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

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

  1. Prydz

    Prydz Friend

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    Its a very good day today. Because this thing arrived!

    Whats the general thoughts on low vs high Z for HD650 with this?

    [​IMG]
     
  2. Taverius

    Taverius Smells like sausages

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    Whichever sounds best to you.

    That's not only the single answer that makes sense, but there's so many variations of the 650/6xx, and then the various mods, that it's impossible to provide an answer even if it made sense to do so.
     
  3. crazychile

    crazychile Eastern Iowa's Spiciest Pepper

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    Mine just showed up today as well. I’m using 3-4 year old HD-650s and started on high z, but after the first 5 songs went to low z and I might like low better so far. But this thing literally arrived less than 2 hours ago.

    There was nothing about the sound that immediately jumped out at me, but I’ve definitely gotten sucked into the recordings and its hard to focus on work. Also, as far as tube amps go it seems to run pretty cool.
     
  4. crazychile

    crazychile Eastern Iowa's Spiciest Pepper

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    I ordered this amp thinking I wanted one last headphone amp to use for the infrequent times I listen to HD-650s, which I also kept as my only serious headphones. -besides Koss 950 and a handful of mostly cheap portable and noise cancelling special purpose stuff. Why? Because I really haven’t listened to headphones since COVID, and before that I was rapidly moving back to 2 channel exclusively which is where I began almost 40 years ago. Headphones were more or less a bandaid for about 15 years when I didn’t have the room to do proper 2 channel.

    The SW51+ has turned out to be the perfect solution for me because the hype was real and the cost was low. With my limited headphone use I couldn’t justify the cost of an EC or DNA amp but this amp isn’t leaving me neurotic for more. It’s easy to listen to. I don’t know if it has the last bit of microdetail, and maybe that’s not possible on HD-650s but I find myself drawn into elements of the recording that are set back farther into the mix and easily tracking them.

    As I mentioned in the previous post, nothing immediately jumps out at me and draws attention to itself. But it’s definitely not a boring amp. I’m also able to listen for a few hours at a time and I can’t remember the last time I did that with a headphone setup.

    This plays as loud as I’d ever want. I did a few songs at 1:00 on low Z and it was rockin but everything was still focused and precise. I would have expected it to get rough when approaching redline, but it held together.

    SW51+ is like meeting a woman with average looks, but after spending some time with her you find out that she’s cool, smart, interesting, and a general pleasure to hang out with. SW51+ is NOT like crazy hot chick, where first meet is fun but later you have to get a restraining order, new phone, delete all social media and move to a new town and start a new life.
     
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  5. Mordy

    Mordy Acquaintance

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    The SW51+ grows on you - it's get better with time.
    I am using it as a preamp for speakers as well. Just connect the lo ohm headphone jack to your amp and you are good to go. I get the bet sound to date using 6F23 Mazda tubes.
     
    Last edited: Aug 25, 2021
  6. Prydz

    Prydz Friend

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    I've done some testing low vs high Z on my HD650 which has spider cage removed, and dampning.
    Low Z is almost too clean for my ears. High Z is just perfect, effortless and yummy
     
  7. Zampotech

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    Dear friends

    I must explain all the delays in sending the amplifiers to you.
    The first thing I want to say is that all the amplifiers are made
    The second thing I want to say is that most of the amplifiers are already in their new homes, with the exception of Australia and New Zealand. there is some complicated delivery route for these countries and they are still on the way.

    Now the most important thing. Our Russian fiscal authorities very closely monitor other people's money and are very upset if the money passes them by. Therefore, I try not to tease our customs and tax services and send parcels in moderate batches. For example, I send a new batch when the previous batch has already passed customs. I do this so that the parcels are not delayed and are guaranteed to get to their owners.

    Please understand me correctly. It is important for me that all the amplifiers get to their owners, and do not receive apologetic letters from me that the parcels are detained by customs.

    I really do not want to have proceedings with our not always sane fiscal services.

    [​IMG]
     
  8. ColdsnapBry

    ColdsnapBry Almost "Made"

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    Hi Zampo, no worries on the NZ amps. We have been in lockdown the past 4'ish weeks, so any packages have been standing still for that time. Might be a lot longer before we see ours, but that's the nature of receiving packages to New Zealand. It tests your patience, then you go and enjoy the great outdoors and forgot about it for a bit :p
     
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  9. crazychile

    crazychile Eastern Iowa's Spiciest Pepper

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    I bought some Siemens EF805S tubes that were dated 1980 on the box. They might be a tad bit cleaner and leaner sounding than the originals. So far I like the originals better. I might have to try some Telefunkens.
     
  10. Mordy

    Mordy Acquaintance

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    Just received EF805S tubes labeled Siemens but said to be Telefunken rebranded tubes. TFK tubes are supposed to have a rhomboid (diamond shape) in the glass at the bottom of the tube at the center of the tube pins and these tubes have that. The construction appears to be identical to TFK as well.
    Initial impression is that they are very clear sounding with good FR overall. Buit, as has been mentioned before, these tubes run very hot, and the amp runs at least 10C hotter (measured at the top of the front transformer cover) than with the standard tubes. Zampotech was OK with using these tubes in the SW51 but not for overly extended periods.
    Thinking of getting a little USB fan blowing air on the tubes and the transformer. A temperature of 80C is detrimental to components in the amp but I would like more of a safety margin and lower the temperature of the amp.
    The temp of the amp cover measures 43C now and the hottest spot in the tubes 77C. My experience has been that tubes run hotter when new and cooler after they are burned in - have only used these 2 hours so far.
     
