audio Viganoni - New Zealand

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sachem pure v.2 hi-end preamplifier

Please click here to read the very first review of the original sachem pure, made by Ashley Kramer on Witchdoctor hi-fi magazine.
the new sachem pure v.2 - black and silver versions - you can choose between the two different sets of knobs
The text below is partly taken from the owner’s manual supplied with every sachem pure v.2. It also includes notes that help explain the "philosophy" behind the pure and highlight technical and hi‑fi issues you will never read about in hi‑fi magazines or hear in a high‑end "temple".
Sachem pure v.2 is the new evolution of the original sachem pure, born from further research, new top-tier components, and a completely redesigned PCB. Unlike the previous version, it houses all electronics in a single enclosure with a clean, linear design, carved from solid aluminium bars, and machined to perfection. We still call it “pure” for the simple reason that no other adjective better conveys the distinctive qualities of its sound, design, and layout. Firstly, the sachem pure v.2 (hereafter referred to as pure) has no inherent timbre or sound. It is neutral, meaning it does not introduce or blend its own "sound" into the musical program. For a hi-fi designer, achieving this neutrality should be both a priority and a challenging objective. However, it seems many of them "forget" to give this parameter the consideration it deserves. Convinced that one of the key "secrets" to achieving an outstanding sonic reproduction lies in minimising the number of components in the signal path, we have designed an ultra‑minimalistic IC circuit. This design incorporates the most modern, high-performance, top-quality components in an ultra-clean layout. The logic and orderliness of the circuits eliminate the need for messy wiring, resulting in a completely wire-free preamp. Fully aware that voluminous preamps with messy wiring defy the principles of hi-fi electronics (regardless of exorbitant pricing, prestigious branding, or the glorious opinions of biased or incompetent reviewers), we have reduced the circuit dimensions to the bare minimum. We have also shortened and widened the signal and ground traces to reduce their electrical resistance. As a result, the specifications reveal that the pure establishes previously unheard-of benchmarks in preamp electrical measurements. Even though many audiophiles and hi-end "gurus" claim that electrical measurements are unimportant to sound quality, they are mistaken. Real hi-fi isn’t a matter of blind faith: it is grounded in physics, and those "numbers" are crucial, unless you want a preamp that behaves like an additional musical instrument, but ... that is the exact opposite of our target! On the other hand, many preamps and amps with excellent "numbers" don't sound well. This doesn’t mean the esoteric crowd is right; it simply suggests that these machines probably have capacitors in the signal path, and not exactly the best‑sounding ones, either. The capacitors have minimal impact on the "numbers", but they can adversely affect the sound's overtones and high harmonics, especially the electrolytic ones. In my opinion, this is the primary reason why you might encounter a preamp (or amp) with impressive specifications but not "celestial" sound quality. By now, you’ve surely figured out my “phobia” of capacitors in the signal path, since they’re the components that most affect and degrade sound quality. So, to stay faithful to our underlying technical principles, we made the pure signal paths completely capacitor-free! As far as I know, the pure is the only preamp with this feature, and it’s a major reason for its distinctive sweetness, unaltered overtones, lightning-fast response, "granitic" bass, and utterly uncoloured sound. The pure is highly resistant to external interference. However, thanks to its incredible frequency response (flat from 0Hz to 4MHz), if you live in an area saturated by radio frequencies and/or magnetic fields (two situations very rare in NZ), the pure could pick up some of them. In this case, we can try to prevent them by adding a small capacitance (47 pF) polystyrene capacitor into the circuit of each channel. This addition will limit the frequency response to 160kHz (-3 dB). The PCB is designed to accommodate these possible “intruders”, and the installation is simple, taking just a few minutes. Importantly, despite the addition, there will be no discernible sonic difference, as the selected capacitors have minimal capacitance and top sonic quality. The pure features an extremely low output impedance (8 Ω) and substantial gain, ensuring an ideal "marriage" with any main amplifier(s). The exceptionally low output impedance makes it possible to use long shielded cables between the preamp and the monoblocks without any deterioration of sound quality. This is paramount and safe for reducing the power‑cable length to the shortest possible run (always highly recommended). Another advantage of low output impedance is that the quality of the shielded cables connecting the preamp to the main amplifier(s) and/or a subwoofer becomes almost irrelevant, which turns into a welcome relief for your wallet! Following our minimalistic “philosophy”, the IC output goes straight to the output sockets, without any resistors or capacitors on the signal path. Surely, this is sonically great, but it leaves the ICs unprotected against short circuits in the output sockets. So, if you need to connect or disconnect any devices to the output sockets (OUT 1 and OUT 2), you must turn the power off and wait 20 seconds before acting. If you fail to follow this rule and any damage occurs to the ICs, the warranty will be void, and you will be responsible for the cost of replacing them. The power supply is a real beauty. It produces and delivers a wonderfully clean DC to feed the audio circuits. The purity of the DC is paramount for a “silky” reproduction of the high frequencies. This section features an oversized 15VA toroidal transformer, feeding twenty audio-grade, very low-impedance and ESR capacitors through a 6A full-wave bridge rectifier. The capacitor bank provides a total capacitance of 9,400 µF, with two high‑speed WIMA polypropylene capacitors (MKP10 series) connected in parallel with the main capacitors. To wrap up the technical details, all resistors, except those in the remote and delay circuits, feature “metal film” technology, with ±0.1% tolerance and a temperature coefficient of ±15 ppm/°C. For those less steeped in electronics jargon, this means perfectly identical channels and veeeery low thermal noise. Another interesting feature of the pure is the USB power supply socket on the back panel. It features a very pure DC (5V - 500mA), suitable for powering a transmitter dongle, which, when connected to the TAPE OUT socket of the v.2, will deliver the musical signal to any piece of wireless audio equipment in other rooms.
