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  1. K

    1956 Lafayette LA-59 Mono Tube Amplifier

    Can't remember where I read it and I certainly can't vouch for accuracy, but it's possible that the iron in this model is made by Sansui.
  2. K

    Making the Magnavox AMP-197 sing

    Just curious Gadget, what kind of voltage are you getting at the input of the 5Y3 rectifier?
  3. K

    Magnavox Flea Power: Getting More Out Of The 8600 Series - A Lot More!

    Actually, to be most technical I believe the output tubes are drawing a combined 88ma since the output tube screens are being powered by the same tap as the input tubes, so it would be 88ma to the output tubes and 13.5ma (screens draw 5ma a piece so 10ma total) for the input tubes and output...
  4. K

    RIP Archie2

    Just saw this. I met Ray on a couple of occasions a while back, the last of which was to purchase a tube tester which I still have to this day. We talked audio stuff for a while, like us AKers are prone to do. He seemed like a real nice guy. All the best to his family.
  5. K

    Bevois Valley Amp Build

    Are you still running into some crossover distortion at higher power or has that resolved with the new operating point? With the loading that those transformers provide, EFB would maximize output power and minimize distortion, though I'm sure it already performs great as is.
  6. K

    Bevois Valley Amp Build

    I wouldn't cut a hole for that PT yet. Wait for the 5AR4 to arrive. I'll bet you lunch that the 5AR4 in combo with the 9300 power transformer is gonna put your voltages right where you want them. Read post 32 of Dave G's epic thread about the 9300 here: More Fun With Magnavox: The 9300...
  7. K

    Bevois Valley Amp Build

    Assuming the last row labeled cathode current is for all four tubes it just demonstrates that each entry in the table is biasing the output tubes too coldly. You simply need more voltage to maximize the operating point and power output as well as be able to maintain regulation for the driver...
  8. K

    Bevois Valley Amp Build

    The 5AR4 uses 1 less AMP of current to light its filaments as compared to the 5U4GB, so this theoretically should free up some current reserve in the power transformer for the rest of the circuit. I would think it would be worthwhile to drop in the 5AR4, experiment with cathode resistor value...
  9. K

    More Fun With Magnavox: The 9300 Series

    The Dyna 565 clones haven't been available for quite some time and no indication that they will be available anytime soon so not sure why we're making that comparison.
  10. K

    Looking for tube magic, warmth, coloration, or other?

    An older Conrad Johnson preamp from the PV series might be right up your alley.
  11. K

    KT88 amp - Kegger version - are the power tubes overdissipating?

    With the power transformer that you have and with the available b+ voltage, what it comes down to is that the KT88 will bias up pretty cool in your amp, EL34 will run a little hotter and be a little more in it's wheelhouse dissipation wise, and the old school 19w 6L6 would probably bias up just...
  12. K

    KT88 amp - Kegger version - are the power tubes overdissipating?

    True, but I'm pretty sure that even though Kegger kept the B+ of the schematic at 400V, he mentions somewhere along the way in that big thread that he would personally bump the B+ higher if possible. Also note that when Blueglow did his version of the amp he didn't just raise the B+ but he also...
  13. K

    KT88 amp - Kegger version - are the power tubes overdissipating?

    Those new sims won't be accurate because as you lower the value of the cathode bias resistor and thus raise the idle current, the voltage (V+) between the anode and cathode will drop from the 327.5 value that it is now. You could maybe run your power transformer and circuit through PSUD2 to see...
  14. K

    KT88 amp - Kegger version - are the power tubes overdissipating?

    For the V+ field in the calculator you need to input 327.5 which is your anode voltage of 362 - the cathode voltage of 34.5. Also under the quiescent operating point you need to input 69ma which is your cathode voltage of 34.5 divided by 500, which is your resistor value. Once you do that...
  15. K

    Maggy Console observation

    Single ended 8600 series I'd bet.
  16. K

    SE Tube Amplifier : Project Preview ...

    Could always plug a 5AR4 in to lower that b+ voltage down while getting benefit of slow voltage ramp up.
  17. K

    Reisong A10: Technical review.

    Agree with Charlie, have to wonder if the over biasing condition exists to protect parts being used that don't meet the specs needed to bias properly..ie 100ma on the output transformers or 200+ ma on the power transformer. Steph, Is the power transformer specd for 110V or 120V?
  18. K

    Check my OT transformer math please

    Then you have to wonder if the power transformer is up to the task of properly biasing the EL34 tubes and the increased current demands doing so would bring. As for the transformers fit for 6V6 tubes, I would think that the 3.2k ohm load into 8 ohms would be low and not optimum.
  19. K

    Seemingly Obscure Power and Output Transformer identification "snipe hunt"...

    Resurrecting an oldish thread here but just wanted to add to the knowledge base. I have a single output transformer of the same markings that Gordon asked about in the original post. Mine is marked TR-125 and 831725 and was pulled off an amplifier chassis that powered a Symphonic 1260 tube...
  20. K

    Magnavox Flea Power: Getting More Out Of The 8600 Series - A Lot More!

    If those are 10K waves I think they look pretty solid.
  21. K

    Magnavox Flea Power: Getting More Out Of The 8600 Series - A Lot More!

    What about this transformer from Edcor? No center tap so you could use either a solid state bridge or set it up as a hybrid graetz using a 6CA4 to get the slow ramp up. Whatever makes more sense voltage wise. https://www.edcorusa.com/xpwr152
  22. K

    Plate current question EL34

    What is the transconductance reading of the tube? Is it also below indicated values?
  23. K

    Re-designing a Hammond H-1 Organ Amp (PSUD2 HELP)

    +1. Fill in the values for the Source Impedance Calculator as precise as you can using the resistance reading for one leg of the power transformer secondary 440-0. This will give you the most accurate estimation of your final voltages.
  24. K

    Need help troubleshooting Conrad Johnson PV-7 preamp

    With these older CJ PV series preamps the power supply/regulator circuits are the first things to go. I owned a PV6 for many years and had to have repairs done to those circuits to bring it up to snuff. Never regreted it though since it sounded great.
  25. K

    Tube Amp build exercise using Fisher Philharmonic V 29T Transformers

    EL95 tubes are cheap. Why not use them since the original circuit is pretty much designed for them and just pick up some 9 pin to 7 pin adapters.
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