SWISSONOR  AM

|  Modular Tube Amplifier Series  |

A CAREFULLY SELECTED LINE OF AMPLIFIERS AND PREAMPLIFIERS

DESIGNED AND BUILT WITH GREAT CARE AND ATTENTION TO DETAIL

 

TRUE TESTIMONIES OF THE SWISS TRADITION OF TIMELESS

DESIGN AND UNCOMPROMISED QUALITY

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HAND MADE - PRODUCT OF SWITZERLAND

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General Intro

This unique modular amplifier system is a 100% tube design, and allows you to get exactly the configuration you need, at the highest quality level and with the best sound possible today.

 

Combining a choice of pre- and power amplifiers on a common mechanical mainframe, the A.M. System cannot only compete with separate components, but outperforms them due to the following physical and electrical advantages :

 

Circuit & General Construction

 

  • Shortest signal path, connectors and cables used for connecting separate components are eliminated.

  • The design eliminates impedance and gain mismatch and reduces the number of active circuits.

  • The oversized common power pack has five separate secondary windings and three voltage regulators.

  • Separate ground wiring together with central ground connection and ground lift for best signal purity and lowest hum and noise.

  • Multiple mechanical suspensions thru damping blocks separate the different elements mechanically and electrically. Between power transformer and RIAA amplifier for example, vibrations are filtered not less than four times!

  • The system's frame is cast from the same austenitic iron alloy as used for the famous swissonor#1 non-magnetic platter for Thorens TD124 .

  • Together with the insulated module front plates, milled from 5 mm aluminium, the design guarantees freedom from vibration, magnetic induction and eddy currents usually found in classical enclosures.

 

Available module blocks

 

Power pack = 1 x Module AM1 ... for one preamplifier and two power amplifier modules, using a vacuum valve as high- voltage rectifier.

 

Power amplifier modules =

  • 2 x Module AM2 : Push-Pull with 6V6 beam-power tetrodes in Ultralinear mode (10W/channel)

  • 2 x Module AM3 : Single Ended 6B4G triode (3,6 Watt/channel)

  • 2 x Module AM4 : Single Ended 300B triode (8 Watt/channel)

  • 2 x Module AMX : Single Ended PX25 triode (6 Watt/channel)

 

Preamplifier modules

  • 1 x Module AM5 : Passive Preamp with four line inputs and line transformers providing +3dB and +9dB gain.

  • 1 x Module AM6 : RIAA / Tube Preamp with 2 phono and 3 line inputs. Optional Hashimoto step-up transformers --  1 or 2 low impedance moving-coil-phono cartridges can be operated simultaneously.

 

Swissonor AM 1 Module.jpg

A.M. 1 = Power Pack module for one preamp and two power amplifiers

 

Goals

  • Stable and precise power pack for two power amplifiers and one preamplifier

  • High voltage rectification with vacuum tube, for subjective reason Security and stability

 

Design

  • Combined Schurter 10A IEC device plug/fuse holder/switch

  • Separate ground-lift switch eliminates earth loops, when necessary

  • Huge, resin-filled power transformer with 5 (!) secondary windings

  • High-voltage rectification with a high-current vacuum tube. Mundorf TubeCap Loading capacitor.

  • Oversized 14H/200mA high-voltage choke. Resin filled Long life, low ESR 105 oC capacitors.

  • C-L-C feed for the output stage with local polypropylene capacitor decoupling.

  • Regulated high voltage output for preamp and phase shifter, with local polypropylene capacitor decoupling.

  • Two separate regulated DC heating circuits for preamp and drivers, AC heating for output tubes 1% Metal-Oxide-Resistors and other selected high-grade parts.

  • Double face Zinkor- PCB (zinc-gold-alloy) , hand-soldered with Cardas silver tri-eutectic alloy.

  • Final check after 12 hour burn-in.

 

This module drives one AM5 or AM6 preamp module and two AM2, AM3, AM4 or AMX power amplifier modules. All connections and operational elements are on the top plates, which is ideal for placement next a disc player, for example.

Swissonor AM 2 Module.jpg

A.M. 2 = 6V6 PP- power amplifier module with 10 watts output (per channel)

 

Goals

  • Use of very reliable 6V6 low power tetrodes in UL circuit, resulting in extremely low amounts of high order distortion, very unpleasant for your ears.

