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Building little vacuum tube amplifier

This log describe the steps on building a little and practical vacuum tube based audio amplifier, using Soviet vacuum tubes.

Miguel Lopez

Jan 25, 2012
255
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Jan 25, 2012
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Miguel Lopez submitted a new Project Log:

Building little vacuum tube amplifier

Hello everybody

I want to share with you the steps on building a little and practical audio amplifier, based on Soviet vacuum tubes. I decided to build this little device in order to use it as an tool in future experimentation on vacuum tube electronics. I have always planned to build a radio using vacuum tubes, but in my modest opinion it would be very useful to have a little and compact amplifier to amplify the signals if I'm able to tune and detect them.

First of all, as this is a log, date of beginning:

2019.03.08

The circuit in question is the one which attracted my attention to vacuum tubes about 7 years ago. In that moment I tried to build it but things went improving, knowledge too, and I finally ended building a bigger stereo amplifier which is currently in use at home. I've been a bit distanced from vacuum electronics in the last couple of years due to time availability, but I think that now I can resume my experimentation (and fun) playing with glass and electrons, so I decided to go for it.

The circuit that I want to build I found it on a Russian website (I don't remember which one right now, sorry). It is shown on Picture #1. Anyway, I will make some variations of this circuit as I want to use a vaccum rectifier. All of the tube-based circuits that I have built, have silicon rectifiers, but I'm interested to use a vacuum full-wave rectifier to experiment with the behaviour of this kind of power supply. Problem is that I also want to use a transformer that I winded for another project (to save time and labour) which has a single HT winding. Then I decided to use the circuit on Picture #2, which appears on The Valve Wizard page about rectifiers. This way I can have the behaviour of a full wave vacuum tube rectifier while I have a single winding transformer. I know, I know.....it will not be an "all-vacuum" set but after all, this is for experimentation.......and fun.

The other thing to have into account is: SPACE. Not outer space, but space in my workshop, my bench and my shelves. My shelves are at full capacity of "probably-I-will-never-use" stuff, as it should be on any DIYER workshop, so space is something very important to have in mind. So, I decided to build the chassis in tower style, in order to save space. This will be a very compact (if I can say so) audio amplifier with a built-in speaker. Oh! I forgot to tell you that it will have a built-in speaker. Well, for the same considerations of space and usefulness,...

Read more about this project log here...
 

Miguel Lopez

Jan 25, 2012
255
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Jan 25, 2012
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255
This project is delayed due to lack of available time but I have been able to do some advances on it. You can check it in the Project Log
 

LaVitaEBella

Sep 3, 2019
5
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Sep 3, 2019
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I can see the progress with your work I hope that it will great success. Looking forward to seeing the final output and if it functions well.
 

Harald Kapp

Moderator
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Nov 17, 2011
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I wouldn't call this a "little" amplifier.;)
Anyway, nice project, looking forward to your progress.
 

Miguel Lopez

Jan 25, 2012
255
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Jan 25, 2012
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255
Well, last weekend I found a suitable speaker on my "war reserve". It fits perfectly on the amplifier and sounds well too. Wait for pictures
 

Miguel Lopez

Jan 25, 2012
255
Joined
Jan 25, 2012
Messages
255
The amplifier is already fully functional. I used it this weekend amplifying the signal from a DVD player. Pictures on the Project Log
 
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