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Technical - last updated 07/09/06 20:30:08


LTSpice and vacuum tube models
Amplifier classes
MOSFET Regulator
Baxandall 2
Preamp Overload
Speaker impedance
Speaker cabinets
Avo CT-160
Avo CT-160 in use
Bias FAQ
Blues Deluxe
Scope biasing
Tube numbering
Valve Matching

This page links to some technical bits and pieces that have been put on these pages, and links to other items of technical importance. Currently, the choices are:

bluebox.gif (813 bytes) Pspice stuff - a whole new page on it!
bluebox.gif (813 bytes) LTSpice/SwitcherCAD III - now gets it's own page.

Power amplifiers
bluebox.gif (813 bytes) Amplifier classes - What is A, AB1, AB2 etc.??  Check here and find out...

Power supplies
bluebox.gif (813 bytes) MOSFET regulator - can these be used for valve amps?  Here's a design that has stood the test of time since the late '80s.  A little over the top maybe, however it delivers high performance and is cheap to make.
bluebox.gif (813 bytes) Power Supply Designer - a software package to help you design power supplies, with choices of solid state or vacuum tube rectifiers.
bluebox.gif (813 bytes) Steve Bench has set up a great series of pages on his web site for Vacuum Tube based regulated power supplies.  Very comprehensive, and very well written.  Added 20/3/2000.

bluebox.gif (813 bytes) Baxandall tone stack - how does the passive Baxandall tone stack compare with the Bass Mid Treble arrangement used on Fender and many other amplifiers.
bluebox.gif (813 bytes) Baxandall - an excellent technical explanation by Mark Garvin.
bluebox.gif (813 bytes) Coupling caps - a nice little Excel 5.0 spreadsheet that works out what those coupling caps are doing to your frequency response [33k].
bluebox.gif (813 bytes) One-knob wide range tone control - Roy Mallory developed this for a reverb unit, but it would be easy to use this for other FX units too.  (Added 26/11/2001).
bluebox.gif (813 bytes) Preamp overload - notice a delay before notes come out, or notes disappear? You may be overloading the preamp stage.
bluebox.gif (813 bytes) Reverb - Roy Mallory walks you through an optimal design for driving a reverb tank from op-amps.  (Added 1/3/99).

bluebox.gif (813 bytes) Impedance of speakers - Tired of working out what the individual power ratings etc.?  Grab an Excel 5 spreadsheet that will do it for you!!
bluebox.gif (813 bytes) Speaker cabinets - Michael Sabolish gives some great advice on how speaker cabinets can be constructed for guitar or bass.  (Added 21/12/99).
bluebox.gif (813 bytes) Speaker terminology - ever wondered what an "aggresive speaker" is??  Check out Weber VST's page on terminology and find out!

Test / Modification / Repair
bluebox.gif (813 bytes) Avo Valve Testers
Avo CT-160 - The finest valve tester in the world.   Need I say more?  Now includes a page on how to use the CT-160.
Other models - some pictures of the other portable and desktop models are now available on this site.
bluebox.gif (813 bytes) Biasing - How to bias your amplifier by Lord Valve.  LV deals with the cathode resistor and transformer shunt bias methods, and some handy tables are included to put you in the right ball park on static bias currents.  (Updated 25/8/2001).
bluebox.gif (813 bytes) Blues Deluxe mod - Need more drive on your Blues Deluxe?  Andy Marshman describes a neat way of utilising an unused triode on these amps....
bluebox.gif (813 bytes) Oscilloscope Bias Method - An excellent posting on alt.guitar.amps by Tom Crocker (alias Tom Hiwatt).
bluebox.gif (813 bytes) Speaker load - A great article by Randall Aiken on the design for a passive speaker load which simulates the impedance and resonances of a real speaker.

bluebox.gif (813 bytes) Transformer laminations - Mike LaFevre of Magnaquest gives some great insight into the different types of laminations and the reasons for choosing them.

Vacuum Tubes
bluebox.gif (813 bytes) Microphonics - A short explanation with follow up from Kevin Deal of Upscale Audio.
bluebox.gif (813 bytes) Nuvistors - What are they?
bluebox.gif (813 bytes) Vacuum tube numbering schemes - Find out what those codes actually mean.
bluebox.gif (813 bytes) Valve matching - find out how it's done!