Reviewer: Srajan Ebaen
Source components: Accustic Arts Drive 1; Zanden Audio Model 5000 MkIV
Preamp: Bel Canto Design PRe2; Wyetech Labs Pearl; Eastern Electric MiniMax
Amplifier: FirstWatt F-1 [on review]; AUDIOPAX Model 88; Eastern Electric MiniMax; Butler Audio 2250 [on review]
Speakers: Cain & Cain Abby [on review]; Omega Loudspeaker Systems TS33 [on review]; Nelson Pass prototype Lowther DX-55 sealed box; [on review]; Avantgarde Acoustic Duo
Headphones: AKG K-1000 with Stefan AudioArt replacement cable
Cables: Crystal Cable Reference speaker cables and power cords; Stealth Audio Cables Indra analogue interconnects and Varidig digital interconnect
Power Delivery: BPT BP 3.5 Signature Plus; Walker Audio Velocitor; 2 x ZCable Cyclone Ref1
Resonance Isolation: Grand Prix Audio Monaco (2); GPA APEX footers underneath stands; Isoclean wall outlet; WorldPower cryo'd Hubbell outlet; Mapleshade butcher block platform underneath BPT conditioner; Walker Audio Super SST
CD Treatments: Furutech RD-2 demagnetizer; Walker Audio Vivid; Audiotop AUT 05.0
Room size: 30' w x 18 d x 10' sloped ceiling, concrete slab, 2 layer carpet; long-wall setup
Review Component Retail:: $2,500

Single-ended. Class A. Zero feedback. Fully balanced operation with both RCA and XLR outputs. Noise of 1/10,000,000th of a watt. Input impedance of 80kohm. Output impedance of 80 ohms. Constant draw of 100 wall watts. Output? 10 music watts. The only aspect of Nelson's FirstWatt's F-1 stereo amp that might suggest thorns with certain lovers of high-efficiency loudspeakers? The same aspect that will have others sit on needles to find out about today's results? This amp ain't gotz toobs. It's solid-state thru and thru. Nothing glows in the dark except for those two cobalt-turqoise power indicators on the front panel. But it has something no tube amp ever had - transconductance or current drive.

Read our two prior articles [1 & 2] in this triptych of F-1 writeups to learn about this rare amplifier topology and what loudspeaker loads are recommended with it and which ones aren't. One above spec will raise eyebrows with those unduly burdened by common wisdom. The output impedance exceeds by a factor of 10 the 'worst' of tube amps struggling for niggling respect with John Atkinson's test bench. Again, refer to our prior installments why Nelson Pass -- who's certainly fully capable of giving us amps with essentially zero output impedance -- has here opted for this counter-intuitive recipe. It deliberately lowers the operative damping factor. In a nutshell, single-driver loudspeakers of high sensitivities use ultra light-weight cones with massive gauss factors behind their motors. That equates to excellent self-damping properties. Add to this self damping action redundant damping from amplifiers and you become guilty of over-damping. And that, friends of single-driver speakers, will kill low-frequency weight and extension. It rolls of das bass prematurely and often to the sorry tune of more than 15dB. Premature - er, roll off? By fifteen inches? Considering how bass extension and displacement are well-acknowledged soft spots for such loudspeaker designs, that's naturally the last thing manly men want to be known for. What the good sound doctor orders instead is a stiffening of the nether regions. Let them no longer telegraph 'compromise, compromise' while the famous immediacy and rhythmic fidelity of zero timing distortion coo 'perfection, perfection' in unison farther up in the frequency range. Redress the balance. Get down - as low as you can.

While designers Terry Cain and Louis Chochos kindly made available speakers for today's test, I will not be focusing on their creations per se. Instead, I'll report on how their speakers' performance with the F-1 differed from that of my other in-house amplifier options specifically in the areas of frequency extension, LF definition, impact and overall tonal balance. I will additionally report on what changes the outboard passive networks made in this regard.

For a first get-to-know-you session of the Abbys, I cued up "Bandari" from Strunz & Farah's Rio de Colores [Selva 1010]. It expands the famous guitar duo to include the virtuoso Greek bouzouki player Danny Papakalos. Fixing center fill by moving the speakers closer together, I was bothered initially by the quality of the bass. It sounded a bit hollow, soft and 'ringy' compared to the rest of the spectrum. Imagine the difference between a string fitted to a thick board versus one fitted to a large resonator. The Abbys' bass suggested generation by a resonator while the remainder of the audible band was board-mounted for firmer attacks and faster stops. And guess what - resonance is exactly how the whizzer-fitted Fostex loading into the 1/4-wave Voight pipe goes about producing its mid bass below the driver's native reach (the 20-40Hz octave is completely missing and roll-off probably sets in somewhere around 60Hz).

