Ampeg SVT 300W
Ampeg · 1969
What It Is
The Ampeg SVT (Super Vacuum Tube) is a 300-watt all-tube bass amplifier head introduced in 1969. At a time when bass amplifiers topped out around 100 watts, the SVT was a seismic leap — powerful enough to fill a stadium without PA reinforcement. Six 6550 power tubes push enormous headroom, and the SVT's preamp adds its own distinctive color when driven. It became the default bass amplifier for stadium and arena rock through the 1970s and 1980s. Nearly every famous hard rock and classic rock recording from that era used an SVT. It remains in production today, largely unchanged.
Tonal Character
Massive, authoritative low end with a tight, focused midrange. The SVT has enormous headroom at lower gain settings — the bass sits deep and wide without blooming. Pushed harder, the preamp adds grind and growl that cuts through a dense guitar wall. The midrange is punchy and defined, not scooped. The Ultra Lo and Hi switches extend its tonal range significantly.
Tube Complement
Not sure what these mean? See the Tube Reference →
Found In
HeadRush
| Model Name | Controls | Notes |
|---|---|---|
| 69 BLUE LINE BASS | Volume, Bass, Midrange, Treble, Ultra Lo (on/off), Ultra Hi (on/off) | The standard SVT 300W model. Full, authoritative low end with the characteristic Ampeg midrange punch. The default starting point for any SVT-style bass tone on the HeadRush. |
| 69 BLUE LINE SCOOP | Volume, Bass, Midrange, Treble, Ultra Lo (on/off), Ultra Hi (on/off) | The SVT 300W with a pre-dialed midrange scoop. Produces the scooped, modern-sounding bass tone where lows and highs are prominent but the midrange is recessed. Sounds huge in isolation but can disappear in a dense band mix — use when the bass role is primarily felt rather than heard, or in sparse arrangements where the scoop works in context. |
Videos
Manual
View ManualFamous Uses
- →Geddy Lee — Rush
- →John Paul Jones — Led Zeppelin
- →Paul McCartney — Wings era
- →Chris Squire — Yes
- →Essentially every arena rock bassist, 1970s–1980s
Best For
Controls Explained
Descriptions reflect the real-world gear these models are inspired by. Your modeler's implementation may vary. Use as a starting point — always trust your ears.
Volume
Overall output level. The SVT's preamp character begins to add color as volume increases. At moderate settings, the SVT delivers clean, authoritative bass tone. Pushed higher, a subtle grind develops — not distortion in the traditional sense, but a harmonic richness that gives the SVT its 'alive' quality at high volume. On a modeler, volume primarily shapes power amp behavior in the simulation — set it at a point where the simulation feels like it's working (around 5–7 is common).
Bass
Low-frequency control. The SVT's bass response is already substantial — even at center (5), there is significant low-end authority. Setting bass above 7 in a modeler context can produce enormous sub-bass weight, but use judgment based on your monitoring situation. In a band mix, excessive bass can obscure the kick drum and mud the low end. The SVT works in the 4–6 range for most modern contexts, with higher settings for solo or studio recording where the full low end can be heard.
Midrange
Active midrange EQ with a switchable center frequency. The Freq knob selects the frequency being boosted or cut — on the HeadRush model this sweeps from 220Hz to 3000Hz, with a default of 800Hz. The Gain knob sets the amount of boost or cut. The midrange control is crucial for bass tone that cuts through a full band mix. Many bass players instinctively scoop the mids, but the SVT's midrange at moderate settings (5–7) provides the punch and presence that makes bass lines audible and rhythmically clear in a dense arrangement. If you're dialing in a modeler patch for a full-band context, resist the urge to cut mids — a slightly mid-forward SVT tone translates far better than a scooped tone in a mix. Start at the default 800Hz center frequency and adjust the Freq knob up or down if you need to target a specific problem frequency or boost a different midrange range.
Treble
High-frequency control. Adds upper harmonic definition and the 'clank' of pick or pluck attack. Low treble settings produce a warm, round bass tone. Moderate treble (5–7) adds useful definition and presence. High treble (8+) adds aggressive top-end bite that cuts through dense arrangements — useful for rock and metal bass, less so for soul or R&B styles.
Ultra Lo
A switch that engages a sub-bass frequency boost — extends the bass response into the very low end. This produces a deep, thick bass weight that is more felt than heard on some systems. Use with caution on modelers and headphone monitoring setups, as excessive sub-bass can be fatiguing. The Ultra Lo is more useful in live large-venue contexts or when working with full-range speaker systems.
Ultra Hi
A switch that adds upper harmonic presence and brightness — extends the high-frequency response. Adds definition and a slightly aggressive character to the attack. Works well for rock bass playing where the bass needs to cut through a wall of guitar. Can sound brittle in isolation but translates well in a band context.
Sample Configurations
Starting points for common tones — dial in from here.
| Name | Volume | Bass | MidFreq | Midrange | Treble | Notes |
|---|---|---|---|---|---|---|
| Classic Rock Bass | 6 | 5 | 800Hz | 6 | 5 | Punchy mids, controlled low end, slight grind. The standard SVT tone. |
| Arena Rock | 8 | 6 | 800Hz | 5 | 6 | Wide open. Massive stage tone — the full SVT experience. Ultra Lo recommended. |
| Modern Mix Bass | 7 | 4 | 800Hz | 7 | 7 | Mid-forward for cutting through in a band mix. Treble adds pick attack. |
Suggested Pairings
- →Ampeg SVT 8×10 Blueline — The standard pairing — massive and focused
- →Ampeg 2×15 (Eminence) — Deeper and more open character