Would you like your Fender Excelsior to have the sound of NOS 6V6 tubes at an unbelievably low price? Well, read on.
The Fender Excelsior has been around for a few years now. It’s a very affordable tube amp that’s currently finding interest in the modding community because it’s affordable, and frankly, because it needs a few mods to get the most out of it.
The Excelsior is an odd duck that runs the plate voltage pretty low and uses cathode biasing with a 470 ohm cathode resistor. Normally a couple of 6V6 tubes will use something around 250 ohms so this value is just odd. Plate voltage is limited by the use of a couple of “sag” resistors in the high voltage line. So how to proceed? Do you remove the sag resistors to raise the plate voltage or change the bias resistors to a more typical value? With a soldering iron a little knowledge and a few parts you can do wonders. But what if you have no idea on how to do mods, or are rightfully afraid of sticking your hands inside a box that contains potentially lethal voltages. Here’s one you can do without opening the amp.
Back in the day, Fender designed a stand-alone reverb tank that was essentially a single ended amplifier much like a Champ. The power tube they used was a 6K6GT tube. The 6K6 is almost identical to a 6V6 but requires a lower plate voltage and a different resistor value for cathode biasing. The specs for this tube call for a 400 ohm bias resistor for a pair of output tubes and about 320 vdc max for the plate supply. This makes it an almost perfect match for a stock Fender Excelsior. All you have to do is remove the small cage that covers the power tubes and change the power tubes. 100% safe if you know how to unplug the amp first.
I was able to get a pair of tubes for around $20 and pop them in. Imagine the sound of vintage RCA or GE tubes for that kind of money. I’ve been running this set up for about a month without any issues, nothing but warm, sweet, tone. Change the preamp to a 12AY7 or 6072 tube and you are starting to get some serious tweed tone.
Give it a try. The 6K6 tube is still available and very affordable. The tube also works in reissue Fender reverb tanks to tame the gain and smooth the reverb. It’s fun and affordable.