Funny how some will at one point say that vacuum tube devices are the most linear while at the same time I have never seen any of this equipment that is not containing steel chassis, and many ferrous metal connection points? Do we really think that this is the answer to the final frontier in solid state circuits, removing any traces of ferrous metal anywhere in or around a circuit? Do we need to use nothing but capacitors with multi-strand copper leads so we couldn't possibly have a single boundary layer imperfection in a lead-out wire using a solid copper wire?
Not to mention the tubes themselves. And transformers. But that doesn't count because... ... ... hey look, a squirrel!
Radiation induced defects in cold diodes is an extreme issue with superconducting accelerators and colliders. The dipole bending magnets are series connected to reduce the number of warm to cold transitions and to keep all the dipoles tracking perfectly. As a consequence, if one of the dipoles quenches (reverts to normal resistive state), it is important to bypass the rest of the ring energy around the quenched magnet. Each magnet can absorb it's own stored magnetic energy without melting, but when there are lots of them, the current has to be bypassed using a cold diode. CERN used 100mm diameter diodes, and put them within a foot of the beam path. As a consequence, the forward voltage increases with time due to radiation damage.
Every year or so, the diodes have to be brought back to room temperature so that the damage is annealed out. The problem is worse in that the diodes are planar to the beam, not normal to it. One side of the diode is closer to the beam and gets more damage as a result. If a quench occurs, the diode will go into thermal runaway in the section farthest from the beam.
I believe the space rad damaged thingy was telstar. After a failure, the engineers created a condition which heated the offending part up, and they annealed the damage out.
Neat. Simulation would have been easier and less expensive than experience.
jn
Read only the results at the beginning . That was a total management failure on the part of both NASA and the maker. Along time ago on a PA install I remember on the bid spec that there would be independent test and verification of system performance that was a job of small town . They knew they where not qualified to sign off on the work so the job was certified by a third party . Interesting that a job worth 100s of millions lacked the same level of do diligence .
HST
There was a second, perfect, backup mirror in storage. All they had to do was replace the bad one with the good one, before launching it into space that is.
Ray
There was a second, perfect, backup mirror in storage. All they had to do was replace the bad one with the good one, before launching it into space that is.
Ray
Very interesting results, Dan. There is certainly a conditioning process taking place, but my suspicions would gravitate strongly to the big smoothing caps - these things are pretty marginal as electrical components,
, I would put them on the front of the suspect list.The big Perreaux amp I started my journey with used to drive me nuts in the early days, SQ issues were clearly linked to the fat, impressive looking caps - I started by working around them, but finally bit the bullet, yanked them out and put in some decent, much smaller units in parallel - never looked back ...
As regards 'conditioning of the mind', the worst headaches for me over the years have been anomalies which do get worse with time - there is an intricate dance going on in a system as it works, some aspects are improving, others degrading - this is at a subtle, but definitely discernable level - there have been many days when I just got fed up, the sound was getting worse and worse the longer the system ran - so, just pulled the plug and forgot about audio for a few days ... then, refreshed, ready do another round of investigating ...
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All my experience in this game has demonstrated that the key factor is accumulating enough 'good points', so to speak, in order to get satisfying sound to emerge. Something in the system can be 'wrong', terribly wrong, by most standards, but if the accumulation of positive ticks in other areas is sufficient then the single bad negative doesn't undermine the subjective nod of approval.
This is why "mediocre" equipment can do it - you squeeze just enough 'goodness' out of what's at hand to get you over the line in terms of the positive attributes needed - and the ear/brain filtering does the rest ...
Well, the transformers are ferrous to start with . . . So I'm kind of confused by this whole ferrous thing to be honest.
let me help a little.... if I am able. The triode is - to very talented and educated man who has studied the sources of non-linearity for IBM etal... says it is the most linear. However, he, I, you and everyone else knows that it isnt perfect and he was only talking about the operation in principle. They are too noisy and other things to use everywhere. Which is why he uses fets instead..... not as linear in principle but can get better results over all.
Now the ferrous thing. In some critical places and with sufficient current flow THRU the part (series) the magnetic part will produce distortion. The level of the harmonics is way below the noise of most audio circuits using tubes. It is masked. But in some of the best low noise and ultra low distortion ss circuits, you can begin to see it intrude.... still at low levels until the currents get high.
I will leave it at that for now. Incomplete as it is.
THx-RNMarsh
Now the ferrous thing. In some critical places and with sufficient current flow THRU the part (series) the magnetic part will produce distortion. The level of the harmonics is way below the noise of most audio circuits using tubes. It is masked. But in some of the best low noise and ultra low distortion ss circuits, you can begin to see it intrude.... still at low levels until the currents get high.
I will leave it at that for now. Incomplete as it is.
THx-RNMarsh
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Ed Simon's doppleganger? Put numbers on these effects in relation to the magnetic non-linearities inherent in almost any speaker motor assembly.
Really, -100db distortion in the presence of 1% is so obvious you would have to be deaf?
Thats what it looks like.... if contribution stays below -100dB... except I might not exclude the drivers to the OPS... they have to supply a few amperes sometimes (bjt).
However, you can easily remove even the high current/ferrous metal distortions into the dirt, if you choose to.
THx-RNMarsh
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> -100db distortion in the presence of 1%
> is so obvious you would have to be deaf?
Is that how you understood my statement ?
No.
I'd venture that @~ -46db distortion starts to
be discernable through 1% distortion.
Perhaps through 5% (or more)
The fact is that ~0.5% is where amplifier distortion
becomes audible through normal speaker systems.
> is so obvious you would have to be deaf?
Is that how you understood my statement ?
No.
I'd venture that @~ -46db distortion starts to
be discernable through 1% distortion.
Perhaps through 5% (or more)
The fact is that ~0.5% is where amplifier distortion
becomes audible through normal speaker systems.
Depends. In case of digital nastiness uncorrelated/correlated to program you will hear it even if lines (not SINGLE line) are about -90dB or less. Sounds like chirps, best heard with headphones during low level parts of music.
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