Valve Guitar Amps

Published August 2024

The HT‑5RH: the ‘RH’ in this range denotes an amp head model, while combo models have just an ‘R’.

These low‑power amp heads are packed with studio‑friendly features.

Valve guitar amps have a character all of their own, but most models that are built for the stage are too loud for home studio use, as they generally need to be cranked up to a certain level to hit their tonal sweet spot. Blackstar have created practical solutions in the form of the 1W HT‑1 MkIII and HT‑5 MkIII amp heads, both of which are revisions of previous HT‑series models. In addition to their low‑power credentials, both models feature direct recording to a computer over USB‑C, with access to the company’s respected CabRig speaker emulation software, which we’ve covered in previous reviews.

The physical presentation is much like a full‑scale head, though obviously these aren’t quite so large: at around 26cm wide, the HT‑1 MkIII comes in a ‘lunchbox amp’ format, while the HT‑5 MkIII is rather larger at a hair under 40cm wide. Both come in wood‑based cabinets finished in black vinyl, and they have full‑size strap handles on the top.

Overview

The HT‑1 MkIII is a pretty straightforward beast, with the rear panel sporting an IEC power socket, the USB‑C port, a speaker out jack and a footswitch jack that allows the overdrive to be turned on/off. On the front we get a power switch, an input jack and further 3.5mm mini‑jacks for line in (useful when jamming along to backing tracks) and a speaker‑emulated headphone out that can also be used for recording if you wish. There are three switchable CabRig presets for the mini‑jack out and the USB out. The valve layout is simply a pair of dual‑triode valves: an ECC83 and an ECC82. Digital circuitry is used for the reverb and, of course, for the USB‑C interface.

The smaller, lower‑power HT‑1RH has fewer features than the HT‑5RH but it still offers a great sound, plenty of level, and some useful options for recording.

There are no conventional tone controls on this model, just Blackstar’s ISF knob that morphs between a British type of tone stack and a US tonality, the US end of the scale being noticeably brighter‑sounding than the UK end. The reverb has its own level control, while gain and volume controls allow the user to juggle between the amount of drive and the overall output level. A small toggle switch brings in the overdrive and there’s a second toggle switch to flip between two tonal characters, providing the user with a choice of American Clean, British Clean, Classic Overdrive and Modern Overdrive via the two switch permutations.

The HT‑5 MkIII has more generous feature set. It sports additional send and return jacks (with switchable +4dBu/‑10dBV levels), emulated outputs on both a quarter‑inch headphone jack (which mutes the speaker when connected) and a balanced XLR that can be used without muting the amp. Again, there’s a USB‑C port and a line in mini‑jack, and there are three switchable CabRig variations. This time, there are three speaker jacks to allow for different speaker impedances, and the footswitch jack in this model accommodates the included dual footswitch, for channel switching and reverb.

The valve line‑up is one ECC83 and one 12BH7, and next to the power switch there’s a 5W/0.5W switch, giving you the option to play at full volume or to reduce the output level for home practice or recording. In the overdrive EQ section the ISF control is teamed with more conventional bass, middle and treble controls. The overdrive channel has its own gain and volume controls plus a Voice toggle switch, while the clean channel has simply one volume and one tone control plus a Voice toggle switch. A further toggle switch changes from clean to overdrive, as an alternative to using the footswitch.

I was surprised by just how loud a single‑Watt amp can be. I’ve played pub gigs needing less level than this one can provide!

In Use

As you’d expect, the sound of these amps is influenced by the type of speaker cabinet you’re working with, and Blackstar provided one of their 12‑inch speaker cabs for our review. Starting with the HT‑1 MkIII, I was surprised by just how loud a single‑Watt amp can be. I’ve played pub gigs needing less level than this one can provide! The clean channel stays very clean unless you get close to the maximum output level for the amp, and there’s a lot of weight to the sound too. The two tonal variations offer two different degrees of brightness, along with whatever other tone‑shaping goes on behind the scenes.

Switching to the overdrive channel reveals that there’s plenty of gain on tap, with a range that goes from a slightly ‘hairy’ clean up to full‑throttle rock. As you’d expect from a valve amp, there’s a useful degree of touch‑responsiveness too. The US voicing is more aggressive in the upper mids than the UK voice, just as you’d expect. Even the digital reverb is nicely judged, adding a welcome ambience to the sound but without swamping it.

Impressive though the HT‑1 MkIII is, I have to say that the HT‑5 MkIII is much more versatile, especially on the overdrive channel, for which the additional EQ really helps you shape the sound. Also, it’s worth noting that the two channels each have their own volume controls. This means you’re able to balance their levels when switching channels — that’s something you can’t do on the HT‑1 MkIII. That 0.5W switch is also a real bonus, as I found even 5W to be louder than necessary for studio use unless playing alongside a drummer, and I found 0.5W ideal for doing overdubs. Again, there are multiple voice permutations courtesy of the voice and channel switches, and the same reverb as in the HT‑1 MkIII.

I found the USB interface on both amps worked smoothly, without the need for any drivers on my Mac. I set the amp as the input device and the output as my usual interface so that I could monitor the results through my own speakers. However, using the headphone sockets on the amps, you can monitor both the ins and outs via the amp if you prefer.

The rear panel of the HT‑5RH sports an array of inputs and outputs, including an effects loop.

If I have any criticism at all, it’s that I’d have liked a way to add just a little ‘hair’ to the clean channels without having to turn the amps up to the point that the output stage starts to saturate (that can also bring in some ‘thumpy’ intermodulation). I’d also have liked to see red plastic nuts on the speaker output jacks, as the lightning symbol printed next to them could get missed in dim lighting conditions, which could lead to an expensive connectivity mistake — especially on the HT‑5 MkIII, which has seven quarter‑inch jack sockets on the back! In the case of the HT‑1 MkIII, It could also be useful to have the option of using the phones/line output without muting the speaker — this would make the HT‑1 MkIII a practical option for smaller live performances where a DI into the PA might be needed to boost the level.

Both models already deliver a big valve amp sound, and cover a useful tonal range, but further variations are available when going via the CabRig emulation, whose three variations all offer an authentic miked cab sound. The first option, a 2x12 cab, is the brightest, while option 2 offers a good classic rock 4x12 sound and 3 is another 4x12 that’s very full at the low end. Recording with any of these options produces a convincing ‘miked big amp’ result. But if you want to experiment further, then the free CabRig Architect software is worth checking out, as that allows you to swap out cabinets, room ambiences and microphones, so that you can customise your DI’ed sound for each recording project. These settings can be saved into the amplifier to overwrite the factory presets but if you’d rather not do that, it is easy enough to change them without saving from CabRig Architect when in the studio. You can save any presets you create to your computer.

The new range also includes higher power amps and a range of cabinets.

In summary, then, these little amps are ideal in a studio setting, where the low power and CabRig DI make recording pleasurably straightforward. If you plan only on using the DI facility rather than playing through a speaker, though, there are probably other modelling solutions, both hardware and software, that are more cost-effective, including Blackstar’s own St James amplifier plug‑ins.

Summary

Both amps are a welcome addition to the range. They sound great, and have feature sets that make life a lot easier in the studio. Furthermore, the HT‑5 MkIII is also loud enough to gig with, and has a balanced DI feed that you could run straight into the PA.