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  1. No, the Vibroverb has no mid pot. I added one...

    No, the Vibroverb has no mid pot. I added one since the removal of the vibrato, tremolo and Vibrato channel left extra chassis pot holes. The 6.8k mid resistor is still there so with the Mid control...
  2. Yes, I suggest the Classictone spec for the real...

    Yes, I suggest the Classictone spec for the real Vibroverb's PT, OT and choke. Of course the 6V6 and micro versions use different iron.
  3. Blackvibe - No Reverb, No Tremolo, 1 Channel AB763 Blackface

    The 1963 Fender AB763 blackface Vibroverb is my favorite amp of all time. It will be forever linked to Stevie Ray Vaughan's amazing tone but building a blackface Vibroverb is a daunting task, even...
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    Thanks Helmholtz, Dr. Irving and R.G., I really...

    Thanks Helmholtz, Dr. Irving and R.G., I really appreciate your complete and understandable answers. I finally understand how we can alter the cathodyne's load resistors and get more voltage swing...
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    Cathodyne PI Gain

    I know cathodyne phase inverters always have a gain of slightly less than unity of around .96 but I can't figure out how that can be shown on a load line chart.

    Here's the load line chart for a...
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    A socket that close to a bathtub should have been...

    A socket that close to a bathtub should have been a GFI so I'm really curious how this happened.
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    Was Relf killed by a widowmaker?

    Was Relf killed by a widowmaker?
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    I believe you are right nick. Every schematic I...

    I believe you are right nick. Every schematic I found has the heater transformer for V1 except the Magnatone 107 (schematic above) and ironically it has a big Underwriter Labs "UL" stamp of approval...
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    The term "widowmaker" does seem to be a strong...

    The term "widowmaker" does seem to be a strong term for power transformerless amps wired like the 1430.

    When we use the term "death cap" everyone knows what you're talking about. Call it an "RFI...
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    Enzo, by adding an isolation transformer without...

    Enzo, by adding an isolation transformer without a three prong cord wouldn't we would lose the RFI shielding for the chassis and guitar cord since there would be no tie to earth ground?

    nosaj,...
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    They don't need to be "upgraded", widowmakers...

    They don't need to be "upgraded", widowmakers already have a death cap.

    My point is we should tell widowmaker amp owners that they need to alter the circuit to remove the death cap and return...
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    An isolation transformer has to be used to allow...

    An isolation transformer has to be used to allow a "normal" chassis grounding scheme. There's no way to ground the input jack safely in a power transformerless amplifier. The chassis and guitar cable...
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    The return resistor returns the V1 cathode...

    The return resistor returns the V1 cathode current to the mains. That's why you can't simply remove the death cap and return resistor to isolate the chassis in a widowmaker.
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    The death cap and return resistor would still tie...

    The death cap and return resistor would still tie the mains to the chassis. What are the benefits of removing ANY direct connection to the mains other than limiting max shock current?

    It seems to...
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    I'm really trying to nail down three points. ...

    I'm really trying to nail down three points.

    Does adding an isolation transformer to a power transformerless amp really make it safer? The only benefit I see is the transformer will reduce the...
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    Cap and resistor to chassis ground in center of...

    Cap and resistor to chassis ground in center of schematic:

    http://music-electronics-forum.com/attachments/28995-magnatone_107-scarlett.jpg?amp;d=1401060485
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    Any amp with a death cap with the plug in...

    Any amp with a death cap with the plug in backwards will shock you like that but the current is limited to about 2.4 milliamps--that's what the death cap will pass with 125 volts at 60Hz.
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    C3 & R6 http://i44.tinypic.com/2r3gw8y.jpg

    C3 & R6

    http://i44.tinypic.com/2r3gw8y.jpg
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    Lectrolab #10 shows the cap and resistor to...

    Lectrolab #10 shows the cap and resistor to chassis:

    http://antiqueradio.org/art/gt051.jpg
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    No disrespect taken R.G., I'm a fan of your work....

    No disrespect taken R.G., I'm a fan of your work.



    I haven't been able to find any schematics of widowmaker guitar amps with the neutral wire wired directly to the chassis like the widowmaker...
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    Guys, I understand the danger of a shorting cap...

    Guys, I understand the danger of a shorting cap in both "normal" amps with two prong cords and in the Silvertone above but what is it about "widowmaker" amps without power transformers that warrants...
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    That 68k resistor will pass less than 2 milliamps...

    That 68k resistor will pass less than 2 milliamps at 125 volts so it has less impact than the death cap's 2.4 milliamps at 60Hz and 125v.
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    R.G., I wired my barn for 240V 200 amp service so...

    R.G., I wired my barn for 240V 200 amp service so I understand hot, neutral and safety ground wiring and how neutral and ground are tied together at the service entrance.

    The Silvertone widowmaker...
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    Why is a widowmaker like the Silvertone above...

    Why is a widowmaker like the Silvertone above considered more dangerous than an amp with a power transformer, a two prong power cord and a death cap?

    Is it because the widowmaker can deliver a...
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    Thanks Tom and Enzo, I didn't consider that a...

    Thanks Tom and Enzo, I didn't consider that a rectifier with a grounded plate but cathode at high negative voltage would function normally but your explanation makes sense.

    Enzo, I had read about...
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    Widowmaker Amps & Isolation Transformers

    I'm trying to nail down my understanding of the dangers of "widowmaker amps" so could you review the below and let me know what I have wrong.

    I have yet to see an amplifier schematic that shows...
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    In Chrome it's the circular arrow in the upper...

    In Chrome it's the circular arrow in the upper left corner of the browser.
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    I want to thank (most of ;) ) you guys for...

    I want to thank (most of ;) ) you guys for providing meaningful guidance. I took it to heart.

    I took a public flogging but I learned a lot in the process.
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