Building A Tube Preamp: The Aikido

Discussion in 'Audio Hardware' started by fully_articulated, Jun 13, 2019.

  1. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    Great! Thanks so much for the link. Very helpful!

    I have the following Miflex set to go in when I get the rest of the parts.

    MIFLEX KPCU Capacitor, 1.0uF 600Vdc, Copper Foil Paper/Polypropylene in Oil

    The Miflex will be bypassed by this Deuland.

    Duelund 0.01uF 600Vdc JDM-Sn/Cu Tinned Copper Foil BYPASS Capacitor

    And since this will do double duty as a LSA and HPA the headphone caps are these.

    Auricap Capacitor 33uF 160Vdc XO Series

    I was lucky enough to pick up most of these when they were on special buys. I also have something special planned for the audio path resistors as well. Just working out the details with the company at this point. I am getting excited to get this thing done.
     
    Last edited: Oct 6, 2021
  2. fully_articulated

    fully_articulated Forum Resident Thread Starter

    You should definitely post some progress pics!
     
  3. B. Scarpia

    B. Scarpia WatchingYouWatchingMe

    Location:
    WNC
    I'm late to the party so forgive if already answered but you must ground a lug of each power transformer and choke to the safety ground.
     
  4. B. Scarpia

    B. Scarpia WatchingYouWatchingMe

    Location:
    WNC
    Must be 15 years ago that I came across John's then new Aikido design and I built the octal dual mono design. He didn't have power supply boards (I used his LV-1 in my latest line stage) back then so I borrowed a schematic from a friend. Hat's off to you, especially as a beginner for executing such a technically advanced build, elegantly completed.

    My effort back then looks horse 'n buggy compared to yours. It was a great sounding component, very neutral but still musical.

    [​IMG]
    [​IMG]
     
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  5. fully_articulated

    fully_articulated Forum Resident Thread Starter

    Better late than not at all! Thanks for the confirmation.

    Thanks again. I appreciate getting such a comment from someone far more technically seasoned.

    That's how I would probably describe it. Can I assume you have built circuits since that you consider "better" sounding? I have been considering a point-to-point project - my first - and haven't decided whether to stick with the Aikido circuit or not.
     
  6. B. Scarpia

    B. Scarpia WatchingYouWatchingMe

    Location:
    WNC
    6 years ago I built in collaboration with diyaudio.com pal Steve Brown Joseph Esmaila's 76 Line Stage and it remains. Steve made some changes but basically it's this:

    [​IMG]
    76 input tubes, 6SN7 outputs, 5AR4 rectifier.

    Joseph's power supply was the main difference in what we built and included, as I mentioned above, the Broskie LV-1 regulator. Somewhere I have, I think, the schematic for the simplified and beefed up power supply and if I can find it I'll scan it and post it. It's more tubey sounding than what you have but in my system which is posted here makes it the closest to the sounds of the orchestras I played in. 76 tubes are relatively cheap but tend towards being microphonic. It was a bear getting it quiet but got it done. Here's a look at the guts which might give you enough in case I can't find the schematic and/or wiring diagram I worked from.
    [​IMG]

    I've since replaced the good sounding but problematic ladder attenuator with a PEC KKA Series Pot and the Obbligato .47 output Caps are now Mundorf EVO Silver/Gold/ Oil.
     
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  7. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    I will see what I can come up with as I get further along. Still acquiring parts for this thing. I have to keep telling myself to slowdown so I can do things right.

     
    fully_articulated likes this.
  8. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    Well, these aren't progress pics per say but I did mention I had something special planned for the audio path. These resistors are the "nude" TX2575's. I have them spec'd in for the audio path for both the LSA and HPA.

    These are the transformers I am using for the build. Low noise R-core transformers.

    I will post some progress photos when I start the assembly. Still acquiring parts. Next on the list to acquire Goldpoint V47 volume control and (2) Goldpoint selector switches.

    Compare Attenuator Types
    Goldpoint Selector Switches
     
  9. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    Might be helpful if I actually posted the pics. lol.
    [​IMG]
    [​IMG]
     
  10. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
  11. Ham Sandwich

    Ham Sandwich Senior Member

    Location:
    Sherwood, OR, USA
    Nice pics. But Google Drive images will go dead shortly. Google rate limits how many people get to see the images before they kill the link. Try hosting the images on Imgur or similar photo hosting site. If you use Imgur I would suggest creating an account so you have control of the images and can delete them later or edit them later.
     
  12. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    I took your advice.
    imgur.com
    imgur.com
     
  13. Ham Sandwich

    Ham Sandwich Senior Member

    Location:
    Sherwood, OR, USA
    Imgur allows you to get a direct link to the image. That will be a link that ends in .jpg for a jpg file. If you post the direct link it will show up as a picture in a post here.

    The direct link to one of your photos is:
    Code:
    https://i.imgur.com/SMu80oR.jpeg
    I'd post that here as an actual image link but the photo is really large at 4032x3024 pixels. That's too big to fit on most peoples monitors here.

    When I upload to imgur I first resize the image down to something 800x600 or smaller. Or use the Imgur editing tools to resize it smaller. Then link directly to the smaller image.
     
  14. fully_articulated

    fully_articulated Forum Resident Thread Starter

    Those James transformers look really good. They have some nice options on their website too. How was their price/service?

    Looks like you have picked out some substantial components for your build. I look forward to seeing more of it!
     
  15. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    The prices were good in my opinion. $25.00 ea for the two heater transformers and $45.00 for the high voltage one.
    I can't wait to get the volume control and the switches......if I only had a money tree! One step at a time.
     