sachem pure v.2 - back panel
It's now time to explain how the pure, unlike other preamps, can correct and optimise the speakers' bass range. Bass range quality troubles (or rather, should torment) the vast majority of audiophiles, including those in the hi-end category. Indeed, “booming” bass is a "hallmark" of many expensive "dinosaur" loudspeakers, especially when positioned close to a wall or in a corner! It’s amusing to see the audiophiles (if and when they become aware of it) attempt to address the issue by investing in outrageously expensive, comical, and perhaps even "blessed" cables. However, the only truly effective way to resolve this sonic "horror" is by feeding the speakers a rolled-off signal, and that’s where the pure makes the difference! In fact, the pure has a built-in electronic high-pass filter, which is essential for rolling off and flattening the bass response in the speakers. This will also create a correct crossover point between a welcome subwoofer and the speakers, resulting in deep, clean, tight bass-infrabass ... free of “boom". Moreover, the main speakers' dynamic range will increase, and the distortion will decrease because their woofers will no longer struggle (with pathetic results) to reproduce the very low frequencies your active sub is much better qualified to manage. Image and clarity in the mid-high range will also improve, thanks to lower distortion of the whole bass range. The same happens to the power amplifier(s) and, whether tube amps, this will be a real invaluable gift to them! However, if you don’t trust me and fall into the crowd that (very wrongly) considers adding a serious active sub to the system a drawback, leave out the sub (for now), and connect the power amp(s) to the pure's OUT1 socket: now, start switching between flat and cut response (F and C on the back switch). You’ll likely be amazed by the transformation of your speakers when in C position! Even if the default roll-off of the pure (130Hz - Bessel) isn't the best for this job, it's already enough to make you realise the incredible potential of this facility! The booming disappears (or at least decreases), and the mid-high becomes clearer and cleaner. This way, you lose the pathetic infra-bass that floorstanders try to deliver, but the bass and the rest of the audio band become ... another story! This happens because the roll-off lowers the “bulge” in the frequency response between 100 and 200Hz, which is in the “DNA” of most of these speakers (without price limits) and causes booming. Anyway, for optimal results in this application, you should select a Bessel roll-off curve with the -3dB point between 130Hz and 250Hz, depending on the degree of "booming" in the speakers. If you're nearby, we can handle this for you, and with the help of the spectrum analyser, we can transform your system!
sachem pure v.2 - close view of the connections
Now, a word on this selectable and very versatile built-in electronic, second-order (12dB/oct) filter, which can be set up with either Butterworth or Bessel roll-off curves. The roll-off -3dB point is continuously adjustable, and its range depends on the type of curve: for the Butterworth curve, the range is 65Hz <-> 300Hz and for the Bessel curve, it is 90Hz <-> 400Hz. Furthermore, each channel is independent and can be set up with different roll-off points and curves. This feature is essential to integrate a sub(s) into the system properly, or for correcting the problems generated by speakers positioned asymmetrically, due to a room with a less-than-ideal layout (e.g. one speaker in a corner and the other in an open space, or just with a wall behind, etc.). In such cases, the left and right speakers will sound different from the mid-bass to infrabass. In this regard, please visit the school of hi-fi page and read the third article, which addresses this huge (normally neglected) problem and provides a thorough solution. However, it’s amusing, if not outright sad, to note how audiophiles focus on negligible details while overlooking paramount problems such as "booming bass" or the left and right speakers producing different sounds! Connections - The preamp output marked OUT1, depending on the position of the toggle switch on the back panel (F or C), respectively delivers a flat response or a rolled-off one; the output marked OUT2 is fixed and always delivers a flat, full-range response. So, if you have a subwoofer, connect the sub to the OUT2 and the main amp(s) to OUT1. If you need to use the rolled-off output (switching on C), please note that the pure leaves the factory with this filter set up for a -3dB crossover point at 130Hz and 12dB/oct Bessel curve. For example, if your speakers are not "booming" and your subwoofer is (hopefully) an Audio Pro, follow these simple steps: connect the sub to OUT2, the main amp(s) to OUT1, position the micro-switch on the back to C, set the sub's low-pass knob to 50Hz, and finally, adjust the sub's volume. That's it, and ... enjoy the sound! The pure features another interesting facility: the BYPASS option. This function is designed exclusively for owners of advanced home-theatre systems who also want the option to convert it into a hi-end stereo system. To illustrate, some users have a serious home-theatre