Maybe rather than suggesting you invest some time in reading all of part one and part two threads, as I'm sure someone will, you might find these interesting?
Amp/Preamp Asylum: REVIEW: CTC Blowtorch preamp Preamplifier (SS) by Mike Currie
48,000???
John has said repeatedly that you can't build it, it is beyond the ability of amateurs to do the requisite parts acquisition and matching. I half-agree with him- I wouldn't tackle it unless I had built quite a few other similar projects from scratch and am perfectly comfortable with how to match FETs. If you can't figure out how to build it from the earlier schematics and discussion, it's probably not the product for you.
On the bright side, it's very easy for an amateur to build a preamp with the same sonic performance. Just not that particular circuit.
I have the background. Well 30 years ago at least.
I was just trying to get at the meat of the matter. I did invest a couple of hours reading posts but 48 thousand some odd would be measured in terms of days...several of them. I read the reviews that flg posted ( by the way, Thank You flg ) and what is not to be impressed with. The problem is I ran across about five different schematics in the posts....for the same preamp. Just as an example of why this is so confusing, most of the PASS DIY projects have minor nuances but have largely the same topology. I am not in any way criticizing the experimental nature of DIY'ers, quite to the contrary, I believe a good many designers and engineers lurk herin to get ideas for their commercial projects all to the betterment of hifi.
Anyway, I was trying to enquire if there was a consensus and if anyone had built the preamp that is in the reviews.
I see this is a commercially available preamp and if all this is an unauthorized knockoff I won't even attempt it...I respect the designers intellectual property. BUY, it is featured here in a DIY site, with the designer's comments and ostensibly - blessings; and it may very well be the longest in the history of this site.
I was hoping for some enlightenment. Is there a consensus for a buildable preamp and does it have a schematic....tested devices, etc?
If SY can do what he boasts, then it will be wonderful for all of us! Yes, let us save time, energy, money, weight, and some of the Earth's resources, by doing it a different way.
However, you have to be HAPPY with the results in OPEN LISTENING as well as it will give double blind testing nulls compared with a CTC Blowtorch.
This is what I can't do yet. I can't just put a few parts together, use just any topology, and part type, and get the kind of WORKING PERFORMANCE that I get from the CTC Blowtorch.
SY only offers double-blind nulls, that is the problem. Almost any component will meet his goals.
However, you have to be HAPPY with the results in OPEN LISTENING as well as it will give double blind testing nulls compared with a CTC Blowtorch.
This is what I can't do yet. I can't just put a few parts together, use just any topology, and part type, and get the kind of WORKING PERFORMANCE that I get from the CTC Blowtorch.
SY only offers double-blind nulls, that is the problem. Almost any component will meet his goals.
If you follow the world of fashion audio you will see that it has moved on. If you bothered to search you can find lukewarm reviews of the CTC BT compared to someone elses latest statement. Not that I care only observing.
The JC-80 schematic has been published in the thread with John's blessing. If you substitute paralleled matched 2SK170's and 2SJ74's for the FET's you will get a pretty nice sounding preamp. The Fairchild verticle MOSFETs will need a substitute but that should be do-able. You won't have Bear's magic silver wire or the chassis machined out of a billet of aircraft grade aluminum but if you think that is what matters I guess you will have to give up.
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And then you run away from the challenge of having our respective designs judged by sound alone. Any time you're ready, I am. You can pick the listener(s) and system, source material, switching times. I only insist on judgment by sound alone, not names, appearance, expectations, nonauditory cuing...
I do strongly recommend that people try to make the JC-80 line amp, rather than the CTC Blowtorch. You can even get reasonable circuit boards and parts over the internet.
Now what do I think of the JC-80? It served me long and well from about 1982-1992, before a firestorm took it. I have another JC-80, in my back closet, and one on my workbench, being checked out. It is a darn good design, made of first class parts. It is NOT a CTC Blowtorch, however, and over the years, I came to know its 'signature' and why I don't use it, today. The CTC as almost NO 'signature'.
To be honest: To pass SY's test, all you have to have is something well behaving, with a good flat frequency response and relatively low distortion and noise. Almost any IC will pass SY's test, so if that is your criterion, then just just a good IC, and save yourself the time and trouble.
