Where's my voltage gain?!

[R.G.]

We were all of us green once. There's no shame in that.

The shame is not even staying green. It's staying green and thinking you're not; worse, staying green and announcing that you're an expert. Even worse, being green, thinking you're not, and arguing with people who really do know what they're talking about. In public.

I mess up all the time. The first thing to do when you find out you're wrong is to admit it and get over it. If you do that, you are wrong less often in the future.

[Enzo]

"It's not easy being green."

-----K.T. Frog

[R.G.]

Good one, Enzo!!

[Wombaticus]

Best thread ever! Gotta feel sorry for the poor confused fellow though, getting tag-teamed by Aiken, Blencowe, and Keen - yikes!

[mooreamps]

Gary, I think your paper might need revising.

All second order contribrutions to the output noise generated by a gain stage. The equations you posted are correct, but do not include noise factor as a function of the receprical of stage gain times the input impedance over the thermal noise constant of the cathode resistor, or as in the case of my preamps, the lack thereof. Thus, addition equations are required to capture the total noise contribution of the gain stage.

[Merlinb]

The equations you posted are correct, but do not include noise factor as a function of the receprical of stage gain times the input impedance over the thermal noise constant of the cathode resistor,

That makes no difference- the noise factor is just an expression of how noisy the stage is overall, and it is very easy to demonstrate that the cathode resistor makes a negligible contribution to the overall noise. It doesn't matter how you chose to express the noise, it's not going to make the cathode resistor any noisier!
(And I have no idea why you would want to plot noise as a function of input impedance?? Especially since the input impedance is essentially infinite at audio frequencies. And I see no reason why you would divide by the noise constant of the cathode resistor... Why don't you just post the paper you wrote, or an extract of it, and prove us wrong)

EDIT: Or perhaps you're applying some sort of noise weighting factor, such as the IEC "la la la I can't hear you" factor?

[Wombaticus]

All second order contribrutions to the output noise generated by a gain stage. The equations you posted are correct, but do not include noise factor as a function of the receprical of stage gain times the input impedance over the thermal noise constant of the cathode resistor, or as in the case of my preamps, the lack thereof. Thus, addition equations are required to capture the total noise contribution of the gain stage.

This gets better and better. You keep talking about some paper that you have written -- so I have a proposition for you Gary --when you have successfully published a finding in any reputable general circulation peer-reviewed EE journal that cathode resistors are a signficant contributor to noise in a stage, I will send you a cheque for $100.

By the way, I checked out several of your youtube clips, and the apparent noise floor on your amps seems to range from fairly abysmal to no-better-than-usual-for-any-commercial-amp, so I'm not sure that your theories are helping out any. In all likelyhood, more attention to boring old things like lead dress, layout, and grounding, and less to highly dubious theories would prove rewarding.

[R.G.]

All second order contribrutions to the output noise generated by a gain stage. The equations you posted are correct, but do not include noise factor as a function of the receprical of stage gain times the input impedance over the thermal noise constant of the cathode resistor, or as in the case of my preamps, the lack thereof. Thus, addition equations are required to capture the total noise contribution of the gain stage.

I keep trying to get you to explain what the devil you're talking about in a way that technically literate people can understand it.

By now you have to have tumbled to the idea that what you're posting comes across in the forum as at best confusing. I'm hoping that there's something behind what you're saying that makes sense. Believe it or not, I'm trying to help you get it out so others can understand it.

You talk about "noise factor as a function of the reciprocal of stage gain times the input impedance over the thermal noise constant of the cathode resistor" and "additional equations are required to capture the total noise contribution of the gain stage". Cool. Whip out those equations and supporting references, define your terms, and let us see how you're really insightful and not just using big words.

Tell us where the reference papers are buried, or even better, post links to them so we can see for ourselves. I for one am always willing to posit that there are things I still need to learn.

If you can't do that on request, it comes across to others like this:
Turbo Lecture.

As you've guessed by now, several people here are familiar and comfortable with running back through the technical backup for things which have to be expressed in equations. Those people are very likely to ask when you post this kind of thing, so you might as well expect the questions.

I learned early that when I was addressing a room on some techie topic that although I could snow some of them, maybe most of them, there just might be a guy there that already understood it as well or better than I did. The prevention I tried to use to get ready for that situation was having the facts, math, and applications correct and available before I opened my mouth. Then if the expert in the audience was only a pseudo-expert, he either wound up agreeing with me or embarrassing himself.

Mother Nature doesn't care who is glib and a great presenter of full-color charts and snappy slogans. **She** is always right.

Or maybe your amps really do use turbo-encabulators.

N.B. The source impedance is important in figuring out total noise, and using the best input impedance device for a load does matter. But so does context. For audio, with tubes, it's hard to change the very high input impedance that's already there. That is NOT true for RF and/or semiconductor devices. Yes, I can point you to the references that lead me to say that if you like.

[mooreamps]

...and, the answer is: ???

The Amp Garage :: View topic - Preamp Design and Bypass Capacitors


-g

[R.G.]

The Amp Garage :: View topic - Preamp Design and Bypass Capacitors

That's a nice link, I guess, but it strikes me as a non-sequitur, as in:

A non sequitur (pronounced /ˌnɒnˈsɛkwɨtər/) is a conversational and literary device, often used for comedic purposes. It is a comment which, because of its apparent lack of meaning relative to what it follows,[1] seems absurd to the point of being humorous or confusing,

Non sequitur - Wikipedia, the free encyclopedia

It does not help that you're flatly refusing to address valid questions about the things you post. It reminds me of the old story about the reporter, upon seeing the aging senator out to dinner with a comely young lady, asking said senator "Excuse me sir, but is this young lady your daughter or your secretary? Or would you like to answer a different question?"

[Albert Kreuzer]

The Amp Garage :: View topic - Preamp Design and Bypass Capacitors

OK, I read all that - but it doesn't answer anything for me. Nothing about noise, input impedance and cathode resistors, just some (non-informative) talk about diode biasing.
What are you trying to tell us?

Edit: R.G. beat me to it.

[vintagekiki]

OK. Vox AC10 is Vox AC10.
But what is with raiken amp designing / building schematics.

about EL84
pair EL84 in PP have Raa = 8 kOhms.
one EL84 in SE have RA = 5.3kOhms
http://www.drtube.com/datasheets/el84-philips1969.pdf

Maybe in designing or building some error. Your schematics please.

[mooreamps]

OK, I read all that - but it doesn't answer anything for me. Nothing about noise, input impedance and cathode resistors, just some (non-informative) talk about diode biasing.
What are you trying to tell us?

Edit: R.G. beat me to it.

Well, at least they are not flaming me for it any more. But then again I owe a great deal of credit to the Judy sisters for stepping in on my behalf.

-g

[mooreamps]

This gets better and better. You keep talking about some paper that you have written -- so I have a proposition for you Gary --when you have successfully published a finding in any reputable general circulation peer-reviewed EE journal that cathode resistors are a signficant contributor to noise in a stage, I will send you a cheque for $100.

It's a very generous offer. But, anything I write, has to be submitted to Corporate Legal, and has to go through them. It's the same rules for all salaried employees. Secondly, it's nothing to do with lead dress, layout, or grounding. It's all math.

-g

[mooreamps]

Perhaps your "colleges at work" were either too polite, or too busy laughing, to say anything when you presented your half-baked theory?
RA

They are other electrical engineers with Masters and PHD degrees. I'm not the one they laugh at ; trust me.. :|

(2) I fired the guy.

Are you going to have me kicked off ??

-g