Kegger/blueglow kt88 project

Discussion in 'Tube Audio' started by Tubeglowpio, Jan 6, 2019.

  1. Tubeglowpio

    Tubeglowpio Active Member

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    I'm with you on that, my RH-84 turned out great but I also want to build a new one with better outputs and better caps so I'm thinking if I build these as monoblocks with enough current ability I can always run even kt-120's and 150's pretty well with a bias adjustment.
     

     

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  2. Tubeglowpio

    Tubeglowpio Active Member

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    I'm going to be building a 2a3 amp while waiting for my edcor iron for this build but I'm thinking of building another RH amp next year so may go that route then or do the parallel rh84.
     
  3. Tubeglowpio

    Tubeglowpio Active Member

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    so it looks like my output stage would have about 50mv of ripple if I use a clc filter, how do I figure out how much will be going to my speakers? I will be using 100 db speakers.
     
  4. Tubeglowpio

    Tubeglowpio Active Member

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    So I ended up messing with the power supply design and got it down to around 1.5 mv. I'm just wondering around how much current the driver will draw for each channel?
     
  5. Tubeglowpio

    Tubeglowpio Active Member

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    Here is how the power supply output tube b+ response looks, wonder how it will sound. Screenshot (8951).png Screenshot (8950).png
     
  6. primosounds

    primosounds Powered with pure tube sounds. Subscriber

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    Well, the umbilical is somewhat of an extra effort, but once you get the hardware sorted it is really not that hard to implement. You have 1 wire for the B+ , 1 wire for the ground, 2 wires for the heaters, That is about it. I have done a couple of amps this way. For a high power SE amp, the weight of the transformers, especially in a LCLC configuration, can be substantial so that is why i did it.
     
    Last edited: Jan 9, 2019
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  7. Tubeglowpio

    Tubeglowpio Active Member

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    I hear you, I will think about it a bit. I've always have wanted to build mirrored mono blocks though and want to see if I notice better stereo separation. I do have some octal plugs for something planned down the line in a couple of years that I nicknamed "King Song" as a joke one late night, cant wait to start building that madness. Anyways I'm thinking my power supply above should work pretty well so I'll be doing a clclc filter. I thought I read somewhere that you've built the Kegger Kt-88 before, how did the sound compare to the rh-84? Was it sweeter?
     
  8. 6DZ7

    6DZ7 Super Member

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    Divide that by the turns ratio of the OPT and reduce that by the efficiency rating.
     
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  9. Tubeglowpio

    Tubeglowpio Active Member

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    Thank you, I ended up looking it up in another thread. I'm going to be under 2mv of ripple on b+ so I'm set. This amp/speaker pair should end up putting out around 110db of clean audio 1 meter away which is plenty loud. For private listening I don't usually go above 95 db.
     
  10. primosounds

    primosounds Powered with pure tube sounds. Subscriber

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    Well, i actually made a SE 6l6 amp that was based on Keggar's schematic. Compared to the Alex Kitic design they both share the same qualities of very natural, dynamic, and realistic sound.
    If you want to extract the most power from your amp you should install fixed bias. This has the advantage of deleting the large cathode bias resistor and all the heat it produces. This adds between 5 to 9% more power. Plus it improves the soundstage by making the instruments and voices bloom, making them more "3D".
     
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  11. Ruidoso Bill

    Ruidoso Bill AK Subscriber Subscriber

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    I just realized we've been chatting around on two different threads, I'm thinking stay on this one with my updates etc.
     
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  12. Tubeglowpio

    Tubeglowpio Active Member

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    Yeah, since I'm planning mono blocks mine will be aimed around the kt-120 tube. I almost want to go parallel and get about 22 watts or so. I do love some 3d sound, I may just have use fixed bias then. I've always heard that fixed bias had less of the "tube sound" which can mean a few different things but I cant knock it till I try it. This will be my first time building mono blocks and also using 2 chokes in the power supply so it should be pretty interesting. I ordered most of the components today and got two different bias resistors and a 5 watt 100 ohm pot to adjust the bias 50 ohms to tweak and roll other tubes.
     
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  13. Tubeglowpio

    Tubeglowpio Active Member

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    That sounds good to me, probably will get a little more traffic that way anyways so maybe more questions will be answered. I'm going a little crazy with this build the more I think about it but I do want this one to be my daily driver.
     
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  14. primosounds

    primosounds Powered with pure tube sounds. Subscriber

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    TGP, Are you building the amp with the pentode driver tube?
     
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  15. Tubeglowpio

    Tubeglowpio Active Member

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    It will be switchable between ul and triode, with a 6aq8 triode driver tube.
     
    Last edited: Jan 10, 2019
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  16. Tubeglowpio

    Tubeglowpio Active Member

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    I haven't sorted out everything yet and may need something more to drive it, I wonder if I could parallel both sides of the 6aq8 for more current? Or maybe use a cathode follower?
     
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  17. primosounds

    primosounds Powered with pure tube sounds. Subscriber

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    If you are going to riff off of Kegmans scheme be sure to allow for changes to the component values to make sure your requirements are met. Tube circuits are much more forgiving than other systems and will work under a wide range of values. But it is hard to know if you are achieving your goals unless you do some measurements.
     
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  18. Tubeglowpio

    Tubeglowpio Active Member

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    I'm going to do more research then throw it together and check the bias and voltages and throw it on the scope to check the sine wave and square wave output and sweep it for freq response, after that I will use an audio analyzer to check distortion vs output. Then of course spend time listening to it:)
     
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  19. Tubeglowpio

    Tubeglowpio Active Member

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    I'm actually am working on building a transistor preamp and it's going pretty well but only because I made sure to calculate everything out, I'm using it to drive the rh-84 and so far it sounds real nice and doesn't take away from the tube goodness at all but makes it even more full sounding. I will be building a tube preamp soon though hopefully.
     
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  20. tubetime

    tubetime New Member

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    I finished this amp a few weeks ago and can say that I believe the Blueglow hype. Best sounding amp I have heard. I used Kegger's schematic and Blueglow's info and layout. 6AQ8 preamp tube. Second power supply cap is nichicon 390uf 500v. Just ultralinear no triode and no volume control. I also JB welded a piece of aluminum down center of amp to increase chassis stiffness (output transformers are heavy) and for sheilding from power supply. Three holes through aluminum. 1 for high voltage. 1 for grounds. 1 for heaters. All my voltages are basically spot on with Blueglow's. Cannot think of a thing I would change. Thanks Kegger for the fantastic schematic! Know you are up there somewhere! Thanks Blueglow for all the wonderful videos and info!

    IMG_3121.JPG IMG_3122.JPG IMG_3123.JPG IMG_3126.JPG
     
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