John Curl's Blowtorch preamplifier part II

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I can forgive you easily John, because our definitions of "Useful" sometimes are very different. I would not call it useful to forget about optimization, and start learning some "no compromise" approach. I don't believe in "No compromise". Such a category does not exist in the real world. What does exist, is a real engineering that is based on optimization. I am an engineer; I have a diploma; and I learned to optimize all that time I spent before I graduated, and still learn after I did.
 
I have 4 commercial power amplifier designs being sold, at present. None are 'perfect', or 'no compromise' but as good as I can do within the price guidelines. I consider this to be 'optimization' at its best. What you are referring to, I have no idea.
 
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Hi John,
Okay, right off the bat, and correct me if I'm wrong, but you are not an engineer either. Your ability to insult everyone here but those you look up to is legendary, and extremely insulting. I do concentrate on service because I enjoy doing that. However, I also design entire applications and engineer design changes in order to solve problems with a product. Please, stop insulting my intelligence, and the intelligence of the many members who are far more capable that you know. Throughout my career in service, people in the engineering departments of large,commercial audio products have commented that I'm more of an engineering technician than a simple technician. Nice to hear on occasion, and it means someone has been listening. I don't know what your involvement is when a project is designed. I do know it's a group effort in commercial audio. One guy in a garage efforts simply do not cover enough design ground to make that commercially successful product - as much as those single designers like to say happens. It's application engineers from the major parts companies who do make creating a product possible. Guys like Scott and Walt Jung, plus others too numerous to mention.

I have had to sign NDAs and other disclosure agreements before, so I am very familiar what you can say or not say openly. That discussion you bring up is terribly boring to the rest of us. That's why I said that you shouldn't even go there if you are not able to provide more general information. You will not even comment on the similarity to the various Carver designs in comparison to what you are doing. Give me a break John! Are you learning here, fishing for ideas from other members that you can package as your own secrets? Heck, it's beginning to look that way to me.

Copied products. That is such a complete cop out John! You build something commercially and it will be reverse engineered, and not by a hobbyist here either. The amount of copies that come from sites such as this is minuscule. Remember what I told you earlier. A schematic gives you basic knowledge only. You do not get component placement. You do not get component types, and you certainly do not get how parts are graded or selected. This entire argument is nothing more than a smoke screen. You want to know how to copy a product John? Buy one and take it apart after measuring all performance parameters! Good lord John, trying to create a copy from the schematic, and PCB info, is the hard way to go. It's far more expensive than taking one apart. So, let's bury that one, it's a red herring and you are aware of that.

So let's put all that fear mongering to rest. You can either talk about products in general terms as you say your intent is, or it's a secret and you can't discuss it. I have put several basic questions to you, all relating to product technologies out on the market already. Sorry, but those you are able to talk about. What I see is a person teasing other people about some design idea superior to all others in it's class, then saying "but I can't talk about it". You are further ahead by not even mentioning it to begin with. Allow me to use Nelson as an example here, he's an excellent example. He will release technical information willingly, and teach others the application and performance considerations. However, he will stop dead on a commercial product and merely state that it's a commercial design. Not once does he tease and he does offer real information that other people can use. His kit products are revealed completely, board layouts and all. See the difference here John? And guess what? He's not paid either, fella. And while we are on the paid service topic, who on earth supplies this site free of charge? Who are the people who attempt to keep it running smoothly? John, I do not get paid. The other moderators from around the globe do not get paid. My technical advice and assistance is given freely as well, I don't get paid for that. There are multitudes of other members who do provide technical services that are chargeable - they have value! They do not get paid. Stop whining about how valuable your services are, I normally charge for my services as well. Maybe not as much as you, but most people here can provide chargeable services of value. We all all in debt to everyone else who provide their services in order to teach and help others.

I'm not saying you should give your commercial property away John. However, you sure as heck can help and provide straight forward, truthful information when circumstances allow. You can do this without insulting the members here, or making them feel small.

