Some are called Spud amplifiers.
One tube, often either only a pentode, or only a beam power, or only a triode.
More than one element (one valve) causes the simple-as-possible to be less simple.
An old recipe for Tiger Soup starts with "First you catch a tiger".
A high output phono cartridge starts with "First you obtain a high output crystal cartridge, or a high output ceramic cartridge".
Not all of them were high output.
Practicality starts in the eye of the designer, but needs to please the ear of the listener.
You can build a 2 stage (2 valve amplifier). Not a lot more complex than a single stage, 1 valve amplifier; almost a step and repeat, with the second stage putting out real power.
One tube, often either only a pentode, or only a beam power, or only a triode.
More than one element (one valve) causes the simple-as-possible to be less simple.
An old recipe for Tiger Soup starts with "First you catch a tiger".
A high output phono cartridge starts with "First you obtain a high output crystal cartridge, or a high output ceramic cartridge".
Not all of them were high output.
Practicality starts in the eye of the designer, but needs to please the ear of the listener.
You can build a 2 stage (2 valve amplifier). Not a lot more complex than a single stage, 1 valve amplifier; almost a step and repeat, with the second stage putting out real power.
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A popular tube arrangement is used in the Mullard 3-3, Three tubes since it is stereo, one tube in each channel plus the rectifier.
So one channel would be the ECL82 triode / pentode while the power supply rectifier used was a full wave EZ80. Three watts per channel all done
Many different tubes have been used in this basic configuration.🙂
I'm thankful for your tips here except this one, with added harmonics, tubes can't be hi-fi, or fidele enough to original source, this is my understanding at this level after going through few first pages of the book I mentioned, the writers dealt with this thing at the very first chapter, as if washing off hands beforehand!
And no prominent valve amp maker advertises using that word anymore, I checked well, must be for legal reasons, otherwise it would cost very dearly, much more than their already costly products 😊
If you want lower distortion, more (20-25mA) anode current needed, but B+ (if you use R loading) is too low for this.
The power supply might be a bit of a pain to build, since the C3M has a 20V heater. If you used a more conventional tube with a 6.3V heater you could easily find a single transformer with an HT and a 6.3V secondary. For the C3M you would likely need two separate transformers, one for the HT and another for the heater.
All a matter of semantics, what something is called doesn't change the fact that all tube amps
& amps in general add harmonics to the original program material. They are all non-linear devices, no matter how complicated.
There is a wide spectrum of people of many backgrounds here on DIY, you will get many opinions & ideas offered.
If you are planning to drive a loudspeaker you will need more than a simple voltage amplifier as in your first post.
At the very least two triodes, separate or combined in a single bottle. And a power supply of about 250VDC & 50 mA or more.
There are many examples of amplifiers such as this all over the iNet. And many here on DIY.
You will need to do some thinking & work yourself, don't expect a complete solution offered on a silver platter.🙂
I just asked simple questions.
There was absolutely no need to mention hi fi at the very first place, hi fi is a myth, just like yeti and loch ness monster!
Some things are needed to keep the tradition of monarchy alive even inside democratic world, to make larger than life image, hi fi is just one of them 😊
It's futile to instruct a self made person what to expect and not, who knows limitations of himself and others.
Silver plate dinner seekers are those who start threads round the clock to garner solidarity in an otherwise empty life.
Where's the time for that?
True contributions are shining like silver above 😊
There was absolutely no need to mention hi fi at the very first place, hi fi is a myth, just like yeti and loch ness monster!
Some things are needed to keep the tradition of monarchy alive even inside democratic world, to make larger than life image, hi fi is just one of them 😊
It's futile to instruct a self made person what to expect and not, who knows limitations of himself and others.
Silver plate dinner seekers are those who start threads round the clock to garner solidarity in an otherwise empty life.
Where's the time for that?
True contributions are shining like silver above 😊
Still some triodes are the most linear devices on the planet. You can look all day long at their equally spaced anode characteristics, till your mouth starts salivating and your eyes get all teary, just thinking how magical those babies will sound.
I think your first post was a bit sparse in details, and the C3m is a bit esoteric, which caused the discussion to get sidelined.
If you build a line amp, what equipment will you use to listen to it? What is your goal?
If you build a line amp, what equipment will you use to listen to it? What is your goal?
Trying to change the English language here will accomplish nothing.
You have been on this forum for eight years & probably others, time enough
to have been witness to several projects that would satisfy your wishes.
The best time to start your project was eight years ago. You appear to have missed that time slot.
The 2nd best time to start your project is today by at least buying one of the books suggested.
And then invest your time by reading the book from the beginning.
