TruetotheMusic ®
Radial Engineering Ltd. JDV-Pre™500 Module
5
Using an active bass or guitar
Active pickups have been around for years. They have become more popular since the
advent of 5 and 6 string basses. And although these can sound absolutely amazing, more
often than not, these instruments are so loud they overload the input on most devices. This
is because traditional passive basses generally produce around 1 volt while their active
counterparts (powered with 9 volt batteries) can deliver well over 6 volts when played hard!
Unless your preamp or DI has enough headroom, you will get distortion. The JDV-Pre
addresses the problem by providing plenty of clean headroom. Connection is the same as
using a passive bass. However, Drag control will have little or no effect on active pickups as
the signal is already buffered by the bass’s internal electronics.
Using piezo pickups
Musicians usually complain that piezo equipped instruments
sound squawky and harsh. This is not so much the fault of
the piezo element as it is the built-in preamp that normally
accompanies it. Piezo pickups sound best when they ‘see’ a
very high input impedance. But when you increase the input
impedance, you also elevate susceptibility to background
noise and hiss. Therefore most manufacturers compromise
by using a 1meg-ohm input.
But few realize that if you couple the output of a piezo transducer directly to a really good high-
impedance preamp, you can produce sounds that are as good as a condenser microphone.
The JDV-Pre has been carefully crafted with a very high input impedance and ultra low noise
circuitry to get the best possible bandwidth and transient response from piezo elements.
By disengaging the Drag Control, the JDV-Pre’s input impedance elevates to 3.9 meg-ohms,
or about four times higher than the typical input impedance found at the input of most guitar
and bass amplifiers. Careful attention is paid to reducing noise while the class-A feed-forward
circuit assures the most natural tone. For best results, try to bypass the internal preamp in
your instrument and connect the piezo directly to the JDV-Pre’s ¼” input on the front panel.
You will immediately notice a much warmer, natural sounding tone.
Piezo element wired
directly to output jack.
Piezo element wired to
battery powered preamp.
This is not only effective on acoustic guitars, but equally so on difficult to amplify instruments
such as violin, mandolin, banjo, and contrabass. In the studio and live on-stage, piezo
pickups offer consistent results as opposed to microphones where placement can vary the
sound from session to session. Those that simply want to use their guitar’s built-in preamp
with the JDV-Pre will benefit from the JDV-Pre’s extra headroom and lower distortion.
