Bass Amplifier Head
pre-amp: 4x 12AX7 lamps (or ECC83)
power amp: 6x KT88 lamps (6550 or cheaper but not original)
400W (RMS) 800W (Peak) 4 ohms
600W (RMS) 2 ohms
HP jack and XLR connector
Input passive / active (-10db)
FX loop send / return

Controls: Gain, Bass, Mid (push-pull boost to 500Hz), Treble, Master.
Switch Loud (cut das acute) Bright (bass cut)

DI Crane, lift / ground, pre / post preamp.

UTILIZATION

Using ultra simple, heat is allowed time will toggle the standby,
we put all the knobs at noon and it sounds like a real monster!
With 2x15 'and 4x12' whole spectrum is there, but the corrections are effective
not necessary (depending on the bass).

In common use it soon heavy (> 20 kg) but built like a tank british.
Virtually indestructible, even the lamps are protected by metal fasteners.

SOUNDS

Suitable for all styles, rock, blues, funk, jazz, ... in all conditions
Live or studio.

The sound is warm but clear round ... the bass is huge but precise.
It is far from an Ampeg SVT, I prefer personal, I find it more colorful but so musical.
And fat.

OVERALL OPINION

I use it for 5 years and live in the studio.

Assets:
Inimitable sound.
The integrated DI is very good, and I'm a fan of HP Output XLR
you're in the studio in front of huge speakers, the amp head next to me for the settings and the cabinet alone in a room with the mics.

Cons:
The fan is quite noisy (hence the cabinet alone rec)
STANDBY time long enough to meet (6 KT88 is fast expensive)
HP min impedance is 4 ohms (two speakers so the min)

Amp imperative to try, it's so great for bass!
John Entwistle used it for a few years ...

Quality / price ratio: it is very good and very expensive ...

I repeat so many see it again a second in case.