What does a preamp do and do I need one?
A preamp is a “pre amplifier” and, as the name suggests, it prepares the signal coming from a pickup or microphones for further amplification. There are a number of reasons to get a preamp:
- It can boost a low signal
- It can clean up a signal so that it sounds better coming through the amp
- It can adjust the signal (e.g. volume control or equalizer)
- It can blend multiple signals into one.
Answering the question of whether or not you need a preamp really comes down to the output of your pickup or microphone. When you plug your pickup or mic directly into the amp, how does it sound? Is the signal loud enough? Is it balanced? Is it smooth? If so, you probably don’t need a preamp.
A pickup that’s plugged directly into an amplifier is a “passive” pickup. A pickup with a preamp, on the other hand, is an “active” pickup. Certain pickups (like our Pure Pickup) are advertised as passive systems, meaning that they’re designed to sound good even without a preamp. The advantage of a passive pickup is that it’s low maintenance and a good passive pickup should produce warm, full, and round tone. Active pickups are usually louder and brighter and the preamp allows you to shape the sound of the pickup in a number of ways: volume, bass, mid, treble, gain, phase, etc. Generally, the more expensive the preamp, the more control it gives you.
Of course, other than controlling the output of your pickup, preamps can also improve their sound. If your pickup output is too low, the sound is thin, the signal is unbalanced, the signal is noisy or scratchy, or you’re having problems with feedback, then a preamp might solve your problems. Most basic preamps (something like our Pure Preamp) will provide volume control and an equalizer. We also add a wide band midrange filter to clean up any noise and an internal gain trimmer to reduce feedback. (How does feedback happen and how do I control it?)
Some preamps (like our Pre-Phrase Miniature Preamp) provide something called a “phase switch.” Phase can make a huge impact on the quality of your sound by making sure the sound waves from your instrument and your pickup output don’t interfere with each other. (What is phase and what does a phase switch do?)
One thing to watch out for when considering a preamp is noise. Whenever a signal is amplified, the goal is to keep the signal-to-noise ratio as low as possible. That makes sense because a little bit of noise from the pickup or the preamp can become a lot of noise when the signal is amplified and loud. In order to avoid introducing extra noise from a preamp, it’s good practice to place the preamp as close to the signal source as possible. K&K preamps are also manufactured with special low-noise circuitry to avoid this problem.
Finally, one reason to get a preamp is to blend multiple signals into one. All combination systems require a preamp. Imagine you have a pickup and a microphone on your instrument and you plugged those into the amp separately. Getting the signals to match up 100 percent is pretty much impossible and listening to multiple signals slightly out of sync isn’t fun for anyone. A multi-channel preamp (like our Dual Channel Pro Preamp) blends the signals for you and creates a single output signal for the amplifier. It also allows you to adjust the EQ and the strength of each signal depending on your tastes, whether that’s 50/50 or 70/30.
Dieter's Sound Bite
Do I need a preamp? This is the big question that many players have. Here is a rundown that hopefully shines some light on the subject of preamps. Right-click to download: Preamp Podcast
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