Single ended heater supply

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C Moore
Posts: 1266
Joined: Mon Oct 22, 2007 9:28 am
Location: USA, California, 94585

Single ended heater supply

Post by C Moore »

On an amp like a Fender Champ/Vibro Champ.....
Is there still a need to twist heater wires?
If you do not have one of the PT, 3.5 Volt leads grounded like Fender did in "the old days"; is it still necessary to reference each 3.5 lead to ground via a 100 ohm resistor?
In short....is it still necessary to follow all the standard procedure for AC wires in a Vibro Champ, the same as you would for an A/B Push-Pull amp?
I hope my question is clear....
Thank You
paulster
Posts: 1299
Joined: Tue Oct 10, 2006 5:08 pm
Location: Los Angeles & London

Re: Single ended heater supply

Post by paulster »

Yep, it all still helps.

You'll probably have more hum (120Hz) get in though the lack of filtering than from the heaters (60Hz) but it doesn't hurt to do it properly.

And that includes using the balancing resistors if the heater supply isn't centre-tapped.
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Structo
Posts: 15446
Joined: Wed Oct 17, 2007 1:01 am
Location: Oregon

Re: Single ended heater supply

Post by Structo »

Some guys really get into the Single Ended amplifiers and there are quite a few tricks they employ for clean power.

The Hi Fi crowd routinely uses SE amps to great advantage and a common tube to be seen is the large 300B power tube.

[img:616:600]http://www.synergyhifi.eu/img/products/300b.jpg[/img]

Some SE tricks include DC heaters, elevated heaters, etc.

Some of that gets a bit too involved for the lowly guitar amplifier but nevertheless, you can learn some neat tricks from those guys.

[img:600:512]http://www.audiophilia.com/hardware/SET300B.jpg[/img]
Tom

Don't let that smoke out!
paulster
Posts: 1299
Joined: Tue Oct 10, 2006 5:08 pm
Location: Los Angeles & London

Re: Single ended heater supply

Post by paulster »

I use regulated DC in my single-ended amps so they're really nice and quiet.

But then I always go and play my big push-pull amps anyway, so it's kind of moot!
Cliff Schecht
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Joined: Wed Dec 30, 2009 7:32 am
Location: Austin
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Re: Single ended heater supply

Post by Cliff Schecht »

I don't bother with DC heaters unless I'm using non-humbucking filament tubes. If you are careful with your grounding scheme and elevate the heaters then noise is quite easy to maintain in SE amps. Chassis grounding schemes or other potentially noisy setups aren't as good to use in SE amps, especially with a steel chassis where the resistance is significantly higher (or better put, aluminum is a much better conductor).
Cliff Schecht - Circuit P.I.
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