The Search for a Transformer

The first thing I will be changing on the amp is the output transformer. This is the most expensive and substantial modification you can perform on a Valve Jr. After doing some research, there are many different output transformers (OT) that other people have used in their Valve Jr's. All that I have seen are Hammond brand OTs, and most are in the 125 series, show here. The Valve Jr is a 5 watt amp from the factory, so many choose to increase the Power output. Most have gone with the 125-DSE (10-watt) or 125-ESE (15-watt). Some have used the 1628SEA OT, shown here, which is a more expensive 30-watt OT. I can't seem to find many of any of these available for sale online, but in the mean time I am still reading about the advantages of each, and deciding on which one to purchase for my amp needs.

Schematic of a stock Valve Jr

This is what the internals of my Valve Jr look like now. The transformer is the part in the upper right corner of the schematic -- the part with the two squiggly lines and the two parallel lines in between them.