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Peeved pets. As only textbook engineers would, Alberto programmed his volume control so its first 30x1dB steps bury in the ambient noise of all normal rooms. Those thirty steps are utterly useless thus wasted. Come 40 on the dial—or later where inner-city din raises the standing noise—you'll hear enough soft sound to be fit for 2AM whisper sessions. Your daytime range however will be 75 and up. That wastes more than 50% of useful gradients. I'll never understand such decisions. Real-world design instead sets 0 at 30dB for its start, then exploits all 99 steps across an actually audible range. It's called proper not partial utility. Non-intuitive too was that before it takes, input selection must be confirmed with a second command. Once I grokked that, the small print ended.
I now got exactly what Dawid had promised: just the right infusion of what he calls pigment filler; with no sacrifices in apparent resolution. Perfection then? For my tastes and this system's tuning, quite – except for a sudden din. In DAC-direct mode, Tempo had been shtum like a felon taking the fall whilst his crime compadres feed the family. In Alto mode, our prisoner snitched with sufficient idle noise to be audible from the midranges to the seat. This sounded like elevated power-supply surf. More likely it was a ground issue from my split monitor/sub arrangement. The little box atop Tempo is its fixed analog crossover.
Taking some colleagial cues from Hifi+…
… I came across this paragraph: "The AGD combo is also fast. While I think they should be considered as a whole, I lay this speed primarily at the mono amps. These amps react to transient information with a speed that borders on the psychic. Couple them with some already transient-friendly cable (like Nordost Odin for example) and the speed of delivery is very much that of an audio system getting completely out of the way of the music it plays. Playing "The Limit" by Darkside [Spiral, Matador] and that idiosyncratic electronica (combining trip hop, EDM and a very fast and almost click-track beat) is played with the sort of pace that is usually the stuff of smaller, responsive single-ended triode designs." Where triodes with phase-shifty bandwidth-robbing output iron are concerned, I'd beg to differ vehemently. On speed they'd not stand a chance against AGD. With everything else I concur absolutely. Ditto Dawid's review. My separate opinion is thus echo-chamber stuff to put things in triplicate. Sign here. For AGD it's just one more notch in the belt. Enter something pervy – bass-only duties for Tempo. This meant reshuffling the above. The Crayon returned to the mains, AGD replaced my Goldmund Job 225 bass amp. This deflated voltage gain from 35dB down to 23dB for necessary adjustments. I then heard no compelling reason to upgrade $1'495 DC-coupled wide-bandwidth Swiss to 4 x costlier American. Mind you, performance didn't waver. I just didn't gain anything extra to justify the higher outlay. The long discontinued direct-selling Job emerged from this duel as really doing the grunt work on those beefy AudioTechnology woofers. I shall doubt thee no more, budget bass buster. In fairness, Tempo outclassed it in full-range use. Time to take the show upstairs where Tempo replaced these $3'700/pr 250-watt DC-coupled 1MHz monos.
Forward sub placement compensates its 2.5ms latency for proper time alignment.
Picture the scene. 4Vrms DAC. Preamp at 91/99. 100wpc transistor amp. 88dB isobaric mini monitors. 2×9½" active sub. Small room. Standard SPL. What's wrong? Gain. Alto runs very low voltage gain. Combine that with Tempo's lower gain. I had no party levels. The downstairs speakers were ~5dB more sensitive. They built in added headroom. Still, my takeaway is that Alberto's Alto/Tempo combo—possibly in pursuit of lowest noise—plays it a bit tight-fisted on raw amplification factor. I'm no banger. If on recordings which flicker between -35 to -10dB I can virtually max out gain on speakers of standard efficiency with already higher 4Vrms XLR DAC outputs, I must believe that many users could do likewise. If so, wouldn't they feel a bit cheated? Incidentally, in this configuration the combo of Alto + Tempo was utterly noise free despite again an active filter splitting post-pre signal into monitor and sub paths. Except for shorted voltage gain, everything was functionally peachy. What about the sound? It was a virtually perfect overlay on my personal ideals. Having on hand an autoformer passive icOn 4Pro and direct-coupled DHT preamp with Elrog VT52, I can also say that Alto fell right between the essentially invisible magnetic volume control and the high-bandwidth ultra-quiet triodes selected for their small infusion of valved laissez-faire. That meant just a modicum of added viscosity and temporal elegance. Alto's dose transformed tuned-for-speed Tempo into a more organic performer; a bit like my Mercan Dede fascination of embedding fluid acoustic instruments in grittier electronica. As already Dawid opined, Alto and Tempo really are made for each other. Not hearing them together doesn't provide the full picture of how Alberto Guerra envisioned his GaNFet tech to act.
The two foremost qualities of his duo were amazingly pure directness from apparently very low noisefloors; and soundstage specificity that could approach the holographic when a multitude of images hung so precisely fixed inside a shimmering 3D dome of inky blackness. All of it has been said before. The value of such repetitiveness is simple predictability. This gear has struck multiple listeners with different rooms, hardware and tastes exactly the same. Individual allegiances to a particular sonic flavor are one thing. Knowing how something behaves regardless is quite another; and ultimately the only thing of true utility. Because it's then that we can know with certainty whether it'll be to our own liking; or not. For myself, 'not' simply wasn't part of the applicable dictionary. That didn't really surprise against my prior AGD exposure; but still was worthwhile confirmation given the more affordable placement of these newer models. Bull's eye I'd say; and bully for Alberto Guerra who serves up the same fancy spread in a less exclusive setting now. Thanks for the opportunity to hear so for myself!
AGD respond: "I'm happy to see that you liked my new little babies. I second your opinion. The AGD Tempo and Alto are a match made in the heavens of the high end. That was the goal of the project of course but it took a lot—and I mean a lot—of listening and testing, more listening, testing, changing components, testing and listening…and repeat from the beginning. But you know that. Designing a product and looking only at the oscilloscope or decimal numbers is no guarantee for good sound. At least we at AGD have this opinion. Regarding the gain, we increased the voltage gain of the Alto output by +6dB with a small upgrade of the buffer stage so the AGD duo is now also good for party time – until the neighbor that lives on the lower floor calls the police of course. And by the way, Alto delivers with the metal Apple remote. Unfortunately the original one of the review unit got lost and I had to replace it quickly with something available immediately from Amazon." Alberto Guerra
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