setup consisting of a 5.1 receiver, a hi-end stereo amplifier (or ideally two monoblocks) driven by the receiver’s PREAMP OUT for the front channels, two high-quality main speakers, top-tier sub(s), and centre and rear speakers powered by the receiver’s built-in amplifiers. When they want to listen to stereo CDs, they select STEREO mode on the receiver. However, the preamp section in such receivers is typically not hi-end. It performs well and is more than acceptable for home-theatre applications, but falls short for hi-end stereo playback. Now, at last, they can solve this problem using a pure. You insert the pure between the receiver and the main amps, connecting the receiver’s output sockets (FRONT L and FRONT R) to the BYPASS socket of the pure and its OUT1 to the main amp(s); be sure to select F on the hi-pass micro-switch, because the position C doesn’t work in this configuration. So, if you want to listen to the 5.1, switch on the pure (compulsory) and select BYPASS: this way, the pure "doesn’t exist", and your home-theatre is exactly like before, but if you select any of the other three inputs, it’s now the turn of your receiver to drop out of existence, and you have a glorious stereo system! It looks very easy, and it is, but if you have a sub, it’s no longer quite so, and many different configurations can be considered.1) If you have a sub (or subs) already connected to the receiver, keep it/them, and the perfect, comprehensive solution is to buy another sub to connect to the pure, as explained before. This way, you have two completely independent systems with independent subs, too; furthermore, you can perfectly tune each sub to the respective system.2) In the case that you have two sachem v.2 (or v.3) or any other main amp with an incorporated crossover, you roll off the frequency response in them and connect the sub in parallel to the inputs of the main amp(s). Now connect the pure as in the previously mentioned system without the sub(s). In this setup, the systems share the sub(s), but that’s absolutely not a problem. However, if you adopt this solution, go to the receiver's “speaker set-up” menu and set the front speakers to “LARGE”, the subwoofer to “NO”, and the CENTRE and SURROUND speakers to “SMALL”. To finish, set the pure's filter switch (on the back panel) to F. These are two of the most common situations, but, as I said before, there could be many others. Anyway, I cannot consider them here, but don’t worry, there is always a solution: if anyone has any particular problems in this regard, I prefer to talk directly with them, so … just call me!
sachem pure v.2 - inside view
Now, let’s finally talk about what truly sets a pure apart from any other preamplifier: when you buy a pure, you’re actually getting not one, but two completely independent preamplifiers. You can switch between them in real time using the remote by pressing the button marked with the circular arrow, located just above the central mute button. To know which preamp is in use, it’s easy: when the second preamp is selected, a yellow LED on the front panel lights up and turns off when the main preamp is selected again. The main preamp features exceptional ICs and delivers top-tier performance, while the second preamp features ICs of a less prestigious pedigree. The most interesting and surprising (even for us) discovery has been that the sound difference between the two preamps is incredibly minimal. This confirms my theory that capacitors in the signal path, rather than transistors or ICs, are the real factors influencing the sound. The pure stands as its proof: it has no capacitors in the signal path, so what you hear is solely the "sound" of the IC itself, and when switching in real time, the differences are barely noticeable! Only when playing very complex, highly dynamic tracks (using my recordings) can one "venture" that the main preamp is slightly superior in clarity, with more precise bass and a better sense of depth. Anyway, to perceive these micro-differences, you need a truly superior system or an electrostatic headphone set. I don't want to sound arrogant, but I think that many of you won’t perceive any difference at all. However, being able to switch between two preamps in real time is useful for evaluating any future upgrade. It’s a fact that contemporary technology brings out on the market new astonishing electronic components every moment, so hi-fi machines become obsolete in quite a short time and this is the miserable end of the ordinary machines (no exceptions for the very expensive ones too), but the pure does not belong to this category and your preamp was thought out so that it will last a long, long time. Indeed, you can upgrade it at any time, spending peanuts! The preamp’s "heart" lies in its ICs, so if a better one comes on the market, you can buy two of them and have them fitted into the second preamp. Then, switching in real time between the main preamp and the upgraded second preamp will help you determine, beyond any doubt, whether there's any real difference and whether the game is worth the candle. Replacing the ICs is quite straightforward, but we strongly advise against doing it yourself! We’re more than happy to handle it for you, free of charge. We also need to ensure