  • No overall negative feedback at all.

  • Only three active stages, from the passive preamp to the output The 6V6 has good input sensitivity and therefore needs no additional driver stage, thus the final result is superior to what can be achieved with less sensitive medium to high power tetrodes such as 6L6, KT66, 6550, KT88.

  • Output power of 10 W per channel, optimised for speakers with a sensitivity from 92 dB (1W, 1m) up.

  • Extremely stable when driving real loudspeakers loads with UL mode and zero overall negative feedback.

 

Design

  • Preamplifier and phase inverter/driver stage using one ECC81 valve (compatible to 12AT) in a bootstrap circuit for high symmetry, extended bandwidth and low output impedance.

  • Optionally available on order with slightly different circuit using E88CC valves, with 4dB less gain.

  • Regulated high voltage line, stabilised with a dedicated Mundorf polypropylene capacitor for the phase shifter and the driver.

  • Regulated and stabilised DC heating for the phase shifter and the driver.

  • 6V6 beam power tetrode (compatible 6V6G, 6V6GT, 6V6GTY, 6V6Y, 5871, 7184 and others)

  • Ultralinear-circuit in AB1-mode combines the advantage of tetrode and triode modes (load driving capability, distortion, damping factor).

  • Perfectly symmetrical output transformer with 14 distinct windings on M85 core made from heat treated M111 oriented grain core.

  • Optimised mass- and signal paths.

  • High grade Mundorf and SCR polypropylen condensers

  • 50 ppm 1% Metal-Oxide-Resistors, 105oC low ESR long life condensers and other selected high-grade parts.

  • Double face Zinkor- PCB (zinc-gold-alloy), hand-soldered with Cardas silver tri-eutectic alloy

  • Final check after 12 hour burn-in

Specification

  • Output power :   10 Watt each channel at 8 Ω

  • Input impedance :  100 kΩ

  • Input sensitivity (E88CC) :  560 mV

  • Input sensitivity (ECC81) :  360 mV

  • Power bandwidth :  15 Hz to 60 kHz +/- 2 dB (without NFB!)

Swissonor AM 3 Module.jpg

A.M. 3 = Single Ended 6B4G (~2A3) power amplifier module with 3.6 watts output (per channel)

 

Goals

  • Implement one direct heated 6B4G Triode in SE class A circuit due to the extremely linear behaviour and finest music reproduction.

  • No overall negative feedback at all.

  • Optimized preamp/driver stage

  • Output power of 3 W per channel, optimised for speakers with sensitivity from 95dB (1W, 1m) up.

  • Stable when driving real loudspeakers loads with triode mode and zero overall negative feedback.

 

Design

  • Preamp/driver stage using ECC 81 Triode (compatible 12AT7) in a bootstrap circuit for high gain, extended bandwidth and lowest distortion.

  • Regulated high voltage line, stabilised with a dedicated Mundorf polypropylene capacitor for the preamp/driver.

  • Regulated and stabilised DC heating for the phase shifter and the driver Sovtek Single Plate 6B4G (compatible 6C4C) in pure Class A single Ended design.

  • Heating of each output tube with separated 6,3V DC, using a Schottky diode rectifier, low drop regulation and stabilization.

  • Output transformer with 9 distinct windings on M102 core made from heat treated M111 oriented grain steel, resin filled.

  • Optimised mass and signal paths.

  • Local stabilisation of cathode resistor and filament with polypropylene capacitor.

  • 50 ppm 1% Metal-Oxide-Resistors, 105oC low ESR long life condensers and other selected high-grade parts Double face.

  • Zinkor- PCB (zinc-gold-alloy) , hand-soldered with Cardas silver tri-eutectic alloy

  • Final check after 12 hour burn-in

 

Specification

  • Output power :   3.6 Watt each channel at 8 Ω

  • Input impedance :  100 kΩ

  • Input sensitivity (ECC81) :  940 mV

  • Power bandwidth :  15 Hz to 75 kHz +/- 2 dB (without NFB!)

Swissonor AM 4 Module .jpg

A.M. 4 = Single Ended 300B power amplifier module  with 8 watts output (per channel)

 

A.M. X = Single Ended PX25 power amplifier module  with 6 watts output (per channel)

Goals

  • Implement one direct heated 300B or PX25 Triode in SE class A circuit due to the fantastic soundstage illumination.

