You may have heard that we restore hand wired tube amps that are found in various Wurlitzer Electronic Pianos. This article is intended to answer some questions on what we do, what our process is and what you can expect.

Whenever you think about modifying a vintage electronic piano, you should think about two things. Is the mod reversible? And, if not, am I actually improving the keyboard?

A Wurlitzer electronic piano has been around for decades. Clearly, Wurlitzer did something right when they manufactured them, because even after all these years they are still desirable. It is important to avoid performing impulsive mods that will irreversibly change the keyboard. Think it through. Consider whether the mod enhances the function of the keyboard. Consider whether there is a less invasive way to reach the same goal.

Before we start, a disclaimer: hum should be addressed on a case-by-case basis, because every vintage amp is special and degrades in its own way. What cures one amp may not work for another. That said, reading this guide should give you a good starting point on how to address your own hum problems. This guide is pretty basic and going to assume that the only piece of test equipment that you have is a multimeter.

Wurlitzer tube amps are in fact very similar to guitar amps.

But before we talk about that, let’s back up a little. The Wurlitzer itself is very analogous to an electric guitar: the heart of both instruments is a pickup that converts vibration into an electrical signal that is ultimately sent to an amplifier. In a guitar, the amplifier is almost always external, but a Wurlitzer’s amplifier is tucked into the body of the instrument.

An effects loop opens up many, many tonal possibilities in your Wurlitzer. Some of the earlier Wurlitzers have a reputation as a one-trick pony. The 112, for instance. How many people on forums have opined that it’s good for that one Ray Charles sound, and that’s it? Three people? Four? That’s not the point. The point is that, once you give the 112 an fx loop, it now has an unlimited amount of sounds.

But what sounds, specifically, should you plug into your Wurlitzer’s effects loop?

A widowmaker amplifier has no power transformer or fuse. Instead, the two-prong, non-polar power cord is wired directly to the rectifier tube. It is very unsafe, because under even minor failure conditions (such as a shorted capacitor or even - in some models - plugging the power cord in backwards), the mains voltage might end up on the guitar strings and the user will be shocked/electrocuted.

On the plus(?) side, power transformers are expensive so widowmaker amps could be manufactured and sold at a lower price. This ensured that every aspiring guitarist in America could own a low-fi death trap if that’s what they really wanted.