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 Post subject: heater wiring
PostPosted: Mon Apr 11, 2011 5:33 pm 
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Both the wiring diagram and the assembly instructions for my TC15 indicate keeping the heater wires polarity constant.
Some other amp building forums or how-tos, show the polarity switching when moving from tube to tube indicating that this is for added noise control. Can anyone explain this and why is this not necessary for the TC15 build. Or is this just a user preference thing.
Thanks.


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 Post subject: Re: heater wiring
PostPosted: Mon Apr 11, 2011 7:05 pm 
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Actually keeping the polarity constant is for minimizing noise.

Most try to maintain polarity on the preamp tubes even though the way the twin triodes (12_ _7) have heaters wired (jumper between pins 4 and 5) in the schematics / layouts it really makes no difference since the twin triodes are humbucking when wired this way.

Output tubes need to have polarity maintained for noise control.


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 Post subject: Re: heater wiring
PostPosted: Mon Apr 11, 2011 10:57 pm 
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jcny is correct, it is for noise control. This is how all the Trinity Amps are wired & I think the noise floor is very low in them. Power tubes & preamp tubes need to be wired the same. Can you post a link to the forum that says otherwise. I'd like to read that explanation.

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 Post subject: Re: heater wiring
PostPosted: Wed Apr 13, 2011 12:25 pm 
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http://www.freewebs.com/valvewizard/heater.html
The section on Layout / lead dress has something to say on single ended amps vs push/pull amps.

http://www.youtube.com/watch?v=7O0_dlKkzSE
This three part series on tube heater wiring.

And there was a thread I was reading on another forum that had diagrams. I'll see if I can dig that up when I get home.


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 Post subject: Re: heater wiring
PostPosted: Wed Apr 13, 2011 7:29 pm 
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anrque wrote:
http://www.freewebs.com/valvewizard/heater.html
The section on Layout / lead dress has something to say on single ended amps vs push/pull amps.

He says, "Valves in push-pull or in balanced stages (such as long tailed pairs using separate valves) should have their heaters wired in phase. Any noise induced will then be common mode and rejected by the stage (mostly). Valves in parallel single-ended stages should have their heaters wires out of phase for mutual cancellation. Using two different colours for the heater wires will make this easier. " This is what I have been advising for some years, and even before Merlin came on the scene.

He then goes on to say, "The common pre-amp valves (ECC83 / 12AX7 etc.) when run from a 6.3V supply, should be wired from one side only [see right], not by looping one heater wire all round the valve socket, which would create a hum loop and cause excessive interference noise (though many amp makers DO make this mistake and get away with it). The wire twisting must be kept very tight right up to the socket, where it matters most. Their pin arrangement is also deliberate, so that the main heater pins (4 and 5) can be orientated towards the chassis wall, allowing heater wires to be run along the wall away from any other sensitive signal wiring." This is total nonsense. Don't trust 100% everything you read from Merlin (or anyone for that matter), although most of what he says is really excellent information. The fact is that heater wires don't actually need to be twisted at all, as long as they run close together. Soldano's SLO 100 is a classic example of a very high gain amp that doesn't use twisted heaters - just a pair of parallel bus bars. Early Marshall 18W amps used flat twin cable (aka zip cord) for their heater wiring, and I've built amps like that myself. Same for the only wiring on one side of the sockets thing, along with sacrificing a chicken at midnight before you first fire up an amp. It's voodoo.

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 Post subject: Re: heater wiring
PostPosted: Fri Apr 15, 2011 10:49 am 
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I also found this from the construction manual from the UK company Ampmakers. It had nice pictures but I had noticed that the two power tubes were wire out of phase.
http://www.ampmaker.com/forum/viewtopic ... iring#p214

Thanks everyone for the input.


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 Post subject: Re: heater wiring
PostPosted: Fri Apr 15, 2011 10:58 am 
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anrque wrote:
I also found this from the construction manual from the UK company Ampmakers. It had nice pictures but I had noticed that the two power tubes were wire out of phase.
http://www.ampmaker.com/forum/viewtopic ... iring#p214

I'll have to mention that to Barry and get him to correct it.

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 Post subject: Re: heater wiring
PostPosted: Wed Aug 24, 2011 11:58 am 
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zaphod wrote:
... The fact is that heater wires don't actually need to be twisted at all, as long as they run close together. Soldano's SLO 100 is a classic example of a very high gain amp that doesn't use twisted heaters - just a pair of parallel bus bars...


I know this is an old thread, but that really jumped out at me. Googled it (or maybe it was Bing), and sure enough. Wow! Found a picture of Soldano guts and those wires were straight as an arrow. Actually, I never really gave those amps much thought, but those are beautiful inside.

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 Post subject: Re: heater wiring
PostPosted: Tue Jul 25, 2023 2:42 am 
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The idea behind this approach is to create a hum-cancelling effect by introducing out-of-phase noise from the heater supply, potentially reducing any noise that might be generated due to power supply-related issues. rainbow friends


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