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Reviewer: Srajan Ebaen
Source: Zanden Audio Model 2000P/5000S; Opera Audio Reference 2.2 Linear
Preamp/Integrated: ModWright SWL 9.0SE; Music First Audio Passive Magnetic; Bel Canto Design PRe3; Wyetech Labs Jade; Supratek Cabernet Dual [on extended loan from owner]
EQ: Rane PEQ55 active merely below 40Hz
Amp: 2 x Audiosector Patek SE; Yamamoto A-08S; Canary Audio CA-308s; FirstWatt F3 & F1; Bel Canto e.One S300; Eastern Electric M-520;
Headphones: AKG K-1000 w. hard-wired Stefan AudioArt harness; audio-technica W-1000
Speakers: Zu Cable Definition Pro; Anthony Gallo Acoustics Ref 3.1
Cables: Zanden Audio proprietary I²S cable, Zu Cable Varial, Gede, Libtech and Ibis; Stealth Audio Cable Indra, MetaCarbon & NanoFiber [on loan]; SilverFi interconnects; Crystal Cable Reference power cords; double cryo'd Acrolink with Furutech UK plug between wall and transformer; Crystal Cable Ultra [on extended loan]
Stands: Grand Prix Audio Monaco Modular five-tier
Powerline conditioning: 2 x Walker Audio Velocitor S fed from custom AudioSector 1.5KV Plitron step-down transformer with balanced power output option; Furutech RTP-6 for 240V connection via Crystal Cable Reference
Sundry accessories: GPA Formula Carbon/Kevlar shelf for transport; GPA Apex footers underneath stand, DAC and amp; Walker Audio Extreme SST on all connections; Walker Audio Vivid CD cleaner; Furutech RD-2 CD demagnetizer
Room size: 16' w x 21' d x 9' h in short-wall setup, with openly adjoining 15' x 35' living room
Review Component Retail: $1,050 plus shipping from Belgrade/Serbia [ca. $200 to US and Japan]

Belgrade, situated in the Balkans at the confluence of the Sava and Danube rivers, is the capital of Serbia with about 1.6 Million inhabitants. It's home also to Dragan Solaja of Solaja Audio. His first -- transistor -- preamp dates back to 1987. Since then, he's evaluated numerous topologies and built various custom preamps and amps [some in faded background above]. All of 'em ended up as valved devices for which Dragan has developed a singular calling. Like many solder jocks before him, he's presently attempting a transition from expanding hobby to full-time business. Today's single-valve spudster, the SA-1 preamp with horizontally mounted 6N1P dual triode, is his first formal full-size entry for Solaja Audio and sells maker-direct.

The polarity-inverting, star-grounded SA-1's topology embraces minimalism inside and out. It's a single-ended zero-feedback Class A affair. It puts a 1.2V nickel-cadmium battery as fixed bias between cathode and ground. The 6.3V cathode heater supply is shunt-regulated, the non-regulated anode supply C-L-C-R-C filtered. We find Vishay-Roderstein MKP 1844 signal path capacitors and Mundorf MCap coupling capacitors. There's an RCD non-inductive anode load resistor, Cornell Dublier electrolytics on the anode supply's HF filter and an ALPS Blue potentiometer. There are two small two-sided circuit boards to house these few parts. The board with the valve is direct-coupled to the i/o ports for shortest paths. The power transformer is of the toroidal sort. Signal and power supply wiring are discrete kinds but both by Dutchie Van den Hul. Specs include an input Z of greater than 100K, output impedance above 1K, a high gain of 26dB and a claimed S/N ratio of >85dB. Four RCA inputs and one fixed and one variable output each adorn the basic back side - plus the ubiquitous power inlet of course. The fascia is equally subdued. It lacks a display, balance control, headphone output, HT bypass, IR eye or other concessions to creature comforts and complexities.