Talking will do nothing to move your project forward, real action by you is what is needed, today!🙂
Hi Fi stands for High Fidelity.
P Fi stands for Perfect Fidelity.
Do not belittle Hi Fi, just because it is Not Perfect.
Do not belittle a particular Concert Hall, just because it does Not have Perfect Acoustics.
Instead, whether Live music, or playback of Recorded music . . .
"Enjoy the Music"
Otherwise, just build things but never use them.
Just my opinions
P Fi stands for Perfect Fidelity.
Do not belittle Hi Fi, just because it is Not Perfect.
Do not belittle a particular Concert Hall, just because it does Not have Perfect Acoustics.
Instead, whether Live music, or playback of Recorded music . . .
"Enjoy the Music"
Otherwise, just build things but never use them.
Just my opinions
I'm considering the working simulations only, the other answers are just lounge talks
Line amps are meant for long transmission needs, have very high impedance at output, my understanding goes as, to get some sound out of this, I've to shunt resistor but the voltage will multiply, or use very high impedance old drivers like Ad3690, those are not made now, or to use transformer, or to match the impedance for a power stage input if a hybrid amp if the above things don't work.
Many 'working' simulations need to be built in order to prove they work.
The original Tacoma Narrows Bridge is a good example.
The simulation forgot to take into account a 15 Mile Per Hour gusty wind, and the mechanical resonance of the bridge.
The original Tacoma Narrows Bridge is a good example.
The simulation forgot to take into account a 15 Mile Per Hour gusty wind, and the mechanical resonance of the bridge.
In 'hi-fi' or domestic recreational audio, a 'line amp' is generally defined as a small voltage amplifier for small signal levels. A line amp could be a simple buffer with high input impedance and low output impedance, designed to drive long cable runs without loading down or slew rate limiting. Or, a line amp could be a 'preamp' or control amplifier, with a small amount of gain, an input selector switch, and a volume control, and maybe even tone controls. Or... A line amp could be the input section of a power amp where the small input signal is amplified to drive a brawny driver stage which in turn drives a brawny output stage that needs 100V peak to peak or more signal drive.
Tube amplifiers for driving speakers almost always use output transformers, because even power output tubes have too high output impedance to drive 4 ohm loads.
It's really difficult for a single tube to both provide enough gain to drive a loudspeaker and an output impedance that's low enough to drive a loudspeaker.
Let's look at an example. Let's say we take a 6J52P and triode wire it.
mu = 80
rp = 2.5k
gm = 32mA/V
We can use a 5000 ohm resistor as its plate load (2*rp for max power out).
That will make the output impedance (Zout) 5k||2.5k or 2k ohms.
Even if we feed 1.5V peak to the 6J52P-triode (close to the maximum input signal it can take), and that makes a whopping 120V peak out from its plate, how do we drive that 4 ohm speaker?
We need an output transformer to step down the output tube's (high) output impedance to match the speaker's (very low) impedance.
Now if we take a transformer with the needed impedance ratio of 5k:4 ohms, that will have a voltage stepdown ratio of 35.4:1.
That 120V peak out from the 6J52P-triode plate will now be only 3.39V peak across the speaker voice coil.
To figure power to the speaker, we multiply that peak voltage by the sq rt of 2 (or *0.707), square that, and divide by the load impedance.
3,39(0.707) = 2.42
2.4(2.4) = 5.74
5.74/4 = 1.4 watts.
In an absolutely ideal world, and not thinking about distortion, a 6J52P-triode could theoretically deliver 1.4W at the very most into your 4 ohm speaker. Of course there's the insertion loss of the output transformer and other losses to factor in, so that single-ended amp will make an absolute maximum of about 1W, and with high distortion too.
In order to deliver 5W of power to the speaker, the output tube needs to swing more volts, which means it needs to have a combination of a 'taller' grid to cathode voltage (let's say -30V instead of the 6J45P's -1.5V) and it needs to still have enough gain to take that maximum 30V peak input signal and swing 240V or more at its plate (mu of 8). That means the DAC's maximum 2.83V peak output needs to be amplified up to 30V peak before the signal goes to the output tube's grid, meaning there needs to be a line stage/driver tube at the power amp input that has gain of about 11X (something like a 6SN7 could do this).
And that is why tube power amplifiers for speakers almost always need to use more than one tube per channel. That also explains why simple single-ended tube power amps often use a 6SN7, 12AU7 or 12AT7 input triode into an EL84, 6V6, 6L6, EL34 or KT88 output tube (often wired triode).
Look at the Tubelab Simple SE design for a good example of exactly this kind of circuit:
http://tubelab.com/designs/tubelab-sse/
http://tubelab.com/designs/tubelab-sse/schematic/
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