Massively overbuilt 45 headphone amp.

Discussion in 'DIY' started by johnjen, Aug 4, 2018.

  1. Cspirou

    Cspirou They call me Sparky

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    Never really seen the grounded leg filtered with a choke before. Seems to offer some isolation between PSU ground and signal ground.
     
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  2. johnjen

    johnjen Friend

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    hahahahahahahahahahahahahahaha
    Ya gotta use a texas drawl when saying iron for the full effect , such as shoot'n iron.

    JJ:)
     
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  3. MrTeaRex

    MrTeaRex His head's not fat, he's my brother!

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    Nobody down here sounds like they're pushing out a log while pronouncing the word iron.
     
  4. johnjen

    johnjen Friend

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    That LCLCL grounding scheme allows for improved common mode rejection according to the Lundahl tech sheets, and a few designers who are involved in this build.

    JJ
     
    Last edited: Sep 23, 2018
  5. famish99

    famish99 Friend

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    I don't, but I kinda wish I did now.
     
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  6. johnjen

    johnjen Friend

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    So we are working on a few design issues, and I have taken the time to tear a portion of the amp apart to re-route/move/reconfigure sections of the amp.

    Here are the latest drawings of the PS innerd's and placement on the board.

    45 amp layout-14.pdf
    45 PSU-2.pdf

    JJ
     

    Attached Files:

  7. johnjen

    johnjen Friend

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    I have re-wired about 50% of the power supply (all the filament wiring and the diode bridge) and about 80% of the analog section with the remaining 20% due when parts arrive.

    I've moved/shuffled/nudged transformers around and have a 4.5 x 4.5 area to handle all the filament power requirements.
    And I can accommodate either ac or dc filament power for the 45 tubes, in that same space.

    And the xfmr count is up from our previous 14, to 17 or 19 if we use dc power for the 45 filaments.


    IMG_1926.jpg

    IMG_1931.jpg

    The yellow cables are the twisted shielded filament runs that will originate in the lower right hand corner.

    JJ
     
    Last edited: Oct 6, 2018
  8. johnjen

    johnjen Friend

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    Tonight I finished the re-wire job and await a couple of resistorators.
    We have devised a solution to the high line voltage and the next step will be to dial in the important voltages and bias currents.

    JJ
     
  9. johnjen

    johnjen Friend

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    So here is a pic of the solution to my 'high' line voltage.
    A hammond 169J, a 750VA multi tapped secondary, line voltage isolation xfmr.

    IMG_2003.jpg

    JJ
     
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  10. johnjen

    johnjen Friend

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    So I completed the re-wire job and have run the amp.
    Further tweaks are inbound as we dial in various key voltages.

    As a result, I have added additional tiers to the 'telephone pole' in the filament distribution center and have installed 'scaffolding' for the B+ tweaks to go in.

    The previous hum and noise issues have been hugely ameliorated, and there are additional tweaks and refinements to reduce it still further, without having to implement ac to dc conversion for the filament supplies.

    At this point the amp is quite listenable with the hum and noise reduction, but I'm figur'n this next level of tweaks should help focus the SQ considerably.

    And I am also building additional power cables and balanced IC's to accommodate this addition to my system.
    I'll be using 2) 14g solid copper wires for each of the hot and neutral runs (≈11AWG), to make 5 sets of 1.5m power cables for ≈ $127 for parts which is ≈ $25ea. (and only using ≈ 1/2 of the wire)
    And a 2m set of balanced cables with Furutech 14g conductors (FA220) with my favorite xlr connectors (Oyaide Focus 1's), for $212.

    And in due course, I'll probably cryo all of these new cables to match my existing cables (≈$150).

    I'm hav'n some fun now, I tells ya…|\/|

    JJ
     
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  11. johnjen

    johnjen Friend

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    WTF????????

    Who is changing the text in my posts?

    This IS NOT what I originally wrote
    "So now that I'm back, a status report on the BIG baby Jesus hates me amp."