The Russian triode coded originally as 6H1Pi is usually labeled 6N1P, made by the Voskhod factory and available for as little as $6.95 from the usual suspects. It is generally regarded as a substitute for the 6DJ8/ECC88 - 6922/E88CC and 7308 family. While the 6N1P is indeed pin-compatible and of similar mu (35 instead of 33), mutual conductance, internal resistance and max anode voltage differ. Heater current is double in fact. This valve sports a larger cathode and higher plate voltage and dissipation ratings than a 6DJ8, "giving it longer life and more transient current capabilities" as per Svetlana's spec sheet. Audio Research uses 6N1Ps as driver tubes in the VS55 and VS110 power amps. They also show up in Bruce Bender's HeadWize OTL headphone amp and numerous Chinese tube kit.
Back to Solaja's preamp. Its open mission is as a lean and mean sonic fighting machine - no frills, no trills and priced to keep decent food in the fridge and the kids in college. Its target audience will be UK-trained to not automatically equate lack of size, weight, glitz and features with bad value or handicapped performance. Au contraire. Audio Lab, Exposure, Naim, Sugden and others have proven the real beauty of simplicity when it comes to demure and three-quarters empty black boxes of good-sounding, fairly priced integrateds. Would Dragan's preamp weigh in as single-mindedly on the aural front as it does so plainly on simplicity's side of the ledger? Instead of a postcard, Dragan sent something a bit heavier and bigger from Belgrade so we could find out.

What arrived was a tidy wooden box with a worrisome rattling inside. Both rechargeable batteries and the valve had come undone in transit to knock out the sleeved plastic shaft from the power switch, thankfully with the blue LED lead still attached. The usually flush-seated aluminum push button now poked through the fascia. Inner and outer holes between U-shaped chassis and face plate had misaligned in transit to where the power button did not want to fit through its dedicated opening again. Džafte kuravte!


Loosening the four inner fascia screws solved that and straightening out the bent tube pins allowed reseating the valve which seemed none the worse from the beating and fired up straightaway. Proper polarity for the batteries, as it turns out, is + left for the upper,  + right for the lower, not as first attempted and shown below. Talking to Dragan about my tattered transit tale, he committed to revising the power switch as a simple rocker relocated to the rear while the batteries will ship either uninstalled or get additionally secured with a quick-release latch.


Closer inspection of the preamp concludes that as compared to the equivalently priced made-in-the-US Quicksilver Audio tube linestage for example, Dragan's SA-1 isn't as nicely detailed yet. The two raw aluminum control knobs aren't recessed but flush-mounted with the requisite clearance to the face plate. Their little indicator points are marked with a dab of black paint whose application betrays DIY roots. The current power mains solution with its metal-on-metal button riding inside a mere fascia hole is somewhat inelegant in execution. The black chassis paint is fully adequate but not as refined as the one on my ModWright SWL 9.0SE. It seems nearly antagonistic to point out but the right Chinese imports in particular have fiercely raised expectations for appearance and workmanship in the value-priced sector. When faced by such competition, the SA-1 currently sells itself just a touch short in these departments. It's as though it hadn't quite shrugged off all memories of the iron curtain era yet. That's prior to listening, mind you.

On the feature front, the lack of remote isn't a deal breaker. After all, there are countless cost-no-object preamps whose designers cannot implement remote volume without sonic sacrifice. My $3,800 Wyetech Labs Jade is unremoted as well. And thoroughly unrepentant for it. Alas, I do feel somewhat differently about the lack of a second pre-out on the SA-1. I'm a member of the bi-amp club. I'd lose the fixed record out (these days nearly redundant) and double up on the variable outputs. That'd support subwoofers and my kind without enforcing Y connectors. So much for nits and initial transit woes. The preamp should be properly protected from the latter by the time you read this. Dragan was crestfallen by my experience and immediately set out to implement the necessary counter measures.



Nice audiophile details beside battery bias include the massive solid-core silver ground bus between rear panel and connector PCB that terminates inside the left rear footer chassis screw; high-quality RCAs that securely chassis-mount, their ends direct-soldered to the board to avoid flying leads altogether; path length between output valve and RCA outputs that's no longer than one AA battery; AC wiring that's nowhere close to the signal path; and one lone valve which will cost peanuts to replace and, based on the unintentional washing machine test of my unit, is impervious enough to even unusual physical abuse. It's quiet too - at my customary SPLs, pausing a CD elicited zero hum, hiss or surf over my potent 101dB speakers. With the usual hurdles cleared and Murphy's meddling with a new maker's nervous first review banished, it was time for show'n'tell.


