5f1 champ build - wire voltage rating?

Discussion in 'Shock Brother's DIY Amps' started by Mfa88, Feb 10, 2020.

  1. Mfa88

    Mfa88 TDPRI Member

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    Hi everyone
    I'm currently building a 5f1 using RobRobs layout , not a kit !

    I have several threads on which wire gauge you should use, however only a few on the voltage rating.

    I already have some wire which says 300/500 V on them, (awg18) , which I have read means u0/u where u0 is RMS voltage to ground , and u=1/sqrt(3)*u0 for three phases (approximately).

    Do you know if this wire is ok for my champ ?
    To my understanding, a champ would reach around 400 volts.

    I have a centertapped PT with 325 Volt on the primary.
     
  2. jimgchord

    jimgchord Tele-Afflicted

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    18 awg wire is overkill except for use on the heater circuit. 22 awg is fine for the rest.
     
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  3. Mfa88

    Mfa88 TDPRI Member

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    Thanks, but I already read several quotes on this without any argumentation.

    Also, the question was related to Vantage rating.
     
  4. Mfa88

    Mfa88 TDPRI Member

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    Sorry, voltage rating *
     
  5. jimgchord

    jimgchord Tele-Afflicted

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    Good luck
     
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  6. King Fan

    King Fan Friend of Leo's

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    EDITED to remove mini-rant.

    Um, basically @jimgchord was right. If you only shop voltage rating you can get poor wire for amp building. The 'right' wire for an amp build depends on workability and fatigue strength, shape retention, ease of soldering, ease of threading through lugs, ease of stripping, etc. And it's not all about voltage, in places you have to consider ampacity.

    So most experienced builders go with good quality, amp-appropriate "hookup" wire in 22ga for everything except heaters (and truth be told you can use 22ga there too, especially downstream of the power tubes -- Marshall did).

    Ordinary hardware-store wire may be stranded but non-tinned (yikes) or solid-core but not fatigue resistant (ack). Some high-voltage wire may be way too fat or stiff to use in amp work.

    So experienced builders tend to use 'hookup' wire *sold by amp-specific shops.* Examples are the vintage solid-core cloth wire sold by Mojotone or Doug Hoffman (good fatigue resistance, superb workability and shape retention) or something like the pre-tinned 'topcoat' wire sold by Valvestorm (decent workability, superb fatigue resistance and strippability).
     
    Last edited: Feb 10, 2020
  7. Stratandtele

    Stratandtele Tele-Meister

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    AWG 22 for everything but the filament circuit, where AWG 18 is usually used. I very much prefer the cloth push back type, because stripping pvc in a tight amp chassis like the champ is sometimes very difficult.
     
  8. sds1

    sds1 Tele-Afflicted

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    The voltage rating is regarding the insulation, the current rating is related to conductor size. I don't feel like OP's question has been answered.

    For tube amps I would think you'd want 22AWG rated for 600VDC.

    Yet 22AWG wire rated at 300V is somehow safe for tube amps.

    Someone explain that as it will likely answer the OP's question.
     
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  9. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Except for the main power supply nodes...most places in a Champ won't reach 300V. Lotsa cathodes, heaters, and signal wiring that doesn't have high voltage.

    I only buy 600V rated hookup wire so I know I can use it at any point in most any amp without having to think twice. I think most of mine is 18g and 20g, more than enough for any amp stuff.
     
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  10. Mfa88

    Mfa88 TDPRI Member

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    Thanks! Have had trouble finding 600v wire at only 22 awg
     
  11. Mfa88

    Mfa88 TDPRI Member

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    Where do you buy your wire ? I found some on eBay, but I don't trust some random seller that could state anything. I feel that shops with data sheets are more reliable.
     
  12. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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  13. sds1

    sds1 Tele-Afflicted

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    So you interpret the ratings literally then?

    From Hoffman's wire page:
    "Note: All the PVC coated wire below is rated at 300 volts.
    300 volt wire is fine for low amperage-High voltage tube amp applications."

    That includes 22g as well as 20g.

    I have always interpreted the ratings literally too, but that's just my shortcut to thinking about it.

    I get my wire here, it's local shopping for me. The best wire I've found (also available at Valvestorm as @King Fan mentioned above):
    https://shop.amppartsdirect.com/Wire_c53.htm

    Searching Google for "UL1015" might help. This spec includes the 600V rating.

    EDIT: looks like that TubeDepot MIL-SPEC stuff is topcoat as well? Google "M16878" for other suppliers.
     
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  14. Snfoilhat

    Snfoilhat Tele-Afflicted

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    Voltage is the difference in electrical potential between two places. A cross-board jumper from let's say the dropping resistor nearby the filter caps to a pair of plate load resistors at in the preamp might have 350VDC with respect to ground. But lead dress may place them physically nowhere near another conductor at ground potential. So it's not just the thickness of the insulating sheath of pvc or cloth or whatever, but air and space between conductors and then consider the voltages between them.

    There are transformers with 60 year old waxed cloth leads still kicking in old amps with what? Peak voltages of close to a kV momentarily developed across them? What's the rating of that material vs the generic 300V stuff from the hardware store?
     
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  15. King Fan

    King Fan Friend of Leo's

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    LOL you guys, now I see why I don't tend to think in terms of voltage rating. Necessary but not sufficient? Not even necessary? What Leo did? What Jim did? What we all do? :D

    You're in the EU? You might try TAD -- they seem to carry what looks like the 'good' cloth-covered solid wire in 18 and 22ga. As for pre-tinned, easy-strip 'topcoat' wire in the EU I don't know. Modulus in the UK sell 600V plastic (?PVC) coated wire but it looks like it *may* be stranded and not pre-tinned, which can be a pain to shape and solder. There are a lot of EU builders on here; you might look at some of their builds.
     
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  16. sds1

    sds1 Tele-Afflicted

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    This is turning out a lot like the recent resistor voltage rating thread. :)
     
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  17. muchxs

    muchxs Doctor of Teleocity

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    22GA VLT BC UL 1015 1230 1032 90C 1000V 105C 600V VW-1 MTW
     
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  18. Mfa88

    Mfa88 TDPRI Member

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    So you wouldn't worry about using 300v 18 ga like I did so far? I'm almost done with my wiring so would love not to change it to a 600v :D
     
  19. Paul-T

    Paul-T Tele-Meister

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    I wanted the cloth-covered solid core wire as sold by mojotone etc (not the cheaper one which has PVC covered with cloth.

    Tube-town has a good selection, postage is always reasonable, but none of the cloth pushback.

    I was recommended this supplier , amptone in Poland. Cables are here. Less expensive than TAD I think, nice efficient people. It's the proper US stuff, if you scroll down their listings, can't remember if it's the same as Hoffman, or Mojotone, someone else might comment. I didn't look for voltage rating as heating effect is more reliant on current than voltage, but am pretty sure 600v is ok.

    I got mine sent regular airmail, which was cheap and arrived quickly.I went for #22 and #20. Price is per 0.5m.
     
    Last edited: Feb 10, 2020
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  20. Lavochkin

    Lavochkin TDPRI Member

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    Since you're talking wire, solid or stranded- which is better?
     
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