that the new ICs are "stable" and don’t introduce any issues like self-oscillation. Anyway, at this point, you have probably realised that by buying a pure, you don’t buy “a preamp”, but an advanced machine, capable of continuous evolution! Speaking about the ICs, the ones used as standard in the main preamp are the result of a personal decision. In my view, they are currently the best option on the market. With my live recordings, they deliver an astonishingly natural sound: a perfectly dimensional rendering of the instruments, with precise performer localisation and a stable soundstage. The bass is tighter, faster, and deeper than anything I’ve heard before, and the high frequencies are silky, ethereal, and incredibly refined, preserving all the original high-order harmonics and overtones. It’s no coincidence that I also use them in the preamp-crossover-mixer of my recording system. Changing the subject, someone has surely noted that I haven’t equipped the pure with balanced inputs and outputs. To me, balanced connections in home audio are just another bait-and-switch scam for credulous audiophiles. I intentionally omitted them because, in a truly hi-end system (if free from any induced noise), I believe it’s better to avoid balanced lines unless the machine is fully balanced. But ... can you tell me how many machines with all the circuits completely balanced exist on the market? So, when faced with the choice between balanced and unbalanced sockets, and the machine is not completely balanced, my recommendation is to use the unbalanced ones, as they provide the "original and true" sound of the machine! Wondering why? Head over to the school of hi-fi page, and you'll find a comprehensive article on this topic. After that, you will fully understand why I didn’t fit the pure out with balanced options. In any case, I can say in advance that it’s because I wanted to keep the signal path completely capacitor‑free and continue calling my “creature” pure.
sachem pure v.2 - front and top view
Looking after the pure is easy: avoid placing the cabinet in direct sunlight (particularly the black version) or in a damp place. It’s also advisable to keep the pure away from Wi-Fi transmitters or extenders to avoid potential interference. We hope you now feel ready to use and care for your pure. So, press the power switch and … silence! No need to worry, the delay circuit is doing its job. Just wait nine more seconds, and you'll be rewarded with the pure’s ... pure sound! We are confident that you will notice and appreciate the improved performance of your system! However, it’s important to realise that the pure won’t work miracles. Rather, it will ruthlessly expose any weaknesses in your hi-fi chain. Likewise, its full potential may be overshadowed by any component in the system that lacks selectivity, speed, or clarity. Unfortunately, a sobering reality in the hi-fi world is that a system's final sound is shaped more by its weakest component than by its finest. So, until all the components in your system match the calibre of your new preamplifier, the pursuit of sonic perfection will remain partly unfulfilled. Please feel free to contact us if you need any assistance or advice regarding the installation or use of our products, or if you have any questions! A note about the name: “sachem” (pronounced seɪtʃəm) refers to an elected paramount Chief of American Indian tribes in northeastern North America. The word originates from the Algonquian language of a tribe that lived near Lake Michigan. The Native Americans also used the epithet “sachem” as an honour for a senior warrior who had distinguished himself with particular merits. My heartfelt thanks to my dear friends Rino Cieri and Allen Gill, who also designed the remote-control circuit. They are exceptionally talented technicians and have often helped me resolve serious problems. Additionally, my gratitude goes to Kevin Munt, who machined the cabinets to perfection.

specifications (main preamplifier)

NOTE: the parameters in RED are paramount, but usually omitted in the specs of preamps. Nominal input sensitivity 200 mVInput impedance (referred to the IC) 5 x 10¹¹ ΩOutput impedance 8 ΩSlew rate (Rload = 1 kΩ, G = +1) 140 V/μsBandwidth @ 0dB DC ~ 4 MHzPhase deviation DC ~ 2 MHz 0ºTHD (Total Harmonic Distortion) at 1 kHz 0.00003 %Input voltage noise (referred to the IC) 12 nV/√HzSettling time to 0.1% (0V to 10V Step, Av = -1) 150 nsGain 12.55 dBHi-pass filter slope (Bessel or Butterworth) 12dB/oct @ xxx HzSignal-to-noise (inputs shorted) NO audible noiseCross-talk between adjacent inputs (second input shorted) NO audible cross-talk Cross-talk between L & R channel (second input shorted) NO audible cross-talk USB power supply socket 5V DC - 500mAOverall dimensions (W-D-H) 400 - 260 - 70 mm Shipping dimensions (W-D-H) 510 - 360 - 170 mmShipping weight 5.2 kg
sachem pure v.2 is on display at the following dealers:
Leonard Lucas - Auckland Signals - Auckland HiFi Auditions - Hamilton Tone Electrical - Paraparaumu (you'll find their contact details on the partners page) PLEASE NOTE: If you're outside the coverage area of our local dealers, feel free to contact us directly. We'll try to find an alternative way to let you experience the sachem "difference".