Slipping into the big rig right behind the $8,000 Supratek Cabernet 'Dual' -- outboard power supply, tube rectification, tube regulation, direct-heated 101Ds for mid/treble, 6SN7s for bass -- the $1,050 SA-1 was obviously at a substantial disadvantage. Only a dreamer would not expect a reduction in performance intensity. And so it was. Bass quantity, bass impact and slammage reduced. Bass quality changed textures. Ultra-dimensional spatiality softened in wow factor. Everything became leaner, slimmer, less suffused by otherness and more matter of fact. I initially used somewhat higher SPLs to make up for this downscaling before acclimatization had me forget the differences. That's of course exactly as it should have been. Among other things, I lost an overbuilt power supply. If ever there was undeniable evidence for how audio signals modulate power supplies to be in the signal path, this was it. Clearly, raw drive softened. Overall dynamic pressure moved back. Bass transients grew less violent and overall textures dried up. This business of textures was especially relevant in the lower register. Its gestalt turned more solid-statish - colder, somewhat bereft of the combination of bloom and impact the Cabernet majors on.



Where the Serbian carves out a subjective advantage is depth of field. It seems to image deeper into the far shadows of the stage. A number of factors converge that make cause-and-effect connections less clear cut, however. By downsizing dynamics and mid to low-bass weight versus the far more expensive preamp, the SA-1 focuses on transparency. This manifests as clear openness, not on top to suggest a different treble balance but by hearing through things. Making the stuff between and around the notes less visible -- downplaying interactions with surrounding space -- the notes themselves become the thing. That moved my listening attention from context to content to seem like more overt transparency. It's a shift of attention, away from the ephemerals -- which cost serious coin to enjoy without parallel fidelity losses -- and onto the factuals.


Despite excessive disparity of price points then, the SA-1 was by no means embarrassed. It simply did without the extras whereby a rare device like the Supratek justifies its cost. The SA-1 is admirable on its own merit. Perhaps because its circuit is simple; perhaps because of those batteries replacing further parts; the noise floor is low. In turn, visibility is high. Additionally, the SA-1 is on the leaner and drier side for valves. That's especially true when you graduate from octals. In wine terms, the Serbian is not fruity like a Muscat from a tiny Cyprus village. It's more sprightly. Cooler. Even were the Muscat chilled, it'd be oilier and heavier than the SA-1's Sauvignon Blanc at room temperature.


The SA-1's overriding attributes are fleetness of foot; articulation; smoothness; and freedom from even subliminal blurriness. These qualities undermine the clumping action that entry-level tube amps tend to be guilty of. This machine is wonderfully passive then in how it avoids thickening and the intrusion of even mild opaqueness. There's that transparency factor again. It's very high indeed. Zero added warmth, zero cobwebs. This is particularly noteworthy in the bass. It lacks bloatedness yet is equally free from hyper articulation. Decays don't seem particularly lengthy, another aspect that probably plays into the cleaner/leaner, articulated/transparent equation.


Where the Solaja Audio preamp shows off its active nature compared to text-book passives is in superior gradations between soft and medium loudness; in more substance or fleshiness across the board; and in a mild texture on the notes. That texture is a very fine glistening, drier than outright glow but more sophisticated than just the bare-boned facts. Things aren't sterile. Yet enhancements are subdued in scope. It's more about fidelity, less about interpretation.


Rare tube preamps can be downright intense. The SA-1 isn't. It's a cooler operator. Others go for luscious and cuddly. The SA-1 completely stays clear here. Yet others are outer space hounds that stretch the soundstage laterally and front to back. The SA-1 elongates the depth domain and layers fairly. Some tube preamps inject air. There's a bit with the SA-1 but it's far too articulated and taut to ever go billowy. Most tube pres inject warmth to varying degrees. Compared to a passive, the SA-1 definitely does something. Yet it seems more subtle texture than warmth. After all, there's no reduction in transparency, no notable increase in density. Of course tube devices are about voltage swings. Microdynamics over the Serbian are alive though not as charged as over the Supratek or even the Wyetech Jade.



