John Curl's Blowtorch preamplifier part II

[scott wurcer]

Originally Posted by PMA

OK.

Cool, there's more there than you would ever get on a datasheet.

[scott wurcer]

Originally Posted by fas42

Well, you could always learn, or use, APL ...

Frank

Been there, how about Don Lancaster and his, "Don't bother with a PC write everything in Postscript and the printing is free." I actually have tried that too, Postscript = Reverse Polish C.

Send this to your printer...

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1 roll translate rand 1 and 1 eq {90 rotate} if newpath 0 -1 moveto -1 -1
1 0 90 arc 0 1 moveto 1 1 1 180 270 arc stroke grestore} for pop} for
showpage

[fas42]

Originally Posted by Esperado

I believe than, when we ear at evidence the sound deterioration produced by a 2N3052 or a TL7202, the sources are good enough in dynamic and bandwidth for you can believe that, if you find an operational amplifier giving near no difference with a wire, it is good enough to listen to this source ? All we care is how dynamic, sound stage, separation, linearity, little details, harshness or distortion are modified...

Everything is a matter of degree. I certainly know myself that the better my system gets, the more easily I can hear external interference being a factor. The better the reproduction, the more fussy I need to be to get the next, newly revealed, layer of the onion, as abraxalito called it, sorted. So, for me, an opamp as substitute for wire may or may not be audible, depending on how "resolving" - a nice weasel word - the system is.

I am perhaps fortunate compared to some, because I have extremely well defined goalposts. I know, because I've experienced it many times, how good sound reproduction can get, and that is the standard, the reference which everything for me is measured against. I have zero interest in comparing 2 versions of 85% sound quality, that is a nothing exercise in boredom. So, I care whether the changes made have moved closer to that notional 100% level. Notional, because it can get better again, but that particular quality is good enough to get the subjective reaction of "it sounds like the real thing" ...

Frank

[kgrlee]

Originally Posted by john curl

I am NOT going to put my personal preamp into some test that I do not control. I do MY controls here at home.

JC, is this an offer to allow Stereophile & the Dynamic Duo to carry out the Blind ABC test in chez Curl? That's very generous of you.

You will have COMPLETE control over whether you are listening to A, B or C. Only you won't know if you are listening to Blowtorch or evil 4558 or something else.

If this is a welsh .. could you then explain your offer/challenge, to those of us who lack facility in English as she is spoken ...

I am constantly confronted by my critics that this is 'reality' and that my 'extreme' efforts are just a waste of time, but I haven't gotten any takers as of yet.

Of course, anybody can take just about any line amp and compare it to another line amp and get a NULL result. Unfortunately, I must insist on an 'open' test, at least a defined A or B, is necessary to hear any difference. Still, A and B could be randomly selected, even by computer, it is just knowing that A is always A, and B is always B when making the comparison, that is important to me.

How do you want to conduct this test? I'm sure the details can be worked out to everyone's satisfaction.

There's no (extra) shame in welshing, JC. You've already welshed twice so this would just be the 3rd time and well in keeping with your reputation.

[kgrlee]

Originally Posted by fas42

Yes, there are several aspects that need to part of the situation to make it fair to the 'victim':

* Switching must be under the control of the subject, and he must be able to listen for as long as he requires to a particular variation
* Source material must approved, or selected by the subject
* Most importantly, he must be able to state whether the playback standard is sufficiently high in the test configuration, and this be accepted a valid reason for not continuing. In other words, if the quality of playback is only 80% at best in the test environment, then all bets are off ...

ABSOLUTELY Frank. All your points and more have been key to the Wharfedale Blind Listening tests from very early on.

JC, do you have anything to add to the list of essential requirements?

I'm glad you want the test at your home cos I was afraid you'd demand an O2 free listening room. May we take it that you consider that playback environment (player, amp, speakers, room, connectors, mains leads etc) at least 98%, maybe even 102% and suitable for conducting listening tests at the highest level?

'Victim' is the wrong word. I'd hope to persuade at least 2 of the best ears in the business to take part. JC, any recommendations for true golden pinnae?

[SY]

Originally Posted by kgrlee

JC, do you have anything to add to the list of essential requirements?

Peeking.

[john curl]

Thanks SY, for the encouragement.

[john curl]

Since I can't stop being subjected to insults, I will just ignore the source.

[Kindhornman]

Like I would trust anything that came out of Stereophile in a listening test. Those have always been so biased as to be useless in my eyes. Now the actual electrical testing using the AP 1 or 2 I will read and can believe most of what is printed, but Stereophiles subjective testing has always been just that with way to much bias as to interconnects and what color a wire was........... JK on that one. But in reality those test are useless to me.

John,
I do not understand the attack on your preamp. It is a product no longer for sale, was not a large volume production and unless someone wants to volunteer their own personal preamp for that test just leave it alone already. Talking about the topology and why John chose to do what he did and what the basis of those choices would seem more informative than bashing the thing already.

[Esperado]

Originally Posted by fas42

Notional, because it can get better again, but that particular quality is good enough to get the subjective reaction of "it sounds like the real thing" ...

I think you don't understand my point Nothing sound like "the real thing". For such a reason that the real thing does not exist. None listen the same thing in a concert hall.
As i said, i'm a sound engineer, the most near the real thing you can imagine. Right ? Original tapes of mine i can compare, listening with the best equipments as possible.

What i said is it is easy to build a preamp, using some current feed-back OPAs, with some care near the power supply, and to get as close to the original as possible. At least with less deterioration than any other part in any system (power amps, enclosures, most of the commercial DACs ).