Now what do I think of the JC-80? It served me long and well from about 1982-1992, before a firestorm took it. I have another JC-80, in my back closet, and one on my workbench, being checked out. It is a darn good design, made of first class parts. It is NOT a CTC Blowtorch, however, and over the years, I came to know its 'signature' and why I don't use it, today. The CTC as almost NO 'signature'.
To be honest: To pass SY's test, all you have to have is something well behaving, with a good flat frequency response and relatively low distortion and noise. Almost any IC will pass SY's test, so if that is your criterion, then just just a good IC, and save yourself the time and trouble.
The other remark that JC made: in addition to the difficulty of obtaining the parts, he has a (well-justified!) concern that he will be forced into the role of supporting various people's efforts to build the thing. That's a major burden, and the man still has a life.
One development that may be helpful since the CTC was in "currency": the existence of surface-mount components allows the physical size of electronics to be a good deal smaller. Although this as well means you won't have as large a selection of the resistors for example, if you do a good layout the loop areas for intercepting magnetic fields will be much smaller. There are also some low-loss board materials available today that were not then. And making things smaller means the hogged-out billet of aluminum gets a little cheaper --- if you are trying to preserve that aspect of the beast.
Will all of this translate into discernibly better audio? Will it have been worth the effort?
A good question
My test procedure is LONG TERM LISTENING TESTS. Virtually any preamp that I have made, sounds OK, at first, and for a short period of time. As the days, weeks, and months go by, the 'signature' of the component becomes detectable and finally somewhat annoying. In 10 years, I have NOT found a 'signature' of the CTC Blowtorch, and that is why it is my REFERENCE in my hi fi setup. Phono cartridges, SACD players, and even amplifiers can come and go, but the Blowtorch always stays.
John, I agree with you, you actually do make the task easier, since unlike others, your electronics do an excellent job of being quiet, having flat frequency response, low distortion, low source impedance, and good stability. I would never offer such a challenge to someone who is building effects boxes instead of true high fidelity, it's much harder to try to duplicate that sound.
Bcarso, surface mount will not help much. We use it now for our servos in the Constellation Audio products, and it just presents an added headache.
The size of the CTC Blowtorch was set for ANY custom modifications that might be put inside. For example, true balanced input was offered at extra cost. One or two units were made that way, BUT the switches get twice as long, TKD pots too, and more expensive.
When we did not utilize this space, it looks empty, but that can't be all bad, since air is an excellent insulator, and space reduces Xtalk between sources.
The size of the CTC Blowtorch was set for ANY custom modifications that might be put inside. For example, true balanced input was offered at extra cost. One or two units were made that way, BUT the switches get twice as long, TKD pots too, and more expensive.
When we did not utilize this space, it looks empty, but that can't be all bad, since air is an excellent insulator, and space reduces Xtalk between sources.
Gentlemen...Gentlemen...Gentlemen:
Please...with all due respect...examine your zippers...your egos are getting out.
What I proposed to SY (picking up on a challenge made by JAM that I interpreted him as accepting) would be a great thing for many of us who would appreciate the opportunity. This is how learning takes place. A group project led by you worthy sages; that sounds patronizing I'm sure but probaly well justified. In my case it would be like being in lab many years ago.
So how about it....Sy, would you be willing to moderate this?
Can you make a set of rules and parameters?
Would you be willing to let someone come up with a "class" of us who want to learn by doing?
Mr. Curl could participate to the extent he would want, and he honored in the process.
Please...with all due respect...examine your zippers...your egos are getting out.
What I proposed to SY (picking up on a challenge made by JAM that I interpreted him as accepting) would be a great thing for many of us who would appreciate the opportunity. This is how learning takes place. A group project led by you worthy sages; that sounds patronizing I'm sure but probaly well justified. In my case it would be like being in lab many years ago.
So how about it....Sy, would you be willing to moderate this?
Can you make a set of rules and parameters?
Would you be willing to let someone come up with a "class" of us who want to learn by doing?
Mr. Curl could participate to the extent he would want, and he honored in the process.
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