John Curl's Blowtorch preamplifier part II

[john curl]

Now, what is really missing from most hi fi design? What really separates mid fi from real hi fi? Guess what, it is still, OPEN LOOP BANDWIDTH! That is the secret of the CTC Blowtorch, Charles Hansen's designs, and most tube products. It is the almost forgotten ingredient, neglected or even suppressed by many engineers, like the use of salt or real butter is by some cooks, today, to improve the taste of food. We have found high open loop bandwidth to be the key ingredient added to an audio design that makes it more successful than other similar designs. It has to do with the generation of PIM that is equal or even more important than TIM. Listening tests prove this to me, as well as theory, and even measurement. That is my opinion, and it works for me. Your opinions may differ, but please don't berate me about it.

[ostripper]

by jc - Several of the best design engineers that I have ever known and worked with did NOT have a college degree in any subject.

Which means they are amateurs...

By jc - Amateurs, you can't reproduce this design properly, anymore than you can make a hi end sports car, just don't bother.

So the best engineers cannot design a blowtorch ...

It has nothing to do with the degree, but the effective background they have to effectively address the issue at hand.

But that is where the "great equalizer" comes into play - the internet.
Do not underestimate the amateurs...
OS

[john curl]

I suspect that English is not your first language, or you would not make such assumptions about definitions. Or perhaps you were joking?

[stinius]

Originally Posted by john curl

Bob Cordell and Scott Wurcer, and even Wavebourn, meet this criterion. Some others don't appear to.

It seems like you forgot Charles, as well as a lot of people that regularly contribute in this thread.

Originally Posted by ostripper

Which means they are amateurs...

Translated from its French origin to the English "lover", the term "amateur" reflects a voluntary motivation to work as a result of personal interest in the activity.

So the best engineers cannot design a blowtorch ...

Who cares?

Do not underestimate the amateurs...

I agree.


OS

Originally Posted by john curl

I suspect that English is not your first language

I’m not sure how many times I’ve seen you using this phrase, but it’s a lot of times. I’m sure that OS knows his English as good as you do. Please also remember that this is an international forum with members from all over the planet, and if it is so that you have to write perfect English to contribute in this thread I personally think that it is something is completely wrong.

Cheers

Stinius (Engineer)

[Wavebourn]

"And even Wavebourn"
I like it.

[anatech]

Hi John,
Well, first off, you are not an engineer. At best, you can be called an "engineering technician" (whatever that means), I've been called that as well. I do recognize that you have some talent, but I have also met others that have far greater talent. Try as you may, you can not distance yourself from the other technicians and hobbyists around you by attempting to include yourself in the engineering fraternity. You should know that real engineers also have instruction in ethics. What constitutes professional conduct is also taught.

Yak alert for John, others can skip
I ran my own high end and semi-pro / pro equipment service center successfully for 16 years before selling it. In that time I was responsible for every aspect of the operation and quality control. I fixed everything that the others couldn't fixed, we also got several items from other shops after failed service attempts. We administered the warranty program for several high end brands, and several mid-fi brands. Let's just say that there is a lot of "mid-fi" equipment that performs spectacularly well, and several "high end" products that are utter failures. I think that defining the quality of device should depend on the performance of the model in question rather than the brand. I hired, trained and fired technicians. Developed in field fixes that turned into the official modification, discussed problems with the engineering staff from different companies and so forth. After that, I worked in a calibration lab (Transcat) and was one of the few certified to create testing limit forms for new (first encountered) test equipment. Not bad. They constituted an integral part of a certification that was included in the paperwork. That's a lot of trust. I then ended up in commercial telephone equipment service. It was better money, more traveling and I met more people. Also, you were expected to work on your own to solve whatever issues came up. I was also on call (yuck) for the government systems, I designed an began installation of a four site integrated system with stand alone redundancy and man down applications. I was certified on our Avaya brand equipment, including voice over IP. The work was easier on the old noodle, but it was at this time a guy ran into the back of my truck - ending my career(s). I had continued to design equipment and provide audio warranty service throughout.

Training courses? Yep, I attended every one I had an opportunity to go to. Self training is nothing special, all technicians and engineers do this. But, hobbyists have my respect because they train themselves without the benefit of industry contacts and even formal training in electronics. In my view, a hobbyist deserves more respect because of their commitment to learn. These people do not deserve to have their time wasted.

