I am rebuilding a mono integrated tube amplifier that has been neglected. I will be replacing all of the capacitors, resistors and wiring. The current wiring is 20 gauge SOLID throughout. I would like to use the same because I find it easier to work with than STRANDED.
The 20 gauge SOLID wire I have is rated at 300 VOLTS, the only 600 VOLT wire I have is STRANDED.
Looking over the schematic, there appears to be only a few wires that carry more than 300 VOLTS, pin 8 of the 5Y3 rectifier to pins 4 of the 6V6's. Also 5Y3 pin 8 to pin 1 of V2 (12AX7).
Is it safe to use 300 VOLT wire for the everything else?
View attachment grommes 55pg schematic.pdf
The 20 gauge SOLID wire I have is rated at 300 VOLTS, the only 600 VOLT wire I have is STRANDED.
Looking over the schematic, there appears to be only a few wires that carry more than 300 VOLTS, pin 8 of the 5Y3 rectifier to pins 4 of the 6V6's. Also 5Y3 pin 8 to pin 1 of V2 (12AX7).
Is it safe to use 300 VOLT wire for the everything else?
View attachment grommes 55pg schematic.pdf
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This is what I purchased, it doesn't specify AC or DC
20 AWG Gauge Solid Hook Up Wire Red 25 ft 0.0320" UL1007 300 Volts | eBay
Unless it actually breaks-over quickly, the voltage rating on insulation is "long term average". The same number works for DC or AC(sine). For AC the wave swings up to 424V and down to zero, so about 300V long-term stress.
A coat of paint will stop 300V. Thickness is about defects and abuse.
The difference in most commercial wire, 300V or 600V, is the testing fee. It costs more to test for 600V. The demand for >300V wire is very small. They may really be the same insulation but not tested for the higher spec.
A "300V" spec is very generous. Are you going to bundle tightly and snake it inside a wooden house wall and leave it powered-up 24/7 for 50 years? In amps we mostly do not tight-bundle and do not leave it run day and night for a lifetime.
How much of a "6V6 amp" is over 300V? OK, Grommes got brave running 380V on 315/350V tubes. Betcha "300V" wire will last a lifetime. And only part of the system runs that hard.
The only part which has much more than 300V is the 6V6 plate leads, which may be kicking to 500V at full roar. Use the output transformer wire, it is sure to be good for the purpose. If you can save a little snip, use it to connect 5Y3 to C1.
A coat of paint will stop 300V. Thickness is about defects and abuse.
The difference in most commercial wire, 300V or 600V, is the testing fee. It costs more to test for 600V. The demand for >300V wire is very small. They may really be the same insulation but not tested for the higher spec.
A "300V" spec is very generous. Are you going to bundle tightly and snake it inside a wooden house wall and leave it powered-up 24/7 for 50 years? In amps we mostly do not tight-bundle and do not leave it run day and night for a lifetime.
How much of a "6V6 amp" is over 300V? OK, Grommes got brave running 380V on 315/350V tubes. Betcha "300V" wire will last a lifetime. And only part of the system runs that hard.
The only part which has much more than 300V is the 6V6 plate leads, which may be kicking to 500V at full roar. Use the output transformer wire, it is sure to be good for the purpose. If you can save a little snip, use it to connect 5Y3 to C1.
There is also fiberglass sheathing in two sizes available Wire Sleeving - Spaghetti, Old-Style, 20 AWG | Antique Electronic Supply
and
Wire Sleeving - Spaghetti, Old-Style, 11 AWG | Antique Electronic Supply
Easy to color code it with a marker.
and
Wire Sleeving - Spaghetti, Old-Style, 11 AWG | Antique Electronic Supply
Easy to color code it with a marker.
Never grab a perfectly insulated wire.
The capacitance to your hand may grab you, if the frequency and voltage is high enough.
I am not going to grab a perfectly insulated wire of an 845 amplifier with 1250V B+, and a full scale 20kHz signal, when the plate is outputting from 250V to 2250V.
The perfect example is the perfectly insulated spark plug wire.
Grab it and feel the capacitive current.
. . . Please do Not do that!
The capacitance to your hand may grab you, if the frequency and voltage is high enough.
I am not going to grab a perfectly insulated wire of an 845 amplifier with 1250V B+, and a full scale 20kHz signal, when the plate is outputting from 250V to 2250V.
The perfect example is the perfectly insulated spark plug wire.
Grab it and feel the capacitive current.
. . . Please do Not do that!
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It is rated: UL 1007 - CSA TR-64
And that spec demands passing:
If not punctured with 1500VAC (so > 2kV DC),after 1 long minute (so it´s not a freak microsecond situation but one long enough to puncture through) then it WILL safely work with , say, 500V (1/3 to 1/4 the test voltage looks like an adequate safety margin margin).
Do you believe a rating on something you buy on E-bay, considering that even 2N3055 power transistors are usually fake? Although most insulation will hold 300 volts, even “primary wire” you buy at the auto parts store. Not “rated” for it though. Biggest issue is getting “gooey” at high temp. Plenty of places you can buy recognized brands like Consolidated Wire without spending a bloody fortune. Their 300 volt stuff seems to be fine. I’ve been known to use THHN or TFFN, sometimes with sleeving or heat shrink on 400v or more B+ wiring - especially where it’s near something generating heat. 600 volt rating “inside signs and fixtures”, and an amplifier is a similar environment. If it’s good enough for fluorescent and HID lamp ballasts which generate very high starting voltages and run hotter than hell, it will be at least as good as the typical primary lead wires on a typical OPT. Even the 1650W doesn’t use anything special, and it’s intended to run at 700 volts.
And 700V is the B+ rating???
So that means the insulation is good for 1,400V, when the vacuum tube goes into cutoff, if the transformer is single ended.
And, that means the insulation is good for 1,350V, when one vacuum tube plate swings down to 50V, if the transformer is push pull.
So that means the insulation is good for 1,400V, when the vacuum tube goes into cutoff, if the transformer is single ended.
And, that means the insulation is good for 1,350V, when one vacuum tube plate swings down to 50V, if the transformer is push pull.
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