Well, Prem's 2A3 SET amplifier is on its way to him. The one with the Dave Slagle / Intact Audio transformers. These are custom wound audio transformers using a 80% nickel alloy core. Hope he enjoys listening to music through it.
I certainly did. After building it, and testing it, I listened to a variety of music through it, and did my own comparisons. The most obvious one was with a stock 2A3 amp, using local Delta manufactured audio transformers, which use a CRGO (cold rolled grain oriented) steel core. The circuits are identical.
There are differences, subjectively major ones. Through Prem's amp, music flows with greater abandon. Tonal colours are fuller, and richer. Instruments are better fleshed out, and vocals have more presence. There's a wealth of detail, but its wedded to the music. So, it doesn't stand out, just makes its presence felt as part of the music. Everything is a cohesive whole. I am describing the sound of a single-ended tube amp - in Prem's amp there is more there!
In Prem's setup there is a further simplification. No preamp is used - just a single input passive autoformer volume control, sourced from Dave Slagle again. This gives more transparency to the sound. There is no loss in drive at all; dynamics in music come through clearly and cleanly. Though, Prem's situation is unique. His turntable has a built in phono preamp, with variable output, upto 9V. So, he'll have no problem with gain at all.
Why does transformer core material matter at all? It's the core that forms the magnetic path for audio signals to pass from one winding to the next. Nickel core materials have higher permeability (the ability to magnetize), and lower core losses. So, more of the signal passes through. More low level information goes through, providing a more complete music waveform, and adding that richness to sound.
So, here are some pictures of the riches that Prem got, in transformers, and after they were installed. The small box contains the autoformer volume control, with its complex wiring.
Viren
