I can't think why it would need to be particularly bad in-band to give terrible results well out of band. Take an NE5534 - according to Samuel Groner's measurements its transfer non-linearity (that's input stage tanh-related) is around 0.1% at 20kHz with 60dB noise gain. It's rising at 20dB/decade so at 20MHz we'd expect 100% non-linearity in this configuration - fairly dire wouldn't you say? Its in-band IMD is nevertheless quite respectable enough to be employed in plenty of professional audio products.
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Joachim, I didn't mean anything PERSONALLY. What I meant was that IF you did NOT know me, and you were given the broken CTC Blowtorch, you may NOT have realized that the V jfets HAVE TO BE at least 15ma or MORE Idss, for the design to work properly. Since the input devices were blown out, HOW would you be able to know this?
Steve, you are showing a certain lack of business experience. Have you ever worked with anyone else? MY BUSINESS PARTNER made the mistake. We shared the cost of repair. However, it was handled on my end, so I paid the bills. When it comes to trusting customers, perhaps you need a little more experience, if something like this has never happened to you. But then, do you do overseas shipments on a regular basis with components that cost many thousands of dollars? Your Monday morning quarterbacking is not appreciated.
Joachim, I think that we have a language difficulty. I do NOT publish the CTC Blowtorch schematic. Before the broken Blowtorch was returned for repair, JJ did mention that he had 'someone' in Europe who might be able to fix it. Was that YOU? Whether it was or was not YOU, it would have been difficult for the engineer or technician to KNOW to use the RIGHT parts, because there is not an INSTRUCTION saying that only the most high Idss parts must be used.
NOW, even if you had used high Idss 2sk170 and 2sj74 devices, the repair would have been obvious and potentially lowered the resale value of the unit. Even so, IF you did not MATCH the devices to within 10mV or so, it is quite possible that the servos would go out of RANGE, and cause further problems. Third, I don't like to share my SOTA schematics with anybody, so it would have been best for me to fix it, in any case, which I did. Fourth, if you repaired it without my permission, the warranty would be voided.
Now, this is NOT personal, just based on practical experience.
NOW, even if you had used high Idss 2sk170 and 2sj74 devices, the repair would have been obvious and potentially lowered the resale value of the unit. Even so, IF you did not MATCH the devices to within 10mV or so, it is quite possible that the servos would go out of RANGE, and cause further problems. Third, I don't like to share my SOTA schematics with anybody, so it would have been best for me to fix it, in any case, which I did. Fourth, if you repaired it without my permission, the warranty would be voided.
Now, this is NOT personal, just based on practical experience.
Mr Curl,
how many of the total did you assemble, and how many did Mr Crump ?
You did not anticipate warranty issues without any formal means of QC during the assembly (intentionally or out of necessity) ?
A very expensive piece of equipment made so that only one person in the world knows how to fix it and he is in only one place. And the parts are unavailable even if someone actually correctly figured out what they are. If he can't or won't fix it and it fails, what you have is a very expensive little scrap heap. All the more reason to avoid it and other such equipment like the plague. This is just one pitfall of buying highly customized equipment made by a small operation with very limited production. It's a gamble that usually doesn't pay off in the long run. Even if it's a wonder of the world, it only remains that way until that unpredictable moment when it stops working and then there may be nothing you can do about it. HH Scott still in business?
Remember, this is a fashion item and performance art. You're buying prestige, status, and the story wrapped around it. One can get just as good sonic performance (questions of subjective impressions from owning a one-of-a-kind piece that costs as much as a house aside) from the very well-designed and built products that John does for Parasound.
Joachim, don't take anything John says personally- whether you're dumber or smarter than him, part of the mystique is that he'll act as if you're a drooling idiot unless you're in the "club." The brighter folks here are perfectly aware that intelligent and experienced designers like you would be able to somehow battle their way through a repair of someone else's straightforward design.
Value is in the Mind of the Investor
To each their own, within budgetary constraints. This same logic can be applied to one-of-a-kind cars, but that does not stop people with the resources from buying them either. Put yourself in the shoes of someone who doesn't have the knowledge of audio engineering as you obviously do. Their choices are limited to that which they can buy. If they are well off, and want a piece of equipment that, because of any number of reasons: performance, investment potential, degree of finish, heft, (you fill in the blank), they could do a LOT worse than to get a Blowtorch.
If your budget cannot withstand getting a Blowtorch, even if you did want it, then it would be approporiate to avoid it. I could never consider spending that kind of money on a preamp, but if I could, I would consider it due to it's performance and 'value' based on John Curl's engineering. His designs retain value with those who can afford them, just like a one-of-a-kind Ferarri.
I have fun messing around with equipment, and if I bought a Blowtorch, I would have to leave it alone, because it is an investment and changing it would lower it's value. This is just another reason I can't own one. Just as putting hood scoops and neon ground effects on a one-of-a-kind Ferarri would lower it's worth in the open market. You keep it stock to retain the investment value.
I wish I knew enough about design to have come up with a successful piece of equipment, never mind many of them. Many of you are in the same boat as John, having designed successful equipment. I look forward to more actual discussion of your circuit ideas.
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill
www.wxyc.org
1st on the Internet
To each their own, within budgetary constraints. This same logic can be applied to one-of-a-kind cars, but that does not stop people with the resources from buying them either. Put yourself in the shoes of someone who doesn't have the knowledge of audio engineering as you obviously do. Their choices are limited to that which they can buy. If they are well off, and want a piece of equipment that, because of any number of reasons: performance, investment potential, degree of finish, heft, (you fill in the blank), they could do a LOT worse than to get a Blowtorch.
