Blackstar St James

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.

Losing Weight

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.

There are 50W and 2W settings – the latter, along with the master volume, tames the levels a bit. A lightweight switch‑mode power supply is used, but there’s the option to emulate (in the analogue domain) the sort of ‘sag’ exhibited by traditionally powered amps.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 that tips the scales at just 12.8kg — that’s just a touch over half what you’d expect a 50W valve combo to weigh. (One weight‑relieving feature I noticed that’s a little less welcome is the absence of a protective cover! I remember the days when all amplifiers used to come with them but now, it seems, they’re optional.)

The valve line‑up for the St James 6L6 (whether the head or the combo) comprises a pair of ECC83 dual‑triodes and a pair of 6L6 power valves. High‑voltage MOSFETS are used for the phase splitter, so that the ECC83s can be deployed where they’re needed to shape the tonality of the amp. The main signal path, of course, is all analogue, but the amp still benefits from plenty of digital cleverness: Blackstar’s customisable Cab Rig DSP speaker simulator is built in, and can be used for recording or to provide a PA feed. This takes the post‑power‑valve output signal to a choice of three direct recording outputs on balanced XLR, a stereo line out or USB. A reactive load allows the amp to function normally without the speaker being active, which makes ‘silent’ recording possible — the DI outputs are fed from an amplifier that is still working into an optimal load.

Cab Rig uses Blackstar’s own simulation algorithms rather than impulse responses, as the designers feel that this gives a more accurate dynamic response while also avoiding the latency and phase issues that can sometimes occur with IR‑based approaches. Many of the settings for Cab Rig can be customised by the user courtesy of Blackstar’s free Architect software, with which you can set up a cab miked using a choice of microphones both on‑ and off‑axis. You can then blend in room ambience and also apply EQ. Other digital cleverness adds a good‑quality reverb, which has a different character for each channel. This amplifier won’t twang when you knock it, and I consider that a plus!

Familiar Face

Outwardly, the amplifier looks very traditional in an open‑back format cabinet, measuring 535 x 462 x 259mm with a user‑friendly control panel on top. A mesh grille keeps prying hands out of the back of the cabinet and also removes the temptation to use the spare space in the back of the amp for storing cables and pedals. In common with most valve amps, there’s a main power switch plus a separate standby switch which, in this case, keeps the amp running but with no sound being produced. In this setting, the internal reactive load is connected and the amp runs in the 2W mode, for silent recording or headphone practice.

As well as the analogue connections, which include speaker, headphone and line‑level outputs, you can record directly via USB.This is a two‑channel amplifier, with channel one catering for clean sounds and channel two overdriven tones, and the drive channel has switchable voicing. The alternative voicing adjusts the overdriven valve preamp for more saturation, but also reconfigures the power amp to be ‘open loop’, to provide a looser feel with more gain and a resonant low‑end thump. The EQ is of the familiar three‑band bass, middle and treble type, but these are all dual‑gang pots, and the associated resistors and capacitors are also all separate, to provide two independently voiced EQ circuits, one for each channel. These can be loosely described as a US‑style EQ for the clean channel and a UK‑style one for the drive channel. There’s a master volume control as well as separate gain and volume controls for the drive channel, and a straightforward volume control for the clean channel. A three‑way toggle switch selects between 50W, 50W plus PSU sag, and 2W, with two other small toggles for channel selection and drive channel voicing. A series effects loop is available on the rear panel, and a two‑way footswitch is included in the price, one of which is used to switch channels and the other to select the voicing option on channel two.

The rear‑panel controls and connectors are accessed from beneath, which makes them a little fiddly to get at but it does protect any connected cables from accidental knocks. From left to right there’s a USB audio port, the footswitch jack, the effects loop jacks (with switchable +4dBu or ‑10dBV levels), the Cab Rig DI outputs (with three switchable options) and external speaker outputs for 8 or 16 Ω speakers. The DI outputs are a mono balanced XLR while the jack is a TRS type, wired for stereo so that the added reverb can be heard in stereo. If the internal speaker is disconnected and no external speaker is plugged in, the amplifier recognises this and switches to low‑power mode to avoid damage. Other than being universal voltage, the mains inlet is the usual IEC type and a cable is included. Note that the DI feed comes after the master volume control.

All this technology would be pointless if the amplifier didn’t sound good — but there are absolutely no worries in that regard!

Sound

All this technology would be pointless if the amplifier didn’t sound good — but there are absolutely no worries in that regard! Channel one offers a very Fender‑like clean tone that also works well with pedals. Channel two is actually very flexible, especially with the two voicing options, and by juggling the volume and gain controls it can go from a gentle crunch to a classic rocky overdrive and then beyond. The lack of a large mains transformer helps minimise stray magnetic fields so there’s less chance of hum leaking into your single‑coil pickups when you stand close to the amplifier. By way of general circuit noise, valve amps are never silent but this one is still surprisingly quiet unless you really max out the drive.

The Sag switch only affects the 50W mode, adding a sense of compression to the sound and more springiness to the playing feel. As ever with this type of amplifier, you need to spend a little time dialling in the best EQ for your own guitar, and relatively small changes can make a subjectively large difference. The 2W mode still goes way louder than I’d ever need in the studio and, being honest, also rather louder than I’d use at most of my own gigs, as I tend to use lower powers and then send a feed to the PA to spread the sound out front. However, you can of course turn down the master volume control, and doing so doesn’t appear to compromise the tonality.

Blackstar have included their algorithmic Cab Rig speaker simulation for recording and practice, and it can be configured using their free Architect software.

I’ve met the Cab Rig processing before, when reviewing the Blackstar Dept. 10 pedals, and I have to say that it sounds exceptionally good. It has also been announced that the free Architect software, which supports Mac OS and Windows, has been updated to support Mac Catalina and Big Sur operating systems, though there’s no mention yet of Monterey support.

The Light Fantastic?

These St James amplifiers are not exactly cheap dates at this price, but then neither are Blackstar asking boutique amp money — and they really could give most boutique amps a good run for their money. The reduction in weight will be welcomed by gigging musicians, of course, but it could also make it better suited than most for use in a smaller multi‑purpose studio where you can’t leave the amp set up all the time. At the same time, these amps have all of the features needed to satisfy the typical studio user. As a Brit myself, it’sIt’s great to see a British company bringing the traditional valve amp kicking and screaming into the modern age!