The B25 features a chrome chassis for models from 1970; later models have a black back panel.

The amp can feature blue graphics, which were only used until the end of 1971, indicating its vintage status.

A common issue is the B25's output being wired for one or two 16 ohm cabs, often requiring a dummy plug for an 8 ohm load.

Cathode bypass caps on the phase inverter are often 125u/16V or 125u/25V, with Sprague offering a compatible 120u/75V alternative.

30uf/600V capacitors are challenging to source; Fliptops is a recommended supplier for these uncommon parts.

The original 7027A power tubes are becoming scarce, with reissues from New Sensor and JJ being viewed as slightly weaker alternatives.

The B25 is brighter than the B15 and similar to channel 2 of a vintage SVT but with less push.

The Ampeg B25, when overdriven with a guitar, closely resembles the sound of the late '60s/early '70s Ampeg SVTs used by the Rolling Stones.

Owners often separate the transformer taps to different jacks for better flexibility in cab connections.

An added impedance selector switch is a beneficial upgrade, allowing for better matching with different cab impedances.

$600 is reasonable for a B25 if no major repairs are needed; expect additional expenses for updates like caps and a 3-prong cord.

The B25 uses a 12AX7-based preamp instead of the octal 6SL7 design found in other Ampeg models like the B18N.

Channel 1 is brighter and better for guitar, while channel 2 provides more low-end, making it ideal for bass use.

The amp includes treble and bass knobs, plus ultra-hi and ultra-lo switches that re-voice the amp for different tonal options.

The B25 pairs well with a 1x12 cab for rehearsals and low-volume shows, while a speaker merger can enhance its performance for gigging.

Players note that the bright inputs reduce bass slightly, offering a unique tonal option.