John Curl's Blowtorch preamplifier part II

[stinius]

Originally Posted by Curly Woods

Thank you Stinius

Curly
You have viewed my public profile.

[jlsem]

Originally Posted by SY

I have the principal violinist for the Dallas Symphony as a drinking buddy. How many points does that get me?

Emanuel Borok? I didn't know he was in Austin.

John

[SY]

He's not. I do travel to Dallas now and then. Concertmaster Levinson makes it down here.


Ooooh. Hope that didn't hit anyone.

[Curly Woods]

Originally Posted by stinius

Curly
You have viewed my public profile.

Not to ignore you Stinius

[john curl]

What is going on here? Kids, get back in your seats and SHUT UP! ;-)

[Curly Woods]

Originally Posted by john curl

What is going on here? Kids, get back in your seats and SHUT UP! ;-)

[anatech]

Hi John,

Chris, you are a man of many opinions, but you are not always right.

Very true, but at least I'm honest about these things, and I'll admit when I'm wrong too. When you spend a long, long time in an industry (as you have as well), you see a great many things. All a person can do is make sense of these things best they can. Still, I've been vindicated more often than I've been wrong.

I find that at least 1 or 2 rooms at CES sound really good to great, every year.

That's excellent! That represents the most I have ever encountered. There are times when maybe even one room is good, and the exhibitors are still not happy. I've talked to many people over the years and the story pretty much remains the same.
A very common problem is the size of the room, and the acoustic properties (walls, glass and often the ceiling). In the open areas, there is often too much ambient noise to listen to anything. In the earlier days, reps used to take you to an entirely different building where the rooms were larger.
In 2004, when I attended the show in London, I found only one room that did sound good. It was the Marantz room. We found some rooms that were okay, but the manufacturers were not happy with the setup.

For what it's worth ...

-Chris

[anatech]

Hi Joshua,

Yet you criticized speakers you never heard.

No I didn't. You are being far to sensitive.

Your speaker topic is done and over with. Let it die in peace, otherwise I feel you may be talking about them in 365 days still.

So I wonder what you may refer to as "truth".

Nothing Joshua, nothing.

It's pretty clear you like to debate with as many people as possible, simply to debate I think. Maybe this allows you to feel included, but no matter what the reason, I know you will continue ad nauseum. Enjoy your perfect loudspeakers.

-Chris

[anatech]

Ahhh, Curly,

I have never worked in any place that was high pressure at all.

That's pretty cool. Now what does this have to do with anything I've said to you? I guess that I can respond by letting you know I have never worked in high pressure sales environments either. Yahoo for me!

Your experiences are yours, but they are not what I have been accustomed to at all. ... Not many dealers had the experienced staff that we had. Not a shot at anyone, just the way it was.

Once again a comment from the left field.
Curly, I left the sales part of the industry as soon as sales people became unprofessional. It was a good move for me then and allowed me to concentrate on the science behind the audio. Before that I had a foot in both dinghys.
The fact that your experience is not the same as mine is not surprising at all. Technicians do not generally make good salespeople, and salespeople are normally not trained in electronics. The gulf between these groups is vast.

Salespeople are given information that is useful for sales. Technicians are given very detailed information about the circuits and service procedures, but not sales information. In fact, as an advanced service depot, I often had information that required I sign a non-disclosure agreement before receiving it. The same discretion was expected to cover any information that came out of communication between the engineering department and ourselves. I also had extensive experience dealing with dealers and salesmen as we were expected to support dealers to some extent.

I'm not looking down on good salespeople, but our jobs are different. Our information would not be helpful to you, and we typically didn't care too much about sales information. You have to believe in the product to sell effectively, and some of the stuff behind the scenes would really rattle salespeople up. In fact, many manufacturers would not release information willingly to us, so it was necessary to figure the truth out for ourselves. Case in point, one brand had an SSM2126 prologic chip in it. The schematics were missing this area! It was apparently secret. So I copied the pages from the data book and faxed it to them. Turns out they didn't even have this information. We did get complete schematics after that.

Suffice to say that there are things salespeople are not meant to know, and there are good reasons for that. It doesn't matter how high end you are as a salesperson, but I recognize the attitude you have on this. Doesn't change a thing.

-Chris

[simon7000]

ikoflexer
The advantage of current out is that there is almost always a resistor across the inputs of an audio power amplifier. The current will produce the voltage to be amplified across this resistor. If there is other resistance (linear or not), magical copper oxide diodes, dielectric barriers, iron copper contamination, or any other bad guy, the voltage to the amplifier will be affected much less or not at all.

Bob,
Thank you for your polite correspondence. I do not think you are being picky. I am afraid we must disagree a bit. But first I agree with just about all you said. In the early days of transistors there was a definite doubling of current gain with every decade of increase of collector current. Modern transistors such as the 2SC2240 are not really NPN devices only, as a result they have much nicer curves. On some good samples this is now only a 5% increase for any decade of current in the range I expect them to be used. Interestingly the gain has a slow increase in the 5-10ma range or more that is consistent with device heating. It is probably harder in a preamp to set the optimum AB bias point due to vastly different loads, levels, and tendency to really make it class A. Again thank you.

SYN08
A nice simulation, but I have measured the results and when the rails are adjusted they essentially provide a nice way of tweaking the distortion level and products. I find a 3 volt difference to be telling.

Also the resistor to bias the output for monolithic ICs will have stunning differences on an older design that uses a poor quality PNP in the output stage if the resistor is in parallel.

Wavebourn
I can't disagree with you at all on this!

Jan
You and Walt are very responsible for showing everyone that they can get better results from improving the power supply. Are you trying to get them to actually use monolithic devices also? It took 20 years just on power supplies! I suspect as all the gear catches up there will be a very slow 20db-ish improvement in what most now consider state of the art.

To all
The bit on loudspeakers is interesting, some even realize the room, listening distance, noise level, etc have a major influence on what we hear. That affects what we perceive.

There is a good reason why many prefer vacuum tube amplifiers. The modern versions really can rival the solid state version in performance specifications at reasonable listening levels. There really is truth to the perception they have greater sound stage and at least one component of it is measurable, but I am pretty sure it is one of those things you cannot find in a simulation.

Simulations do not include all of the variables, only models of the devices using parameters that are recognized and well understood.

The mechanism for improved sound stage is well understood, not included in any model I have seen, and in many designs considered a problem. It is the vibration induced voltage changes in tubes. When obvious and at higher frequencies it is called microphonic, at low levels and frequencies it adds warmth and depth. All mechanical structures from phono cartridges to capacitor windings have resonances.

Please don't bother me about this until you measure the sound induced vibration on equipment cases. I have, it is there and at levels that show up in the components.