John Curl's Blowtorch preamplifier part II

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Mark and Mark 🙂

The typical switch on a UK wall socket is well away from the neutral and earth with no real visibly open path should an arc occur. Its probably the safest option for switching such a load with hindsight. The load (laptop) was connected at the time and the wall switch was on.

The trailing white plug is OK. I had to rewire it for a new charger lead (different connector at the charger input) because I simply couldn't trust the old one just on the basis that it still worked. Close examination of the pins does show some pitting that will have occurred during the years of occasional connecting with it live.
 
I saw this on another site and it made me smile:
Understanding the Metric System

10**12 microphones = 1 megaphone
1 million bicycles = 2 megacycles
52 cards = 1 decacards
1/2 lavatory = 1 demijohn
2000 mockingbirds = 2 kilomockingbirds
3-1/3 tridents = 1 decadent
10 monologs = 5 dialogues
2 monograms = 1 diagram
1 millionth of a fish = 1 microfiche
10 rations = 1 decoration
10 millipedes = 1 centipede
 
Well, hopefully I can get back to serious audio design.
I find that many here simply do not experience audio quality design like I have for the last 50 years.
Nothing is ever perfectly designed well enough to be called 'truly transparent'. It is just that we don't seem to have the answers for what our ears hear, although we can now make designs that measure very well. It isn't frequency response differences, for example, that always makes one amp sound 'brighter' than another, yet many persist in this belief. AND, one can make a preamp design with op amps that measures almost perfectly, yet another vacuum tube or discrete solid state design might sound better enough to establish a reputation for quality sound throughout the world. WHY? (And don't tell me I am imagining things, I know better!)
 
Well, hopefully I can get back to serious audio design.
I find that many here simply do not experience audio quality design like I have for the last 50 years.
Nothing is ever perfectly designed well enough to be called 'truly transparent'. It is just that we don't seem to have the answers for what our ears hear, although we can now make designs that measure very well. It isn't frequency response differences, for example, that always makes one amp sound 'brighter' than another, yet many persist in this belief. AND, one can make a preamp design with op amps that measures almost perfectly, yet another vacuum tube or discrete solid state design might sound better enough to establish a reputation for quality sound throughout the world. WHY? (And don't tell me I am imagining things, I know better!)

We probably have some pretty good ideas why for some of those things. Brighter? Low level 3rd harmonic. Tubes? 2nd order distortion makes it sound thicker in a nice way and higher order distortion products masked by noise, the net effect being perhaps pleasant warmth rather than hard sounding (to some people who can hear that, and depending on circumstances). There is no reason to make it all so mysterious any more. It's all, or nearly all, measurable. What's left is to do a is little, or possibly a lot, more research relating perception to what we already know how to measure. For another example, the illusion of burn-in is likely explainable by psychological adaptation and long term listening effects. As is often the case, audiophiles have the theory wrong, but there is, or can be, a perceptual effect.
 
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Interesting news, morinix. EQ is something that is relatively sparse when it comes to real quality. One of my associates is working on one for this reason.
Yes, break-in is real, at least to serious audiophiles who know the sound of their equipment. Simple explanations just don't wash.
 
Interesting news, morinix. EQ is something that is relatively sparse when it comes to real quality. One of my associates is working on one for this reason.
I sat there boosting speech frequencies (4k, 5k hz) all the way and was stunned at how clean it was. It's nothing like a normal Pultec or Manley unit. Dynamics also held up with minimal compression.
 
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Break in is easily measured. Just take ten new identical capacitors in a 4-1/1-4 bridge and measure the distortion. It will drop nicely with hours of signal. Also will drop if you desicate them. I suspect you can do the same with resistors.

So, do they sound worse in humid climates?

Is is a surface effect? If so, what about alcohol rinse followed by deionized water, then air dry? Works pretty well for electrometer circuits...
 
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