It seems that these transformers are all quite costly.
I'm thinking about skipping the transformer, and go directly from the wall AC, to the bridge rectifier, and then choosing a smaller value for the resistors going to the tube, giving approximately 207 V, to use (I'm gonna check with the links given, thanks for all the info!), instead of the 250 & 225 there is now. I saw a guy on youtube, who built a tube amp running on 24 V, so it should work.
What do you Think? Is it a good idea. Any problems you can Think of?
I'm thinking about skipping the transformer, and go directly from the wall AC, to the bridge rectifier, and then choosing a smaller value for the resistors going to the tube, giving approximately 207 V, to use (I'm gonna check with the links given, thanks for all the info!), instead of the 250 & 225 there is now. I saw a guy on youtube, who built a tube amp running on 24 V, so it should work.
What do you Think? Is it a good idea. Any problems you can Think of?
NO!!!
This is a very BAD idea. This is DANGEROUS! In fact, the discussion of not using a transformer is FORBIDDEN on this forum.
For safety, you need an isolation transformer. I think you need to do some reading about high voltage electronics before you jump into this project. You are dealing with dangerous voltages that have the potential to kill you or someone else that is using your equipment.
12AX7 stereo tube preamp only 12 volts - YouTube
Here is the guy on youtube, and he uses 12 V!
Why is it so dangerous to not use a transformer, is the wall output varying alot, or something like that?
Maybe one could just use a 1 : 1 transformer? Are they cheaper?
Here is the guy on youtube, and he uses 12 V!
Why is it so dangerous to not use a transformer, is the wall output varying alot, or something like that?
Maybe one could just use a 1 : 1 transformer? Are they cheaper?
It sounds ok, and I assume that you read that I may use around 200 V, not 12V. It was just referenced, since it may work great to use a lower voltage than stated in the Circuit diagram.
If anyone can answer this, that is great.
Also, Mr. assazello, I believ everyone appreciates a correct tone, and not speculations, that as a matter of fact, are quite wrong in your case.
Fun Stuff, a lot of people here have spent many years in school and many more years, like azazello building and repairing electronic equipment. It will take years to learn electronics over a forum, and there is not enough room to explain everything in electronics. Electronic and electrical safety will fill a large book. It will take forever for you to learn about your project, unless you learn some on your own, or have someone there to teach you.
I learned using the US Navy's NEETS (Navy Electricity and Electronics Training Series) manuals, but then I was also in the Navy. I spent 3 months in Basic Electricity and Electronics, 10 months in ET 'A' school and 6 months in 2 'C' schools. You don't have to read all of the manuals, just 1 through 9.
NEETS - Navy Electricity and Electronics Training Series
I learned using the US Navy's NEETS (Navy Electricity and Electronics Training Series) manuals, but then I was also in the Navy. I spent 3 months in Basic Electricity and Electronics, 10 months in ET 'A' school and 6 months in 2 'C' schools. You don't have to read all of the manuals, just 1 through 9.
NEETS - Navy Electricity and Electronics Training Series
As I assume you all may know, tube audio is a niche, which is not commonly tought at universities these days, due to the appearance of transistors and later IC's.
So, as you may have noticed, this is certainly the first time I'm building a tube device.
Normally when building a power supply, it's easy. But with tube devices, the transformers get expensive (since tube devises are more uncommon, I guess, these step up transformers are expensive, as mentioned). I do have a limited budget for this particular Project, and therefore these questions have arrissen.
That is, a 1:1 transformer is much less expensive, so therefore my question is, as mentioned, if it is suitable in this Circuit, to go with a 1:1 transformer, and thus using a smaller voltage, arround 200 V? It is not hard to get the same amplification level from the tube stages with this, since one just Changes the values of the resistors connected to the tube.
I would also appreciate if people here, that have experience, can help with answering these and questions.
So, as you may have noticed, this is certainly the first time I'm building a tube device.
Normally when building a power supply, it's easy. But with tube devices, the transformers get expensive (since tube devises are more uncommon, I guess, these step up transformers are expensive, as mentioned). I do have a limited budget for this particular Project, and therefore these questions have arrissen.
That is, a 1:1 transformer is much less expensive, so therefore my question is, as mentioned, if it is suitable in this Circuit, to go with a 1:1 transformer, and thus using a smaller voltage, arround 200 V? It is not hard to get the same amplification level from the tube stages with this, since one just Changes the values of the resistors connected to the tube.
I would also appreciate if people here, that have experience, can help with answering these and questions.
Basic electronic knowledge has nothing to do with whether it's tube or transistors. Tube is just a device or means to do a job. You study transistors, tube is in a big extend, very similar. Each device has their own peculiarity, like MOSFET works a little different from BJT or tube, but all in all, they follow a trend. You study transistor good, you are at least 90% there. Transition to tube is just matter of reading some tube theory and work your way into it. I designed transistors and IC my whole life, I have no problem learning tubes in a very short time. The question is not whether you can learn this in school, the question is whether it's worth your while to go to school just to design an amplifier if it's not going to be your career as this is not for the weak of heart.
There are a lot of hands on experience that you can gain by tinkering with amplifier circuit, but the tube circuits are dangerous to tinker if you are green. You might want to consider tinkering with transistor amp, start small. The basic configuration like common emitter(common cathode in tube), common collector(cathode follower) and common base ( common grid which almost never use in audio) are exactly the same no matter what device you use.
