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  1. Replies
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    Sucking air in and blowing it at the CPU will be...

    Sucking air in and blowing it at the CPU will be best (assuming its cool air)


    https://youtu.be/H5ELwOLb7ss
  2. Good luck - I once disassembled and re-assembled...

    Good luck - I once disassembled and re-assembled a C30 13 times over 2 days trying to find a broken trace/jumper. I'll never get those 2 days of my life back again.

    If you can't find a broken...
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    If you want accuracy sheet metal drilling with a...

    If you want accuracy sheet metal drilling with a hand drill, you need to make a small guide indent by hammer-punching a guide-indent for the drill bit. A 3 to 4 inch nail makes a handy punch. Lay...
  4. All I have are these?

    All I have are these?
  5. Me too. Best solution is to clip off those...

    Me too. Best solution is to clip off those terminals and solder the heater leads from the PT directly to the spade terminals. Eliminates arcing.

    These terminals see just over 11A in normal...
  6. yes, one could replace one or more of the 100k...

    yes, one could replace one or more of the 100k plate resistors on the first two stages with between 150k to 470k (depending on whim), or reduce the cathode resistance (to get hotter bias and more...
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    I know this is 1) an old ghost thread, and ...

    I know this is

    1) an old ghost thread, and

    2) I'm probably going to be frowned on because it has nothing about plate dissipation in it (but Fender obviously didn't care about that when they...
  8. I got a few pairs of RI TS6V6s sitting in my...

    I got a few pairs of RI TS6V6s sitting in my stash unused from about 10 years ago. They're spare ones I ordered when they first cam out. But when I went to try them in an amp that ran about 380 or...
  9. Replies
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    9,074

    Yes I have, and it works perfectly if you follow...

    Yes I have, and it works perfectly if you follow it.
  10. Replies
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    Doesn’t matter if you run the output tube cathode...

    Doesn’t matter if you run the output tube cathode ground return to the daisy chain end with its own wire. Just make sure you follow Merlin’s ground layout. The amp won’t smoke itself if the PT...
  11. Don’t know if this has been suggested already (as...

    Don’t know if this has been suggested already (as I haven’t read all the replies above), but you could add a pair of anti-parallel 6A diodes in series with one side of the heater winding before you...
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    Screen dissipation under heavy signal conditions...

    Screen dissipation under heavy signal conditions is partly dependent on the load resistance on the plates. A higher load resistance has a shallower load line, putting the line below the knee of the...
  13. If you’re thinking about the 6P3S, which has a...

    If you’re thinking about the 6P3S, which has a 900mA filament and is rated for 20W, they don’t handle plate voltage over 400 very well when run as a 6L6, but may do better with colder biasing, and...
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    If the screen supply resistor is burning up,...

    If the screen supply resistor is burning up, could be a shorted screen in the 6v6, or a shorted smoothing cap (screen supply node filter cap) - assuming the ‘470R’ is the screen supply dropping...
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    Yes

    Yes
  16. Replies
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    A good rule of thumb would be 1mA per 12AX7...

    A good rule of thumb would be 1mA per 12AX7 triode and 4-5mA per 6L6 screen. See the diagram at the bottom of Merlin’s page here (albeit that it uses EL34s)
    ...
  17. Replies
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    I've used a shared 10W 270R cathode resistor in a...

    I've used a shared 10W 270R cathode resistor in a few t-bolt style builds. Bypassing with 25uF yields more grunt.

    For the screen grids, allow for 5-6mA idle screen current per tube for 5881s or...
  18. Replies
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    9,074

    This would be fine. If you want, you could build...

    This would be fine. If you want, you could build it with both SS rectification (2-phase rectifier) and tube rectification, so you can swap between them and get the different characteristics.
  19. Replies
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    then pull the tubes and measure the VDC on the...

    then pull the tubes and measure the VDC on the grid pins

    (edit: a common issue I’ve found with a lot of RIs that I’ve fixed, apart from the Illinois caps, is dodgy PCB traces)
  20. Replies
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    regardless of whether the bias supply caps ‘test...

    regardless of whether the bias supply caps ‘test well’, Replace then and see what the working result is.

    (In fact, if it is an RI amp with ILLinois caps, might as well replace them all)

    also,...
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    I'd approach any design aimed at wringing more...

    I'd approach any design aimed at wringing more gain out of a tube, by thinking about how it compares to an efficient loadline in a common cathode amplifier, and then work backwards. So the starting...
  22. Replies
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    Bootstrapping can also be employed to increase...

    Bootstrapping can also be employed to increase the gain of an inverting gain stage, as Merlin Blencowe demonstrated in the ‘designing tube preamps for guitars’ books. Works the same way helmholtz...
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    What was the plate voltage and the screen voltage?

    What was the plate voltage and the screen voltage?
  24. Replies
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    Not quite. In the 'daisy chain' system Merlin...

    Not quite. In the 'daisy chain' system Merlin describes, all the grounds are daisy-chained together into one ground buss/wire, but only the input stage end of this daisy chain ground wire is attached...
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    Will hum less if it’s connected directly to the...

    Will hum less if it’s connected directly to the ground lead of the reservoir cap. I suggest following the grounding layout in Merlin Blencowe’s grounding article. (Especially Fig 15.12 and Fig 15.14)...
  26. Thread: 6P14P-K

    by tubeswell
    Replies
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    6P14P are good well over 300V (and are long-life...

    6P14P are good well over 300V (and are long-life tubes as long as you keep the screens under 300), and are 14W tubes.

    The rutubes poster (#4) on this thread explains the longevity ratings:...
  27. Weber do a 6 x 9 and they probably have recone...

    Weber do a 6 x 9 and they probably have recone parts for these (although nothing listed on their website). Email Brian Spane at Weber (their speaker parts guy).
  28. That pan input impedance might work better driven...

    That pan input impedance might work better driven straight from a transformerless SRPP driver (using the 6111s - which are comparable to a 12AU7) - seeing as how you expressed concern about power...
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