Minimum ohm load for all Markbass heads is 4 ohms.

Markbass amps/combos are manufactured to be sold and used in the country of purchase, and they are factory preset to that country’s voltage.
Due to homologation issues, the voltage may not be changed.

Rack ear kit included.

INPUTS

PASSIVE INPUT
impedance: 500 Kohm, maximum voltage: 4 Vpp
ACTIVE INPUT
impedance: 500 Kohm, maximum voltage: 10 Vpp
EFFECT RETURN
impedance: 500 Kohm, maximum voltage: 10 Vpp

CONTROLS

GAIN
-80 dB to +35 dB range
MASTER VOLUME
LINE OUT
level control on front panel
PRE/POST EQ (for line out)
switch on rear panel
GROUND LIFT
switch on rear panel
FOOTSWITCH
mute; EQ bypass

EQUALIZATION

LOW
semi-parametric: frequency 40-300 Hz; level ±16 dB
LOW-MID
semi-parametric: frequency 100-800 Hz, level ±16 dB
HIGH-MID
semi-parametric: frequency 700 Hz-6 kHz, level ±16 dB
HIGH
semi-parametric: frequency 1.5-10 kHz, level ±16 dB
VPF (Variable Pre-shape Filter)
center frequency 380 Hz (cut)
VLE (Vintage Loudspeaker Emulator)
250 Hz-20 kHz cut

OUTPUTS

EFFECT SEND
unbalanced, max. voltage 20 Vpp (pre-EQ)
TUNER OUT
unbalanced, max. voltage 2 Vpp
LINE OUT
balanced XLR, max. voltage 15 Vpp
SPEAKER OUT
speakon, 1/4"

OTHER

HEIGHT
3.39 in. / 8.6 cm (2U)
WIDTH
14.5" / 36.8 cm (with rack ears: 19" / 48.3 cm)
DEPTH
11.89 in. / 30.2 cm
WEIGHT
8.16 lbs / 3.7 kg
TUBES
1 x EECC81, 1 x ECC83 (JJ Electronic)
OUTPUT POWER
300W RMS @ 8 ohm, 500W RMS @ 4 ohm
POWER REQUIREMENT
100/120V; 230V; 240V
50/60Hz
(Voltage is factory preset according to region of sale)

Our premium tube preamp head features tube warmth and clarity at the same time. The TA 503 also boasts our most flexible EQ, with four-band semi-parametric tone control as well as our signature VLE and VPF filters. Like its brother the TA501, this unit gives you mute-to-tune and EQ bypass control using an optional footswitch.