Anyone tried a hi-voltage project as their first? - diyAudio
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Old 15th May 2006, 01:44 AM   #1
JoshK is offline JoshK  Canada
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Default Anyone tried a hi-voltage project as their first?

I am about to laugh at what you must think. I want to build some higher powered SET amps, maybe 845, maybe 805 as a first tube amp project.

I do know high-voltage safety practice, at least I have read all the stuff I should. I have spent a lot of time reading about how these work, but haven't built any tube amps, only preamps.

Should I start smaller, even though my speakers won't like them (not high-eff)?
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Old 15th May 2006, 01:50 AM   #2
anatech is offline anatech  Canada
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Hi Josh,
We'd like to keep you as a member. Please start with something smaller. Possibly a 6BQ5 P-P project at least. That could still kill you if you are not very careful. If you have built tube preamps, then this 6BQ5 type should be within your range.

I suggested the P-P type because it will give you around 10~14W and you can compare it with a big SET giving similar power later.

There is a big difference between reading about something and actually working with it. This is very true with high voltage.

-Chris
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Old 15th May 2006, 01:59 AM   #3
JoshK is offline JoshK  Canada
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Quote:
Originally posted by anatech
There is a big difference between reading about something and actually working with it. This is very true with high voltage.

-Chris
Very good point, and why I asked! I've been working with 120V for most of my life, building houses and doing lots of electrical, including my own. Live and not live. Working with live boxes, etc. I know and have read lots of live voltage safety practices. 400VDC live testing doesn't scare me too much but 1000VDC has got my undivided attention.
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Old 15th May 2006, 02:09 AM   #4
JoshK is offline JoshK  Canada
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Actually, I was thinking of an alternative would be the 6C33C...not so high voltage but puts out decent wattage for a SET.
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Old 15th May 2006, 02:34 AM   #5
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400VDC live testing doesn't scare me too much but 1000VDC has got my undivided attention.
Really, either will fry you dead! My first tube projects (a long, long time ago) were guitar amps made from old TV and HiFi (before stereo) sets.

I got this idea to build a ham radio transmitter from WWII surplus electronics (still relatively common in the early 60's). I built it like I built my other electronic projects, except that it used about 700 volts for B+. The short story is it worked. For a short while. Those terminal strips that you take out of an old TV tend to catch fire at 700 volts. Ditto for octal sockets. This was the first project that I had to throw into the trash out of frustration. There have been others (mostly solid state).

A project that operates above 450 volts requires speciallized components and construction techniques that are not commonly available. I agree that your first project should be something more mainstream. The chances of success are much higher. Nothing will kill a new hobby faster than spending a bunch of time and money on a project, and having it refuse to work, or blow up.
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Old 15th May 2006, 02:39 AM   #6
JoshK is offline JoshK  Canada
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Thanks for your input tubelab, since your site was my main inspiration. I read most all of it, including all your safety tips. I think it was about the most common sense tutorial on high-voltage I have read.

I really dig your 845SE project. That was what I was gunning for, but I understand your caution. I take this seriously, as I know this stuff can kill.
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Old 15th May 2006, 02:43 AM   #7
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Well, until the late-ish 1960's anyone involved with audio or ham stuff routinely worked with high voltages -- then again we played tackle football in the street until the lights came on at night, drank from the garden hose, got smacked by our parents if we lipped off to them, walked to school in snowstorms uphill bothways, survived a polio epidemic (2) and the draft ... sic transit gloria mundi
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Old 15th May 2006, 02:49 AM   #8
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then again we played tackle football in the street until the lights came on at night
Yeah, being tackled by a 1957 Chevy wasn't much fun, but it scared the **** out of the lady driving the Chevy. Hey, she was driving in MY end zone.

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walked to school in snowstorms
Nah, hurricanes, no snow storms in Miami.
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Old 15th May 2006, 02:56 AM   #9
JoshK is offline JoshK  Canada
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And I was raised my such folk. My grandfathers were a general contractor who did all his own electrical and the other an electrician on jets for the airforce (who died of emphozima (sic) from the azbestos). Its in my blood as I see it. It isn't going to keep me away, but I don't want to be cocky and start prematurely.

I know from experience with programming that what you think should work, can not work for the lamest of reasons, that can take you by surprise. That isnt' cool when it is high-voltage.
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Old 15th May 2006, 06:07 AM   #10
jleaman is offline jleaman  Belgium
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I think ill follow this Im going to be building my first set of tube amps 811 Tube's I know i'm a newbie In tubes but in other areas i'm not. So i have been reading and what to do and WHAT not to do

I think the first basic tool is to get a bleeder resistor on a well pair of isolated alligator clips for putting on caps to bleed them right after working / testing tube amps. This was suggested to me to save my life. One other member said if you must tackle this type of thing why not buy a pair of gloves.

A 5$ pair of gloves that make your hands sweaty / big will save your heart of course ill be more care full BUT for now id take the other caution's.
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