Kenzie headphone amp review (ampsandsound)

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by allegro, Dec 17, 2017.

  1. PacoTaco

    PacoTaco Friend

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    It's not 100% a stability thing. The issue is worse with solid state amps, but the rise of output impedance does change the FR (which has been measured and proven in the past.) A relatively clean headphone won't be ducked with much, but a driver that cant handle the boost will get more distortion. My HD580, for example, got brighter and bassier out of the 600ohm. The Auteur got bloated a bit and darker. It just depends entirely on the headphone.
     
  2. ampsandsound

    ampsandsound MOT - Ampsandsound

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    Various tube topologies are more sensitive to presented load. FR shifts can be affected by many factors for which output impedance is only one. I would suggest that most sennheisers would sound best on the 32ohm or 300ohm taps. The ZMFs have seemed their best on the 300 and 600ohm. Again, use your ear and decide what works best for you.
    Allegro, glad you like the input transformers. I tried to make as tidy a package as possible.
    Anyone with a Mogwai can try using the speaker taps, you'd have access to an 8om tap. Ive listened to it, and felt it wasn't the best choice. Ive had customers with HE6s that swore by it, again I leave it to personal choice.
     
  3. ampsandsound

    ampsandsound MOT - Ampsandsound

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    No poof. Sonics change between the output taps, Id suggest listening and deciding which is the best choice. No damage to be done to headphones or amp. Ive never ventured into OTLs, I loves transformers too much :).
    I still have a futterman design if Im ever brave enough to build it.
     
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  4. captkirk

    captkirk Khan's BFF

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    OT

    @ampsandsound, teach me something...

    The input transformers that you use, are they spec'd to your specific application, or are the transformers a general spec. that would permit use with other amps?

    ... like if someone wanted to experiment with one of your external input transformer boxes with other amps?

    /OT
     
  5. ampsandsound

    ampsandsound MOT - Ampsandsound

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    They are can be paired with other amps. I use a set with my 2ch system as well.
    To some degree its a system matching question. The Specific model we select do to pair will with the 10K presented by the Alps pot.
    If your system is still a Gumby into a Kenzie it would be a fun addition but could also try with other system matches.
    For me, the I used a tube pre into the input transformers I felt it was too much of a good thing. But when going Dig Source into pre or into amp it was a worthwhile addition.
    PM me, I can lend them out for a week to try. (Mine are in the lab equipment look) but work great, just less pretty casework.
     
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  6. allegro

    allegro Almost "Made"

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    I decided to try some new tubes in my Kenzie. I replaced the stock 1626s with a matched pair of wartime NOS 1626 RCAs. Needed to have some spares around just in case of failure but I was surprised the Kenzie sounded slightly better with the replacement tubes. I was hearing more detail, more air around performers and instruments. What impressed me most was how lifelike cymbals and bells sounded. OK so I now know replacement tubes same type can sound different.

    Well time to try a replacement for the 12SL7GT. 2C52 seemed to be favoured so I got some in. The first I received was defective out of the box and sent back. Next order was for two from a different company. The first I tried was OK, warmer than the 12SL7 but lacked high end and air. Not bad but no cigar. Then I tried the second one which was a winner.

    The good 2C52 is more dynamic than the 12SL7 while keeping the soundstage and great high end and bass has more impact. I will have to try the 2C52 against the 12SL7 for a few days to pick the best for me but it is nice to have a choice.

    You guys and gals with amps with multiple tubes to roll must have fun but I hate to think of the expense.
     
  7. allegro

    allegro Almost "Made"

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    Still trying to find a pair of Tung Sol 1626 to try they seem to have all been bought up. The Hytron 1626 is considered close to the Tung Sol I located a matched pair and on the way. Will try next week.

    After trying several other input tubes the WWII vintage RCA gray coated glass black round plates 12SL7GT has been my favorite the past month. Better than the 2C52 IMO. After some input from other members I decided to get an adaptor from eBay to be able to try the ECC801S. The Siemens from the '80s I first tried was inexpensive but had no soundstage to speak of.

    I found out that it seems if you want a very good ECC801S you need to locate a tube from the '60's either Siemens-Halske or Telefunken. I am listening to a 1963 Telefunken Diamond Bottom ECC801S right now and the soundstage and imaging is best I have heard from my Kenzie. Need to get a few days listening in but most likely have a new favorite.
     
