. And that
means that the full unloaded B+ voltage will be applied to the poor
low-rated electrolytics in your preamp section.

In other words, if the main B+ is 450v and your preamp supply is
320v, the preamp will usually have electro's rated at 350v or so.
If the tubes aren't warmed up when the standby is flipped, the
preamp will get a shot of 450v!

How about that for motivation?

Regards,
Mark Garvin

Index:

Amp Shipping	Dealer Cost Vs List Price	Death Switch	Diodes on Plates
Dont Use Stereo Speakers	Effects FAQ	Effects FAQ	Effects FAQ
Fix Reverb Ground Hum	Flea Market Checkout	Hammond Organ Buys	Hammond Tonewheel Organs
How Long Do Tubes Last	How Many Watts	Magnetics for Morons	Microphone Placement
NOS defined	Stage Placement	What Are Optoisolators	What are orange drops
What Dealers Pay	What is 6V6GTA	What is a Fetron	What is a Klystron
What is a Plexi	What is Bias	What is Blue Glow	What is Ground Lift
What is Kinkless Tetrode	What is Single Ended	What Is Tube Glow	What JBL Means
Which 4x12 Impedance	Who Made Delco Tubes	Who Makes Kendrick Spkrs	Why 16ohm Loads
Why AC on heaters	Why Blackface an Amp	Why Bleeder Resistors	Why Cap Value Spread
Why Care About Phase	Why Change SF Lead Dress	Why Microphonic Cords	Why Not Bias By Scope
Why Opto Trem	Why rectifier is separate	Why Select Highest Z Tap	Why Sprague Caps
Why Use Grid Stoppers	Why Use Standby