Blackstar aim to take the weight out of valve amplification, without compromising on tone.
A good valve amplifier can sound truly fantastic — but they’re generally very heavy things. There are good reasons for that, of course: they require hefty transformer‑based power supplies to provide the HT and heater voltages for the valves; they may also use heavy smoothing chokes; and then, of course, there’s an output transformer. And that’s before you add on the weight of the loudspeaker and the cabinet. But it won’t do your playing any good if you dislocate your shoulder carrying your amp from your car into the venue!
British manufacturers Blackstar have decided to take on the challenge of building a more manageable valve amplifier, without compromising on the sound. The result is the new St James range, which apparently draws its name from an historic part of Northampton, where the company is based. The range includes two amp models, each available as a head or combo, and a matching speaker cabinet. For this review, I chose to focus on the 50W St James 6L6 combo, which comes in black and is fitted with a single 12‑inch Celestion G12Z‑70 Zephyr speaker. The other options are EL34 equivalents, which come in a fawn colour and boast the same features but offer a more ‘British’ tone. The cabinets are available in black or fawn, to match your choice of amp.
So, how did Blackstar manage the trick of keeping the weight down? Firstly, it seems that the heavy traditional power supply was replaced by a more efficient switch‑mode (SMPS) one. Before you put your hand up to tell me that this means it won’t produce authentic voltage sag like an old‑school power supply, Blackstar have thought of that: they’ve included a switchable sag setting, which puts some resistance in series with the HT feed for those who appreciate the sense of compression that provides. The valve heater voltage is also DC, which avoids hum being induced from a more typical AC heater supply. Another advantage of the SMPS approach is that you don’t need a voltage selector as the amp can run on mains supplies from 90 to 264 Volts, 50 or 60 Hz. Perhaps those same hands will reach up to inform us that 50W is too loud for playing at the local pub gig or for typical recording studio use but, again, Blackstar have pre‑empted that, this time by adding a switchable 2W mode that’s achieved by adjusting the power stage voltages — it is surprisingly loud, actually, but certainly much more appropriate in those scenarios.
More weight loss comes courtesy of the Celestion Zephyr speaker, which has a shallow magnet that might look like it should be neodymium. Actually, it’s a new ceramic design that gets close to the fabled ‘Greenback’ tone but in a much lighter package. Then there’s the cabinet, which makes use of candlenut (a hardwood) ply to save more weight. Add all these savings together and you have a valve amplifier...