Power Supply Tube Preamplifier.

[Pim Driessen]

Dear Forum Members,
I have a question about a current limitation in a power supply for a Tube preamplifier output 215 Volt.
The question is Does this work if you accidentally create a short circuit?.
Here is the diagram of 2 different power supplies, the first one broke due to a measurement error, of which it is not entirely clear what went wrong.
The second diagram is of a tube preamplifier from Audio and Technology from a long time ago, I personally think the current limitation of Audio and Technology looks better.
When I simulate in Tina Software, the current limitations of both seem to work, but as I wrote before, the power supply board of the first diagram broke after a short circuit.
What is the opinion of this Forum about the two power supply diagrams?.
Greetings,
Pim

 

[Nigel Goodwin]

Out of curiosity, that would sound even better, but now that I have a power supply of electrolytic capacitors and resistors I am not dissatisfied with how it sounds, but would still like to know if there is a difference in the sound.

The whole point of a valve preamp, or power amp is to provide lower quality, high distortion, poorer frequency response etc. - if you want higher quality just use transistors or opamps.

 

[Pim Driessen]

The whole point of a valve preamp, or power amp is to provide lower quality, high distortion, poorer frequency response etc. - if you want higher quality just use transistors or opamps.

I own a preamplifier with transistor and also power amplifiers with transistors, with mosfets in the output stages, and every now and then you want something different, hence the idea to build a tube preamplifier, a few years ago a few mono power amplifiers were also built with EL84, Audio is my hobby, every evening I listen for hours to classical music, among other things, and then play all kinds of things, pop and jazz.

 

[Nigel Goodwin]

I own a preamplifier with transistor and also power amplifiers with transistors, with mosfets in the output stages, and every now and then you want something different, hence the idea to build a tube preamplifier, a few years ago a few mono power amplifiers were also built with EL84, Audio is my hobby, every evening I listen for hours to classical music, among other things, and then play all kinds of things, pop and jazz.

So why try and improve the sound quality from the very reason you're wanting to use valves?.

 

[crutschow]

So why try and improve the sound quality from the very reason you're wanting to use valves?.

Some audionuts say they like the "warmer" sound of a tube amp and vinyl records, which basically comes from the poorer high frequency response of the record, tubes and output transformer.

 

[Pim Driessen]

Some audionuts say they like the "warmer" sound of a tube amp and vinyl records, which basically comes from the poorer high frequency response of the record, tubes and output transformer.

Sound is a matter of taste, and tube sound is sometimes a pleasant change.It is a matter of switching cables and my other transistor preamp is playing again.Tomorrow I want to try the electronic fuse on the 19 volt power supply, can that be done with the same resistor values R5 510K and R4 1 Meg?.

 

[schmitt trigger]

Agree, sound is a matter of taste.
Nostalgia plays a part, too.

When I was a young teenager I grew up listening to Rock, mostly from progressive British bands. My hifi equipment was 100% tube based. I remember evenings listening to my favorite band, in a darkened room watching the warm filaments glowing, and the output power-tetrode’s blue ionization dancing with the music.

 

[Pim Driessen]

Sound is a matter of taste, and tube sound is sometimes a pleasant change.It is a matter of switching cables and my other transistor preamp is playing again.Tomorrow I want to try the electronic fuse on the 19 volt power supply, can that be done with the same resistor values R5 510K and R4 1 Meg?.
View attachment 148729View attachment 148730

I had changed something else to not put the Q5 collector on the base of the output transistor.

 

[Pim Driessen]

Agree, sound is a matter of taste.
Nostalgia plays a part, too.

When I was a young teenager I grew up listening to Rock, mostly from progressive British bands. My hifi equipment was 100% tube based. I remember evenings listening to my favorite band, in a darkened room watching the warm filaments glowing, and the output power-tetrode’s blue ionization dancing with the music.

It's about enjoyment, sometimes I can play certain music very often, and then it's just too much, the same with transistor and tube amplifiers.

 

[crutschow]

can that be done with the same resistor values R5 510K and R4 1 Meg?.

No.
Reduce the value by the ratio of the voltages, 19/250, or R5=40k and R4=75k

 

[crutschow]

Agree, sound is a matter of taste.
Nostalgia plays a part, too.

I listened to a lot of stereo music with vinyl records through tube amps.
I have absolutely no nostalgia feelings to ever go back to them, as the sound was significantly inferior to that from a CD played through a good solid-state amplifier.

 

[Pim Driessen]

No.
Reduce the value by the ratio of the voltages, 19/250, or R5=40k and R4=75k

Thank you very much, did you have time to look at my last picture where the Q5 connection is connected via a 1k resistor.

 

[crutschow]

did you have time to look at my last picture where the Q5 connection is connected via a 1k resistor.

No, but I just did.
Q5 should go to the base of T8 with no resistor.
Why did you add the resistor?

 

[schmitt trigger]

I once knew a large broker of vintage automobiles.
I once asked him what vehicle “era” was the most in demand. He provided an insightful answer: with whatever the current peak-earning generation grew up with, those vehicles will have the highest demand at the moment.
Nostalgia, pure and simple.
How else could you explain the surge in demand of the “malaise era” cars, some of the worst-ever vehicles? How do you explain the recent fascination in Germany with Trabants?

Of course, there will always be legitimate classic eras of exceptional desirable vehicles, like the big-block American V8s of the 1960s.

 

[Nigel Goodwin]

How else could you explain the surge in demand of the “malaise era” cars, some of the worst-ever vehicles? How do you explain the recent fascination in Germany with Trabants?

I used to know an old (and weird) guy through work, he lived at Middleton By Youlgreave, and he collected Trabants - he had the largest collection in the UK, if not outside East Germany?. Last I heard the local council were taking legal action against him to have them removed.

 

[Pim Driessen]

No, but I just did.
Q5 should go to the base of T8 with no resistor.
Why did you add the resistor?

That was an inspiration for no real reason, just wanted to try it out.

 

[Pim Driessen]

That was an inspiration for no real reason, just wanted to try it out.

I was looking at your circuit that you set up in LTSpice-sim, but I don't think it will work in the last 19 volt supply, because Q3 is not included in it.

 

[crutschow]

I was looking at your circuit that you set up in LTSpice-sim, but I don't think it will work in the last 19 volt supply, because Q3 is not included in it.

Yes, your last circuit has no current limit.
What is that?

 

[Pim Driessen]

Yes, your last circuit has no current limit.
What is that?

That's because it's a power supply for a preamplifier, which normally only needs to supply 100 mA.But I found a unit for a Nixie cash register in an electronics store, where a lot of dump material is sold, it was only € 9.00, I couldn't leave it there.This can supply 165 volts at 110 volts, there is also a 120 volt winding at 20 mA, that's enough to test on the 215 power supply.But the question is can a 230 volt primary be made from these separated windings?

 

[Pim Driessen]

That's because it's a power supply for a preamplifier, which normally only needs to supply 100 mA.But I found a unit for a Nixie cash register in an electronics store, where a lot of dump material is sold, it was only € 9.00, I couldn't leave it there.This can supply 165 volts at 110 volts, there is also a 120 volt winding at 20 mA, that's enough to test on the 215 power supply.But the question is can a 230 volt primary be made from these separated windings?
View attachment 148741View attachment 148742

 

[rjenkinsgb]

But the question is can a 230 volt primary be made from these separated windings?

Just connect them in series:
0V on the first one to Neutral, 120V on that to 0V on the second one; the "120V" terminal on the second winding is the 230/240V input.