  11. ColdsnapBry

    ColdsnapBry Almost "Made"

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    @Zampotech Great work getting this to NZ!

    This could be a status update, but very excited to have my SW51+ arrive this week. I ordered a Schiit Bifrost 2 the same day in April and Zampotech beat them to delivery by what looks to be about a week! Epic work.

    [​IMG]
     
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  12. Elnrik

    Elnrik Super Friendly

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    I really like my Aeolus & '51+. Congrats

    Let us know what you think of the final chain when the BF2 gets in. :)
     
  13. Zimmer266

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    I am liking the high output setting from SW51 to HD650. I have heard new things in a recording I thought that I knew very well. These moments are enlightening and rewarding all at once. Project DS2 CDT > Holo Spring KTE > Coda 0.2b > SW51 > HD 650. I had a Bifrost 2, returned to me from the home shoppe after a warranty replacement of the analog output. I think that I will put it back in the chain instead of the Holo for a bit.

    Then I kind of want to pick a ZMF to try. Aeolus has most of the vowels, and a strong synergy recommendation.
     
  14. Zampotech

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    There is a downside to this effect. Short-path amplifiers (usually tube amplifiers made according to classical schemes) will clearly show recording defects and coding defects. It's probably like if I washed a cloudy window and the cigarette butts and dog feces on the lawn became visible.
    When I made my first tube amplifier and bought SENN580 headphones, I was disappointed with my first audio collection, it was unpleasant to listen, there were coding artifacts, some howls were heard at very low volume. It was a collection of music compressed by MP3
     
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  15. mdr30

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    Bought a lot of five 6J51P from a Mr Jaroslav in Ukraine, a mixed bag. Two were definitely pulled (you can see some brown smoke in the glass), the other three may be NOS. Not sure though, difficult to tell from the pins.

    [​IMG]

    I put two in the SW51 without looking close at them. Turned out to be the pulled ones, Oktober/Vinnitsa from 1977. They sounded good! As good as any I’ve tested. The third one was also from Oktober, 1980. Put aside. The last two were Reflektor/Saratov from 1972 and 1975, respectively. Also mighty fine sounding.

    Got these tubes just to get some perspective compared to Zampotech’s Russian ones, also from the Oktober factory. Not much that differs between these pairs, but Reflektor could be my choice after some extended listening.

    [​IMG]

    [​IMG]

    The Oktober/Reflektor tubes look almost identical, but there is a small difference in the getter support. Guess similar machinery was used in the Soviet tube factories. Zampotech would know. Great fun tube rolling on a Sunday afternoon with my favourite recordings at the moment.

    Have some surplus tubes of different brands, check my profile.
     
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  16. Mordy

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    The Telefunken EF805S tubes run hot so I rigged up an inexpensive cooling fan. The fan is 80mm (3") and comes from an old PC power supply. Also connected an old 12V power supply from a discarded portable phone to the fan.

    The fan is just lying flat on the front transformer which tends to get hot using these tubes. In order to cushion the fan and leave it a little above the transformer I put down a silicone bracelet band that I had lying around.

    I experimented with the fan pulling air out from the chassis and the fan blowing directly on the chassis. Then I measured after an hour with an infrared thermometer. Blowing directly on the transformer worked better, and the temperature dropped from 40C to 27C (room temperature 21C).

    It is possible to buy USB powered fans specially made for this purpose but this solution, although a drop noisy, did not incur any expense.

    I wquld like to post a picture but haven't figured it out yet. Supposedly there is a field where you can add a picture, but I cannot find it on my screen.
     
    Last edited: Sep 29, 2021
  17. famish99

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    Unless you live somewhere without HVAC, tubes are designed to run hot and will be sounding their best at operational temp, the fan is probably making it sound worse and not necessarily improving tube life, if anything it could be making it worse.
     
  18. Mordy

    Mordy Acquaintance

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    I appreciate your concerns, but the fan is ecaxtly the size of the transformer cover and since it is placed on top of it, it only cools the transformer, leaving the tubes to operate at normal hot temperatures.
    I did actually check for any change in sound with this set-up, but could not hear any difference.
    As it is, I would only use the fan when using the TFK EF805S tubes which are the only tubes that make the amp run hot - all other tubes I tried do not make the amp hot at all.
    You may very well be right about the scenario you describe above if the fan was used for tubes that do not make the amp run hot and if the fan was blowing directly on the tubes as well.
     
  19. Mordy

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    EF182, EF184, EF814, 6N51P, Z749, 6EJ7, 6F23, 6F24, EF805S. These are all tubes that can be used in the SW51. IMHO the best sounding are the Mullard 6EJ7/EF184, Mazda 6F23 and the Telefunken EF805S. The Mullard and Mazda referenced have a sweet mid range, but my current favorite (requires a lengthy burn-in - at least 80 hours) is the Telefunken EF805S.
    Got a good deal on Siemens branded TFK EF805S - look for the shape of a diamond in the glass in the center of the base between the tube pins to verify that it is a TFK tube.
     
  20. Mordy

    Mordy Acquaintance

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    In adition, the stock tubes supplied are also very good sounding.
     

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