When I questioned myself about whether I'd really noticed any of the bluesy
aspects ascribed to the 6V6, I couldn't much relate. Absence of bite, snarl and treble glossiness could seem sweet, absence of high-strung wiriness and dry slam in the lower octaves warm. But sweet and warm is not how I heard it. Whilst those qualities might have figured in small doses, they weren't different enough to attract initial attention. What did, immediately
, was the sensation of breath, elasticity and fluidity. According to my hardware exposure, that really is the
quintessential tube quality which Alexey Syomin managed to distill and magnify. As such, it's not anything my transistor amps can do. At this potency, it also seems far more typical of single-ended not push/pull circuits. Yet to get useful power and transcend oft-compromised linearity, SETs and their designer triodes tend to get expensive; and can be challenging relative to multi-kilovolt rails. At 15/30wpc into 8/4Ω, the Blackbird SE read quite tailor made for my needs at a price not even close to what a high-performance equally spec'd SET would command. Of course I committed on faith that going after twice the power wouldn't undermine or dilute my primary reason for buying one: this
Blackbird's flavour, just with more grunt to expand potential speaker choices. The power raise comes from 6L6
tubes operated in tetrode which can be rolled for 6П3; and 5kg more iron in more complex bigger transformers. For a whisker more than €1K, our 6V6 recession buster is a radically superior proposition to any like-priced 300B amp with which it'd only share the power rating. Though unapologetically push/pull and without a big boutique bottle to brag about, it exhibits more of the good stuff direct-heated triode SETs are famous for; and far less of their 'bad' stuff (unless one got onto Ancient Audio to Wavac turf).Grunt.
By giving me some specs on his own speakers, room size and loudness needs, reader Wayne Beyer asked whether the Blackbird would float or sink his boat on achievable SPL. Here are some additional data points to help you predict that. To obtain hard figures, I used Vinnie Rossi's LIO as passive autoformer volume and bypassed the Blackbird's own pot. 63 on the LIO's dial equals a max 7dB up from unity gain via passive transformer gain. 56 equals running DAC-direct into the Blackbird. Because I couldn't use my DAC's 4V XLR outputs—the LIO is purely single-ended—my source sat at a max 2V out. Our room is 100sqm with a 2-storey ceiling above the speakers. I consider 75dB median SPL with 10-15dB peaks in the seat loud
and routinely listen lower. Given these parameters, I sat at 13 decibels below unity gain. If I added our 12dB-gain Nagra Jazz and ran my DAC's 4V XLR outputs into that, I'd pad the gain bill and loudness potential to well beyond what my ears could pay. That such trickery might eventually overload the Blackbird's inputs goes without saying. But for my needs, even the 6V6 Blackbird off a bog-standard 2V source went loud enough. Literary detour closed.
To revisit and wrap the Lustbader/Lagercrantz connection—there's also Anthony Horowitz's Sherlock Holmes and Sophia Hannah's Hercule Poirot—the co-creative
change of perspective which Alexey Syomin's all-tube circuit creates is from the vertical to the horizontal. Music's horizontal axis is the realm of melody. It connects and transcends the choppy vertical divisions of beat keeping. The best and easiest way to imagine this shift is by removing the drums from a piece of music.
I have a CD of an Indian vocalist which sports the same track with and without tablas. The effect is very interesting and, for Indian music, typical of so-called alap
intros of melodic improvisation which omit percussion. Western popular music is so reliant on the drum section that we often forget how our own classic chamber music operated for centuries without it. It's far from required to imbue music with a recurring pulse that organizes it in cyclical intervals. Eliminating it gives emphasis to melody. It also makes timing more fluid. The performers can more easily stretch and compress the sense of a metronomic beat by playing 'between the lines', by accelerating and slowing fluidly across their phrasing without invoking syncopation which relies on the contrast/conflict with a regular beat. This quasi suspension of time is far closer to the process of breathing and ebb and flow than it is to a bopping heel or clapping hands. Because he's so well known, calling it the Chopin effect
is a useful bit of literary license which most can relate to immediately. It's what the Blackbird applies to its readings just as premium single-ended triodes would. It's about a different more organic feel
.Stacking the deck; but which way?
When Heco's twin down-ported Direkt 11" 2-way with 95dB in-room sensitivity showed up, I wanted another by-the-numbers scenario about system gain. Now I used our Nagra Jazz preamp set to 0dB to act as a quasi actively-buffered passive preamp. Its XLR input took the fully balanced 4V DAC output; its XLR output drove the XA30.8, its RCA output the Blackbird. In the latter scenario, Nagra's volume sat at 10:00 o'clock. By providing a silk-screened scale around their control, I knew how this equated to 30dB below unity gain; a lot
of headroom. However, on this seemingly even happier speaker match and via the XA30.8, the Blackbird's bass power suffered more. Most likely this was due to the Direkt's 22/23Ω port peaks at 28/70Hz. Into such high impedances, most amps will deliver a 1/3rd or less of their output than they do into 8Ω. If the 8Ω rating is padded for the application, no problem. If not, those high-Ω zones in the low and mid bass attenuate and compress dynamically. If Heco wanted to really optimize their retro box for low-power tube amps all around, they'd need to linearize their impedance plot with many more crossover parts just as designer Gregorz of Sounddeco did for our Sigma 2. Sometimes more is more.