John Curl's Blowtorch preamplifier part II - Page 508 - diyAudio
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Old 22nd July 2010, 11:18 PM   #5071
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Quote:
Originally Posted by bear View Post
could you please be more specific - I read 3-4 pages and found no reference to the comparison between tubes and anything solid state...
How 'bout this?

There are some decided engineering advantages to using tubes as the voltage amplification devices. At the top of the list are high linearity and overload immunity. My old unit was a hybrid using FETs in cascode with tubes (not unlike Allen Wright's excellent designs, though not claiming the same performance), and while it was good enough to live with for a quarter century, I still feel that its performance can be surpassed with an all-tube amplification lineup. Of course, I will still not hesitate to use semiconductors where they do best, i.e., for providing power, increasing power supply immunity, and controlling operating points- for constant voltages and constant currents, silicon is the way to go.

From the Requirements page of His Masters Noise.

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Old 22nd July 2010, 11:18 PM   #5072
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Originally Posted by Joshua_G View Post
Who did you ask?
I'm pretty sure he was asking SY.

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Old 23rd July 2010, 12:13 AM   #5073
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Perhaps SY ought to start a thread on his design concepts??
Serious.

I posted when there were no other responses, but somehow now there are a bunch... weird... heh.

I guess everyone has their own design philosophy, mine is somewhat different than SY's or Curl's or anyone else's, but is not fixed.

Not sure I see a genuine need for gain in a line stage as things now stand with the technology... so I don't use one. That obviates 99% of what SY is claiming as an advantage? Surely no active device is more linear than any active device??

In a phono stage it is virtually impossible to get a tube to be as low in noise as a good bunch of jfets or the right bipolars... so the cascode looks good to me. Dunno, pick ur poison(s)?

Or maybe you prefer some of those new dandy ultra super maximal duper low distortion opamps for these applications? They do measure low, right? Impossibly so... how could they be bad??

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Old 23rd July 2010, 12:15 AM   #5074
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Quote:
Originally Posted by SY View Post
The Blowtorch is analogous to
A better analogy is an Audemars Piquet Offshore.
Virtually indestructable and not 10 minutes per year off like some other chick chasers, looks good and pricey as H.
I hate it when a watch is really off every couple of months, or breaks down too frequently, no Omega or Rolex hype ever again.

I got round to auditing Mr Hansen's kx-r some time ago, brought along a <<0.004% preamp, didn't sound the same as a decent opamp pre to me.
If some cash burner fool would flogg the kx-r for a go-dutch rate maybe i could score some babes after all, i'm ugly as H too.
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Old 23rd July 2010, 12:31 AM   #5075
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Quote:
Originally Posted by bear View Post
Fill in the blanks - work with the general concept. It's the concept that counts.
SY has the concept, I can only guess. But this statement of his strongly parallels his remarks in the now closed cable audibility thread where his weasel phrase was 'non-mundane differences'. Requests to pin down these phrases (as might be required were we to to do real science i.e. falsifying his hypothesis) have proved fruitless
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Old 23rd July 2010, 12:46 AM   #5076
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Quote:
Originally Posted by Rod Coleman View Post
Rigid Scientific thinking, at its worst, ends up with the kind of designs of D. Self, who only discusses distortion measurement
This is obviously false - I've read his 5th edition book and whilst he is excessively (IMO) strong on distortion he does cover other aspects of amplifier measurements - such as slew rate and noise just to give two examples.

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and omits listening tests completely.
I agree, this is the primary weakness of his book. But then he gives no PCB layouts either - schematics can't be listened to. The second weakness of his book is citing Randi.

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Attempts to build amps based on his principles often end in complete disappointment, unsurprisingly.
I've designed and built a few amps on his principles since he first expounded on them in E&WW and have never suffered complete disappointment. So do you have any examples to offer where the disappointment can be laid at the feet of Mr. Self's principles, rather than say sheer incompetence?
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Old 23rd July 2010, 01:31 AM   #5077
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I agree, Rod.
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Old 23rd July 2010, 01:58 AM   #5078
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Quote:
Originally Posted by Joshua_G View Post
My questions are clear, yet you reply to what I didn't ask. One possible reason for this is that you may be an ingenious designer who is reluctant to disclose his trade secrets, thus deterring others from copying them.
No, they're not.

The idea that I have "trade secrets" is totally hilarious, since I publish my schematics, detailed design information, show my calculations, and my exact thoughts on design tradeoffs. Even more hilarious because I don't do audio professionally. Never even sold a circuit board. The most I've done is made some pizza money from my articles. My profession is polymer science. Ask me how to formulate a polypropylene without antioxidants that cause endocrine disruption and THEN it's likely I'll clam up.

It might help to actually read the stuff I've published. I'm not designing for you, but there's a slim possibility that you could learn something.

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So, what I see from you, in various threads, is nullification of the value and use of listening tests
Really? You must be confusing me with someone else.
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Old 23rd July 2010, 03:11 AM   #5079
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Quote:
Originally Posted by bear View Post

Not sure I see a genuine need for gain in a line stage as things now stand with the technology... so I don't use one. That obviates 99% of what SY is claiming as an advantage? Surely no active device is more linear than any active device??
In setups where it's possible, I would 100% agree. Now if you have to drive any length of cables and have multiple inputs to feed, then a unity gain line amp is (IMO) the best solution. If you don't, a switch and a pot are absolutely the best way to go, assuming your goal is having no effect on the sound by the electronics, other than raising and lowering the volume.

You could certainly make an excellent (i.e., sonically transparent in a blind bypass test) unity gain stage using bipolars, FETs, opamps, or tubes. Rolex or Patek-Philippe? It's still 4:20.
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Old 23rd July 2010, 04:29 AM   #5080
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I'm sorry SY, but what you should be comparing, is a Timex to an atomic clock. After all, accurate time is now possible, but NOT super accurate time from a Timex, unless it is calibrated to WWV. This is possible, but I suspect that you don't have that accuracy, or even bother. Jewelry does not do much either, but people often buy it. I have a Casio, myself, but I once owned an Omega and I loved it at the time.
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