1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Where we are now: The site is back up and running! The character set encoding issue has been fixed so old posts should now look ok. I am currently working on themes/skins etc and I will be deleting the temporary green skin very soon as it has many issues. I will do a very quick variation on the stock blue skin first just to get a light-grey background and san-serif font, and I will set this as default. Later this week I will hopefully add a professional third-party skin in pfm colours (life is way too short to do this crap myself, and I've found one I really like than needs next to no tweaking). We are getting there slowly...
    Dismiss Notice
  3. May I please request people check and update their email address if it is out if date. I ask as I’m getting countless bounce errors as the server fails to send notifications through etc. I’ll eventually figure out how to send these to a black hole somewhere, but it makes sense to address it at source as quite a few folk are obviously not getting the thread and conversations notifications they have set in their preferences.
    Dismiss Notice
  4. Things you need to know about the new ‘Conversations’ PM system:

    a) DO NOT REPLY TO THE NOTIFICATION EMAIL! I get them, not the intended recipient. I get a lot of them and I do not want them! It is just a notification, log into the site and reply from there.

    b) To delete old conversations use the ‘Leave conversation’ option. This is just delete by another name.
    Dismiss Notice

SJS resuscitated

Discussion in 'trade discussion' started by sjs, Jul 13, 2015.

  1. sjs

    sjs Trade: SJS Electroacoustics

    Following a number of requests for service, repairs and upgrades to the original SJS Arcadia line level pre-amplifiers, the time has come to declare that SJS Electroacoustics is once more operational

    The following services are currently offered:

    - service, upgrades, repairs and general tlc to the original SJS Arcadia amplifiers,
    - bespoke commissions for single ended valve phono, line, headphone and power amplifiers

    Many thanks for looking
    Simon
     
  2. Ducatiist

    Ducatiist pfm Member

    Hi Simon,
    That's wonderful news, I've enquires previously about a check up on my SJS Arcadia and Border Patrol power amp.
    I knew you was happy to do the servicing, I just haven't had the time/opportunity to arrange to get to you with my kit, as work seems to have taken over at the moment.
    Let me be the first to wish you luck, in this new venture!
    Stuart
     
  3. sjs

    sjs Trade: SJS Electroacoustics

    Many thanks Stuart
    I have had quite a few preamps come through recently for servicing and upgrades, so happy to help you out once things calm down a little for you.
    Cheers
    Simon
     
  4. sjs

    sjs Trade: SJS Electroacoustics

    A couple of weeks ago an original SJS Arcadia Model 1 line stage preamp last seen in 1997 came in for a service and full set of upgrades.

    It was an early model built with 5687 valves and was in original condition, apart from a thick layer of dust throughout. The volume pot had become rather noisy,but otherwise all was good.

    [​IMG]

    It went through a full strip down, clean up, and complete rebuild:

    • Change to 6111wa valves
    • Tantalum resistors
    • Hovland, MusiCap and ClarityCap bypass caps on all electrolytics
    • Pure silver solid core signal wire with ptfe insulation
    • Alps Blue volume pot in shunt mode
    • NOS 5Y3GTA rectifier

    [​IMG]

    Should be good for a few more years
     
  5. sjs

    sjs Trade: SJS Electroacoustics

    WE ARE PLEASED TO ANNOUNCE WE WILL BE EXHIBITING
    AT THE NORTH WEST AUDIO SHOW ON SUNDAY 26TH JUNE 2016

    [​IMG]

    THE SHOW
    Now in its third year, the Northwest Audio Show is set to become one of the highlights in the audiophile calendar. With great exhibitors, top brands and a superb venue, we believe that the North West Audio Show gives attendees the opportunity to hear the very best audio in surroundings that are second to none. Register and secure your free tickets today.

    IT’S FREE
    Free entry, free parking, a day surrounded by the best in audio and all in the beautiful settings of Cranage Hall and Wychwood Hall, Cheshire. The event organisers will also be laying on a free shuttle bus between the venues.
     
  6. BD-Audio

    BD-Audio Trade: BD-Audio

    Great news....... You can help me carry in my speakers on setup day.

    Joking aside it'll be great to see SJS equipment there, I really enjoyed listening to it the day you visited Malvern.

    All the best,

    Jack
     
  7. sjs

    sjs Trade: SJS Electroacoustics

    Thanks Jack, although I am not sure my back is up to lifting those speakers :)

    I am on track to present a new stereo SE 300B power amp at the show and plan to show it alongside the Model 3 MM Phono amp and an original line stage preamp.