  • No overall negative feedback at all.

  • Optimized preamp/driver stage for the extremely demanding 300B driving.

  • Output power of 8 W (300B) / 6W (PX25) per channel, optimised for speakers with sensitivity from 92dB (1W, 1m) up.

  • Extremely stable when driving real loudspeakers loads with triode mode and zero overall negative feedback.

 

Design

  • Preamp/driver stage using a ECC 803 Triode (compatible 12AT7) in μ-follower circuit for highest gain and output voltage, extended bandwidth and low distortion.

  • Regulated high voltage line, stabilised with a dedicated Mundorf polypropylene capacitor for the preamp driver.

  • Regulated and stabilised DC heating for the phase shifter and the driver.

  • EH Gold Grid 300B or Full Music PX25 tube in pure Class A Single Ended design. Other tubes on demand.

  • Heating of each output tube with separated 5V DC, using a Schottky diode rectifier, discrete Darlington regulation and stabilization.

  • Output transformer with 9 distinct windings on M102 core made from heat treated M111 oriented grain steel, resin filled.

  • Optimised mass and signal paths.

  • Local stabilisation of cathode resistor and filament with polypropylene capacitor.

  • 50 ppm 1% Metal-Oxide-Resistors, 105oC low ESR long life condensers and other selected high-grade parts Double face.

  • Zinkor- PCB (zinc-gold-alloy) , hand-soldered with Cardas silver tri-eutectic alloy

  • Final check after 12 hour burn-in

 

Specification

  • Output power :   8 Watt (300B) / 6W (PX25) each channel at 8 Ω

  • Input impedance :  100 kΩ

  • Input sensitivity :  600 mV

  • Power bandwidth / 300B :  35 Hz to 75 kHz +/- 2 dB (without NFB!)

  • Power bandwidth / PX25 :  20 Hz to 75 kHz +/- 2 dB (without NFB!)

Swissonor AM5 Line Pre Module.png

A.M. 5 = Passive Transformer Gain Preamp module 

Goals

  • Highest sound quality with Gain amplification via step-up transformers.

  • Shortest signal paths.

  • Cabling and operation on top side, ideal for placement next to other equipment.

 

Design

  • Input selection by totally closed double relays, positioned directly at the input socket.

  • Pair of very high quality 1:1,5 / 1:3 encapsulated input transformers.

  • Gain selector +3 / +9 dB.

  • ALPS blue power attenuator.

  • Double face Zinkor- PCB (zinc-gold-alloy) , hand-soldered with Cardas silver tri-eutectic alloy.

 

Specification

  • Input impedance :  45 kΩ (+3 dB), 11 kΩ (+9 dB)

  • Gain :  +3 dB or +9 dB switchable

  • Bandwidth :  11 Hz to 85 kHz -3 dB

Swissonor AM6 Tube Phono Stage Module.png

A.M. 6 = RIAA preamplifier module with 2 phono and three line inputs

Goals

  • Highest sound quality through a no compromise full-tube design.

  • Shortest signal paths.

  • High output voltage of the RIAA stage, eliminating the need for additional active line amplification stages.

  • Use of MM and/or MC phono cartridges.

  • Flexibility due to separate PCB for RIAA circuit, plugged into the line preamplifiers PCB.

  • Cabling and operation on top side, ideal for placement next to other equipment.

 

Design

  • Input selection via totally closed double relays, positioned directly at the input socket.

  • Additional relay for phono switching.

  • Optional integrated Hashimoto step-up transformers (choice of HM-3 or HM-X, or HM-7 with 3Ω or 12 Ωinput impedance for use with low impedance high-end phone cartridges such as the Ortofon SPU type.

  • Phono preamplifier with symmetrical circuit and separate symmetrical ground lines for lowest noise.

  • 3-stage RIAA preamplifier/equalizer (based on Marantz 7 circuit) using three ECC83 triodes (compatible with 12AX7, E83CC, ECC 803).

  • Regulated high voltage line, stabilised with dedicated Mundorf polypropylene capacitors for each stage.

  • Regulated DC heating, stabilised.

  • ALPS blue power attenuator, 1% 50ppm Metal-Oxide-Resistors, silver/mica and Styroflex condensers and other selected high-grade parts.