  8. Erikdayo

    Erikdayo Friend

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    Might give the Raytheon 2C52 a shot. Didn't hear about them before today when I happened to come across it while searching for the 12SL7 on various sites.

    Has anyone tried Tung Sol 12SL7GT with black glass? Thinking about picking up a pair. I'm not sure what the most well regarded 12SL7s are. Just running with whatever Justin sent me currently, and it sounds great.

    Also @allegro
    What did you think of those Hytron 1626? Thanks!
     
  9. allegro

    allegro Almost "Made"

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    I was not pleased with the Raytheon 2C52 I got in; tried three different ones.

    The Hytron I got in sounded like the WWII RCA 1626 no advantage I hear. The Tung Sol 1626 are still the best sounding 1626 but everyone knows it and just try to find any for sale. I have not tried the Tung Sol 12SL7GT with black glass just ordered a matched pair these don't come up for sale often either but there are a few on ebay right now could be gone anytime. I should have next week will compare to ECC801S I am using now. Thanks for the tip!
     
    Last edited: Mar 28, 2018
  10. Erikdayo

    Erikdayo Friend

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    Yea I mentioned the Tung Sol black glass because I saw a pair on eBay. Not sure if I want to buy without any impressions.

    Thanks for the input on the other tubes. Guess I might hold off on the 2C52.
     
  11. allegro

    allegro Almost "Made"

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    At the moment my favorite input tube for the Kenzie (should include Encore also) is the 1960's Telefunken ECC801S used with adaptor. By a wide margin ... you have to hear it to appreciate it. Imaging and soundstage is excellent and the clarity, ability to hear inner detail is superior to any 2C52 or 12SL7GT I have tried. Midrange is accurate, not lush or romantic. Female vocals just sound right to my ears. Runner up to the ECC801S is the WWII vintage RCA gray coated glass black round plates 12SL7GT.

    Looking forward to trying the Tung Sol 12SL7GT with black glass next week.
     
  12. Erikdayo

    Erikdayo Friend

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    I've seen that Telefunken mentioned a few times, but I'm not ready to spend $200+ on one as good as it may sound. Curious about the Tung Sol black glass though. Definitely would love to hear what you think. They might not still be available for purchase on eBay by then, but that's okay. It's better for me if I don't spend too much tube rolling.
     
  13. allegro

    allegro Almost "Made"

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    I hear you about the cost of a good ECC801S. A great one is $220. Worth it to me though. Look for (!!!!) if you buy from that site where I got mine.

    A lower cost option is a Siemens Halske E81CC should be from the 1960's. A friend also with a Kenzie was using the Siemens Halske and bought the same Telefunken I have.

    The Tung Sol 12SL7GT with black glass is no better than any other 12SL7GT in my collection and I have tried most of them. My experience with Kenzie are the input transformers are a must have. The only 1626 that sounds better than a good matched pair of WWII RCAs are the Tung Sol 1626. I hear more air and a wider and deeper sound stage with the Tung Sol compared to RCA but the major difference in SQ comes from the early 1960's Telefunken "Diamond Bottom" ECC801S used with adaptor for input.

    It is almost impossible to find a matched pair of Tung Sol 1626 right now. I have the Hytron: no better than RCA. I put my RCA 1626 back in today and they sound just fine with the Telefunken ECC801S. I lose a little bit of air and sound stage depth compared to the Tung Sol 1626 but unless you had heard the Tung Sols you would not miss them.

    If I owned a Kenzie or Encore and wanted to tube roll I would just get an early 1960's Telefunken ECC801S and adaptor and just enjoy the amp. Grab a matched pair of Tung Sol 1626 if you ever see them for sale from a reputable vendor.
     
    Last edited: Apr 10, 2018
  14. allegro

    allegro Almost "Made"

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    Just had a Tung Sol 1626 power tube go bad: 60 cycle hum and crackling. Put my spare pair of Tung Sols in and found out they are defective out of the box. Last time I buy tubes on eBay. Back to RCA 1626.
     
  15. Erikdayo

    Erikdayo Friend

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    Maybe it’s excessive, but every time I bought new tubes I tried them say day whenever possible. Didn’t want to wait til months or years later only to find that they’re junk.
     
