This slide illustrates master volume locations within an amplifier circuit. These are referred to as pre and post-phase inverter implementations.

 PDF Technical Information

First and formost this is where quality matters. The old-school transformer companies here in North America have supplied to musical instrument amplification for decades. I rountinely service gear that is fourty to sixty years old and there is nothing to suggest that they won't deliver tone for another fourty years. In fact, transformer failures of this quality are rare.

When suggesting replacement iron or upgrades to a customer, I will recommend based on sound engineering consistent with the customer's desires. Engineering of course is predicated on access to technical specifications. Should recommendations be based on marketing hype or by using detailed technical information and sound engineering practices? Most manufacturer's offer complete information about their transformer products.

Ultimately it's about my customer's ears and the ability to stand behind my work. Better to swap iron based on technology rather than marketing language that could easily be applied to wine tasting.

In future conversations we'll talk about the mystery and fallacy of transformer saturation and transformer construction.

An immaculate Silverface Vibro Champ was brought to me with no output and a burning smell. The power transformer got smoking hot in the few seconds before the fuse opens! I perfect example of a vintage amplifier worthy of a quality replacement transformer.

PDF Hammond 290AX Technical Evaluation

This is an output transferfromer evaluation that I performed for the good folks at Magic Parts. The test platform is a vintage Blackface Super Reverb. The owner of this amplifier agreed that the replacement sounds and performs like the original. Of course this is exactly what you want from a quality replacement transformer.

PDF KA_Ruby TF125 Evaluation