Thursday, June 10, 2010

Building Amp - the battle plan

It is always best to plan ahead. No exception in amp building project.

The first thing I look into is the chassis. Chassis can make or break the project.

My choice is, 17in (432mm) wide, 12in (305mm) deep & 4in (100mm) height.
17 inch wide is the commonly accepted "full width" of any Audio/Video home equipment.
12 inches deep is the size I experienced as "just big enough" physically yet not too clumsy visually.
4 inches is the height that is "just-tall-enough" to mount most audio components such as power capacitors & chokes; This I learn through years of experience.

I like to keep the power transformers to a corner of their own to keep potential electromagnetism headache which it is associated with. In this particular build, the power trans I am using is a bare, its ugly & exposed, no covers or bells, so I for safety & aesthetic reasons, will keep them out of sight by mounting it inside the chassis. is ugly...
Took some time to create a 3D model of my intended chassis, its only partly completed but these which are drawn will be final. Eagle eye readers will notice I have a larger bottom board for mounting the transformer. This is important, transformer is a chunk of metal & it's really heavy... So a strong base is important. Too lazy to put in all the components in the 3D model. I draw a 2D layout instead.

Thursday, June 3, 2010

Building Valve Amplifiers

This is a series of article on the actual work & design consideration when I build valve amplifier.

Tube amplifier is an electronic equipment, so it is natural to neglect the need for the mechanical works involved... you can't get anywhere without planing the mechanical layout of a valve amplifier.

The mechanical works involved are mostly in the chassis.

How about aesthetic appeal?
This is too subjective a subject to discuss, in my humble opinion, If the chassis layout is superb, it will always look good. but one thing for sure, a poor layout always looks ugly.

Chassis Layout
There is enough stuff to write a book on this topic alone but I won't torture the readers with my lousy writing skill... Instead, a summarised criteria.
  • Rigid Chassis to take the weight of the irons & owner abuse.
  • Electromagnetic induction, Components must be positioned/spaced correctly in relative to each other to minimise electromagnetic induction, mostly concern the placement of transformer, chokes & valves.
  • The connecting wires between each components should be as short as possible to minimise chances of hum induce into the signal & excessive voltage drop.
  • All components must be mounted securely & rigidly as all components are microphonic to some degree, hence any vibration will affect the final acoustical result.
  • Provide sufficient ventilation to minimise heat build up.