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My new tube preamp build

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Comments

  •   PWRRYD said:
    I have greatly reduced the 6V6 tubes' microphonics by adding these high temperature silicone rubber o-rings.  There are places on line that sell the exact same "damping" rings for $5 each.  I got these from McMaster-Carr...  package of 10 for $6.69  :)



    And even if they had no effect at reducing microphonics at all,  those red rubber O-rings look just plain cool. B)  Well worth the 5 bucks!! 
    tajanes
  • Raising an old thread of mine from the dead (I can do that, right?)

    Sitting at breakfast Saturday morning in Ankeny, IA with some friends of mine I stated that I was done building tube projects.  I even offered to sell my stuff to Bill.  After seeing Ani's "new toy" thread and digging through my tube stock I got bit by the tube bug yet again and decided to revisit this 6V6 tube preamp project.  I never was really happy with the overall sound of this preamp.  The first try was a simple grounded cathode topology that had WAY to much gain and was terribly microphonic.  The next rewire was a cathode follower circuit that has zero gain, still somewhat microphonic, but no dynamic "sound" at all.

    Anyone who has built a tube project knows that the largest amount of labor and cost of building these tube projects is making a nice looking hardwood case and top plate, and the parts for the power supply (power transformers and high voltage caps get pricey).

    Guess what, I already have a nice looking finished case and top plate, and a very well filtered power supply.  So my next step is to try another tube type and circuit topology.  Probably something like the 6SN7 tube in a CCDA circuit.  There is no deadline for this project.  I don't have any NOS 6SN7 tubes in my stock.  I'll probably buy some cheap chinese or russian tubes to play with first.  I'll try to update the project when I make any progress.
    ani_1014thtry
  • Never say never!! Tubes are just too cool.

    I have read good things about the Aikido linestage. I'm pretty sure that uses the 6SN7 and other close cousin octals. Let me know if you need anything.
  • Tubes should never be cool....that means they're off !
    ani_101PWRRYDS79104thtry
  • Tom,
    My very first project with tubes was an Aikido cathode follower preamp, using 6DJ8's that you were kind enough to gift me in that care package you sent about 9 years ago.  It has been in my system continuously for that long because it sounds so good.  I direct copied the main circuit topology from TubeCad's website then scratch designed my own tube rectified power supply.  That's why I was asking if you had anymore NOS 6DJ8's  ;)
  • If I remember correctly you said you had a small stash of them you pulled from some old oscilloscopes.
  • Ahhh - either I didn't know or had forgotten you had built that design. My memory sure isn't my strongest asset these days! I'm guessing the Aikido is a better linestage than my little SRPP 6BH7. I might have to build one for myself now.

    9 years ago? Has it been that long? Man, time flies! I do have a bunch of those 6DJ8s - not NOS, but they tested fine. Do you need a quad?
  •  Good to hear.  Look forward to seeing more of your excellent point to point wiring technique.  Now that you are back into tubes, you will have give your industrial TV-7 the "self-calibration" treatment. :)   Which reminds me, I still have to "self-calibrate" my Heath-Kit TT1.     Then I can start running up matched pairs of power output tubes taking actual transconductance (gm) measurements, and comparing them to the published figures in the RCA receiving tube manuals.
  • Tom, one of the tubes you sent me was a 6dj8. 

    Craig, you got some tube for dummies links to the Aikido pre? 
  • Let me look Kornbread.  I think all those pages on Tubecad's site are still good.
  • I've decided to add a small 12.6 volt filament transformer to this project so that I can use 12SN7 and 12SX7 tubes instead of the 6 volt 6SN7 tubes.  Cost wise the 12 volt filament tubes are a fraction of the cost for NOS tubes.  Like $6 per tube vs $50 to the moon!
  • Craig - Do you just need a pair of 6SN7's? $50 is ridiculous! There are tons of NOS 6SN7s around. Somebody is seriously hyping these things up just to raise prices. I can sure send you a few of those. Heck, I have a small stack of NOS on the shelf right next me. If you want 12SN7s, I'm pretty sure I have a few of those, but they might not be cosmetic matches.

    I think you need a tube care package - xSN7s & 6DJ8s! I'll see if I still have your address.

    I started reading that CCDA article. Interesting stuff - I might be able to convert my little VTV 6SN7 linestage to that topology. I'll have to see if I can get a B+ of 200v with the PT on that chassis. I never loved the VTV circuit - at least not my build of it. 
  • Can I request something on the 6DJ8/6692/E8CC8 family? or rather specifically for the following tubes 6H6, 6n11, 6H30, E88CC, 6922, 6DJ8

    any details on these or opinions?
  • edited November 2019
    Ani, those 6DJ8's are nine pin tubes, not the octal bases that your amp takes.
  • PWRRYD said:
    Ani, those 6DJ8's are nine pin tubes, not the octal that your amp takes.
    yes, not for the tube amp, but for something else on the way.... (pre-amp / DAC). Will add to the thread, as soon as I get it...
  • I'm sure you guys built yours from scratch, but which one of these kits would it be, or which one do you guys  recommend? 

    linked to from the Tube Cad Journal.  


     
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