Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Power Tube Preamp

Dear Forum Members,
The plan is to make a tube preamplifier, the amplifier itself is actually already present as far as the schematic is concerned.
But the stabilized power suply is not quite as desired.
Would like to put in a power source to make the zener diodes more stable and thus make the whole power supply more stable.
Since we are talking about 250 volts DC voltage, not many components are eligible, an LR8N has been thought of that can be used up to 450 volts, but can only be used up to 10 mA and then with this IC the difference between in and output are 20 volts.
Using a TL783 might be possible, but I wouldn't know how to fit it myself.
Who has an idea for a power source that is capable of doing its job at high voltage.
Greeting,
Pim
 

Attachments

  • ScreenShot862.jpg
    ScreenShot862.jpg
    77.1 KB · Views: 22
  • ScreenShot873.jpg
    ScreenShot873.jpg
    103.2 KB · Views: 21

Nigel Goodwin

Super Moderator
Most Helpful Member
Why do you want a stabilized power supply?, the whole point of a valve amp/preamp is to give lower quality, and HT variation is a very big part of that. Stabilizing it will make it sound less like a valve amp.

However, if you really want to?, first thing is to determine what the current requirements are.
 
Hi Nigel, In the first instance it is about the lowest possible hum level, and that does not seem the most obvious option with a tube rectifier.
That is why I opted for a power supply with transistors.
Now I just got an idea through a forum that actually makes the power source superfluous, here's the schematic.
Greeting,
pim
 

Attachments

  • ScreenShot879.jpg
    ScreenShot879.jpg
    66.1 KB · Views: 18

Nigel Goodwin

Super Moderator
Most Helpful Member
Hi Nigel, In the first instance it is about the lowest possible hum level, and that does not seem the most obvious option with a tube rectifier.
That is why I opted for a power supply with transistors.
Now I just got an idea through a forum that actually makes the power source superfluous, here's the schematic.
Greeting,
pim
It's very similar to what you posted in the first post :D

But again, why are you wanting the lowest possible hum level? - that's part of what people are looking for with valve amps. If you want low noise and high quality, just build a transistor amp :D

However, historically (as I said) they didn't stabilise voltage rails, and the preamps were just fed from the main HT via a dropper resistor and smoothing capacitor - this was often done in two stages, so the first dropper feeding the phase splitter etc. then a second dropper from that to the preamp. If it was a multi-stage preamp, then there would probably be another dropper and smoothing capacitor between the stages.

In this highly rated valve preamp, there are actually three stages of dropper - R32/C15, R25/C12, R20/C7

 
Hi Nigel,
There are also manufacturers of tube amplifiers that use stabilized power supplies, such as Audio Research, here is a schematic of the SP-6C preamplifier.
Greeting,
pim
 

Attachments

  • ScreenShot881.jpg
    ScreenShot881.jpg
    74.4 KB · Views: 20

rjenkinsgb

Well-Known Member
Most Helpful Member
As Nigel says - gimmickry to sell to people with more money that sense or technical knowledge.
 
Dear Nigel, rjenkinsgb,
Thanks for the advice, but I promise that when the tube preamp is finished, the listening experience will be shared by me here.
Greeting,
Pim
 

audioguru

Well-Known Member
Most Helpful Member
I sold my vacuum tubes kit amplifier 58 years ago and have never seen another one since then.
I replaced it with a solid state amplifier that still works today.
 

crutschow

Well-Known Member
Most Helpful Member
when the tube preamp is finished, the listening experience will be shared by me here.
So we can hear why you prefer the sound of music altered by the distortion characteristics of a tube amp? :rolleyes:
 

audioguru

Well-Known Member
Most Helpful Member
Some people think that an old tubes AM radio sounds fine. Maybe their hearing (or brain?) muffles the highs and rectifies the waveform creating massive distortion like the radio.
 

Latest threads

Top