Back to your question of cost of power transformer. Of cause you can use a 1:1 isolation transformer to do something, but getting 200V is not the only thing, you need 6.3V, -45V also. Go on ebay, look for some used power transformers. I did look at 1:1 isolation transformer, what make you think they are cheap. I sure did not find one that cheap that gave me the power I want.
The way you ask question, I almost reluctant to make suggestion because you might be too green to get into this and I don't want to be blamed in getting you hurt. But if I were to get my feet wet, I would consider getting a cheap used tube amp and poke around. But this is still dangerous.
There are a lot of hands on experience that you can gain by tinkering with amplifier circuit, but the tube circuits are dangerous to tinker if you are green. You might want to consider tinkering with transistor amp, start small. The basic configuration like common emitter(common cathode in tube), common collector(cathode follower) and common base ( common grid which almost never use in audio) are exactly the same no matter what device you use.
Back to your question of cost of power transformer. Of cause you can use a 1:1 isolation transformer to do something, but getting 200V is not the only thing, you need 6.3V, -45V also. Go on ebay, look for some used power transformers. I did look at 1:1 isolation transformer, what make you think they are cheap. I sure did not find one that cheap that gave me the power I want.
The way you ask question, I almost reluctant to make suggestion because you might be too green to get into this and I don't want to be blamed in getting you hurt. But if I were to get my feet wet, I would consider getting a cheap used tube amp and poke around. But this is still dangerous.
Ok everyone, relax. Before building the circuit, of course I will read up more on the theory of tubes.
And I do get that the transformer is there to isolate the amplifier from the network and protects it from electrical shock.
However, I allready have a thing with this function, since it's recommended for studios (protects all my equipment from electrical shock, and plugs in into the wall output). Therefore, I thought it might be omitted. But I will not do it, it was just a thought.
Of course, it's different to build a tube amp compared to transformer ones and IC, or op amps, (higher voltage).
why do I need -45 V, in your opinion? The schematic states no -45 V. Also it states 6 V, not 6,3 V. But then that 6V is connected with a potentiometer, and therefore it is variable upwards, as may be seen in the schematic.
Regarding the price. The power transformers for 1:1, was a lot cheaper, at the sites I looked, I guess it is, since the step up transformers are more speciality devises, the come at a different price point.
You cannot increase a voltage to a value above the supply voltage with a potentiometer! In any case, the potentiometr you reference is simply a ground reference that enables a balancing of the voltages across it to reduce hum.
Not knowing much, but knowing your limitations is safe. Not knowing much, having no idea what your limitations are and being overconfident is dangerous.
I think you need to do some reading before you stat this project.
Not knowing much, but knowing your limitations is safe. Not knowing much, having no idea what your limitations are and being overconfident is dangerous.
I think you need to do some reading before you stat this project.
Nominal for heating the tubes, acc. data sheet, is 6.3 v with deviation 10%. Tubes work better with 6.3-6.4 v /All offered PT has AC 2.5, 5 and 6.3 v and You can choice, that You need/. Potentiometer 200-500 ohm You must connect between wires of 6.3 v, middle point to ground and You can adjust to decrease hummm. 6 V doesn't enough to heating. Of course tube will work, but.....
/Sorry for my "sharp" tone.../.
/Sorry for my "sharp" tone.../.
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First of all, thanks for all the people on here who has answered the questions. I now have most of the design ready for this.
I have one more question, it is regarding the resistor that connects the grid to ground, that is used to make shure we don't have distortion and such things (the 2,2 M Ohm resistor after the 220 pF capacitor).
According to what I have read, the higher value this resistor have, the more amplification we have.
My question is, if we change the value of the resistor going to the anode, and from the cathode to ground, to lower values, do we also need to change the value of the resistor connecting the grid to ground, mentioned above?
I have looked at a few Circuits, and it seems that this resistor is often chosen to have the value of 1 M Ohm, regardless of the voltage over the anode to cathode of the tube, in other Words, it seems to be rather independent of the rest of the circuit.
Is this so, is it independent of the rest of the circuit?
I have one more question, it is regarding the resistor that connects the grid to ground, that is used to make shure we don't have distortion and such things (the 2,2 M Ohm resistor after the 220 pF capacitor).
According to what I have read, the higher value this resistor have, the more amplification we have.
My question is, if we change the value of the resistor going to the anode, and from the cathode to ground, to lower values, do we also need to change the value of the resistor connecting the grid to ground, mentioned above?
I have looked at a few Circuits, and it seems that this resistor is often chosen to have the value of 1 M Ohm, regardless of the voltage over the anode to cathode of the tube, in other Words, it seems to be rather independent of the rest of the circuit.
Is this so, is it independent of the rest of the circuit?
In some circuits the value of the grid leak resistor is critical. In other circuits it does not matter too much and can be varied by a ratio of 2 or so in either direction. This resistor (typically if 1M or below) just sets the grid to ground potential. If above 1M then it may be using grid current bias, and then the value should be left as it is. A particularly low value for this resistor (say, below 220k) may mean that it is being used as part of a high pass filter with a coupling capacitor so again it should not be altered.
I would advise against modifying the circuit, given your current level of knowledge and experience. Build it as it is. Get it working. Then think about changes, if necessary.
I would advise against modifying the circuit, given your current level of knowledge and experience. Build it as it is. Get it working. Then think about changes, if necessary.
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