Polyfill to the rescue. Nelson Pass had thoughtfully dispatched a 12oz. bag and recommended stuffing each speaker enclosure with half of it. Our local Walmart sells the same brand for a few bucks in the fabric department. Places that cater to doll or pillow makers carry it as well. Bingo - once the mouth of the line was stuffed, the 'organ pipe resonance' quality of the bass noticeably firmed up to no longer suggest a discontinuity of texture and mien between the vocal range and the upper bass/lower mid transition. While the lowest notes of an upright bass were still attenuated, most of that range had now locked in to be considered well integrated. Despite neccessarily lacking raw displacement, mounting the speakers to their 'Russian onion'-shaped brass footers; optimizing toe-in (very moderate); fixing speaker-to-speaker distance for the right amount of upper bass/lower mid warmth (less distance than I commonly use in my room); I was now able to follow Rene Camacho's bass without feeling cheated or as though listening to two different systems.

Inserting the custom outboard networks was next. Those were crafted with clip leads to allow experimentation with different resistor values. An owner would settle on the preferred value to likely mount the finalized passive filter inside the speaker. Remember, these were compensation networks deliberately designed to flesh out the speaker's bottom: Nelson's Jenny Craig diet in reverse. On this particular rear-loaded speaker, this scheme did not do much to recover certain lower MIA notes previously masked. If it shifted downward the 'fading zone' below which things clearly rolled off, it was subtle. However, proper speaker positioning in the room in conjunction with the Polyfill and F-1 driver extended to around 45Hz and respectable reach into the high 30s, with a listener distance of ca. 12' while the speakers were still out in the open by 54 inches. Moving them back by another foot to play on some boundary reinforcement with the wall behind them really locked things into place.

Obviously, my measurements both in inches and electrical network values were a function of room and personal taste. Yours would vary. The benefits including the polyfill damping were three-fold thus far: The stuffing altered the quality of bass. The networks subtly improved the quantity of the bass. Combined, both improved top-to-bottom coherence and tonal balance. The latter shifted downwards to remedy the relative lite-on-the-feet sensation of the very first encounter. Bass freaks will still insist on Terry's own Bailey subwoofer for oomphosity. But devotees of acoustic music in the Strunz & Farah vein -- and set up in not too large a space -- would not need to sub out bass duties to get the LF goods on their CDs.

Next up on my to-do list? Replace the 10wpc F-1 with the 250-watt Butler Audio monster to stand in as an example of a low-output-impedance amplifier endowed with oodles of power and solid-state-type current from a voltage-drive design. If the claims for the transconductance amp were factual, this amp despite it superiority on paper should take away certain LF gains into Terry's sort of specialty speaker load. Naturally, one would also expect changes in harmonic distortion content (the Butler amp is a novel hybrid with one 6SN7 per channel). But at this point, I'd be focused not on a comparison between hybrid valves and solid-state but one between current and voltage drive.

And indeed, compared to the F-1 with the networks, the Butler's bass reach and subjective weight took a step backwards into the shadows. What prevented a subjective tipping up of the tonal balance was the enhanced timbral density in the vocal range. Harmonically richer, the Butler amp added weight in another domain. Concentrating specifically on the audibility and relative prominence of the lowest notes, however, the F-1 took the prize. By comparison, the Butler incurred the hollowness of octave-doubling whereby certain fundamentals were now completely masked by the first harmonic.

By now, I had progressed to Luciano Pavarotti's first-ever crossover album Ti Adoro [Decca B0001096-02]. I had orchestral complexity, stellar vocals and tympani and massed basses to contend with. The F-1 was faster, something particularly noteworthy on vocal climaxes. It was also leaner and more lit-up, translating subjectively as greater transparency. However, the sheer headroom of the Butler even into a load that apparently didn't require it made for more across-the-board fullness. Returning to the guitar music with its intricate rhythms and percussive string attacks, the Butler's tonal juiciness -- very impressive on Luciano -- degraded to sound clearly sluggish, distinctly - er, indistinct around the edges and in dire need of a blood infusion to regain life and energy.

