My cheap Chinese amplifier kit came with really small wire. It's all 22AWG as best I can tell by comparing it to some 22AWG that I have. Even the filament wires are that small. It's unmarked of course. So, this seems inadequate for the heater filaments, and also not ideal for the connections from the output transformers to the 4Ω and 8Ω speaker binding posts. The AC power wire provided also is 22 AWG as best I can tell. This isn't a high power amplifier at 12 watts per channel, but still that power wire seems inadequate for the job.
So I started digging through my wire box from previous projects and untangling various colors. I have some 20 AWG that actually has 300 volts printed on it. I have a bunch of 18 AWG that has no voltage rating printed on it, but good insulation. I stripped it out of a 3-conductor heavy duty extension cord, and some other 18 AWG came from AC power cords from old electronics like TVs and monitors, also with no voltage rating printed on it but good insulation.
1) 120V AC in -> to power switch -> to power transformer.
2) 275V from power transformer to power supply PCB.
3) 6.3V filaments for four 6P14 tubes (0.76A current per spec sheet).
4) 6.3V filaments for two 6N1 tubes (0.6A current per spec sheet).
5) 300V from the power supply PCB to the amplifier PCB.
6) 350V from the power supply PCB to the amplifier PCB.
7) 350V from the amplifier PCB to the output transformers.
8) Wiring from the output tubes on the amplifier PCB to the output transformers.
9) Wiring from the outputs of the power transformers to the speaker binding posts.
10) A half dozen ground wires that all run to a single ground point on the chassis.
I think that accounts for all of the wires used in the kit.
Advice appreciated. If I need to buy special high-voltage wire for the 275V, 300V, and 350V connections, please let me know. The last thing I want is to flip on the power switch one day only to hear a loud spark inside the amp and then smell electrical smoke (pew 🦨)!
So I started digging through my wire box from previous projects and untangling various colors. I have some 20 AWG that actually has 300 volts printed on it. I have a bunch of 18 AWG that has no voltage rating printed on it, but good insulation. I stripped it out of a 3-conductor heavy duty extension cord, and some other 18 AWG came from AC power cords from old electronics like TVs and monitors, also with no voltage rating printed on it but good insulation.
- My first concern is what is the best AWG to use for what parts of the circuit.
- My second concern is the voltages involved since my wire (except the 20 AWG) has no voltage rating printed on it.
1) 120V AC in -> to power switch -> to power transformer.
2) 275V from power transformer to power supply PCB.
3) 6.3V filaments for four 6P14 tubes (0.76A current per spec sheet).
4) 6.3V filaments for two 6N1 tubes (0.6A current per spec sheet).
5) 300V from the power supply PCB to the amplifier PCB.
6) 350V from the power supply PCB to the amplifier PCB.
7) 350V from the amplifier PCB to the output transformers.
8) Wiring from the output tubes on the amplifier PCB to the output transformers.
9) Wiring from the outputs of the power transformers to the speaker binding posts.
10) A half dozen ground wires that all run to a single ground point on the chassis.
I think that accounts for all of the wires used in the kit.
Advice appreciated. If I need to buy special high-voltage wire for the 275V, 300V, and 350V connections, please let me know. The last thing I want is to flip on the power switch one day only to hear a loud spark inside the amp and then smell electrical smoke (pew 🦨)!
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Everything here ...
Wiring and current limits
Chassis wiring currents permitted are a lot greater than for transmission purposes, so you don't need to concern yourself too much.
Wiring and current limits
Chassis wiring currents permitted are a lot greater than for transmission purposes, so you don't need to concern yourself too much.
22AWG (translates to .65mm) is good for 1A.
That should be plenty for a 2* 12W amplifier.
It's almost enough for the 8 ohm output, but since it's a very short connection and you don't listen at full power continuously, is doubtful you'd hear any difference with thicker wire.
As for voltage rating, you can always put some heat shrink.
That should be plenty for a 2* 12W amplifier.
It's almost enough for the 8 ohm output, but since it's a very short connection and you don't listen at full power continuously, is doubtful you'd hear any difference with thicker wire.
As for voltage rating, you can always put some heat shrink.