So, that's my gripe with your attitude and the realities of the statements you hide behind.

-Chris
 
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Okay, now on to some of your comments John.

Unfortunately, my associates tell me to shut up about it, when they found out that I have said anything about this design.
I guess you can't be trusted then?
You're not a stupid man John, you're either a junior partner with no experience in the audio business (obviously not true), or you are trying to generate interest in a new product or design. Your partners are possibly very nervous about what you're going to say, in which case they will not deal with you again because you really can't control yourself. I don't find it very difficult to participate in a project without talking about it. I'm sure that goes for many other members here as well.
They work for powerful companies who could get around just about any patent that they wanted to. This is WHY I don't produce patent numbers, even when demanded, on this website. Does this really surprise or disappoint anyone?
I skipped the incredible insults you leveled. Grow up John, and talk about things you truly know about.
So, once you apply for a patent, you are afforded protection. Patents are searchable, they are a matter of public record. Your competition is adept at finding out everything you disclose. If a patent contains too much information, the jig is already up where you have to worry. You can't give out patent numbers because they a) don't exist, or b) someone else's patent and not your idea. Let's be truthful here. Releasing patent numbers is exactly what you do. Getting around patents is also normal business, and the reason a patent lawyer prepares the patent to begin with. Fighting patent infringements is what your partners will do John, you will not. Patents are only fought over when there is enough monetary gain to be had. John, this is only audio, it isn't an industrial process or test and measurement technique. What Scott knows is worth far more than what an audio designer protects. It's all a question of money, and audio sales are just a blip on that meter. Scott, sorry for using you as an example often.
Since this Blowtorch thread has existed, how many people have reverse engineered the design JUST with the pictured that Bob Crump took and published many years ago? One, ten, one hundred?
Who cares???
John, how many did you sell? How many other brands did you consult for using similar concepts? Adcom for one, as a popular "mid-fi" brand in your book. John, the money is not there for one. It's an old model for two and the construction detail is of greater importance than the schematic. Stop wringing your hands over something you are not selling any more, and was produced in tiny numbers. I got news for you John, every commercial design will be examined. Most of the time, it's only the understanding that is the prize. Once someone figures this out, the financial plan precludes mass production of the copy - here anyway. There is no control over what happens in countries where labour is cheap, so don't worry about stuff you can't change. That's free advice from a business owner and project manager (me). :)
We are going to MAKE SURE that that simple path is blocked with this new design, in future.
Why worry so much. The world will continue turning without your design. It's only audio and you are selling your name. The only real reason to hide the technology is to hide the fact you are using someone else's patented idea. A copy. I don't know what is true, but I do know that you have normal protections and that in other countries, your product will be reverse engineered no matter what you do. You're kidding yourself, aren't you? That horse you're on died a long time ago. It smells to high heaven these days.
If you want an actual design from my associates or me, please contact us professionally, and pay the rate.
Hmmm, does that mean you are going to pay anyone here whose idea you use? Nah, you'll just use it without giving credit. Same goes for any other idea you find. Human nature, especially people with this outlook. Aren't we lucky that many other people here don't think this way?
I know why you don't use integrated circuits (like op amps). The manufacturer releases all the information to the world on these parts. Application engineers suggest circuits that are worth real money, and you can't allow that to happen! If it's an op amp, the uses are out in the wild by now. You can only use these in so many ways you know. :D
My interest here has been to give GENERAL INFORMATION, at significant cost in frustration to me, that I think that all designers should come to know.
No one else's time is worth anything here John? I know mine is, Nelson Pass' is, Scott Wurcer's certainly is too. Anatoliy also, ah heck! Too many to name.
Significant frustration? John, you frustrate me with your attitude, and I pay significantly in pain in order to post here. I can promise you that if you stop playing games, your frustration will subside. In fact, you will find the experiences in the world far more enjoyable. Do you have any clue as to how many other members are dealing with great pain and injuries? There are a great many who can't do much else, so they help people out. It gives them meaning, I can say that from experience.