  • Double face Zinkor- PCB (zinc-gold-alloy) , hand-soldered with Cardas silver tri-eutectic alloy.

  • Final check after 12 hour burn-in.

 

Specification

 

Phono section :

  • Input impedance : 47 kΩ (Optional 3Ω or 12Ω)

  • Gain (without step-up transformer) : 43 dB

  • Input sensitivity (without step-up transformer) : 7 mV for 1 V (1kHz)

  • Distortion at 2V Output voltage : 0,01 %

  • Signal-to-noise ratio at 2V : >88 dB

MC-section (optional) :

  • Step-up Hashimoto HM-3 / Gain : 26 dB (12Ω) or 32 dB (3Ω)

  • Bandwidth : 15 Hz to 50 kHz +/- 1 dB

  • Step-up Hashimoto HM-X / Gain : 23 dB (12Ω) or 29 dB (3Ω)

  • Bandwidth : 15 Hz to 100 kHz +/- 1 dB

 

Line section :

  • Input impedance : 100 kΩB

SWISSONOR AM Series Pricing

 

SWISSONOR AM 5221  /  2 x 6V6 Power Modules + 1 x Line Preamp Module

Price    $ 9,400

SPECIAL OFFER  (valid until end 10/2021)   $ 8,550 

 

SWISSONOR AM 5331  /  2 x 6B4G Power Modules + 1 x Line Preamp Module

Price    $ 11,250

SPECIAL OFFER  (valid until end 10/2021)   $ 10,225

 

SWISSONOR AM 5441  /  2 x 300B Power Modules + 1 x Line Preamp Module

Price    $ 13,450

SPECIAL OFFER  (valid until end 10/2021)   $ 12,225

 

SWISSONOR AM 5XX1  /  2 x PX25 Power Modules + 1 x Line Preamp Module

Price    $ 13,450

SPECIAL OFFER  (valid until end 10/2021)   $ 12,225 

 

RIAA MM Phono Stage Options  / Replace Line Module with all-tube AM 6 RIAA Stage 

Price    $ 1,100

 

RIAA MC Phono Stage Options  / Add Hashimoto SUTs to AM 6 MM RIAA Stage

Price - Hashimoto SUT HM-3    $ 1,000

Price - Hashimoto SUT HM-X    + $ 1,650

Price - Hashimoto SUT HM-7    + $ 1,975

What they say ...

 

 

Fidelity Online (Germany)

by ROLAND KRAFT | February 28, 2016

The word "modular" (as in in Amplificateur Modulaire) is to be understood here as meaning that an amplifier set is put together in a customer-specific manner and built into a heavy non-magnetic cast frame. The AM6441 is - and this explains the cryptic name - made up of a power supply unit called AM1, two single-ended 300B power amplifiers called AM4, and a matching phono stage AM6, which has two phono MC and three high-level inputs. Instead of the phono stage, a module with a passive high-level pre-stage (AM5) could also be used. So, with the help of the preamp modules, the 300B and its power supply unit become an integrated amplifier.
 

Each of the modules is built on a five millimeter thick aluminum plate, which is resiliently decoupled and sits in the cast frame with rather massive screws ... sheer mass is the guarantee that neither transformer nor electrolytic capacitor vibrations can spread. Even the tube sockets are mounted with rubber bearings, which experience has shown to be one of the best recipes for combating microphonic problems. If you look very closely, you will also discover that the mains transformer and transformer are not simply screwed directly onto the chassis, but rather mounted in isolation, one of the many little secrets of hum-free design (transformers should only have ground or earth contact at one point or screw).

 

And because the topic is so important, especially when working in a team with "loud" speakers, let's stick with the "signal-to-noise ratio" - the so-called signal-to-noise ratio. In this regard, the Swissonor is awe-inspiring. Even with a 96 dB loudspeaker, not the slightest hum can be heard, not even with the level control fully turned up in Phono-MC mode ! In addition, there is extremely low residual noise. Wish everyone would imitate the Swiss !

 

Pre-stage instead of Phono Stage

Incidentally, the term “phono stage” doesn't quite apply to the AM6 : Rather, it is a complete preamplifier, the inputs of which are all switched via relays directly on the socket panel. Two pairs of phono sockets can also be selected via a switch, fine Hashimoto transformers are used in the MC version before a phono stage built in the style of the legendary Marantz 7 circuit takes over the RIAA equalization.

