Input impedance is a measure of how much resistance a tube amp’s input jack offers to the signal coming from a guitar or other instrument. It is measured in ohms, and a higher impedance means that the amp will load the instrument’s output less, which can result in a cleaner, louder sound.
The ideal input impedance for a tube amp will vary depending on the type of instrument being used and the amp’s output power. For electric guitars, a good starting point is an input impedance of 1M ohms. This will provide a good balance between output level and clarity. For bass guitars, a higher input impedance of 500K ohms or more is often preferred. This will help to prevent the amp from overloading and distorting the sound.
If you are using a passive pickup, such as a single-coil pickup, you may want to use an amp with a higher input impedance. This will help to prevent the amp from loading the pickup too much and losing output level. If you are using an active pickup, such as a humbucker pickup, you can use an amp with a lower input impedance. This will help to preserve the pickup’s output level and clarity.
It is important to note that input impedance is not the only factor that affects the sound of a tube amp. The amp’s output power, speaker configuration, and other settings will also play a role. However, input impedance is an important consideration, and choosing the right impedance can help to improve the sound of your amp.
Table of Input Impedance Recommendations
| Instrument | Ideal Input Impedance |
|---|---|
| Electric guitar | 1M ohms |
| Bass guitar | 500K ohms or more |
| Passive pickup | 1M ohms or more |
| Active pickup | 500K ohms or less |
If you are unsure what input impedance to use, it is always best to consult the manufacturer’s specifications. You can also ask a qualified technician for advice.
