another bizarre audio circuit

Yep - I'm not a complete "n00b"... :) What I mean though is with that circuit with the input BJT's emitter at ground if its base is at

0.7 volts the minute its base goes negative it's going to cut off. Maybe the emitter should be connected to the negative supply?

I'm foggy on how such a cascode reduces noise - improved distortion, bandwidth, and PSRR I can understand but how does two transistors end up less noisy than one? I know with tubes a cascode was considered a low noise alternative since two triodes in cascode would have lower noise than a single pentode, with similar gain.

He's not playing your game, which involves telling John Larkin how cute his circuits are.

It's half the story - a few component values make it a lot easier to work out what a circuit is doing.

-- Bill Sloman, Nijmegen

That's what transistors do!

Actually, in Vlad's circuit, the cascode probably doesn't help much. But it sure is cute!

John

Right, but the gain of that stage is going to be very unsymmetrical. I guess with so much gain and the negative feedback it doesn't matter though.

He's not designing circuits, which is what this newsgroup is about.

You aren't either. Both of you start to cluck and peck when people do design circuits. No surprise.

You can't look at a circuit this simple and see what it's doing? OK, no surprise.

John

Well, I thought designing a circuit included supplying component values. No?

I posted topologies. Values can be scaled to the application, but you need a topology first. If I were actually going to build this, for money, of course I'd have to define specs and then compute values. That's just grunt work.

John

Bullshit. You do not know the facts in the first case you cite, and you are off the mark in the second case you cite.

Electronics is far more than a mere circuit. There are several physical disciplines involved. This group is about ALL aspects of the science of electronics design, and that extends BEYOND only circuits.

Grow the f*ck up, you mouthy little school marm wanna be bitch!

You have no clue what John does or does not do.

So you need to grow the f*ck up in that respect as well, you pissy little bitch.

Word salad.

JF? He clucks. Like you, he doesn't post circuits.

Well, maybe once in a great while. To my knowledge, you have never posted a circuit, or shown any evidence that you know how to design electronics.

Show is some circuits, Big Man. How about an original headphone amp?

John

Not really. I have a few circuits I could throw out and claim that they are topologies and you would not be able to use them without values. Granted, mine are more complex than the one being discussed, but I'm hoping to make a point.

John (not Larkin)

Good challenge, John. I expect more word salad from him since he has never shown any technical abilities. I expect mostly a host of profanities.

John (not Larson)

Consider the target. Impossible task.

He is hard wired stupid.

I think circuit topologies are fun to play with. Lots of textbooks show, and discuss, circuits without explicit values. Once you have a topology, then you can proceed to specs and component values.

If you think all circuits should be posted with values, post some.

John

Don't forget DimBulb's love of poop.

You are correct, John. Now you have a topology. Please post the component values.

Thanks, John

Ah, yes. For some reason I don't think that much about feces like he does.

Given i/o specs, the DC analysis is simple. But there are two AC aspects that are sort of interesting: the lf response, and loop stability. I'm sort of disappointed that nobody has commented on either.

As I'm disappointed in how many people want to whine and cluck about personalities, and avoid actually discussing electronics.

John

BF862s are much better--cutoff to full on in half a volt or so. Their transconductance is so high that even with a 2.5:1 range of I_DSS, the spread of V_GS is pretty reasonable.

They're also very quiet, go about 700 MHz, and cost 20 cents. Other than that, they stink.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

As far as I can see, a cascode has the same noise as its bottom transistor, near enough. The virtue of a cascode is that it greatly reduces the effect of the Miller capacitance, so you get more bandwidth and less input capacitance.

Jeroen Belleman