How about tone color? It's not an isolated attribute but related to others. Whenever it lacks, it becomes audible as paleness or whitishness. The SA-1 suffers none of it. Its subtle thermionic action fills out the palette of hues and gradations to be more about tone feel than outright color. Certain preamps add substantial weight at the bottom. The SA-1 does not. That'd likely require a more overkill power supply. In the bass, call the Solaja pre's behavior neutral yet admirably -- surprisingly -- controlled and delineated. Overall, I think mild blood thinner. It makes the music move forward on its own momentum, with just a deft touch of assistance. If to unclutter were more of a verb than it is, that'd be the perfect action to describe the SA-1's main contribution.


Comparisons. The ModWright SWL 9.0SE has more apparent drive. It's also weightier in the bottom though no more defined. Its macrodynamics peaks seem more enthusiastic and its presentation more vivid. Yet on balance, the overall gestalt of presentation is quite similar. Which is to say, not typically thermionic. The 9.0 sits at the knee of the sharply diminishing return line by what it's been formally compared against. For less than half its cost, the SA-1 gets within 90% of its sonics. It then takes away from cosmetics and tosses the remote. Depending on your priorities, that math could add up nicely. The Wyetech Jade somewhat eclipses the ModWright in tonal elegance and transient attack. It beefs up the build yet further, is even quieter but loses the remote again. As we know, the ascent up Mount Olympus gets progressively steeper and more punishing. Less and less oxygen, smaller and smaller steps; lower and lower returns for higher and higher financial pain. C'est la vie l'audiofille. Audio follies.


While admittedly demure in appearance and functionality, Solaja Audio's first entry for commercial consumer audio is a true performer. It suggests an emerging designer endowed with good ears who has whittled away on a core circuit until only that which is essential to him and true remained. If you value clarity, honesty, precision, speed and a smooth texture and have always wanted at least one tube in your system, the SA-1 offers exactly that. It's a well-aimed proposition at those who value simplicity and the promise of very low maintenance. And who cherish value (as though that word needed repeating by now)...
Solaja Audio replies:
First of all, I would like to thank you for reviewing the SA-1 preamplifier. After the initial trouble with the shipper's way of handling the package, (I hope it's the exception and not rule but I took the precautions necessary to prevent consequences of such handling in the future anyway), I was really glad to see that after you've put things back into place, the preamplifier worked fine. I really appreciate your effort in overcoming the problem.


Reading your listening impressions, I'm very glad that you've pinpointed the exact sound character that I wanted my SA-1 to have. Specifically transparency, speed, bass definition and fairly decent soundstage depth are the exact things that I hoped would be recognized as features of this circuit topology.


As for the aesthetics of the preamplifier and overall layout, I took your observations very seriously and redesigned it. I was worried that regarding the housing and certain other solutions, I might be too far on the minimalist side of the fence. So I made numerous improvements in the design instead of making it a Mark II model.


At exactly the same price, the new SA-1 will be in a completely new housing, with a sub chassis carrying all the parts inside and a very sophisticated powder coat finish. The power switch will be a reliable rocker switch on the back. As for the items that may detach in transit, the bias batteries will be secured under a small lid on the back so no opening of the unit will be necessary to change them and the tube will be kept in place with a tube fastener. I hope that with these improvements, the transport liabilities of the SA-1 will be a thing of the past.


As this is the first appearance of Solaja Audio in a formal review magazine, let me express my gratitude once more for your fair and honest review of the SA-1.

Sincerely,
Dragan Solaja
PS: Toward the end of October, Dragan submitted the above photos to document the changes he has implemented since the review. The power switch has been relocated to the back and now is a simple rocker switch. The batteries have gained their own outside compartment to eliminate having to remove the top cover or having the batteries come loose in transit. The small toroid now sits upright mounted to its own steel brace which further isolated the transformer's magnetic field from the circuit board. Lastly, the chassis finish has improved.


Kudos to Solaja Audio for receiving the review criticisms and suggestions in the intended spirit and implementing them to physically improve an affordable product whose sonics had already been highly commendable - Ed.
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