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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 10th April 2013, 03:32 AM   #37901
bcarso is offline bcarso  United States
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OK that sounds harsh. Let me put it this way: suppose I offered the complete drawings for construction of a 1929 L-29 Cord Phaeton. How helpful would that be if one wished to build one of them?
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Old 10th April 2013, 03:38 AM   #37902
scott wurcer is offline scott wurcer  United States
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Quote:
Originally Posted by ridikas View Post
Why would it do no good?
For starters you don't have Bob Crump, or Bear's directional silver wire. Read the thread. it's clear the BT is not a "schematic".
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Old 10th April 2013, 03:54 AM   #37903
fas42 is offline fas42  Australia
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Or, at this level of performance it becomes an "everything matters" issue. Yes, glib, but it doesn't stop it being true ..
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Old 10th April 2013, 10:24 AM   #37904
godfrey is offline godfrey  South Africa
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Quote:
Originally Posted by ridikas View Post
Why would it do no good?
Snarky comments aside...

If you try to copy the Blowtorch, you'll run into a couple of problems from a purely practical point of view:

Firstly, it uses components that are no longer in production and are extremely difficult (if not impossible) to get hold of today.

Secondly, the schematic you copy will only show you component values and part numbers. It won't tell you e.g. how to measure, match and select individual components.

So even if you find the "right" parts and build a clone that looks identical to the original in every detail down to component values, PCB layout and materials, it still won't work properly or perform the same as the original.

(I'd prefer to stay out of the arguments about whether different types of resistor, capacitor and wire sound different etc, so just pointing out a couple of practical non-contentious issues)
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Old 10th April 2013, 01:04 PM   #37905
PMA is offline PMA  Europe
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John Curl's Blowtorch preamplifier part II
Quote:
So even if you find the "right" parts and build a clone that looks identical to the original in every detail down to component values, PCB layout and materials, it still won't work properly or perform the same as the original.
Maybe. Or there is still a space for improvements. How about discussing possible improvements of the original CTC Blowtorch?
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Old 10th April 2013, 01:19 PM   #37906
marce is offline marce  United Kingdom
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John Curl's Blowtorch preamplifier part II
Can we have a PCB layout to admire, then, John Gerbers will do (in fact prefferable)

Last edited by marce; 10th April 2013 at 01:21 PM.
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Old 10th April 2013, 02:20 PM   #37907
elektroj is offline elektroj  Europe
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Originally Posted by marce View Post
Can we have a PCB layout to admire, then, John Gerbers will do (in fact prefferable)
To quote one colourful character from the Russian satirical literature of the 1920s:

"Perhaps you'd also like the key to the apartment where the money is stashed?"

:-D
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Old 10th April 2013, 02:34 PM   #37908
marce is offline marce  United Kingdom
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John Curl's Blowtorch preamplifier part II
Yes please.
Please note these Gerbers would not be used in any way to reverse engineer a product, I would not read them into CAM350, select and create components, extract nets then export a CADIF or similar format that I could use to check a schematic against
Actually this would be a purely academic exercise for my own enjoyment, i like to study PCB layouts...(very sad person).
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Old 10th April 2013, 02:38 PM   #37909
john curl is offline john curl  United States
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When it comes to building the exact CTC Blowtorch, that is almost impossible, but perhaps many of you can do better. PMA certainly thinks so. It is just like making a 'successful' automobile model, maybe subjectively better than many of its 'successors'. It is not the Gerber files or blueprints that are going to make a difference, but the 'ideas' and 'concepts' put into the 'successful model' to be hopefully passed on to the next generation of auto builders. Many of the 'ideals' that we put into the Blowtorch are snarked at by Scott, SY and others, but to me they are the ESSENCE of what makes the design successful, NOT JUST THE SCHEMATIC. And the simplified schematic has been put forth here, by others, with my encouragement, years ago, and even simulated by PMA, who did an excellent job, by the way.
Once again, much of the success with by BEST designs is in the 'physics' rather than the engineering, or just the schematic. What makes me controversial here is that I try to 'give away' the 'secret' of my success, and typical engineers don't believe me. So be it.
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Old 10th April 2013, 02:47 PM   #37910
john curl is offline john curl  United States
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Now, in order to complete my original 'promise' to tell everyone the 'secret' to my success as a phonostage designer:
I have found that to reduce the annoyance of ticks on a record, that a gain stage that is very fast, very linear and with very high dynamic headroom, is necessary, in order to minimize the duration of the 'ticks' and mistracking artifacts (that often happen with many recordings and MC cartridges). This necessitates a two gain block phono stage, rather than a single one, like the original Levinson JC-2. I did not invent this approach, it was first done by HK in germanium, and later by Electrocompaniet, following the HK approach. I have just taken it a bit further, with some success, I might add.
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