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Heater Wiring - the Good the Bad and the Ugly
Heater Wiring - the Good the Bad and the Ugly
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Old 1st August 2020, 05:27 AM   #151
pong Tsui is offline pong Tsui  Hong Kong
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Hi ,AC for heater sound is better,dynamic ,bass,etc....but have some digital device,streaming device,router,switch in home,AC it will absort some EMI noise,
Are you agree?
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Old 1st August 2020, 07:23 AM   #152
AllenB is offline AllenB  Australia
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Heater Wiring - the Good the Bad and the Ugly
AC can be very good. Have you considered filtering your AC supply using chokes? Although this could be used to trim the available Voltage, it can also remove higher frequency problems.
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Old 1st August 2020, 09:06 AM   #153
jean-paul is offline jean-paul  Netherlands
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Maybe it has been discussed before in this thread but I am too lazy to read everything. Anyway, in my limited experience I have seen and still see sometimes quite expensive tube equipment with hum problems.

Often the build quality is questionable but what I do see often is audio GND connected to the metal casing and not even use the PE connection (even when a PE IEC Socket is used!). It completely beats me why anyone would do such a thing but it is more common than one would think. I classify such equipment as unsafe despite the price tag. It also leads to dubious experiments with "ground wires" to get the stuff quiet. Why people /companies do not adhere to decade old safety regulations and why do these devices pass any quality check? In general tube DIY is one of the worst areas in DIY audio with regards to build quality and safety probably because stuff is large and accessible to many.

Especially tube stuff that carries high voltages should have the metal casing ALWAYS connected to PE for safety. One may connect audio GND lifted to PE. When done like this hum is not an issue. When I get the reply that homes in area X don't have PE well PE is out there for a lifetime Even if this would be true one can have PE applied by a certified electrician or one better buys low voltage stuff.
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Last edited by jean-paul; 1st August 2020 at 09:14 AM.
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Old 27th August 2020, 06:37 PM   #154
El Sid is offline El Sid  South Africa
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@jean-paul by PE you mean protective earth? I'm taking it you mean the earth in the mains L-N-E.

Last edited by AllenB; 28th August 2020 at 02:19 AM. Reason: Remove excess quoting
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Old 27th August 2020, 08:01 PM   #155
jean-paul is offline jean-paul  Netherlands
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Yes, Protective Earth.
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Old 6th September 2020, 04:15 AM   #156
andyjevans is offline andyjevans  United Kingdom
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What's the best way to supply heaters for a 19v, 300mA tube like the PL33?

- DC floating
- DC with the negative side grounded, if so where and how?
- AC with a centre tap connected to ground (again, where and how?)

Bias voltage is only around 4v. a-k around 160v, 15-30mA current.
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Old 24th November 2020, 06:59 PM   #157
OferB is offline OferB  Israel
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Heater Wiring - the Good the Bad and the Ugly
Hello guys - I am new here - building a KT88 SE amp. Re heaters - why not shield them like a coaxial cable - ground on one end - and avoid most of the induction noise? - Also - anybody knows what I should do with pin 9 's' on the ecc85?
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Old 25th November 2020, 05:15 PM   #158
batteryman is offline batteryman  United Kingdom
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See post no. 150.
Its the way I'll be doing the heater wiring in my parallel SE KT77 amp.
You can tightly twist wires using an electric drill.
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Old 26th November 2020, 06:43 AM   #159
Diabolical Artificer is offline Diabolical Artificer  United Kingdom
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andyjevans AFAIK heaters should never be floating, they should always be referenced to ground. Just connect your DC supply to ground. The best way to stopAC heater hum is with a humbucker, EG a 250r - 500r WW pot, wiper to gnd or elevated.

OferB, see - The Valve Wizard

Andy.
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Old 26th November 2020, 08:34 AM   #160
TonyTecson is offline TonyTecson  Philippines
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no element inside the tube should be left hanging not connecting to anything, i think this is the basic rule...
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