Stereo Power Amp

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Stereo Power Amp

Postby honda2000 » Mon Jul 18, 2005 9:47 pm

Hey guys, I've posted some questions on 35 colum, but I'm building a 6V6GT stereo amp from the remants of an amp my dad built way back when!!!
It's a RCA tube manual circuit, and I have almost all the parts from the first build. It was my stereo as a kid growing up, and then I used it for a guitar rig before I bought one. I have a MP1 stereo midi preamp I've had for years with a stereo solid state power amp. eeeeeeeeeeewwwwwwww!
I was thinking of just buying a Boogie 50-50 power amp, but I remember something really magical about those 6V6's.
Anyway, I plan to build a turret board to lay everything out neatly, and make it easier to troubleshoot. I've been laying the circuit out on Excel to make it easier to make changes.
A really dumb question, what is everybody using for hookup wire, and where are you getting it from?

Thanks,
Chris Reinhardt
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Postby EWBrown » Tue Jul 19, 2005 5:21 am

I use just about anything I can find fir free/cheap for hookup wire.
For instance, scrapped computer power supplies, I cut off the wire bundle, that supplies a fair amount of #18 wire, in several colors, with either 300V or 600V insulation.

For lower current reqiurements, teflon insulated, solid core #22 or #24 wire - they were throwing outs lots of that from the lab here at work a while ago. Bottlehead uses it, so it must be OK Yellow_Light_Colorz_PDT_01

I don't subscribe to the "oxygen free, long crystal, oriented grain, plutonium plated gold core platinum wire from the planet Netpune" theories. Wire is wire, it conducts electricity. Period.

The computer power supplies also yield some HV electrolytics, power resistors and other useful parts. Free is good.

/ed B in NH
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Postby honda2000 » Tue Jul 19, 2005 3:52 pm

EW, thanks for the tips and free is very good!!!
I was putting a Mouser order together and they have a bundle of 20 awg stranded that's like $80!!! That's more than I have in all the parts!!!!
I think I might, dare I say, "buy" a couple of spools from the shack. I was thinking 18 awg to the heaters, 20 awg to everything else.

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Postby EWBrown » Wed Jul 20, 2005 4:58 am

18 ga would be more than sufficient for the heaters, even 20 ga would be OK unless you have a real heavy current load. Solid or stranded wire is OK to use, it's more of a matter of personal choice rather than any technical requirements.

/ed B in NH
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22AWG starnded aircraft teflon

Postby Shannon Parks » Wed Jul 20, 2005 6:52 am

My boss has a huge spool of 22AWG stranded, teflon coated aircraft wire that he bought years ago from an employer. Except for the heavier filament loads, this stuff is fantastic. Just so I wouldn't mooch from it too often, I've tried some from Mouser (in the ST70 driver parts list to replace the original hookup wire):
100’ Wire Red TFE
566-83005-100-02
$21.12

I like it a lot.

Shannon
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Postby honda2000 » Thu Jul 21, 2005 9:58 am

Guys, thanks for the info.... My thought was to use several colors to help with the troubleshooting. Maybe even just a couple of colors would help identify things. Green=Heaters, Red=B+, Black=Ground, etc....
Any thoughts?

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Postby EWBrown » Thu Jul 21, 2005 11:23 am

Those colors are pretty much "standard"... Sometimes I add yellow for 5VAC, orange (or other colors) for lower voltage B+, etc.
For short run signal runs, I use twisted pair 22, for longer (or those passing near AC lines) I use shielded cable.

'ed B in NH
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Postby Vortexion » Fri Feb 06, 2009 10:13 am

EWBrown wrote:I use just about anything I can find fir free/cheap for hookup wire.
For instance, scrapped computer power supplies, I cut off the wire bundle, that supplies a fair amount of #18 wire, in several colors, with either 300V or 600V insulation..../ /....The computer power supplies also yield some HV electrolytics, power resistors and other useful parts. Free is good.

Nice to know I'm not the only one who does this. I also have the singular joy of living only 200 yards from a scrap metal dealer's yard. He's a great bloke, which is just as well: he's now very used to me turning up at his railway arch premises with a pair of cutters in my hand, an LED searchlight on my head and THAT LOOK on my face - the one that says "Can I have a crawl about in your wire bin, mister?"

