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Thread: SJS resuscitated

  1. #31
    Join Date: Nov 2011

    Location: Manchester, UK

    Posts: 222
    I'm Simon.

    Default SJS Model 2 preamp

    getting my first listen to Audio Note Non-Magnetic Silver Tantalum resistors and Dueland Hybrid capacitors in one of the copper cased SJS Arcadia Model 2 preamps back in for some tlc



    too early to make any detailed appraisal, as there are number of other changes:

    • new first HT cap and shunt resistor
    • new silver tantalum film resistors
    • new Dueland silver/copper hybrid capacitors
    • new phono sockets
    • new valves


    I find the Dueland caps take at least a couple of days before they really settle down into what they do, but early signs of the whole shebang are really rather nice
    SJS Arcadia Line Level Pre-amplifiers, Headphone amps, MM Phono Stages and SET Power amps - service, repairs, upgrades

  2. #32
    Join Date: Nov 2011

    Location: Manchester, UK

    Posts: 222
    I'm Simon.

    Default

    An original Voyd turntable from about 1986 back in for repair. the psu had dead and needed all the voltage regs, darlingtons and fets replacing before it was up and running properly, then I replaced all the electrolytic caps to help it last the next 30 years



    next up is this second Voyd turntable, which is one of the later units with the smaller sized Split Phase PSU, however this has 2 motors which have seized up. A full strip down and thorough clean up should see then right

    SJS Arcadia Line Level Pre-amplifiers, Headphone amps, MM Phono Stages and SET Power amps - service, repairs, upgrades

  3. #33
    Join Date: Nov 2011

    Location: Manchester, UK

    Posts: 222
    I'm Simon.

    Default

    The original Model 1 and 2 preamps, and the newer Model 7 preamp were all designed to work with valve power amps with a 100 kOhm input impedance.

    They can be used successfully down to 50 kOhm, but I wouldn't recommend them for amps with a 20 kOhm or 10 kOhm input, which is now typical among a lot of solid state power amps.

    This recently led to a challenge being presented when I was asked to develop a line stage preamp which could be used with a 10 kOhm input solid state power amp. Having thought about this I came up with two prototype amps rusttled up from parts left over form other amps, including a pair of rejected top panels from the Oyide headphone amps.

    The first one uses a triode strapped 8608 pentode, to give a low plate impedance high gm triode, using custom made double C-core output transformers with a centre tapped secondary to provide a balanced or single ended output.



    The second amp uses a 6EW7 double triode. The two triodes are dissimilar, and this uses the 2nd triode which has a mu of about 8 and plate impedance of less than 800 ohms. It is used with a choke load on the anode and output coupling caps.



    In the interest of fairness, both use the same mains TX and psu choke, both use a 5Y3 rectifier, with choke input and Mundorf HV+ cap, followed by an LC filter to each channel.

    They have many similar characteristics, but also interesting differences.
    SJS Arcadia Line Level Pre-amplifiers, Headphone amps, MM Phono Stages and SET Power amps - service, repairs, upgrades

  4. #34
    Join Date: Nov 2011

    Location: Manchester, UK

    Posts: 222
    I'm Simon.

    Default Munich High end 2018

    This year marked the debut of SJS Electroacoustics Arcadia amplifiers at the Munich High End show, probably the largest high end audio trade fair in Europe.



    Two SJS Arcadia Model 3 Enhanced MM phono stage amplifiers were present, one in the Living Voice room and the other in the Engström room.

    The Living Voice room featured the Vox Olympian and Vox Elysium loudspeakers, partnered with vintage Kondo M77 and Gakuoh amplifiers. the vinyl front end was the Grand Prix Audio Monaco 2.0 turntable, with a Kuzma 4-point tonearm, and a Fuuga MC cartridge connected via a Living Voice step-up transformer to the Model 3 in oak with natural aluminium panels.



    The Engström room featured the Vox Palladian & Palladiam Basso loudspeakers, partnered with Engström Monica and Lars pre and power amp combination, or the new Arne 300B integrated amplifier. The vinyl front end was a Kuzma Stabi M turntable, with Stogi S 12 VTA tonearm and Van den Hul MC catridge with a Kondo SFz step-up-transformers to the Model 3 in walnut with black aluminium panels.



    Both Model 3 phono stages used in Munich were a customised version of the Enhanced Model 3. They were voiced in collaboration with Kevin Scott of Living Voice ahead of the show and feature NOS Shinkoh tantalum film resistors and Duelund Audio CAST copper coupling capacitors.