If your budget cannot withstand getting a Blowtorch, even if you did want it, then it would be approporiate to avoid it. I could never consider spending that kind of money on a preamp, but if I could, I would consider it due to it's performance and 'value' based on John Curl's engineering. His designs retain value with those who can afford them, just like a one-of-a-kind Ferarri.
I have fun messing around with equipment, and if I bought a Blowtorch, I would have to leave it alone, because it is an investment and changing it would lower it's value. This is just another reason I can't own one. Just as putting hood scoops and neon ground effects on a one-of-a-kind Ferarri would lower it's worth in the open market. You keep it stock to retain the investment value.
I wish I knew enough about design to have come up with a successful piece of equipment, never mind many of them. Many of you are in the same boat as John, having designed successful equipment. I look forward to more actual discussion of your circuit ideas.
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill
www.wxyc.org
1st on the Internet
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It seems to me "fashion statement" is the best descriptor I can think of to define what this and other high end audio is about. Performance art seems not merely far fetched but entirely inappropriate. So far I have yet to see any piece of high end audio equipment justify itself by some unique engineering principle that warrants its prestige. (For example I read most of Passes' paper and found it seriously flawed like Cheever's but I'm not even going to waste my time discussing it, it seems too trivial to bother with.) What I've tried to glean from JC's postings is whether or not there is a coherent engineering concept embodied in his approach that justifies his products' high prices or explains his claimed superiority that is backed up by something more concrete than testimonials. He says he will not publish the schematic which I understand and accept but as far as I can tell, the only thing that drove the design is an approach that says I tried the kind of things I like, I like this best, so it must be best, and you can take my word for it and buy it if you like it too and can afford it or ignore it. I'm sure he has magazine articles reviewing his products with stunning accolades just like many of them do. I once chided Peter Breunniger on another board before he left Stereophile Magazine for TAS about all of those articles proclaiming "the greatest speaker in the world of the month." IMO that's how all of them are. As the new ones come along, the old ones fall by the wayside like so much used junk, yesterday's whiz-bang world beater having been consigned by this niche market to obsolete in a realm of technology that when seen clearly in perspective never seems to go anywhere. It's a point of view those who make money in this market don't ever want to hear and would like to suppress if they can, especially when it comes from someone with training. But if you talk to people who install professional (commercial) sound systems for a living where cost is not often the only major consideration, most of them will just shake their heads and laugh about it.
I think I used a term that you misunderstood, sorry. Performance art: think Marguerite Duras, for example. It isn't just the movie, it's the whole package.
Commercial sound is a totally different proposition than high end home audio. It's misleading, IMO, to use the metrics of one to judge the other.
Commercial sound is a totally different proposition than high end home audio. It's misleading, IMO, to use the metrics of one to judge the other.
In summary, most here have a 'personality' issue with the CTC Blowtorch and me.
IF any of you watch extra channels on cable here in the USA, you will find programs on 'How they do it', that is how they make specific items. Particularly fascinating, just this week, was how they make fine automobiles like Mercedes and Bentley.
IF you want to understand what we attempted to do, when making the CTC Blowtorch, then you should watch these programs. Then you can hoot, holler, and criticize the VERY IDEA of one-off, ultra high quality. Maybe you could notify the quality auto manufacturers of your opinion as well.
In any case, Joachim, of course YOU and many others could make the CTC Blowtorch work in time. But working blind, without 100's of 'obsolete' (not made anymore) parts to chose from, you would 'compromise' the design, just by not having all the information available to you.
I have had the same problem with the Vendetta Research SCP-2 phono stage. I am the only person who has the parts and knowledge to fix it. Yet, it remains a highly sought out item, just try to find and buy one! STILL, quoted in the magazines often as one of the finest phono stages ever made.
Why just yesterday some guy e-mailed me about the 'operating manual' for the VENDETTA RESEARCH SCP-1, a design I have not made or sold in over 20 years. Yet, I called him up and helped him with his problem. I directed him to the vendettaresearch.com website where the instruction sheet for the SCP-2 is online, a site paid for by ME, and told him how to get the important info from it. This is what I do for follow-up.
In truth, who cares what people who do NOT do audio for a living think about something outside their area of interest and concern? I would not expect ANY of you to buy a CTC Blowtorch. Why would you? It is massive, expensive, clunky, and hard to get fixed if it EVER breaks. And so it goes.
IF any of you watch extra channels on cable here in the USA, you will find programs on 'How they do it', that is how they make specific items. Particularly fascinating, just this week, was how they make fine automobiles like Mercedes and Bentley.
IF you want to understand what we attempted to do, when making the CTC Blowtorch, then you should watch these programs. Then you can hoot, holler, and criticize the VERY IDEA of one-off, ultra high quality. Maybe you could notify the quality auto manufacturers of your opinion as well.
In any case, Joachim, of course YOU and many others could make the CTC Blowtorch work in time. But working blind, without 100's of 'obsolete' (not made anymore) parts to chose from, you would 'compromise' the design, just by not having all the information available to you.
I have had the same problem with the Vendetta Research SCP-2 phono stage. I am the only person who has the parts and knowledge to fix it. Yet, it remains a highly sought out item, just try to find and buy one! STILL, quoted in the magazines often as one of the finest phono stages ever made.
Why just yesterday some guy e-mailed me about the 'operating manual' for the VENDETTA RESEARCH SCP-1, a design I have not made or sold in over 20 years. Yet, I called him up and helped him with his problem. I directed him to the vendettaresearch.com website where the instruction sheet for the SCP-2 is online, a site paid for by ME, and told him how to get the important info from it. This is what I do for follow-up.
In truth, who cares what people who do NOT do audio for a living think about something outside their area of interest and concern? I would not expect ANY of you to buy a CTC Blowtorch. Why would you? It is massive, expensive, clunky, and hard to get fixed if it EVER breaks. And so it goes.
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