    Cheers
    Simon
     
  8. sjs

    sjs Trade: SJS Electroacoustics

    The first prototype SJS Aoide headphone amplifier is assembled and undergoing final testing.

    [​IMG]

    It is effectively a mW level integrated SET amplifier using triode strapped E55L valves, with custom designed and made HiB Double C core output transformers. These have secondaries which enable switching for low impedance (30 to 100 ohms) or high impedance (120 to 600 ohms) headphones, and either balanced or unbalanced connection. The PSU is valve rectified with choke input filter and second stage LC filters per channel. There are 3 line level inputs, input selector and volume control.

    It came about as a result of a commission from a long time Model 1 preamp owner who has switched over to using Audeze headphones. It was designed to be an integrated amp, but a "power amp" version could be made for use with an existing preamp.

    It's a prototype at the moment, and I need to sort out the switching arrangement and possibly get different wooden frames, but otherwise it's up and running quite nicely.

    Almost forgot, it can also be built as a line stage pre-amplifier by changing the output transformers. I have this version built in another box which greengoblin heard recently when he visited.

    The design was developed to match the phono stages built a few years ago

    [​IMG]

    Any PFM members in South Manchester who are big headphone users and interested in hearing the prototype, please contact me
     
  9. sjs

    sjs Trade: SJS Electroacoustics

    Last year I was asked to revamp a stereo SE 300B amplifier

    It is the classic 6SN7-6SN7-300B circuit which has seen many implementations over the years, and for good reason because when it is well executed it can provide great results.

    Having seen that work I was ask if I could implement the same amplifier in one of the chassis used for the Model 3 phono amplifier
    http://www.pinkfishmedia.net/forum/showpost.php?p=2647256&postcount=1

    After designing the layout and panels, the work of bringing it all together began

    [​IMG]

    [​IMG]
     
  10. sjs

    sjs Trade: SJS Electroacoustics

    after completing the work on the top panel

    [​IMG]
     
  11. sjs

    sjs Trade: SJS Electroacoustics

    the next step was to mount the top panel into the chassis and wire up the back panel

    [​IMG]

    Finishing touches, and it is up and running nicely

    [​IMG]

    [​IMG]
     
  12. sjs

    sjs Trade: SJS Electroacoustics

    About 15 years ago I was presented with a DAC built for me by a good friend who used to work at Audio Note, I have been using as-is ever since however I realised that it isn't the most handsome of DACs, nor the safest :shock: so it was time for a make over

    Here is the customary before shot

    [​IMG]

    I decided to change to a valve rectified, choke input psu for the HT, and then separate mains tx for the heater supply and DAC board. some components upgrades throughout and a bit of a rearrangement to fit into a new chassis

    [​IMG]

    [​IMG]

    overall seems like a worthwhile effort, bass impact has improved significantly and the midrange is cleaner with better depth and finesse
     
  13. sjs

    sjs Trade: SJS Electroacoustics

    This week I have been enjoying a very nice Border Patrol P20 power amplifier.

    [​IMG]

    2 x 300B per channel for around 18W of push pull goodness. This is the "low gain" version with a 6S45PI input/driver valve per channel and interstage driver/phase splitter transformer.

    It has two outboard power supplies, making it effectively a three-box-dual-mono-amplifier

    [​IMG]

    6 valve rectifiers :D each channel has a separate valve rectifier feeding a choke-input power supply for the output stage, driver stage and negative bias supplies, nice!

    The amp came in for a check over, service and a few component upgrades. It was fitted with new 6S45PI valves channel matched to within 0.1 dB, tantalum film resistors in the audio circuit, carbon film resistors in the PSU, new HT caps for the output stage and driver stage, and Elna Silmic II bypass caps for the driver stage and bias supply and quite a bit of re-wiring with solid core silver.

    [​IMG]

    Overall a really nice improvement in clarity, tone and soundstage depth, whilst retaining that strength and dynamics the Border Patrol philosophy delivers.

    Really nice sounding amp.
     
  14. sjs

    sjs Trade: SJS Electroacoustics

    In a slightly tangential move compared to the valve amplifiers I generally get to work on, I was approach by Phil, The Count, and asked if I could help with his Snell AII loudspeakers.

    In the time before marriage I was lucky enough to have a pair of Snell AII speakers for about 10 years, during which I refinished the wood veneer, replaced the grill cloth and worked on the crossovers, mainly replacing the old electrolytic caps with newer Black Gate bipolar caps :D

    Phil had a problem, one of the tweeters had died. He had hunted down the appropriate replacements and supplied a new pair along with the speakers. First step was the assess the current situation......