Clearly, the excitement, blister, accuracy and sheer verve of rhythmic propulsion had followed Elvis and his butler to leave the building. On this type of music, there was no contest - the F-1 was a Formula 1 racer while the Butler was a passenger car with softly-sprung suspension. However, in a perfect world, I would dig some of the Butler's harmonic saturation especially on power music. Eastern Electric's MiniMax preamp to the rescue. Trading a bit of dynamic speed
-- one of the Wyetech Pearl's aces -- the MiniMax added a becoming degree of tonal development. The critical amplifier/ speaker interface remained untouched so as to not sacrifice control or 'cone velocity'. Those aspects, I was quite convinced by now, the FirstWatt amp owned in its back pocket like a street thug owns his back alley. To be sure, I inserted the MiniMax amp into the rig. I substituted its namesake preamplifier for the Wyetech to not overdo the tonal aspects of going MiniMax-squared. Ayee! Likely because it lacked the Butler's headroom and drive, I had suddenly relocated to the fog-ridden highlands of my Scottish ancestors. Now that I'd heard what the FirstWatt could do, the soft-focus romanticized rendition of the MiniMax despite its push-pull cancellation of heavy THD clearly played in a lower league of accuracy, incisiveness and involvement. Too much honey, not enough vinegar, pep and spunk.

Having thus sorted through some of the available 'spice mixtures' my on-hand components afforded, I returned to the MiniMax/F-1 combo as the one that gave me the perfect mix of tone and speed, warmth and excitement, beauty and accuracy. Despite being less than 20% of the Wyetech Pearl's asking price, this match-up made the unassuming MiniMax preferable because it can be made to sound more tubey than the more neutral Canadian champ. And that's what you need to squeeze from them tubes and butter the F-1's bread with: Some inside-the-notes body without smearing their articulated beginnings and ends. Without some fat, the F-1 operates on the lean and precise side of the fence. It doesn't inject color but is solely concerned with translating input voltages into output current that grips the voice coils without booking any what-ifs. I'm not just being cavalier with the language here, either. Consider the infamous AKG K-1000s.

With their ring magnets and off-the-ear 'free space' environment, they're inefficient as hell (74dB/1w/1m). Common sense suggests to drive them with a sufficiently powerful amplifier. But sometimes, common sense is just that - common and not very special. Special sense + AKG K-1000s = FirstWatt F-1. What these 'phones crave is current, not unreasonable headroom reserves. Remember Witches of Eastwick the movie ? Horny lech Jack Nickolson entertains his harem-of-three on the tennis court. As the game gets into high gear, he and one of his ladies are facing off inches removed from the net. The ball ricochets back and forth rapidissimo between their rackets which don't move at all. Jack hammer time of staccato volleys, superior reflexes, lightning-fast exchanges and child's play control, so virtuoso yet apparently easy. That visual perfectly captures the sensation of listening to the K-1000s when driven by the F-1. You suddenly discover a whole nudder level of precision and resolution. It's well beyond what you already knew these cans could do. And just like with the Abbys, the ideal scenario is to precede the signal chain with the Eastern Electric preamp or something like it.

Most owners agree that the Austrian earspeakers need tubes. I wholeheartedly concur. Alas, based on my FirstWatt experience (and I've often confessed how I was still looking for that perfect K driver), I will now recommend to not drive 'em with valves but merely to inject the thermionic aroma via the preamp or CDP or both. When it comes to broad-shouldered moxy, let transistor current do the dirty control work. What Nelson's amp does for the K-1000s is a rare thing of beauty. It transcends any prior best-case scenario I've encountered thus far. It's become my new favored setup for these specialty cans and I use the MiniMax voiced on the warm side of neutral to get my tube rush. I'm not sure whether admiral Nelson considered this particular employ for his transconductance amplifier. Still, I'm hear to tell you that this is one ride you won't want to miss if you're a fan of the AKGs like I am. The MiniMax/F-1 combo gets you the luv with archetypal recording monitor precision. And that is arguably the best of both worlds - very high fidelity and musical persuasiveness. To get that level of sonic perfection from a speaker-based system costs an enormous amount of money easily outside x 10 as much and involves endless fights against room-induced issues. But this isn't a headphone review so back to the subject of speaker drive.