Explain please. I am a novice. According to that chart, the 22 AWG wire actually would be ok for the filament wiring? It says 7A on the chart, which astounds me. It's such thin wire.
Also, I assume you are saying that all of the wire I have on hand shouldn't be much of a concern at 350V inside the chassis?
Everything you have in that kit has to comply with basic equipment safety standards. That is one good reason to start with a kit, where the supplier has to consider the safety of the built product. 350VDC is about the upper limit of the specs of most commonly used electronic items, e.g. resistors, but you should not be concerned that the supplied parts are not up to spec, IMO.
standards ... in China. 😉
Also not known for best quality or quality control.
Then there is the issue of best practices, which also is my question.
Can most ordinary USA hookup wire be used at 350 volts or is special silicone insulated 600V wire needed?
If nobody ever hears from me again ... assume ... ZAP because I try 300V wire at 350V. ⚡⚡⚡⚡⚡
The people selling these kits and other cheap projects have no clue about them. Ask the seller a technical question and they can't answer. My phone is made in China as well, however it has no voltages inside higher than 4.2vdc.
I like OldHectors very complete wire chart.
But in the not so distant past if we were working in the field or otherwise, quick answers were sometimes needed.
Here is something I put together several years ago describing how I did that. All on one page & easily remembered.
Quick answers right off the top!👍
But in the not so distant past if we were working in the field or otherwise, quick answers were sometimes needed.
Here is something I put together several years ago describing how I did that. All on one page & easily remembered.
Quick answers right off the top!👍
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I'm surprised nobody has any thoughts on 350-400 volt wire insulation. I'll bet a lot of people have used common US wiring (old extension cords, hookup wire, etc.) that they had in a project box (like me), but I don't want to be the one to have an arc inside my amplifier and then have to fix the mess. When working on an old Fisher tube stereo receiver many years ago, I don't recall seeing any special wiring. I don't think 600V silicone insulated wire existed. I don't recall seeing any extra insulation added to any of the wires.
Maybe, like the current ratings shown in the previously linked table (which I saved), the voltage rating is different if used for connections inside a chassis instead of transmission outside a chassis where the wire might be handled regularly and the risk of shock is much greater?
I can order 600 volt silicone insulated wire that is quite nice, but I am wondering if it's overkill for short 350-400 volt runs inside the chassis of a tube amp. I'm not just talking about this little kit, I'm talking about future projects.
Maybe, like the current ratings shown in the previously linked table (which I saved), the voltage rating is different if used for connections inside a chassis instead of transmission outside a chassis where the wire might be handled regularly and the risk of shock is much greater?
I can order 600 volt silicone insulated wire that is quite nice, but I am wondering if it's overkill for short 350-400 volt runs inside the chassis of a tube amp. I'm not just talking about this little kit, I'm talking about future projects.
Did anyone suggest checking the specs on Belden Hookup wire? Some are rated 300V but better available at 600V.
No way to know which is in a kit amp. But building the amp with better wire is not a big expense, To cover my building
for many years I simply bought a collection of different Belden wire 25 yrs ago. 👍
https://www.belden.com/products/cab...bdisplaypriority ascending&numberOfResults=25
No way to know which is in a kit amp. But building the amp with better wire is not a big expense, To cover my building
for many years I simply bought a collection of different Belden wire 25 yrs ago. 👍
https://www.belden.com/products/cab...bdisplaypriority ascending&numberOfResults=25
It’s close enough to working in dB, so that every rule of thumb you use for dB without a calculator works for the most part. Most of the time you’re only working in a 10dB range, and when wire sizes go above #6 ampacities don’t go up linearly with CSA anymore anyway (So you either remember them or look it up, and need to know whether the lugs are good for 60, 75, or 90C). Nobody (sane) uses wire that big in an amplifier, and you’d have to be totally off your rocker to try winding a transformer with it by hand.
In a pinch I have used the wires off fluorescent and HID ballasts for B+ wiring that goes above 600 volts. I did find a 500 foot roll of #18 stranded (600V rated, 1200V “in signs and fixtures”), for same price per pound as the usual #14 which is hard to work with but available everywhere. Lifetime supply.