 

Obviously responsible for this are first-class double triodes ECC803S (JJ) and a 12AX7WS from Sovtek. The Hashimoto SUT is optionally available in three versions, one of which is ideally suited for low-resistance, "quiet" SPU-type cartridges. An MM input is of course also possible as an option. Below deck there is - perhaps contrary to the expectations of this machine - no point-to-point wiring, but rather circuit boards with zinc / gold conductor tracks, which are processed using Cardas silver solder. Stabilized anode voltage and regulated heating voltages are a matter of course, as are excellent components, such as lots of Mundorf capacities. The connection to the power amplifier wing is “underground”, which means that the input sockets of the two 300B modules remain idle.

The Path to Full Music

 

The two mighty 300Bs immediately catch your eye - these are 300B / n by "Full Music" from TJ with mesh anodes and "pear" glass bulbs ... magnificent pieces that are controlled by a 12BZ7. And yes, admittedly, Western 300Bs cannot keep up with that in terms of purely aesthetic technology.

 

Urs Frei opted for a so-called "μ-follower" circuit for the 12BZ7 driver stage, which guarantees low distortion, high bandwidth and low output impedance. This technology is by no means found every day in mass-produced single-ended devices ... As far as the transformer is concerned, the Swiss relies on a nine-fold nested winding on an M102 core, consequently only equipped with a secondary winding. In plain language this means that only an eight-ohm tap is available on the loudspeaker side, other impedances can be ordered at no extra charge. This is consistent, because output transformers with several secondary taps are by no means better, but are subject to compromises.

 

The well-known critical direct heating of the 300B received a similar amount of attention. Here, a discretely constructed direct voltage heating regulated by Darlington transistors is used. The anode voltage for the driver section is also regulated, the heating voltage is also stabilized - electronically, this is a "modern" approach to a 300B amp, quite in contrast to the numerous retro concepts whose representatives, for example, outlaw voltage stabilization as pure blasphemy. Experience has shown, however, that one shouldn't make religion out of the different approaches straight away, but consider the individual case.

 

A largely undisputed audiophile commonality are of course whole batteries of high-quality polypropylene capacitors at critical points of the amplifier train, and in this regard the Swissonor tube amp is no exception. Incidentally, often unjustifiably highly praised retro components cannot be found in the amp. Except for the beautiful black "Chickenhead" knobs, yes! 

 

 

New Fashion?

 

Despite the newfangled control technology, the AM1 supply module contains a good old transformer with five secondary windings, a rectifier tube of the type 5U4G and a bulky, encapsulated 14 Henry sieve coil together with a Mundorf “tube cap” as a charging capacitor. The CLC filtering in the power supply unit (it consists of high-quality, temperature-resistant electrolytic capacitors with a long service life) is once again supported in the respective modules by film capacitors. To “fiddle” with the type 5U4G tube used “for subjective reasons” - as the Swiss put it - would not be a good idea; less powerful rectifiers might have problems supplying the powerful device. The "Ground Lift" switch on the back of the power supply module also serves to eliminate residual hum, but is not really used much in practice. 
 

 

Subjective impressions

With regard to the Swissonor “construction quality”, let me perhaps add a few more subjective impressions ... no, not yet about the sound, but rather about the way in which this device - not only for me - was received. Here you have that seldom occurring feeling of correctness, of absolutely trustworthy solidity and a price-performance ratio that allows the work of art and the customer to go home satisfied with each other. The whole design of this extremely impressive amplifier speaks for itself. For example, the chassis is more reminiscent of mechanical engineering than of entertainment electronics.

 

And, by the way, a measurement, test and equipment protocol that is probably drawn up with typical Swiss meticulousness also contributes to the overall impression : The document “Control final and configuration de l'appareil SE 300B” is signed and enclosed with the “apparatus”.

 

However, one thing I have so far wrongly withheld from you : In the meantime, Swissonor also offers small cast chassis for individual (preamplifier) ​​modules. In addition to the amp, we also had the passive “transformer preamp” AM5 available, which is equipped with a set of relay-controlled high-level inputs, two step-up transformers and a level controller. With a choice of plus three or plus nine decibels gain factor on the transformers, I was immediately impressed by this little passive solution, because somehow the story "locked" in place immediately, when working as a team with an AcousticPlan DAC, the unbelievable Einstein phono preamp and various tubes - No eye stayed dry for power amplifiers. More is not yet revealed, because the Swissonor AM5 undoubtedly deserves its own story.