He always says yes and never charges me a penny, even when I'm leaving the place barely able to walk under the weight of copper slung round me neck! Yellow_Light_Colorz_PDT_07
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Postby EWBrown » Fri Feb 06, 2009 11:10 am

It's always good to be lucky enough to have neighbours like that Yellow_Light_Colorz_PDT_03

Sometimes a bottle or tin or two of his favorite beer can also work wonders (I call it applying the beer wrench)

There used to be a huge "junk" place like that in Merrimack NH, which I often frequented. It is now long gone, and the property is now part of "The PC Connection" , who filled up the entire old strip mall, except for the movie theater and steak house at the end of the parking lot..
Merrimack Metals used to sell "by the pound" and it didn't matter if it was an old rusty truck bumper, a lot of transformers, or other asorted electronic junque.

/ed B
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Postby Vortexion » Fri Feb 06, 2009 11:30 am

You're making me misty-eyed with nostalgia, Mr. Brown. What I really miss from my upbringing are the old-fashioned surplus dealers. You know: a shop (or sometimes just a big room) lined ceiling-high with dexion shelves, groaning with every imaginable variety of electronica, most of it ex-military. The perfect place to pick up a dummy load, some seriously well-made rotary switches and - oh hell, why not - a torpedo guidance console. Well, you never know when it might come in handy!

Gone....all gone. Yellow_Light_Colorz_PDT_13

Well, I suppose there may still be some in the USA, but over here, the few that were still operating by the 1990s have either retired or gone over to exclusively online business. Can't blame them. Lower overheads. Clicking links and looking through lists isn't the same as rummaging in boxes of actual stuff, though, is it?
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Postby WA4SWJ » Fri Feb 06, 2009 11:42 am

Guys,

Some of you may be aware of this company but just in case - they have a lot of surplus stuff:

http://www.fairradio.com/

Regards,
Ed Long
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Postby Mackortoyota » Fri Feb 06, 2009 9:15 pm

i also know of a military surplus dealer, and best of all its all electrical stuff HTTP://surplussales.com
they also have a pretty large tube section, but no 12AX7's the last time i checked :o
I believe solid state is the future, but only tubes should be entrusted with the task of audio amplification.
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Postby EWBrown » Sat Feb 07, 2009 10:04 am

I dunno if it's still around, but if you are in the Orlando Florida area, check out "Skycraft" on Fairbanks Ave, just off I-4. It's easy to spot, it has (had) a missile and a big "UFO" on the roof. Last time I was there was around 15 years ago, and it did have an amazing array of military, commercial and NASA related electronic surplus goodies. And lots of tubed stuff.

There was also another place named "Green's", or perhaps "Greene's" in Avon Park, Fla, as well. More "stuff" and somewhat less electronics.

THen there was another aircraft-related salvage yard in Stark Frorida, not too far from the Florida "state pen" (and home of "old sparky" ) :o

Last I knew "Uncle Ned" was over in "Old Hampshire" in the UK, gathering up lots of tubes and related parts. Check the "Tube Zone" website for his "discovered treasures".


/ed B
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Postby Gingertube » Mon Feb 09, 2009 9:52 pm

Guys,
Some comments on stuff above. When I was a lowly apprentice yonks ago we were taught a "standard" wiring color code for tube circuits.
I still use this to this day.

Grounds and Returns are BLACK
Heaters are BROWN
B+ runs are RED
Screens are ORANGE
Cathodes are YELLOW
Control Grids are GREEN
Anodes are BLUE
Negative rails are VIOLET

And guidance on wire current capacity.
The 100 degrees C wire temperature, wires in bundles of up to 6 wires, de-rated current capacity (from aircraft wiring standards) is:
12 AWG - 16 Amps
16 AWG - 8 Amps
18 AWG - 5.7 Amps
20 AWG - 4 Amps
22 AWG - 2.8 Amps
24 AWG -2 Amps
26 AWG - 1.4 Amps
28 AWG - 1 Amp
30 AWG - 0.7 Amps
32 AWG - 0.5 Amps

If using single wires (not bundled or loomed) these current ratings can be multiplied by 1.4

If bundling more than 6 wires together in a loom then divide by 1.2

These are conservative ratings BUT sticking to these will ensure you never have a problem.

Hope this is useful info.

Cheers,
Ian
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