Introduction

The Vanderkley VA615 is a fully hand-wired all tube (2x ECC 83/12AX7) bass pre-amplifier.
This preamp is designed to maintain a brilliant, natural, open and deep bass sound under all circumstances.

The unit has very large headroom and extremely low noise and hum making it one of the most silent preamps on the market. High input impedances, low output impedances make it possible to drive difficult loads and/or use long cables.

With the Eq-section switched off the preamp gives natural open sound, when the Eq is switched on this natural character is maintained. The 5-band passive tone controls with first order (6dB/octave) shelving or band-pass filters are used to tune the sound to your personal requirements. This type of tone control guarantees an open and musical character at each setting.

The VA615 has a built in parallel effect-loop with phase correction for true deep bass reproduction. The level of effect can be added to your original signal via a potentiometer on the front panel.

A floating transformer prevents any ground-loop hum when the balanced D.I. output is used. This makes the D.I. extremely silent and therefore suitable for advanced studio applications. In a worst-case live situation, there is also a ground-lift switch on the back- panel.

The preamp is not sensitive to mains clicks and distortions on mains voltage variations and features a soft switch on/off.

PASSIVE INPUT (JACK)
Input for passive- or instruments with low output level. Can also be used for most active instruments.

MUTE/OPERATE SWITCH
Set to Mute all outputs are muted except   the Tuner Out (backside). Set to Operate    all outputs give signal.

ACTIVE INPUT (JACK)
Input (-18dB) for active- or instruments
with very high output level.

EQ ON/OFF SWITCH
Turns on or off the EQ section as a whole.

TONE CONTROLS (5-BAND)
The tone controls are used to tune the
sound to your personal requirements.
Frequencies are:
Low 30Hz, Low Mid 100Hz, Mid 300Hz, Mid High 1000Hz, High 10 kHz.
The tone controls are passive, first order band-pass or shelving filters (6dB/oct.).
This filtering allows for adjusting the tonal balance, while maintaining the natural character of the instrument.

LOOP ON+/OFF/ON- SWITCH
Activates the parallel effects loop. The Send and Return jacks are located on the backside. On+ and On- deliver Send signal in inverse phase to prevent bass weakening. Turned to Off, the Loop section is truly bypassed.

EFFECT LEVEL CONTROL
Mix the amount of effect signal with the original signal. 0 to 90% dry/wet.

MASTER VOLUME CONTROL
Controls the volume at the Line Out, which goes to the power amp.

MAINS
The Vanderkley VA615 can be supplied for nominal mains voltage of 115V or 230V

FUSE
Easy replaceable fuse 1A @ 230V

GROUND/LIFT SWITCH
Set to lift to get rid off hum problems
caused by ground loops.

LINE OUT (JACK, 2 XLR)
To be connected to the power amplifier.
Z-out = 1kΩ; +27dBV in 100k load,
+17dBV in 10k load a-symmetrical.
Extremely low hum and noise.

EQ PRE/POST SWITCH
This switch either sends the signal to the D.I. before (Pre) or after (Post) it has gone trough the tone controls (if active).

D.I. (BALANCED XLR)
To be connected to house mixer.
Z-out = 1kΩ; symmetrical, floating (output transformer separating grounds to prevent hum).

LOOP SEND/RETURN (JACK)
Send to be connected to effect device’s input.
Return to be connected to effect device’s output.
Return can be used to add an external signal such as a metronome, drum machine or CD-player to your playing.

TUNER OUT (JACK)
To be connected to an external tuning device. This one is always active.
(Before Mute)