Gibson have just released new (& very expensive) amps based on the old GA series, this sounds far better. A genuine class A, made in the UK in the 90’s and covered in a Lifton style tolex to match the high end Gibson cases. A pure tone machine with a single volume, single tone, and a knob for Reverb. There is a bright switch, and a switch to go from Pentode to triode mode (drops it down to about 6 W). The amp is all original, I gigged it last weekend with a full band and it was on about half volume and still cutting through. Breaks up beautifully when pushed and lower volumes as a typical vintage, creamy valve tone. It works perfectly, there is slight microphonic tinkle from one preamp valves at low volume, it doesn’t bother me, but I’ll have a look, and if I have a spare valve, I’ll put it in. The tolex is in very good condition but is lifting slightly on one side and one leg of the ‘N’ on the Gibson badge has come away (most are missing their badges), that’s everything negative. I can find to say about it, but I reckon 95% of 30 year-old amps are in far worse condition.

Here's a description of the amp from Guitar World...

"With its square corners and round speaker cutout, the GA-15RV bears a striking resemblance to Gibson’s EH-100 from the 1930s. In contrast, a close-up look at the rear-mounted control panel reveals more up-to-date accouterments, such as Reverb and a Triode/Pentode switch.

Along with its single Volume knob, the GA-15RV (which was originally designed for Trace Elliot by Paul Stevens, and called the Velocette) has a particularly clever Tone control that uses a dual-ganged pot to simultaneously adjust treble and midrange. Here’s how it works: Turning the pot counter-clockwise increases midrange while decreasing treble. Conversely, turning the pot clockwise increases treble and decreases mids.

The Triode/Pentode switch also greatly expands the amp’s range of tonal textures. In Pentode mode, the GA-15RV sounds surprisingly taut and punchy—easily loud enough for small club gigs. Driven by a Strat’s bridge pickup, the EL84s combine with the Celestion Vintage 30 to produce a sweetly detailed treble that is further enhanced by a sub-layer of aggressive British midrange grind and gristle. In Triode mode, the volume drops significantly and the tone becomes thick and creamy-smooth. Overdriven tones occur also at much lower volumes, with less British bite and a more resilient feel. The Bright switch adds tasty top-end chime and ring—a nice thing with humbuckers.