    Main unit with grill removed:
    [​IMG]

    Inside to uncover the crossover for the midrange and tweeter:
    [​IMG]
    Note the Audioquest speaker cable which is noticeably green under the clear cover :(

    Then inside the bass cabinet to uncover the crossover:
    [​IMG]

    Unfortunately, the "chuffing" noise in the low bass was caused by the perished foam surround on the bass unit:
    [​IMG]

    Not a great result overall, but for speakers originally built in 1983 they weren't doing too badly. The worst problems were the (1) dead tweeter, (2) perished foam surround on one bass unit, and (3) copper oxide cables :(

    Having one fully working unit, a bunch of measurements were taken to give an understanding of the baseline situation before any work was begun.
    Acoustic measurements were taken of all 5 working drive units, with and without crossovers.
    The crossovers were all taken apart carefully, the circuit drawn out and every component individually measured using an LCR meter.
    The crossovers were then modelled in LTSpice in order to understand how they worked, and what the slight differences between left and right did to the output of the filters.
    Very interesting :eek::rolleyes: :rolleyes:

    First off, replace the dead tweeter, unfortunately this required a switch of face plate:
    [​IMG]

    Then strip down the bass unit to remove the perished foam surround:
    [​IMG]

    Which seemed to work out quite nicely:
    [​IMG]

    The bass crossover was then upgraded: replace the old cable; replace the inductor with a low dcr unit; and film caps to replace the old electrolytics:
    [​IMG]
    The reduced dcr should help re-align the bass to work more nicely with the valve power amps Phil favours, and the film caps help to really improve the clarity of the bass.

    Then the big challenge, the midrange and tweeter crossovers:
    [​IMG]
    The old electrolytic caps were replaced with a combination of new bipolar and film caps, the cement clad resistors replaced, and all the old cable replaced.

    All went back together, and it was then a long and careful process of integrating the new tweeters into the midrange. The new units were far more sensitive than the old ones, so they needed to be padded down, and it took a lot of measure/listen/tweak/repeat :eek: :confused: :eek: :) before the right balance was struck.

    Definitely one of the more challenging projects, but very interesting, and hopefully a nice pair of speakers ready for many more years making music.
     
  15. sjs

    sjs Trade: SJS Electroacoustics

    Inspired in part by some L'Amp and Le Monstre builds, it appears I am about to break a 25 year embargo on sand based amplifiers :eek:

    [​IMG]

    when I say "about", one must interpret that in a very loose way :rolleyes:

    Designed by Nelson Pass using original Sony VFETs which he has personally tested and matched. It should be good for about 15W per channel, and as I want to use a bit R-core mains tx and LCLC PSU design it will be monoblocks.

    Should be interesting.....
     
  16. sjs

    sjs Trade: SJS Electroacoustics

    Just finished this little project making up a nice little SUT using Hashimoto HM-7 transformers.

    Dual primaries can be switched for high/low impedance carts, and the grnd connection on the primary can be isolated for floating the MC coils. The casework is lined with mu metal sheet for screening, and solid core silver hook up wire and WBT silver loaded solder helps to up the foo factor :)

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Sounds really nice with my Ortofon cart, probably prefer it to the T-3000 as it has more body and a bit more drama to the presentation.
     
  17. Jag Audio

    Jag Audio Trade: Jag Audio

    Looks very nice, are you able to source Hashimoto SUT's to make a similar unit?
     
  18. sjs

    sjs Trade: SJS Electroacoustics

    Yes

    It can be built with any of the Hashimoto SUTS, HM-3, HM-X or HM-7. You can supply them or I can source them.
     
  19. sjs

    sjs Trade: SJS Electroacoustics

    Double post deleted
     
  20. sjs

    sjs Trade: SJS Electroacoustics

    This year marks the 20th anniversary since the first SJS Arcadia Model 1 preamplifiers were delivered, so it's nice to have one come back for servicing and upgrades

    [​IMG]

    This unit now has tantalum resistors, new psu caps, silver wire and new valves.

    [​IMG]



    What was really good to see was one of only two matching mm phono stages which were built as prototypes

    [​IMG]


    This shows it after it's rebuild with tantalum film resistors and new psu capacitors.

    [​IMG]

    and this is the power supply

    [​IMG]

    not bad for a phono amp :)
     

Share This Page