John Curl's Blowtorch preamplifier part II

[john curl]

Wavebourn, ever heard of 'differential phase' or PIM? Time to read up.

 

[Wavebourn]

Gee Bill, what is your criticism of my design?

He said, his criticism is impolite.

 

[Wavebourn]

Wavebourn, ever heard of 'differential phase' or PIM? Time to read up.

I will read history books when retire. Not the time yet.

 

[31697B]

Why rock bottomer from symmetric topologies, and why zero or small amount of fb?

Why rock bottom? because the right topology does that without any effort. And fb will only be needed for stability of operation variables and other issues... there are other parameters beside distortion. But a good compl-sym topology makes it easy to get low distortion thus a good starting point.

What is the best OPS topology for low OPS distortion...... besides biasing ......?


-RM

 

[hitsware]

complication does not make sophistication

I am talking about a little more sophistication:

 

[scott wurcer]

I will read history books when retire. Not the time yet.

The beat goes on.

 

[Wavebourn]

The beat goes on.

Right. As well as mantras.

Why rock bottom? because the right topology does that without any effort. And fb will only be needed for stability of operation variables and other issues... there are other parameters beside distortion. But a good compl-sym topology makes it easy to get low distortion thus a good starting point.

 

[simon7000]

I find starting cutting the underbelly open first is the best way to skin a cat. Important note for the folks around here, be sure it is dead.

 

[scott wurcer]

I find starting cutting the underbelly open first is the best way to skin a cat. Important note for the folks around here, be sure it is dead.

We are doing a mostly vegetable based diet these days. What you describe is repulsive on several levels. If the universe is expanding into nothing I guess the audio world can too.

 

[john curl]

Oh, you want simple?

 

[Wavebourn]

...

Well; when 21 workers screw 1 light bulb, it can be a dance!

 

[Wavebourn]

Oh, you want simple?

All that dirts that go to power rails... well... it would work, but can we call it high end?

Simple does not mean elegant, while elegant means simple.

 

[simon7000]

We are doing a mostly vegetable based diet these days. What you describe is repulsive on several levels. If the universe is expanding into nothing I guess the audio world can too.

As usual we don't really communicate. BTY the emperor really does not have any clothes.

Let me know the next time you try to pet a tiger.

 

[Jim the Oldbie]

Well; when 21 workers screw 1 light bulb, it can be a dance!

Sounds more like Emergency Room Russian Roulette.

 

[scott wurcer]

As usual we don't really communicate. BTY the emperor really does not have any clothes.

Let me know the next time you try to pet a tiger.

Get serious Ed and have a sense of humor. Irony?

 

[Wavebourn]

Sounds more like Emergency Room Russian Roulette.

Well; may be in terms of resulting MTBF and troubleshooting, but who troubleshoots today? Swap a board, that's it!

 

[anatech]

Hi Ed,

Important note for the folks around here, be sure it is dead.

They'll know as soon as they start! No damage to the cat necessary.

-Chris

 

[john curl]

I used this cheap design first in 1969, and ran a K-horn with it for years. I used it in Class A mode, but it works better and faster than one would expect just glancing at the schematic. I did not design the topology, I am pretty sure that Bob Widlar did it first. I found it in an app. note, using a uA741, I am pretty sure.

 

[Ultima Thule]

See what happens when I put up a SERIOUS schematic? No response. '-)

Ok JC, why FET's? C. Hansen seem to be fond of symmetric bridged FET amp topologies as well..

 

[Wavebourn]

It was used in many mediocre PA amps. Also, I saw one hybrid opamp that had inside something like caseless 741 and a pair of transistors. Sooo slooow!