Introductions to the Thunderbird will be short and sweet as it wasn't yet listed on their website upon my receipt and the designer wasn't exactly forthcoming with details. The Thunderbird looks and weighs more like an integrated amplifier and ships in a Russian military-grade flight base but is actually a phono preamplifier for moving magnet cartridges that offers volume control and three line level inputs. I could describe it as a preamplifier with two MM inputs but the Thunderbird lacks many of the features one would expect from a high-end full function preamplifier; things like multiple variable outputs, balanced inputs (those can be added as an option though), mute function, remote control or headphone outputs. On the other hand, the inclusion of two moving magnet cartridge inputs, a sophisticated tubed phono stage and balanced outputs would seem to indicate that the Thunderbird is first and foremost a phono preamplifier with the added convenience of allowing vinylholics to easily integrate a digital source to their system

Now that we sort of know what the Thunderbird is and to whom it may appeal, it is time to take a look around. The orange Corian faceplate won't be to everybody's liking but I found it very clean and elegant, a feeling unfortunately not shared by anybody else in our household. The power button on the left triggers a loud turn-on noise followed by tube rush for about twenty seconds before the circuit settles down. On fairly high-sensitivity speakers I highly recommend to turn the volume all the way down prior to pressing the on switch. The startup noise is only temporary though and the Thunderbird is very quiet after the initial assault. As always with SA Lab, build quality is superlative with solid connectors fastened to the back plate, two MM inputs, three line level inputs, one variable output on RCA and one on XLR plus one fixed output only recommended for recording purposes, not to feed an integrated or headphone amplifier for example. Without an appropriate set of tiny hex keys, I unfortunately wasn't able to get into the Thunderbird to take a direct peek at the two massive transformers in the center of the beast or the six unusual metal tubes I could see through the cooling slots on top.

Speaking of unusual tubes, the first gain stage where RIAA correction happens for the moving magnet inputs, uses a pair of Russian 6Ж4 anode tubes, equivalent to the US 6CA7 type in metallic sleeve. The same tube provides gain for the second stage while the third stage relies on 6П9 pentodes, equivalent to US 6AG7 also in metal dress. Very early tube designs used metallic cases because the technology to actually make glass tubes had not been invented yet. By the late 1930s tube production moved massively to glass as we know it today because it was cheaper and allowed smaller tube sizes and better dissipation. During World War II, metallic tubes made a resurgence because of their better mechanical resistance to shocks as well as expected better shielding from electromagnetic waves. The latter actually turned out not to be that critical as external lead shielding of glass tubes proved to be even more effective than metallic enclosures. Still, metal-sleeve tubes remained in production during the war for their superior physical strength. The tubes in the Thunderbird, selected for their musicality, come from the massive stocks of Russian NOS tubes from that era and can be easily replaced on eBay for about $10 to $12 per tube.

Testing of the Thunderbird mostly relied on the FirstWatt F5 as power amplifier with both the Ocellia and Finale Vivace mini speakers while phono preamp comparisons relied on either the Genesis Gold or Lounge Audio LCR and Copla suite. For initial context and understanding of the sonic signature of the Thunderbird, it is important to understand that the SOtM DAC I used also offers analog volume control and can therefore be run directly into the FirstWatt F5 without the resolution decimation of digital attenuation. When set up that way, the sound of my system is fast, lean, detailed but also somewhat sterile, lacking in weight, texture or flow. I never run my system this way but it is a good reference to know where my ditches are. Other listeners may find this presentation exciting. I find it fatiguing and very far from anything I'd hear in concert. It was therefore quite a surprise to listen to the complete transformation that happened when I inserted the Thunderbird between DAC and amplifier. It was like finally getting the best of both tubes and solid state which is a synergy often talked about but which I have very rarely experienced.

The Thunderbird completely fleshed out the tonal richness of instruments, injected flow without taking anything away on resolution, added weight and drive to the bass and had great macrodynamic ability. Compared to the amplifier being driven direct, the only area that suffered was microdynamics, the little ripples of energy that run through the music and give it its ultimate drive. But even then the effect was not overly negative, just a gentle relaxation that highly benefitted older CDs and poorer digital recordings. Compared to my reference Triode Lab 2A3 integrated, staging was certainly not as deep or wide and the three-dimensionality of triodes was missing but both frequency extremes gained speed, tightness, finesse and drive. The overall flavour of both setups was surprisingly similar in the midrange, with great richness and resolution. The Triode offered greater visual effects while the Thunderbird and F5 combo won on control and extension. For the first time I found a tube and solid-state combination that rivaled and in some aspects exceeded what a great triode can achieve with the Ocellias. That's a sound I could easily live with.