    I wrote (and it remains in the text I'm looking at as I edit his post
    "So now that I'm back, a status report on the BIG eyerrnnn amp."
    (yes I did edit the BIG eyerrnnn amp so the intercept of the original text wouldn't trigger on this shorter version.)

    So the mods are changing the text of posts now???
    Is this how the site is run now?

    11/22/18



    So now that I'm back, a status report on the BIG eyerrrrnnn amp.

    I've almost got the filament voltages dialed in with just another 0.03v adjustment to make on the 45 tubes (the DHT triodes).

    The hum and noise has precipitously dropped but is still audible when the music stops or drops to a very low level.
    I have a plan for this with more transformers, which is yet further confirmation that 'there is no problem that moar eyeyrrrnnn will not solve'.

    I have figured a way to further reduce the mains voltage that feeds this amp from the existing range of 120 to 125Vac, down to 115 to 118Vac using an isolation mains xfrms and a step down transformer. The 750VA rated Hammond 169J I started with is a tad bit of overkill and I now have a 250VA version (169E) and have wired it all up.

    It looks like this setup will reduce the range of variance from ≈ 6volts down to ≈ 4volts AND lower it at the same time, which for this amp is MUCH better, especially since there are NO regulators, of any kind, anywhere in this entire amp.

    So I am in the process of balancing and tweaking the PSU to handle this lowered and reduced range of mains voltages.

    JJ
     
    Last edited: Nov 23, 2018
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  12. johnjen

    johnjen Friend

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    WTF????????

    Who is changing the text in my posts?

    This IS NOT what I originally wrote
    "So now that I'm back, a status report on the BIG baby Jesus hates me amp."

    I wrote (and it remains in the text I'm looking at as I edit his post
    "So now that I'm back, a status report on the BIG transformers amp."
    (yes I did edit the BIG transformers amp so that the intercept of the original text wouldn't trigger on this shorter version.)

    So the mods are changing the text of posts now???
    Is this how the site is run now?

    JJ
     
    Last edited: Nov 23, 2018
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  13. Riotvan

    Riotvan Got lost for three weeks at Delft City Hall

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    It's the ai man, it's the fucking ai... we were warned but we did not listen.
     
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  14. Priidik

    Priidik Friend

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    I've long suspected no human could be so cold hard bastid like @zerodeefex.
    Human kind will now experience what we have done to pigs.
     
  15. Riotvan

    Riotvan Got lost for three weeks at Delft City Hall

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    I heard a rumor he turns off his emotion chip willy nilly and he doesn't actually get grumpy.
     
  16. JoshMorr

    JoshMorr Friend

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    Weird, its almost like someone was trying to have fun or make this thread interesting.
     
  17. Cspirou

    Cspirou They call me Sparky

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    There also seems to be a filter for Gungnir Multibit and Yggdrasil

    Edit: hey! I've been spelling this out in full like a chump this whole time
     
  18. atomicbob

    atomicbob dScope Yoda

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    You aren't the only one ... I've been doing the same.
     
  19. Tristan Jones

    Tristan Jones Rando

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    Wait wait wait, you guys can say fuck on this forum but god forbid you say big irrrrron?

    BIGFUCKINGIRRRRRROOOOOONNNNNN

    Although I will say that technically its not big iron. Its just many pieces of small iron : P

    ------------------

    Also, hello, I am the one designing the amp and helping with the building.
     
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  20. johnjen

    johnjen Friend

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    The BIG ayrn amp continues to improve and I'm spending more and more time listening to it.
    (Since the edit of my amps name it really should be 15 transformers not 10. Just say'n is all)

    The Magic in the Mids is starting to blossom and the overall SQ is the equal or is better than the Rok amp.

    And the plans to take it to the next level are already in the works.
    Yes that means changing/adding yet more transformers.

    JJ
     
    Last edited: Dec 4, 2018
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