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    What was the plate voltage and the screen voltage?

    What was the plate voltage and the screen voltage?
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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)...
  4. Thread: 6P14P-K

    by tubeswell
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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:...
  5. 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).
  6. 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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    In theory there might be for an amp with plates...

    In theory there might be for an amp with plates sitting at 500V, but in practice amps aren’t that efficient. You can easily write off 10-20% of the hypothetical peak-to-peak swing once you factor in...
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    here you go

    here you go
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    but if you keep a 1M permanently across the...

    but if you keep a 1M permanently across the switch (as discussed in the previous posts), then the screen is not disconnected from HT at any time
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    It’s the voltage ‘across the switch’ that is key....

    It’s the voltage ‘across the switch’ that is key. There isn’t much voltage difference between most screens and plates in most amps.
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    If those voltages in that Hot Cat 30 schematic...

    If those voltages in that Hot Cat 30 schematic are correct, I'm not surprised it eats tubes.
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    In the Hot Cat 30, V1a in the gain channel is...

    In the Hot Cat 30, V1a in the gain channel is grid-leak biased, (but is it very hot biasing - most grid leak biased triodes use a bigger grid leak resistor to get the bias e.g. 5M,it it still ends up...
  13. It relies on having g3 biased negatively enough...

    It relies on having g3 biased negatively enough to repel electrons back to the screen apparently.
    (and it does work, but is tricky to set up, and ‘works’ with high gm tubes better)
  14. When you're done reading Ian's very informative...

    When you're done reading Ian's very informative post, just for laughs, get your head around this Sulzer PI (at pages 10-11).
    ...
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    Heyboer also sells stuff via the WebetVST site....

    Heyboer also sells stuff via the WebetVST site. (They are pricier equivalents of the Weber spec transformers)
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    Go Chinese (if your government hasn’t banned...

    Go Chinese (if your government hasn’t banned Chinese imports yet 🙁). They seem to be robust.

    Treat them as 20W tubes (= bias them cooler).

    Be wary of customers who run their amps through power...
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    Also, make sure you have enough currrent rating...

    Also, make sure you have enough currrent rating on the HT (and heater) winding(s).

    For a ballpark guesstimate for a 300-0-300 HT, you want about 200mA to be sure the PT will cope well with the...
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    If you’re using SS diodes in a 2- phase...

    If you’re using SS diodes in a 2- phase rectifier, I vote for 300-0-300. Others may have different views.
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    About PT regulation...

    About PT regulation https://www.ecmweb.com/basics/basics-transformer-voltage-regulation A PT’s load regulation is a ‘measure’ of the PT’s ability to cope with a load.

    Besides, When you run the...
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    Depends what you mean by lower voltages I guess....

    Depends what you mean by lower voltages I guess. I don't consider 400V particularly 'low'.

    As to new build tubes, manufacturing tolerances tend to be a bit variable (not so many items going into...
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    Depends on what sort of rectification you use....

    Depends on what sort of rectification you use. 0-290 with FW bridge rectifier using SS diodes. 290-0-290 with 2 phase rectifier using SS diodes



    435 B+ or so, using a FW bridge



    ...
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    Heater elevation and humdinger is particularly...

    Heater elevation and humdinger is particularly useful with S:N ratio in the first stage.

    The James tone stack setup in this schematic gives a fairly flat response with the pots at mid rotation,...
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    It makes it a bit louder and tighter sounding...

    It makes it a bit louder and tighter sounding when cranked
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    Fixed :-)

    Fixed :-)
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    53878 I've built a few tbolt 6420 amp...

    53878

    I've built a few tbolt 6420 amp circuits. I like 'em with a B+ around 400 and 5881s running off a shared 270R cathode resistor that is fully bypassed. The spare triode is useful for goosing...
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    And yes, you can run heaters in series or...

    And yes, you can run heaters in series or parallel. 3 x 12.6Vac haters in series requires a 37.8VAC supply. Each 12.6Vac filament draws 0.15A, but since they are in series, the same current goes...
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    ... and here's the picture

    ... and here's the picture
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    Agree with Chuck H’s 1st reply. FX loops are...

    Agree with Chuck H’s 1st reply. FX loops are especially nice for delay, phaser, chorus, flanger, frequency-comb/harmonic, or other similar complex signal processing FX. Much nicer to do these after...
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