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March 31, 2023, 05:54:13 PM

Author Topic: Preamp Headphone  (Read 788 times)

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Offline reglys

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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

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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.

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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

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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

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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

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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