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  16. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    Hi all! I thought I'd post up some progress pictures as I had agreed to do. Just some mockup work being done. I will be using a case from here, though the actual case is not pictured in the photos.

    Slimline 4U

    What you see in the photos below are the optional baseplate and risers for the above case. The transformers, the input board (MOV protection and on/off relay), the DC blocker/stage 1 emi/rfi board and the 2nd & 3rd stage emi/rfi board are all shown in the photos after mockup.

    Before final assembly I will be powder coating the baseplate and risers. Still a work in progress!

    [​IMG]

    [​IMG]

    [​IMG]
     
    fully_articulated likes this.
  17. fully_articulated

    fully_articulated Forum Resident Thread Starter

    What a beast! Would love some more details on those input/protection boards.

    The baseplate and risers are galvanised aren't they? For some reason I thought you couldn't paint or powder-coat over that. Am I wrong?

    Please continue showing your progress!
     
  18. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    After reading your comment, I have been researching this. They are a galvanized iron product. I had no idea you couldn't powder coat galvanized products. It does appear I can paint them through a special process though. I will investigate that some more. Great heads up though.

    I had recently built 2 of the LPF-4000's for a different system. See the link below.

    AC Mains Line Power Filter LPF-4000 – ATL Audio Ltd.

    I asked Aleksander if he would sell me them as a kit so I could build them myself. He agreed and during that process I was able to build a contact and that allowed me to order the 3 boards for this project. None of the boards in the LPF-4000 are sold as individual boards but he has boards on his website that are very similar. Links below to the DC blocker/emi & rfi board and a second stage emi/rfi board. The one I use is 2 of these boards side by side that I turn into 2nd and 3rd stage emi/rfi filters.

    PCB for Combined DC Blocker (trap) & EMI/RFI filter – ATL Audio Ltd.

    PCB for Common Mode Filter (EMI/RFI filter) – ATL Audio Ltd.

    I could send you more details via PM
     
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  19. Jaytor

    Jaytor DIY Enthusiast

    Location:
    Oregon
    I ran across this thread several months ago when I was thinking about building my first tube DIY project. I never got around to thanking you for the great information you provided and tell you how much I admired your build.

    Your thread and everyone's reaction to it was one of the strong motivators for me to do a build thread on my 300B monoblocks.

    I will likely build an Aikido preamp sometime in the next year. I have already ordered a couple of Octal All-in-One PCBs - I'm planning to use one board for each channel, operated in a fully balanced configuration. Getting everything into a single chassis will be the biggest challenge. Are you still happy with the sound quality?

    Did the change you made to your Khozmo 5V supply solve the problem with the Khozmo shutting off? When I bought my first Khozmo attenuator, Arek recommended that I use a 5.1V supply. But the ones I use are a different model using an OLED display, so this might not apply to the model you are using.
     
  20. fully_articulated

    fully_articulated Forum Resident Thread Starter

    Thanks @Jaytor, I really appreciate the comment. As you probably know I'm a great fan of your 300B thread and having some small responsibility for it is very gratifying.

    I am. Every so often I do look around for another project to build as a comparison but haven't really found one that enthuses enough. The Aikido, while being relatively neutral sounding rather than lush or 'tubey' does have enough magic to keep me happy. In fact it's looking like my next project may be another Aikido, in the same vein as the ANK DAC rebuild I did. At the moment I'm trying to design my own monolithic PCB that includes the Aikido stage married to the ANK M2x regulated power supply, filament supplies, the Khozmo supply, a relay input switcher and output mute.

    So far I'm not entirely convinced it's doable (by me anyway).

    Tentatively, yes. However the problem really kicked off during a particularly cold period, and temperatures haven't been that low since I did the conversion. I'll let you know next winter!
     
    bluezee3228 likes this.
  21. Jaytor

    Jaytor DIY Enthusiast

    Location:
    Oregon
    I'm not familiar with the ANK M2X. I will check it out.

    I'm thinking I will take the output of the B+ supply after the tube rectifier and first filter bank (on the All-in-one board) and feed it to a Neurochrome Maida regulator and then back to the Aikido board (this for each channel).

    I want to have a 12V trigger output as well so that I can automatically turn on/off my monoblocks from the preamp power switch. So I'm thinking of using a Traco-Power TMP-15252C 15W dual output supply (5V + 12V) to drive the trigger and power the Khozmo. I'm just not sure if the 5V output is going to be a high enough voltage to drive the Khozmo. In the limited testing I've done, it seems to work fine on 5V, but this might not be reliable under all conditions (i.e. when it is cold as you noted).

    The other project I am considering is a DDDAC parallel NOS DAC. I suspect I will end up doing both of these over the next year or so - just not sure which one first.
     
  22. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    Latest mockup pictures.

    [​IMG]

    [​IMG]

    [​IMG]

    Still waiting on the Goldpoint switches and volume control. The latest twist I'm working on will be LED backlighting of the 3 knobs. Wish me luck on that one!
     
  23. fully_articulated

    fully_articulated Forum Resident Thread Starter

    Good luck!

    Your build is shaping up really nicely.
     
    bluezee3228 likes this.
  24. Jaytor

    Jaytor DIY Enthusiast

    Location:
    Oregon
    Coming along nice. Looks like an interesting power supply. I'm looking forward to seeing future progress.
     
    bluezee3228 likes this.
  25. bluezee3228

    bluezee3228 Forum Resident

    Location:
    United States
    Volume control.

    [​IMG]

    Output selector switch. Switches R6, R7, R16, C7 and C8 values.

    [​IMG]

    Input selector switch.

    [​IMG]
     

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