Even before I was injured, I enjoyed giving of my time to help members (and many others) here. I teach others what I can, as I can. Some I do here at my home. The rest of my time is given to a couple repairs I can charge for, and great pain waiting for the day to end so I can do it all over again the next day. I know you are not very well John, and I do wish you the best with that. In fact, I always have. It's the feeling of entitlement that you seem to have coupled with the constant put-downs of other people's abilities. John, you do not have the right to do that. That is what motivates me to speak up.

That's enough for me. Pills are working finally and I can get some sleep. One thing you have to think about John is how much help you do give to people, explanations of the craft to assist others. Otherwise, you are not wasting your time. You are wasting everyone else's time looking for an "attaboy". Try to consider your value to others from another viewpoint.

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

...

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Let me try to set things straight. I am not here to either 'tease' or 'insult' people, even though many find me to be an easy target for 'teasing' or 'insulting'.
Now what about the definition: design engineer?
Several of the best design engineers that I have ever known and worked with did NOT have a college degree in any subject. It can also be learned by certain people by innate ability and heavy experience.
First, how did I become a design engineer? (at least in my own opinion)
1962, first real job as technician UL labs, 1 year, worked under real engineers, trained new engineers on specific tasks. 2 years of EE training completed.
1964, first electronic job, as technician, lasted only one month, forgot to do something, in fact to charge a battery, and was let go.
1965, first hi fi repair job, as technician, 1 year, repaired hi fi equipment, and sold and installed first class hi fi. (refraining from 'name dropping' of component brands)
1966 first professional job, as 'designer' or engineering interface. Friden Inc
Worked with experienced engineers (as good as they get) as an interfacer between them and the techs. I directed the techs, and made their circuits that they wired, work. The engineers directed me, and gave me the schematics to make work. (still not an engineer) 1 year
1967 AMPEX, started as jr engineer, instrumentation, audio, and research. 2 1/2 years with almost daily visits to engineering library, night courses, etc.
By the time I left AMPEX, I was a design engineer, as I had been put in charge of several design projects and had completed them. By this time, 40 years ago, I had independently invented the comp differential input stage, completed 3 separate servo designs and made a working 2000W power amp with comp diff, 4 quadrant symmetry, current output, using both + and - feedback loops, and 50 A output capability for Ampex research.
I don't care if someone has an engineering degree, what I care about is if they understand what engineers are taught in class, at least for the subject being discussed. Bob Cordell and Scott Wurcer, and even Wavebourn, meet this criterion. Some others don't appear to.
When someone confronts me with something, I sometimes react by reminding them that they are not an engineer. It has nothing to do with the degree, but the effective background they have to effectively address the issue at hand.
It would be like me going up the Professor R.G. Meyer, and saying that I have the experience and background of a professor, and that he and I should spend hours, debating each other. It so happens that he is, in fact, slightly younger than me, and I was a paid consultant to him once, (on low noise design), but that doesn't make me a full professor. So if I went up to his office, which I presume is still within walking distance of my apartment, I should be able to challenge him with impunity. Why not? I have just as much experience as he does! And I know a few things he doesn't know, as well. Do you see the 'problem' with this?
Anatech, I am NOT after you, in any way. However, I will defend myself, when necessary on this thread. I like spirited debate. It is easier to convey different opinions this way, but it doesn't have to be thought of as 'attacking' or 'bragging', just because you get upset by it.
My goal here has been to give new direction to audio design from whatever I have learned in the last 40+ years, little more than that. I am here to help AND learn from others, on occasion. The 'debate' is just part of the process, and sometimes I wonder if it is worth it, myself. Time will tell.
 
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.
 
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
 
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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.

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

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):)
 
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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
 
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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.
 
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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 : http://www.diyaudio.com/forums/showthread.php?t=149324&page=4
For this , many are thankful. He did not have to divulge any "secrets" :eek: ,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
 
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?
 
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