John Curl's Blowtorch preamplifier part II

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I like some highend interconnects, but primarily because they use good RCA plugs, those connectors being the biggest mistake introduced into external audio connections until the advent of 3.5mm stereo miniplugs :)
You're worrying about RCA plugs? Have a good, close look at how 99% of RCA sockets are made, all the metal bits, and tell me that is good engineering ...

Frank
 
Hi Frank,


If you make it an intellectual exercise for someone to determine something, …

For me it's a practical issue, not an intellectual exercise.

What I worry about is whether I perceive the reproduction as being convincing, not someone else. And I have found that to be achievable.

I also have a setup which I'm pleased with. However, I know it cannot reproduce live music with absolute faithfulness. That knowledge prevents me from trying to attain the unattainable. It frees me to concentrate on what is attainable.

I've been building up a repertoire of understanding of why systems sound convincing, or not, over the years, and I'm quite comfortable with my knowledge to this point.

I didn't and I do not bother much about the 'why', I was and I am concerned mainly with what pieces of gear and what combinations of them get me closer to my aim, within my available finances. I listen, rather than try to 'understand'.

The reasons why playback works, or doesn't, at creating an illusion are extremely important, because that understanding can transform the capabilities of a system.

Again, to my view and experience, it is choosing the right gear and the right combination of the gear (including acoustic treatment) which transforms the capabilities of the setup.

Now, I'm not trying to say that my approach is better, it is only what works for me. Other approaches work for other people.
 
I remember from when dino's roamed the earth...Ford used some kind of steel pokey thingy to bleed off static charge caused by tribo buildup...but because they were losing wheel bearings. Seemed the discharge arcs were pitting the wheel bearing rollers and killing them.
A clear demonstration of how triboelectric mechanisms will be always of low level, and therefore have negligible effect in audio ... ;), ;)

Frank
 
I was a too little quick, the delay sim could be considered "unfair" since the noise correlates in both channels

adding 2 different sequences to each of the delayed sine bursts you need to keep noise to < 10 mVpp to get low single digit us variance

of course even less than 1mVpp noise should be handily possible in electrical instrumentation at audio frequency

1 mVpp independent noise sequences, 1 kHz center 100 ms envelope
 

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And yet, fashion oriented audiophiles love Teflon and silver, the worst actors.

With less exotic materials and decently engineered equipment (low source impedances), these effects vanish into nothingness.
So, if the external insulator of the cable happens to be resting on a material on the run from source to destination, which is also a bad partner on the triboelectric table, and is being nicely vibrated by the heavy bass being reproduced in the room, will it, or won't it have an audible impact?

Frank
 
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phantom power in pro use "polarizes" the cable, balance should reject most the deformation caused charge pulse noise

tirboelectric effect is known too

low impedance on either end of the cable shorts out the small amout of charge thats moving around

What about handling noise?
The triboelectric effect that causes impact-related "slapping" noise as the cable hits the stage or is
stepped upon during use is related to capacitance, specifically the change in capacitance that takes
place as the insulation or dielectric is deformed. This causes it to behave as a crude piezoelectric
transducer, a relative of an electret condenser microphone. Because such transducers are extremely
high-impedance sources, the drastic impedance mismatch presented by a low-impedance
microphone and its preamp or input transformer makes the extraneous noise generated by
triboelectric effects negligible except in cases involving very low-level signals. In low-impedance
applications, handling noise is best addressed by using soft, impact-absorbing insulation and jacket
materials in a very solid construction with ample fillers to insure that the cable retains its shape. Note
that it is totally invalid to evaluate the handling noise of a low-impedance mic cable without using a
resistive termination to simulate the microphone element. A cable with no termination essentially
presents an infinitely high source impedance, a situation that is beyond worst-case!

FILLERS, TNT TAPE & HANDLING NOISE The triboelectric effect that causes impact-related "slapping" noise as the cable hits the stage or is stepped upon during use is related to capacitance, specifically the change in capacitance that takes place as the insulation or dielectric is deformed. This causes it to behave as a crude piezoelectric transducer, a relative of an electret condenser microphone. Handling noise is best addressed by using soft, impact-absorbing insulation and jacket materials in a very solid construction with ample cotton or plastic fillers to insure that the cable retains its shape. TNT tape wrapped around the outer shield greatly enhances solidness and electrical parameters uniformity along the cable.
 
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The tek109 style solution is simple, elegant, gives me up to 100 volt 350 pico transitions into 50 ohms with no problems. So it's trivial to produce 8 volt steps as a source, with brickwall output impedance for the reflections off the load, and knowing the device will support the final current of 2 amperes into the load.

jn

I had the original Lumitron sampling scope and charged line pulse generator circa 1963. Barrie Gilbert is the only person that I have ever met that knows the history. This is my most regreted give away ever, GE TD11 tunnel diodes,6CW4 Nuvistor sampler probably the greatest achievment of making do with what you have that I have ever seen. 25ps resolution in 1963, think about it.
 
So, if the external insulator of the cable happens to be resting on a material on the run from source to destination, which is also a bad partner on the triboelectric table, and is being nicely vibrated by the heavy bass being reproduced in the room, will it, or won't it have an audible impact?

Hint: impedance. Think that one through.

The triboelectric effect of what the cable is laying on? No way. Pure pataphysics.

edit: x-posted with jcx, who gets it exactly right.
 
and is being nicely vibrated by the heavy bass being reproduced in the room
You just have to chose the phase in order the capacitance effects between the two wires compensate the mechanical effect.
Well, i'm joking.
Play a 1000hz tone. Hit your loudspeaker cable heavily. What did you hear ?
We all know the microphonic effects on cables... in very low levels signals and very high impedance charges, with HUGE gain, like electric guitars when the volume is set at 11 (Spinal tap) and booster ON.
 
I can select and change out cables. It's a bit more labor to change jacks, not to mention voiding warranties (not that I care much about that).
25 years ago I did experiments to learn how much "damage" was done by using normal connectors, for getting good audio replay, and ever since have always hardwired, completely, my systems. I wouldn't be able to tolerate the signature distortions caused by this weakness if left "untweaked" ...

Frank
 
You just have to chose the phase in order the capacitance effects between the two wires compensate the mechanical effect.
Well, i'm joking.
Play a 1000hz tone. Hit your loudspeaker cable heavily. What did you hear ?
We all know the microphonic effects on cables... in very low levels signals and very high impedance charges, with HUGE gain, like electric guitars when the volume is set at 11 (Spinal tap) and booster ON.
You're missing the point, as are the others. There is not an immediate obvious audible effect - a sizzle or buzz or fart from the speaker - but a slow degradation in quality. What static is about is a buildup in potential difference, which may take 10's of minutes to occur, again, depending on just about everything. Which ultimately changes the operating state of some part of the circuitry to a point where it no longer performs as well as it should. You can learn to recognise this change taking place by deliberately manipulating the system to cause the effect, and then shorting out the buildup.

Many systems have a greyness, a dreary quality about the tone, which is easy to discern when you don't pay direct attention to the sound, a type of unnatural, unpleasantness. This is a classic symptom of this problem ...

Frank
 
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So, if the external insulator of the cable happens to be resting on a material on the run from source to destination, which is also a bad partner on the triboelectric table, and is being nicely vibrated by the heavy bass being reproduced in the room, will it, or won't it have an audible impact?

Frank
You mean is in -- nylon carpet or a nylon jacket/sheeth around the cable or both -- being vibrated against one another and in proxy to the conductors?
 
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