Wurlitzer 120 / 700 Amplifier Rebuild Components
Wurlitzer 120 / 700 Amplifier Rebuild Components
This kit contains hand-selected replacements for components that commonly fail in Wurlitzer 120 and 700 tube amps. Installing the parts in this kit can help you achieve a more reliable, cleaner-sounding Wurlitzer.
The Basic kit includes:
All electrolytic capacitors
Power supply resistors
Selected input components
Coupling capacitors, additional resistors, and a bright cap can optionally be added. Use the drop-down menus to select the components that you would like included in your kit. Selecting “no” to all options will select the Basic kit components only.
Over time, components in vintage amps will degrade, resulting in noise and poor performance. This kit contains hand-selected replacements for components that commonly fail in Wurlitzer 120 and 700 amplifiers. Installing the parts in this kit can help you achieve a more reliable, cleaner-sounding Wurlitzer.
Choosing which components to replace and which components to keep depends on a number of factors, including the condition of the amplifier as well as the personal preference of its user. For this reason, we offer several kit options that will allow you to replace as many or as few components as your specific amp requires.
Features of this kit include:
High-quality components hand-picked for suitability in a point-to-point circuit
Components individually bagged and labeled
Can be installed in all Wurlitzer 120 and Wurlitzer 700 amplifiers
Warning: The Wurlitzer 120/700 amplifier contains high voltages that can persist even when the amplifier is turned off and unplugged. Safe and effective installation of the components in this kit requires some electronics experience. Incorrect installation of these components can result in damage to your amplifier or injury to yourself. If you are unsure how to install these components yourself, you can mail in your amp or drop it off at our Tuckahoe, NY location and we will install the components for you.
About the Basic Kit
The Basic kit includes all of the electrolytic capacitors, all power resistors, and a small selection of critical preamp components. This kit will improve the reliability and performance of your Wurlitzer with a minimum of replacement components. It includes:
All filter capacitors
The cathode bypass capacitor for V1 as well as the shared bypass capacitor for V2 & V3
One polypropylene coupling capacitor
Selected input resistors
Why replace these components?
Electrolytic capacitors deteriorate over time, which can cause hum, poor frequency response, or otherwise reduced performance. Note that although new electrolytics can improve the noise floor of your amplifier, they are not a magic bullet. There are many factors that can introduce hum into a vintage circuit. However, even if the electrolytics are not the primary cause of your Wurlitzer’s hum, it is always worthwhile to replace them for the overall health and longevity of your amplifier.
Power supply resistors perform under conditions of high heat and stress that, over time, can cause their values to drift. Deteriorated resistors can also introduce noise into circuits. We recommend replacing power supply resistors at the same time as the electrolytic capacitors.
The coupling capacitor and input resistors are intended for your amplifier’s input circuit. Although components at an amplifier’s input are no more likely to deteriorate than components elsewhere in the circuit, the input is very sensitive. Noise and poor frequency characteristics at the input will be amplifier by the rest of the circuit. For that reason, we prefer to replace input components in many amplifiers that we repair. We have included them in the Basic kit so that you will have that option as well.
About the Optional Add-On Kits
You can also select one or more optional add-on kits. For further details, check out our guide: What components should I replace in my vintage amp, and why?
All coupling capacitors. This option includes new polypropylene replacements for all remaining coupling capacitors. These capacitors are low-noise and excellent for audio applications. It also includes a replacement for C14, the capacitor in the Zobel network. Replace the coupling capacitors if they are shorted or otherwise nonfunctional, or if you feel that your Wurlitzer’s frequency response could be improved.
Bright capacitor. Early 120 schematics show a bright capacitor placed across the volume pot. This capacitor allows high frequencies to bypass the potentiometer, resulting in a brighter tone at low volumes. The bright cap was removed in later versions of the circuit. If you think that was a mistake, our bright cap option allows you to put one back in. Note that the original schematic shows a capacitor value of 500 pf. This is pretty intense for a bright cap, so we’ve also included two smaller values: 50 pf and 150 pf. The higher the value, the more frequencies bypass the potentiometer.
All resistors. This option includes a complete set of resistors for the Wurlitzer 120 amplifier. The small-wattage resistors in this kit are high-quality, low-noise metal film resistors. If your Wurlitzer happens to have one or more noisy or damaged preamp resistors, this kit will have you covered.