Ampeg SVT-4PRO-U
Ampeg SVT-4PRO-U
Ampeg SVT-4PRO-U
Ampeg SVT-4PRO-U SVT Pro All-Tube Bass Amplifier Head, 1200W
Archive images of this model, kept as part of the record. Finishes, hardware and appointments changed across production runs, so yours may well differ in the details — and if it does, that difference is worth documenting. Add your photos to this record ›

At A Glance

RMS Power Output
300-Watts x 2/900 (mono-bridged @ 8 Ohms)
RMS Power Output
490-Watts x 2/1200 (mono-bridged @ 4 Ohms)
RMS Power Output (2 Ohms
600-Watts x 2
Preamp
Tubes (3 x 12AX7)
Power Amp
Solid State
Tone Controls
3-Band
Mid Tone Control
5-Position
Graphic EQ
Yes, 9-Band
Ultra Low/High Boosts
Yes
Balanced Line Out
Yes x 2 Pre/Post with Level
Effects Loop
Yes x 2
Preamp Out/Power Amp In
Yes x 2
Dimensions (W x H x D inches
19 x 5.6 x 15.5
Weight
39.5 Pounds
Configuration
Rackmount
Description

Ampeg positioned the SVT-4PRO within its SVT Pro series as a high-powered, rackmount bass amplifier head combining a tube preamp section with a solid-state power stage. It was designed for players who required SVT tonal character alongside a flexible, rack-format form factor.

The preamp ran three 12AX7 tubes and offered a 3-band tone stack with a 5-position Frequency control that selected the center frequency for the midrange band, yielding five distinct midrange voicings. A 9-band graphic EQ provided additional fine-tuning and could be engaged independently via footswitch, making it usable as a footswitchable second channel with its own volume level. Ultra Low and Ultra High boost switches were also present. The solid-state power section delivered 490 watts per side into 4 ohms in stereo, 600 watts per side at 2 ohms, and 1,200 watts bridged-mono at 4 ohms. Connectivity included two balanced line outputs with pre/post switching and level control, two effects loops, and two preamp out/power amp in jacks for signal chain flexibility. The unit occupied a rackmount chassis measuring 19 × 5.6 × 15.5 inches and weighed 39.5 pounds.

Owners requiring service, recalibration of the preamp tubes, or assistance matching the unit to speaker cabinet loads should consult a qualified amplifier technician familiar with bass amplification systems.

Expert Analysis
Specifications
RMS Power Output: 300-Watts x 2/900 (mono-bridged @ 8 Ohms)
RMS Power Output: 490-Watts x 2/1200 (mono-bridged @ 4 Ohms)
RMS Power Output (2 Ohms: 600-Watts x 2
Preamp: Tubes (3 x 12AX7)
Power Amp: Solid State
Tone Controls: 3-Band
Mid Tone Control: 5-Position
Graphic EQ: Yes, 9-Band
Ultra Low/High Boosts: Yes
Balanced Line Out: Yes x 2 Pre/Post with Level
Effects Loop: Yes x 2
Preamp Out/Power Amp In: Yes x 2
Dimensions (W x H x D inches: 19 x 5.6 x 15.5
Weight: 39.5 Pounds
Configuration: Rackmount
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Ampeg SVT-4PRO-U SVT Pro All-Tube Bass Amplifier Head, 1200W

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