What Design to Use?

[jwatts]

Which of the three designs listed below should produce the best performance. What would be the preferred design?

1. Common-cathode stage, fully-bypassed cathode:

2. Common-cathode stage, unbypassed cathode:

3. Single-stage inverting feedback amplifier:

See the link below.
http://www.aikenamps.com/Equations.htm

[leadbelly]

Originally posted by Jason Watts
Which of the three designs listed below should produce the best performance. What would be the preferred design?

1. Common-cathode stage, fully-bypassed cathode:

2. Common-cathode stage, unbypassed cathode:

3. Single-stage inverting feedback amplifier:

See the link below.
http://www.aikenamps.com/Equations.htm

Even a newbie like me knows you can't just compare tube stages on a philosophical basis like that. What is the application? What is the gain and output impedance required? What surrounds that stage, active loading, passive loading, regulation, etc.

[EC8010]

Which is the preferred method of breaking open atoms?

1 A hammer, fully shrouded rubber handle:

2. A laser, paid for by somebody else:

3. A star, not paid for, but quite a long way away:

As a physicist, you owe it to yourself to frame questions better.

[EZ_Angus]

Oooh Oooh, I know this one, its the hammer, innit??

[jwatts]

A neutron is the preferred way to split an atom. By the way I get paid to prevent neutrons from splitting atoms. It’s a great job if you like high stress and high liability one calculation screw up and large quantities of atoms get split. Very ugly. I am sorry for asking such a vague question. My intent was to eliminate the need to do a large quality of research and rapidly eliminate a few of the possibilities. I will be more specific next time.

[EC8010]

Not to worry. Having avoided splitting atoms, what did you want to do with your gain stage?

[jwatts]

What are they advantages and disadvantages between a fully-bypassed and unbypassed cathode? What is the typical input impedance of an off the shelf tuner or CD player? What is a nominal voltage gain typical desired during amplifier construction? Why are they two different outputs for the unbypassed cathode amplifier? Should I try to design the amplifier such that the output impedance is equivalent to my driver impedance?

[leadbelly]

Originally posted by Jason Watts
What are they advantages and disadvantages between a fully-bypassed and unbypassed cathode? What is the typical input impedance of an off the shelf tuner or CD player? What is a nominal voltage gain typical desired during amplifier construction? Why are they two different outputs for the unbypassed cathode amplifier? Should I try to design the amplifier such that the output impedance is equivalent to my driver impedance?

You're still missing our point. You've told us what comes before, tuner or CD, but what comes after

[tubelab.com]

Not to worry. Having avoided splitting atoms, what did you want to do with your gain stage?

Avoid splitting ears! Sorry I just couldn't help it.


The answer to the question obviously depends on the application, which determines the required amount of gain. Once this is known then some choices can be made.

[EC8010]

Originally posted by tubelab.com
Avoid splitting ears! Sorry I just couldn't help it.

With your avatar?

Back on-topic: In the absence of anything else, I'll make some sweeping assumptions, pronounce a few edicts, then go to bed before the fur flies.

A standard CD player produces a maximum output of 2VRMS. That's quite a handy sensitivity for a power amplifier. Ergo, all power amplifiers should have a sensitivity of 2VRMS for full power. Oh, there are other sources? All digital sources tend to produce 2VRMS. Analogue? What do you mean, analogue? LP? Make the RIAA stage produce 2VRMS. Tape? I'm biased against the stuff. FM tuner? In the unlikely event of you having an FM station that doesn't hammer the Optimod multiband compressor, its future is short-lived and obsolescence beckons (dastardly digits).

Well, that made everything easy. All you need for a pre-amplifier is unity gain. Have a look at SYs Heretical stage.

I'll run away now.