  16. ampsandsound

    ampsandsound MOT - Ampsandsound

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    I wanted to give everyone an old new idea.
    12B4A tubes will work as drop in with an adapter.
    The adapters have become very common on eBay ~$10 each... $25 for 2 to your door.
    The 12B4A is an amazing tube, its different but sounds amazing.
    The 12B4A tubes are VERY inexpensive and NOS.
    And Oh by the way... they nearly double your power out.
    Measures are from a brand new Encore 8/32 with input transformers and caps headed to a customer.
    On av. there will be ~10% more power after break-in.
    As good 1626 are still easy to get, its not such an issue but its fun to roll.

    Before plopping down $ on a TS you might try the 12B4As.
     
  17. ampsandsound

    ampsandsound MOT - Ampsandsound

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    I have a bench report but can't fig how to upload the pic.I have a full bench report with the only difference being the power tubes. I can figure out how to upload.
     
  18. Elnrik

    Elnrik Super Friendly

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    Easiest way is to upload to imgur or another host, then link here via URL.
     
  19. allegro

    allegro Almost "Made"

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    @ampsandsound is this the 1626 to 12B4A adaptor you recommend? There are plenty of good RCA but Tung Sol 1626 are almost impossible to source now.
     
  20. allegro

    allegro Almost "Made"

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    After enjoying my Kenzie for six months and doing a lot of tube rolling I wanted to share some impressions.

    Using 1626 power tubes

    Your options are limited here. I have used RCA, Hytron and Tung-Sol. Tung-Sol 1626 provide the best SQ but are now impossible to find. I found no advantage to using Hytron over RCA so I just buy the best matched WWII RCA I can find.
    I have used most 12SL7GT input tube brands and my favorite is the RCA grey glass mentioned before in this thread.

    In my experience there is no 12SL7GT, 2C52 or 5755 that comes close to the SQ you get from a 1960's Telefunken "Diamond Bottom" ECC801S used with adaptor. You have to hear one to appreciate it. Expensive at $220 - $230 but worth it. If you have that Telefunken you really don't miss the Tung-Sol 1626 so much.

    Using 12B4A power tubes

    When I first tried 12B4A power tubes I still had the Telefunken ECC801S in place and the SQ was horrid: I felt like sound was projected on a flat glass plate centered on my ears. There was no depth and glare had me shutting the amp off within 5 minutes. It turns out the Telefunken is in some way incompatible with the 12B4A. Changing to a 12SL7GT input tube corrected the mismatch problem. I did note that the 12B4A bass sounded soft and lacked punch so I ordered a 5755 adaptor from Hong Kong and a 1950's Western Electric 5755/420A.

    After a two week wait the adaptor arrived and I was able to finally listen to the 12B4A with the 5755. Using some of my reference tracks on Tidal the first thing I noticed was soft bass that lacked weight and slam. Midrange and treble was fine but the 12B4A/5755 was inferior to the 1626/ECC801S. Noticeably less air and sound stage depth and width. I used two different brands of matched 12B4A's both had the soft bass issue.

    The soft bass could not be corrected with my Loki and seems to be inherent to the 12B4A in my rig. Leaving the 5755 in place and changing back to RCA 1626 tubes brought back the bass but I found the 5755 no better than a 12SL7GT.

    Conclusions

    I wound up putting the Telefunken ECC801S and RCA 1626 back in. For my ears, with my phones and DAC I found no advantage to the 12B4A/5755 power/input tubes. YMMV the experiment is not expensive. I am still on the prowl for some Tung-Sol 1626 power tubes while I enjoy the Kenzie with RCA 1626 and Telefunken ECC801S.

    It would be helpful if other Kenzie/Encore owners post their results with the 12B4A/5755 tubes. It would cost you roughly $110 to try. You need this 5755 to 12SL7 adaptor, two 12B4A to 1626 adaptors, along with the 5755 input tube and two 12B4A power tubes.

    As an aside all my tube links point to tubeworldexpress. NFI I like to buy from Brendan because he ships fast and I have never received a bad tube from him. Can't say that for eBay sellers. He also grades the tubes he sells with (!) exclamation points. Exceptional tubes get three or four points.
     
    Last edited: May 27, 2018

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