    SJS Arcadia Model 3 phono amplifiers are available for demonstration at Definitive Audio in Nottingham, or here in Manchester.
    SJS Arcadia Line Level Pre-amplifiers, Headphone amps, MM Phono Stages and SET Power amps - service, repairs, upgrades

  5. #35
    Join Date: Nov 2008

    Location: Banbury, Oxfordshire/Panteg is where my late father was born

    Posts: 4,323
    I'm Chris.

    Default

    I would go to Munich just for these two systems alone.
    Chris

    We've gone on holiday by mistake !

  6. #36
    Join Date: Jan 2013

    Location: Bristol

    Posts: 6,050
    I'm Justin.

    Default

    Quote Originally Posted by chris@panteg View Post
    I would go to Munich just for these two systems alone.
    I did go, but not for these two systems. However, the analogue front end sounded fabulous in the Olympian room and on one particular record I was very impressed indeed.

  7. #37
    Join Date: Nov 2011

    Location: Manchester, UK

    Posts: 222
    I'm Simon.

    Default

    A couple more Voyd power supplies that were in need of some tlc.

    On the left a late version split phase PSU which had failed on one phase. As it is about 30 years old, all the electrolytic caps were replaced, along with the darlington outputs and the small FETs. A couple of the resistors have a tendency to overheat, so they have also been replaced with higher power types.



    On the right is a very old PSU, about the oldest type I have seen to date. The design and layout are both very different from the later units, but unfortunately it had a history of failure so it was decided to rebuild it as close as possible to the final design, like the unit on the left.

    This meant a new mains tx to reduce the rail voltages, replacement of all the old electrolytic caps, the addition of voltage regulators for the oscillator and preamp stages, and a complete rebuild of the power stage.

    The confined space and design of the original layout made it an interesting challenge, but all seems to have worked out nicely.
    SJS Arcadia Line Level Pre-amplifiers, Headphone amps, MM Phono Stages and SET Power amps - service, repairs, upgrades

  8. #38
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 856
    I'm Chris.

    Default

    Quote Originally Posted by sjs View Post

    Not a great result overall, but for speakers originally built in 1983 they weren't doing too badly.
    I have drivers that are still performing brilliantly and are twice as old as those. Makes me wonder how far Hi-Fi has come in all those years
    SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
    SW1X USB I Signature
    SW1X DAC III Special
    SW1X Open Baffle Speakers containing both vintage and modern alnico drivers and paper cones. All silver wired and crossover-less where possible - 4" vintage Siemens Klangfilm tweeters, 8" SEAS exotic W8 midrange drivers and vintage 15" Altec VOTT 416 bass drivers
    DRD 45 single ended, 45 triode, monoblocks,
    Silver mains cables, interconnects and speaker cables by SW1X

  9. #39
    Join Date: Nov 2011

    Location: Manchester, UK

    Posts: 222
    I'm Simon.

    Default

    It is two years since the first of the new SJS Arcadia Model 7 linestage preamplifiers were developed.

    During this time we have continued with research and development to further refine the musicality of the amplifiers, as well as offering both a Standard and Enhanced version of the design.

    The Standard version has carbon film resistors and an RC couple gain stage:






    The Enhanced version has tantalum film resistors, a choke loaded LC couple gain stage and enhanced psu choke:





    Both versions feature 6111wa NOS military twin triode valves in the gain stage, Duelund Coherent Audio copper foil coupling capacitors, and the common SJS design elements:

    • Single Ended circuit topology
    • Pure Class A operation
    • Zero negative feedback
    • Valve rectification and choke-input HT power supply
    • Custom made HT T-network power supply capacitors with silver leads
    • Point-to-point circuit wiring without PCBs
    • Hand built
    • PTFE board for component mounting
    • High quality components throughout
    • Custom made aluminium chassis


    Each amplifier comes with 2 years parts a labour warranty, except for the valves which have a 6 month warranty.

    SJS Arcadia amplifiers are available from Definitive Audio in Nottingham.
    SJS Arcadia Line Level Pre-amplifiers, Headphone amps, MM Phono Stages and SET Power amps - service, repairs, upgrades

  10. #40
    Join Date: May 2015

    Location: Shrewsbury

    Posts: 57
    I'm Michael.

    Default

    SJS Arcadia amplifiers are available from Definitive Audio in Nottingham.[/QUOTE]

    I could not see any reference to SJS on the website linked to

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