Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ewdaviee on August 01, 2018, 10:45:56 pm
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I ordered wire directly from the 5F6-A Tweed Bassman Parts List and after I wired up my board, I happened to look closer at the fine print on both the 18 ga and the 20 ga Alpha wire purchased from the site parts store. To my surprise, both gauge wiring are marked 300V. I can understand the 20 ga signal wire being rated at 300V, but the 18 ga wire carry's up to 432V, per the original Fender 5F6-A schematic in the power circuit. Is the wire linked to the parts list incorrect? I haven't completed component installation yet, but I'm thinking I have to rip out the power circuit wiring. ????
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Where did you use 18AWG wire in that amp? Nothing in that amp requires 18AWG. Well, maybe the 6.3VAC filament string for the 6L6 tubes, but 20AWG is fine for that too.
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This has been asked a million times here and on the internet
300V rated wire is just fine
If you do a search, you can find many answers as to why
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Doug, you'll have to add a note in big red letters to your wire page. "This is fine dang it, just wire your amp!" :icon_biggrin:
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Ah, the old 300 volt wire rating discussion. If you really want to open Pandora's Box take a look at the voltage rating of the resistors we use. Not the power rating, the voltage rating.
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18 ga wire: This is my first amp build from the ground up. As such, I used the Hoffman store's 5F6-A parts list to order most of my parts. That parts list includes both 18 and 20 ga wire on the list of parts to build the 5F6-A circuit, so that is what I ordered. In the actual wire/cable section of the parts store, the 18 ga stranded core wire description states: “Use this wire for tube amp switches, filter caps and power section hookups”. That is where I used the 18 AWG wire, based on that description. I had researched all over the internet regarding wire sizes for tube amps, and the answers I found ranged from using anywhere from 18 ga to 24 ga (with multiple conflicting variations as what was acceptable wire size for either power circuits or signal circuits).
Wire voltage rating: I have worked in the aerospace/aviation industries for 39 years, so far (but in mechanical systems, not electronics). In those industries, it is ingrained that you must use materials that are rated for the physical requirements where those materials are used. So, naturally (and apparently in my ignorance) I assumed that a power circuit carrying up to 432 volts in an amplifier would require wire rated in excess of 432 volts (yes, I know it is low amperage).
Sorry to bother y’all with what was apparently a stupid question, but thanks for the answers.
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a stupid question
Naw, you only have 2 posts, when you get 128 posts and ask, then it might be a valid statement :icon_biggrin:
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Ewdaviee there are no stupid questions. As to the 300 volt rating on the wire===there have been 1000's of amps built using 300 volt wire...That being said, I am a lot like you on the requirements...I use 600 volt wire myself. As to wire size, this works pretty good. http://www.ax84.com/faq.html#wire-gauge
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Welcome to the forum Ewdaviee !!
I use what ever I can get from computer power supplies, vintage reel-to-reel, or what ever can be used to wire up the amp as far as it is thick enough or is in the voltage wise range! Pretty much anything tthat I can salvage from other stuff ! :icon_biggrin:
The amp in the picture have about 85% salvaged parts, all the wires are salvaged from something else! :laugh:
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a stupid question
Naw, you only have 2 posts, when you get 128 posts and ask, then it might be a valid statement :icon_biggrin:
Or 1809 ;). I don't remember asking about the wire (but might have) but I know I was concerned because the new coupling caps I got were so much smaller than what I was taking out. :laugh:
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18 ga wire: This is my first amp build from the ground up. As such, I used the Hoffman store's 5F6-A parts list to order most of my parts. That parts list includes both 18 and 20 ga wire on the list of parts to build the 5F6-A circuit, so that is what I ordered. In the actual wire/cable section of the parts store, the 18 ga stranded core wire description states: “Use this wire for tube amp switches, filter caps and power section hookups”. That is where I used the 18 AWG wire, based on that description. I had researched all over the internet regarding wire sizes for tube amps, and the answers I found ranged from using anywhere from 18 ga to 24 ga (with multiple conflicting variations as what was acceptable wire size for either power circuits or signal circuits).
Wire voltage rating: I have worked in the aerospace/aviation industries for 39 years, so far (but in mechanical systems, not electronics). In those industries, it is ingrained that you must use materials that are rated for the physical requirements where those materials are used. So, naturally (and apparently in my ignorance) I assumed that a power circuit carrying up to 432 volts in an amplifier would require wire rated in excess of 432 volts (yes, I know it is low amperage).
Sorry to bother y’all with what was apparently a stupid question, but thanks for the answers.
If you follow all the build documents for your Hoffman board on the library page here, you will be fine
https://el34world.com/schematics.htm