 

... Now, back to the 300B integrated amplifier, on which the loudspeaker connections still deserve a mention : Insulated banana sockets instead of fashionable fat pole terminals, is the understatement motto - with which I deeply agree. With proper banana plugs, perfect electrical contact is guaranteed, and the annoying terminal fiddling is no longer necessary. Sure, real tweaks like to choke monstrous welding clamps with the pliers (and finally off), but sound improvements are definitely not achievable in this way. That should put an end to the complaint, because I have nothing to criticize about the amplifier. Or maybe I do ... namely, the fact that this beautiful piece will be delivered to its new owner in the next few days ... and unfortunately it is not me.

 

Therefore, do not regard the following as judgmental - because a place on the winner's podium is already certain - but rather as simply descriptive : 

I like to roughly divide such amps into two categories :

  • Casual, rather muscular “gliders” who nonchalantly ignore one or the other tiny detail ...

  • ... and more meticulous "gentlemen" who indulge in delicate, almost floating sound webs with relish (sorry, if I'm prosaic become).

 

The Swissonor is more of the latter, clearly pointing in the clear, slim direction, but without the skeleton becoming immediately visible. Its vocal presentation is opulent, colorful and wonderfully focused and devoted to the finest accents in front of a horizon-wide spatial background - so fascinating, so detached and so tangible, as one could wish.

 

This amplifier exhibits a thoroughly “audiophile” precision, which would normally not be ascribed to a 300B... a precision accompanied with unusual intensity and speed, with light-footed, springy dynamics ... instead of massive, large-caliber ones.

 

 

Magical potential

This sound also has magical potential, appears completely natural, timeless, and it pulls the listener under its spell without immediately waving the candy bowl. The Swiss construction remains as supple as oiled silk. The performance comes across with a "perfectionistic" touch in places, has enough radiance and tension, and  does not lose - as is so often the case - intensity and speed.

 

Even with whisper-quiet passages, this amp can still play touchingly, the picture even gets wider and deeper, no definition is lost. The focused connoisseur learns to ultimately appreciate the silence more than the storm ...

 

But for all of this, you really need a "real" loudspeaker which reacts without delay to the slightest touch of electrical voltage ... the use of such a speakers with the Swissonor will negate any "old experiences and prejudices" one may have had.

LP Magazin (Germany)

by HOLGER BARSKE | Issue # 3, 2011

Who invented it? The Swiss, of course. In this specific case, Urs Frei from Swiss company Swissonor, a small but fine manufacturer located in Geneva region, not far from the French border. Initially active as supplier, they developed and produced a non magnetic cast iron platter for another ancient familiar Swiss product, the legendary friction-wheel driven Thorens TD124. To follow-up the sustained demand, a specific company for spare- and upgrade parts and other special equipment was founded.

 

Concept

 

This effort resulted in a worldwide unique amplifier concept in full tube design, the “AM System”. The base is a support frame receiving four modules, building an integrated amplifier tailored for individual needs. Actually, there are six modules available :

  • The power block AM1 constitutes the basic operating element, available in power-amplifier-specific. There is a choice of four power amplifier modules : 

  • The component under test in this issue contains a pair of the most powerful module named AM-2, based on a 6V6 in push-pull, which provides 10 Watts per channel in an exclusive way.

  • Alternatively, the customer can choose the single-ended AM-3 based on the 6B4G tube, a close cousin to the well known 2A3, and offering 3.6 Watts per channel.

  • The third module named AM-4 is based on the “inevitable ”300B", with an output power or 8W.

  • And finally, the AM-X which sports the PX25 tube delivering 6W.

 

As for the preamplifier module, there is some choice here as well.

  • The AM-5 module is a purely passive transformer preamplifier for line sources exclusively ...

  • And the AM-6 has a configurable full-tube MM phono stage with two phono and three line inputs. Optional Hashimoto SUT for MC are available.

 

 

The AM 6221

 

Our test component's name is the “AM6221”, the number indicates use of one power pack (1x AM-1), two push-pull 6V6 power amplifiers (2x AM-2) and the one MM/MC phono preamplifier (1x AM-6). Our phono preamp is configured with one MM input and a MC input using the optional Hashimoto HM-3 MC SUT transformers.

