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Heater CT in RobRob's Deluxe Micro

Discussion in 'Shock Brother's DIY Amps' started by TonyPan, Apr 13, 2021.

  1. TonyPan

    TonyPan TDPRI Member

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    I am building the Deluxe Micro from RobRob's website and I see in the schematic that the center tap of the 6.3 heater winding is grounded (as they usually are). However on the layout diagram the 6.3 CT is going to the top of the cathode resistor (not the grounded side). This connection point is often used in the case of artificial center taps with two 100 ohm resistors, but I have never seen it done with the actual 6.3 center tap from the PT.
    Assuming this is not a mistake, has anyone seen this before, and what is the benefit ?
     
  2. Paul-T

    Paul-T Tele-Holic

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    It's called an elevated heater, works just the same as with the artifical center taps. I did exactly the same on a recent 5E3 following ROb's mods, it helps ensure lower noise from the heater circuit.

    THere's a longish article on it here, if I can find a simpler one I'll post

    http://www.valvewizard.co.uk/heater.html
     
    DrPepper and King Fan like this.
  3. TonyPan

    TonyPan TDPRI Member

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    Thanks very much for your post Paul-T. Funny thing is that I have read this article in the past, but I forgot that the actual CT can also be elevated (not just when using artificial CT's). I also have Merlin's book "Designing Tube Preamps for Guitar and Bass", and I found the explanation in there too on pg. 77. What originally concerned me was the discrepancy between RobRob's schematic and his layout diagram, not sure which one he actually intended. (The CT is grounded in the schematic). I guess I will just elevate the heater as shown in the layout diagram.
     
    robrob and Paul-T like this.
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