John Curl's Blowtorch preamplifier part II

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I believe those were designed for thermal/IR imaging in spacecraft and not intended to be used as diff pairs originally.
I believe Interfet got going when TI, who were making by far the best JFETs for nuclear science charge preamps, abandoned that business.

The really big ones are pretty decent noise matches to really large area semiconductor particle detectors. Both will be cooled a lot to reduce leakage currents, and a small additional advantage is an increase in gm and consequent noise voltage reduction. The typical operating temps can be near 100 K. Much lower than that and carrier freezout becomes serious and performance swiftly deteriorates. 77 K (liquid N2) is not optimal, despite the relative convenience. I ran TI 2N4416s at considerably higher temperatures, near dry ice, and still got decent results, to the point that dielectric loss noise in the borosilicate glass packaging was a dominant noise source.

I agree that well-matched differential pairs were not per se a design goal.
 
Where do we get to see the optical bias generator? it might even have credibility with fashion audio if its unusual. I remember some nutcase was popping the tops off of power transistors and controlling them with light, using a bunch of magical claims for it.

It was a proposal for ikoflexer here on diyAudio. Essentially a LED that shines on a photodiode array, originally intended for biasing fat MOSFETs.

Completely unusable for fashion audio where amplifiers must preheat for a week until they sound ooooh soo good. In that week the transistors try to remember their operating points, because the designer failed to enforce them for not having understood feedback.
 
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I believe Interfet got going when TI, who were making by far the best JFETs for nuclear science charge preamps, abandoned that business.

I recently found a few TI P8002 JFETs in a drawer, a variant of the P8000 not in TO-220 but slightly smaller (like BD138/BD139).

Oh, what lame transistors! 35 years ago, they were the biggest thing since sliced bread in ham radio receivers because one could use them for 50 Ohm termination of ring mixers with good IP3. I could never find a data sheet for them.

They probably sound excellent because they are made from weapons-grade unobtainium.

What has happened to the Teledyne CP-643 in TO-5??

regards, Gerhard
 
Well, if you want to generate a ton of misleading and incorrect data to prove a pre-determined hypothesis, it helps to not know much about the thing you're measuring, then take advice from a person who knows even less (or knows more and is happy to spread misinformation). Add in bad experimental technique and impressive-seeming instruments and you've got fashion audio in a nutshell.

CD & CD-R,
Ennemoser / C37 CDs,
"demagnetized" CDs or Bedini "ultra clarified" CDs,
principally everything that you can do to your CD,
different CD-transports,

If you then remove (lessen) the jitter something happens that is best described in Ennemoser's book "The Character of Sound":

"If the brain, however, receives sound patterns of C37 or similar quality, it has little processing to do and rewards the owner with positive images such as: saturated, full, warm, melting brilliant ..."

Grade A charlatan. Nice choice of guru.
 
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When this first came up, I thought, good idea to use the same resistors in series in a feedback network, except for thermal modulation - in an inverting setup that is.

It works for tempco's as well as V-coefficient. All R's change (to a first order) all the same way (they all have the same current) so the ratio between the two legs remains constant. Assuming negligible amp input current of course.

Jan
 
Do you know why?


-RNM

No, But I got an invite to come and try to figure it out.

Ed - Sorry I promise to behave, if you want to do disclosure and have a discussion it's fine. If you want plots with no labels and 20 questions, that always seems like a train wreck waiting to happen. I remember the charge not "the charge" moving at c in the wire and piling up, well I guess like a train wreck.
 
South Korea to upgrade national stereo defence system for US$16m ? The Register

South Korea want a new 'wall of sound'. Sure we can help them there :)

Reminds me of Pink Floyd at the Berlin Reichstag. They had an extra wall of speakers turned to the side so that the East Germans could have some fun also. I could hear the sound check in all of the west Berlin city.

During the concert I used ear plugs and proceeded to the stage. The air moved the legs of my jeans. A close 2nd place after Disaster Area.
(that Plutonium rock band from the hitchhiker's guide to the galaxy)
 
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Loudest thing I ever heard was a Tangerine Dream concert in the late 70s... No mics, all synthesised, very low bass frequencies, massive sound system... You could feel your chest cavity move! Would be banned now of course.

When I saw them around 89 wasn't as loud.

not sure whether motorhead or Hawkwind were the loudest I heard.

Aswad were known to be a bit loud on the student circuit, but when everyone is crammed into a marquee its easier to deafen them all :)
 
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