 

Adding all these modules and options to the "package", the final price adds uo to about 11’000 EUR. Not cheap, but this is real Swiss handcraft and is not available everywhere.

 

Let’s begin by looking at the chassis frame design : This is nothing less than a "complex casting" out of a non-magnetic cast iron alloy. The cost / investment parameters of this approach are very different from screwing together a number of metal sheets ... very ! On this "lead-like" heavy support, the modules are screwed whilst respecting careful decoupling requirements.

 

The power block module is basically situated on the right hand side of the chassis' frame. The solid power transformer, individually decoupled and damped, has five secondary windings delivering the raw voltages, where the high voltage is rectified by a tube (here a GZ34), is then filtered by a massive choke (the second heavy transformer-like block on the AM-1 plate), and by-passed by a special Mundorf foil capacitor. The power supply rails for driver and preamp are separately stabilised and filtered. Even the heater current supplies enjoy separate electronic "attention".

 

This is definitely a luxury concept, and can only in very few aspects be viewed as a Vintage design. Rather, this is a most modern amplifier solution.

 

The power amplifier is a feedback-free design based on the sturdy 6V6 tube, a tube that is less demanding on loudspeaker performance than the three single-ended designs. The manufacturer recommends the use of loudspeakers with an efficiency of 92 dB (1W) and higher, but our experience proved that far lower efficiencies are possible too. Notably, such efficient loudspeakers can be found in Swissonor's product portfolio (Swissonor B.A.C.H. Series).

 

Thanks to the highly sensitive power tube, the amplifier is electrically “short”, needing only one ECC81 double triode type as phase splitter and driver. An alternative variant uses the ECC88S (with 4 dB less gain).

 

The output stage works in ultra-linear mode, and the output transformer with its 14 windings is a real piece of splendour. As with all other modules, a gold-plated PCB constitutes the base of the electrical circuit. The AM-6 RIAA module hosts a phono preamplifier based on the good old Marantz Model 7 circuit, making use of three ECC83 double triode tubes. The phono section’s 43 dB gain is comfortable for all moving magnet cartridges, while a pair of Hashimoto step-up transformers bring the additional gain required for low output cartridges. Swissonor offers a choice of three SUTs : HM-3, HM-X and HM-7.

 

Genuine chicken-head knobs serve as input switch and volume control on the module’s top plate. The placement of all input sockets on the top is a fine choice and facilitates largely the setup’s cabling. As partners for this system setup, we selected a pair of loudspeakers which promised a trouble-free match for the amplifier. The “Coco 15” employs a coaxial driver issued from professional public address market and allows an efficiency of about 96 dB. As safe value for use with the HM step-uptransformers, a Miyabi-based MFSL C3.5 delivered the input signal.

 

Sonic Palette

 

Both choices proved to be a perfect match, and the result was totally in a class of its own. Paul Wilbur Klipsch (the famous loudspeaker designer) once said : “The midrange is where we live”, and he was completely right. The Swissonor amplifier delivers an incredibly clear, clean, free flowing midrange that dominates the action in such an energetically and sovereign manner that the rest of the spectrum apparently takes a rear seat.

 

I recommend an audition with Nina Simone’s fantastic Carnegie Hall Concert. Thanks to this setup, the listener is involved in such an intense manner, that he gets shivers. Fortunately, there is no absolute need for such extreme speakers to get that incredibly vivid and emotional sound. The Swissonor amp -- as a temporary replacement for The Quad II Classic integrated amp -- drove the Progressive Audio Diablo ... and lo and behold - this combo works, too. The Quad acts somewhat larger and more eased-up at the extremities of the spectrum, but does not offer the same measure of unique clarity and expression.

 

Additionally, the Swissonor amplifier throws an extremely well structured and clean image ... and its low noise level does the rest. Even at full-tilt volume, there’s only a slightly perceptible noise level – a quality much appreciated when using the MC phono input. This is certainly not an amplifier for heavy metal freaks ... if you favor this genre, please stay away ... but for voice, instrumental aficionados who primarily enjoy Classical, Jazz, 70's Rock and Folk, there’s hardly a more impressive solution.

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Handmade in Switzerland

Swissonor 6221 Detail 2
Swissonor 6221