John Curl's Blowtorch preamplifier part II

[Wavebourn]

Originally posted by john curl
Waste of words. Most cannot understand, others will not. I wish that I could help, but I am not able to. In short, classical op amps will always be problematic in audio amplification. Video amps have a good chance of being more successful. It is entirely due to the open loop bandwidth, high enough slew rate, and reasonably low distortion, especially higher order odd. That is all there is to it.

I am glad John we are coming to common conclusions and common beliefs. I would call it, "International Solidarity". The cold war is over. Welcome to the camp of heretics!

[MikeBettinger]

Originally posted by Wavebourn
You are over-generalizing again. There is a lot of good professionals that is coming from an educational system today. However, most of them are trained for narrow thinking that is needed for steady day-to-day professional work, but some of them are very widely educated. However, Soviet system could afford very broad education so we used to say that "our research work is the way to satisfy own curiosity for government expenses", but it is unpractical in a free market economy that reacts on demand. But it's reaction is massive and delayed, that causes oscillations like in amplifiers with negative feedback.

I didn't relize I was over generalizing again, but your right, it sounds that way. Although I was referring to my specific experiences with a significant number of younger educated engineers in my day to day functions. It's the rare one that's been taught how (or has the ability) to do and most Excel at PowerPoint engineering; probably aced the MS suite classes.

I didn't intend for this to spiral out like this. John made a comment about something I could not relate back to audio circuitry in the vague hope he might throw out some point of reference to allow me to dig deeper into the concept. He says most cannot/will not understand, yet provides, as I originally pointed out, nothing other than a cryptic reference. Now a few words trickle down mentioning video op-amps. Great, that frames the thoughts for me and I'll leave it at that.

So he is correct, this has been a waste of words.

[john curl]

Why are most video op amps OK, and most audio op amps marginal?

[AndrewT]

because the general public/viewers are much more interested in what they see rather than what they hear.

[infinia]

Video opamps use transconductance topologies and are optimized for wide BW. They don't care about performance down to DC , and don't have to deal with 1/f noise and high impedance issues as audio op-amps.

[john curl]

Video amps, USED AS AUDIO PREAMPS, tend to sound better than audio preamps. Why?

[Wavebourn]

Originally posted by john curl
Why are most video op amps OK, and most audio op amps marginal?

Because some designers of audio amps don't see results of own creations, so they are free to follow traditions, while designers of video amps don't have such privileges so they are free to use "non-standard" and "non-traditional" topologies to get results, while the same schematic ideas that lead to wide bandwidth, low phase and amplitude distortions in video amps, would make audio implementations happier. And what is called "transients" in audio in video reality is the usual plain signal that has to be taken care of.

[infinia]

Originally posted by john curl
Video amps, USED AS AUDIO PREAMPS, tend to sound better than audio preamps. Why?

First time I heard of that. Do you mean sound better but measure worse?

[PMA]

Originally posted by john curl
Video amps, USED AS AUDIO PREAMPS, tend to sound better than audio preamps. Why?

Not influenced by interferences - that's what I have been saying for years.

[john curl]

PMA good for you. NOW, the answer is because of quadrature. Mark this well, please.