News:
May 16, 2022, 01:35:39 AM

Author Topic: Preamp Headphone  (Read 163 times)

0 Members and 1 Guest are viewing this topic.

Offline reglys

  • Newbie
  • *
  • Posts: 9
Preamp Headphone
« on: April 09, 2022, 03:21:36 PM »
Hi

If we forget the 6.3 Vac voltage needed for the tube heaters, would it be possible to get enough DC voltage for the output tubes by rectifying 120 Vac powerline without a power transformer in a headphone preamp for instance.

Thank you in advance 

Offline Paul Joppa

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5434
Re: Preamp Headphone
« Reply #1 on: April 09, 2022, 05:09:10 PM »
This is universally accepted as an unsafe practice. It's like removing the brakes on a car to save weight.
Paul Joppa

Offline Doc B.

  • Administrator
  • Hero Member
  • *****
  • Posts: 8976
    • Bottlehead
Re: Preamp Headphone
« Reply #2 on: April 11, 2022, 08:14:23 AM »
They used to make radios like that in the 30s and 40s. They were called widowmakers for reason.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Thermioniclife

  • Sr. Member
  • ****
  • Posts: 592
Re: Preamp Headphone
« Reply #3 on: April 11, 2022, 12:06:39 PM »
Yeah. also called curtain burners. Many old tube radios have a built in resistance in the power cord that if replaced with a modern cord disaster is sure to happen. Also they were designed for 110 Vac.
Lee R.

Offline reglys

  • Newbie
  • *
  • Posts: 9
Re: Preamp Headphone
« Reply #4 on: April 11, 2022, 12:26:04 PM »
Yes I understand at that time they had plug with 2 prongs and they didn't care about the polarity and you could have a hot chassis.

However it is amazing when we see what Apple is doing with their tiny IPAD power supply . First time I used it in Paris, France during an oversea trip, I was sure this tiny power supply will blow out at 230 Vac.

Offline Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 16779
Re: Preamp Headphone
« Reply #5 on: April 11, 2022, 12:31:13 PM »
You could certainly use a 6V wall wart to power your heaters.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man