Okay, so what does that make me? Not much, I'm a motivated technician with a wide skill set and a good understanding of many technologies. I guess I was lucky also in that I learned from many excellent technicians in all three major careers I had. But that's it John, I don't have to try and sell myself off as anything more than a curious guy and good technician (at least I think I am). Trying to claim more than that is insulting to the profession you claim to be part of.
End yak alert - sorry about that.

Now, you claim that tube amplifiers are wide band devices? No they aren't! The output transformer dictates how much open loop gain you have, then closing the feedback loop will really put a lid on bandwidth. If you are referring to pre-amplifiers, then the standing current coupled with stray capacitance will shut the lid on high bandwidth. Vertical amplifiers in high end oscilloscopes are a very specialized form of amplifier, seldom seen in the audio market It's true that special amplifiers called transmitters are high frequency amplifiers, but they are not wide band devices. They have narrow band-passes to reduce the generation of harmonics. I think what you actually meant to say is that they are forced to be linear before you close the feedback loop because there is seldom more than 12 dB of available feedback you can use before the entire circuit takes off into some type of oscillation. Otherwise John, your Blowtorch would have been realized with vacuum tubes rather than the solid state devices you did use. The amount of feedback you choose to use is entirely up to the designer, and isn't a bad thing unless you are trying to dress up a poor design. Feedback will then work against you.

I completely disagree that high open loop bandwidth differentiates mid-fi designs from high-end designs John. There are also other factors at play and you just happen to focus on this. You are trying to define your products as high-end by introducing a factor used only to exclude other capable designs. I will say that I agree that a high bandwidth makes achieving high performance easier, but there are other things to consider too.

You know what you need to do for other people to accept your view of yourself John? I don't know everything, but start by answering questions directly and truthfully. Skip the entire claim that you are better, or above, almost everyone else. One thing you ought to consider. There is nothing you can do that someone else can not do. There are things others can do that you really can't as well. In other words, enhance your "soft people skills" (god, I hate that phrase! ), be more human and accepting of flaws that you and everyone else has. As soon as you start beating your chest, you really are wasting everyone's time here.

All the best and I hope you're feeling better John.

-Chris

[PMA]

Personal fights do not help at all. How about splitting that to a thread where you both can mutually explain your point of view?

[Wavebourn]

Originally Posted by anatech

Now, you claim that tube amplifiers are wide band devices? No they aren't!

Tube amplifiers may be not, but tubes are!

You may put some four pentodes into a machined aluminum box, damp them acoustically, power from nice power supplies, add input transformers to get low S/N, output transformers to get low linear output impedance, and you have a nice sounding vinyl corrector. It is easier to achieve desired sonic results using tubes than complementary SS devices. Much easier. I don't say cheaper, I say easier.

[ostripper]

As a example of "professional misconduct" versus genuine helpfulness....

By jc - Amateurs, you can't reproduce this design properly, anymore than you can make a hi end sports car, just don't bother.

Or ,

I suspect that English is not your first language, or you would not make such assumptions about definitions.

I was joking , as well as bringing a contradiction to light.

A professional will help if he can , without the air of snobbery ,like Mr. cordell did here : Self type 3 EF (hybrid triple)... any pointers ??
For this , many are thankful. He did not have to divulge any "secrets" ,but explained things in a very casual professional manner. That is the purpose of this forum. So , amateurs (who might have novel construction techniques) and engineers , (who can tell you why your OP stage oscillates) , and legends (I heard the name "john curl" long before I became an audiofool) should contribute to the common good.
OS

[john curl]

Please everyone, you put me between a ROCK and a HARD PLACE. This is a dilemma that means being in an almost impossible situation.
I am NOT attacking Chris or anyone else. I am DEFENDING myself and my limited, if not cryptic, input here, partially due to my bad vision and other limitations. I try to convey as much as I can, without upsetting my business partners, because I find the subject of audio very interesting and I want to show that it isn't really as dull as it often seems to be.
To me, an amateur, is someone who does NOT design audio electronics for a living. Is that such an insult?
I have been an amateur ballet dancer, folk guitarist, automobile mechanic, and tape recordist, for example. I was pretty good at it all, but never a professional. When I mention that something is too difficult, well I don't think that I could design a SACD recorder, yet, I converse with people who are in that position, on occasion, and don't worry about it.
When I warn someone off, it is to save them the trouble of trying and probably failing. In the latest case with this new amp, it is so complex as a system, that oscillation is difficult to control, except at the board level, and working closely with the board layout expert as well. At least this is what I am told. I would not lightly take it all on, myself, so why would I expose anyone else to it?