"Shortest Way" SW51 Amp Impressions (Simple SET Amp)

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Hands, Jul 12, 2019.

  1. Zampotech

    Zampotech Friend

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    The number of applications for the 4st batch amplifiers exceeded my forecasts and I started production of the 4+batch. Of course, the 4+ batch will be sent a little later than the main batch, the delay will be one and a half to two months.

    With your help, I have provided myself with machines for the production of cases and this has closed the most slippery issue.
    Making cases has been my sore spot so far. Now I am independent in the production of cases.

    As before, these amps will not be shown on other sites.. Only on SBAF.
     
    Last edited: Feb 16, 2021
  2. Pancakes

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    Can’t wait! But take your time. But hurry up lol.
     
  3. Raidersfan8118

    Raidersfan8118 New

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    Hello was wondering if it was still possible to order one of these?
     
  4. Erroneous

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    PM @Zampotech, who makes these.
     
  5. gaspasser

    gaspasser Flatulence Maestro

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  6. Raidersfan8118

    Raidersfan8118 New

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    Thanks, I just wanted to make sure that all the orders weren’t filled up before I placed an order.
     
  7. roughroad

    roughroad formerly mephisto56

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    @Raidersfan8118 I was in the same situation recently. Zampotech is a great guy to deal with. I PM'd him and ordered a SW51+ all within the past week.
     
    Last edited: Feb 20, 2021
  8. gixxerwimp

    gixxerwimp Professional tricycle rider

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    How's everyone tube life going on this most excellent of amps? I've gone through 2 sets of my favoured Mullards, both starting out measuring "like new", but then developing whistley noises and increased microphonics. No idea how many hours, but less than a year of "moderate" use on each pair. Just wondering if it's the design of the amp that puts stress on the tubes (I doubt this given @Zampotech's skillz), or just bad luck for me with tube longevity. I've also had 2 Telefunken E88CCs go the same way running on MCTH.
     
  9. Sqveak

    Sqveak Friend

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    @gixxerwimp You're probably just having rotten luck. My stock tubes are still going strong. Same with the MCTH. My Night Blues Mini got staticy after sitting on a shelf for most of a year. A quick re-seating solved it though.

    I'm curious about the noises you hear when they crap out. How does it present? Is it only when playing something or always there?
     
  10. YMO

    YMO Chief Fun Officer

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    I'm still on the stock tubes with no issues. Even have five pack up pairs of the stock. SW51+ is my daily driver.
     
  11. gixxerwimp

    gixxerwimp Professional tricycle rider

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    I should throw the stockers in to see if the Mullards really sound that different or it was just nervosa placebo.

    They don't crap out per se, just start making wheezy, whistley, quiet-staticky sounds that get louder commensurate with volume setting. They're intermittent at first, then fairly constant, sometimes in slow pulses (if that makes sense). It's noticeable between songs and during quiet passages. Louder with low Z sensitive phones, less noticeable with high Z Senns.
     
  12. dllmsch

    dllmsch Friend

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    Have been using 6J51P from 1974 for the past 3 months. Bought them in packs of 12 so I left my amp on a lot, the first 2 still going strong. btw the difference, if any, between 1974 and 1986 stock tubes is smaller than what I perceived from changing fuse I think. Maybe I'm high.
     
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  13. atomicbob

    atomicbob dScope Yoda

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    Have you tried re-seating the tubes?
    Cleaning the tube pins?

    Mullards and Stock tubes have been used since arrival of amps. Going strong and no noises other than occasional faint power on pings during the first minute or two.
     
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  14. FlySweep

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    SW51+ is my daily driver, as well. Powered on/used 2-3 hrs every (or every other) evening. I cycle through stock tubes, Tungsram, Mullard, Amperex (all get an equal amount of use.. Amperex and stock more so as of late). No issues with any of the tubes as far as reliability so far.
     
  15. Zampotech

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    It looks like a current leak. This can happen in humid climates or if the PCB is contaminated with active flux. I do not use active flux in principle. To check, open the bottom cover. The PCB near the sockets of the tubes should be cleaned with a brush with alcohol, 94-96 degrees (you can make an alcohol-gasoline mixture of 50/50) After washing, dry with a hair dryer (you can secretly take a hair dryer from your wife)
     
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    Last edited: Mar 5, 2021
  16. ushanka

    ushanka Facebook Friend

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    Do you mean 94-96% alcohol? In English "degrees" corresponds to "degrees proof" which is 2*(% alcohol content), unlike Russian where degrees and % map 1:1. Of course moonshine is a possible solution to problems =).
     
  17. gixxerwimp

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    Yes, I tried reseating, as well as sanding them with fine grit sandpaper and then cleaning with 75% iso. No change.

    Thanks for the info! I will clean and report back. Does the current leak generate the noise? Or result in reduced lifetime of tubes (i.e. age the tubes prematurely so they make noise)? When I put fresh tubes in, the noise goes away.
     
    Last edited: Mar 6, 2021
  18. gixxerwimp

    gixxerwimp Professional tricycle rider

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    So just to confirm, do I want to scrub away all the yellow stuff around each solder joint on the tube sockets? Should I clean anything else? There's no need to flip the PCB over, right?

    20210306_175122.jpg

    20210306_173739.jpg
     
  19. Zampotech

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    No need to scrape. No sharp tools. You must first moisten with a brush with alcohol, and wash off with the same brush. Yellow stuff is pine rosin, it is perfectly soluble in alcohol.

    The second point. You said that the volume of the interference depends on the position of the volume control. The source of the interference may be coming from outside the amplifier. Are there workshops, construction sites near you, or perhaps where repairs are carried out using power tools?

    In addition, the noise can create tubes with a low vacuum or a poisoned cathode.
     
  20. gixxerwimp

    gixxerwimp Professional tricycle rider

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    This is not exactly what's going on (I'm also debugging a noise issue with my recently acquired vintage DAC and conflated the behaviours). There are intermittent noises that don't necessarily get louder with the volume setting. But if I twist the volume knob quickly back and forth between around 12 to 5 o'clock, I can instigate more noise. The tubes are also much more microphonic than when "new". If I put in a fresh set of tubes, everything is quiet.

    I soaked cotton swabs in 75% isopropyl (what everyone is using for Covid sterilization) and wiped away the yellow stuff. There was a sickly sweet odour as it was dissolved by the alcohol, and there were some thin lines of it(?) between a few traces that I cleaned off. I'm pretty sure the alcohol evaporated away quickly, but used an electric fan just to make sure (my wife had just finished taking a shower and was blow drying her hair).

    I put the noisy tubes back in and they sound the same. So hopefully, with the rosin/flux cleaned off, the next set of tubes will have a longer and healthier life :rolleyes:
     

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