John Curl's Blowtorch preamplifier part III

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#26,222
PMA said:
It happened to be the DC offset issue, as BV has suggested. "B" had output DC about 50mV, "A" 0.2mV. DC offset made a shift on the trafo transfer curve.
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In other words, the simple output stage works just as well on a reactive load?

syn08 said:
Yes, but there always could be non-entropic local processes. Life is an example, Gibbs function (free entalpy) in chemistry is another one. So it is not obvious your audio system is affected by the Universe Global Entropy, and if an increased entropy correlates with a worse or better sound.

Having some fun, as usual :rofl:.
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1/f noise at the low end could be caused by the effects of entropy on your system, but who knows where 1/f noise really comes from, and just shouting 'entropy' doesn't point to a clear mechanism either.
 
#26,223
Max Headroom said:
OTOH somehow it seems that there is something deeper going on and more is recorded than just ones and zeros and that energy storage, energy transfer and energy transduction are more complex than we consider.
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Pure alchemy. Perhaps a little more essence of toad is needed in the mix?

On the other hand, it may simply be the old idea 'I do not understand physics and information theory, therefore nobody can understand it'. A variant of this is 'nobody fully understands it therefore my ramblings are equivalent in value to a book written by an acknowledged expert'.
 
#26,224
johnego said:
Not always better, can become worse too. In CFP output amplifiers, bias current is very critical and a few mV (or mA) can change sound quality (not just sound difference). So when bias current is increasing after turn on and the lower bias is the good one, then the sound will be worse after settling in. The time to settling in condition can vary from seconds to half an hour, depends on the design of the Vbe or temperature compensation scheme (and stability too, of course).
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Well in my case it’s better after warm up / turn on settling.

So instead of questioning my hearing or faculties some have actually come up with a couple of highly likely explanations for what I’m hearing. :worship:

I’m just trying to learn here.....idk why there’s such a need for degradation and insult to those that want to identify what they are hearing in their ‘sound’ system......sound being the key word. 😛
 
#26,225
I thought you didn't want to waste anymore time on this 😉 Seriously though I don't think anyone has insulted you. Your statement of "fact" below though is like a red flag to some, in case you didn't know, even Mark uses plenty of qualifiers 🙂
mountainman bob said:
Well if the amp was off for 10 min and 60% of the cooling takes place in the first third of the time it takes to heat up (30 min) the math says that it should sound as though it was only on for around 10 minutes from a cool start. Which in fact is how it sounded.......
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#26,231
"I don't know the mechanism and neither do you, I standby my proposal that different system noise during write process causes different write errors and subsequent different error correction during read process."


How can that be the case if the files are bit perfect copies of each other?

😕
 
#26,232
Bonsai said:
"I don't know the mechanism and neither do you, I standby my proposal that different system noise during write process causes different write errors and subsequent different error correction during read process."
How can that be the case if the files are bit perfect copies of each other?
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Flash memories are multiple bits per cell, hence noise prone during both write and read operations.
Read error correction processing ensures that operating system level output data is correct.
It seems that different error rates at flash storage level are audible is a possible explanation for audible differences when playing back wav files from usb thumb drive.

Dan.
 
#26,234
Bonsai said:
How can that be the case if the files are bit perfect copies of each other?
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It is one and the same file, but two instances of it at different locations on the media. During the actual playback process this may, very very indirectly, alter the jitter signature that reaches the DAC (via USB or SPDIF) which isn't good enough to supress it.

So yes, at least theoretically, there is a mechanism that could cause different sound of one and the same file depending on the circumstances of the readout and playback. You need a very mediocre DAC for this to happen, though.

Most reports on differences of identical files usually relate to the two copies being on different media (SSD, HD, RAM, SD-Card). Dan is known to stretch out things, so he even has differences with the same media. We have these kind of types here, too, people claiming sound differences from bit-identical CD rips made with different drives, or with the laptop being battery- vs mains-powered while ripping, all kind of weird stuff...
 
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#26,235
Bonsai said:
That does not explain how, if the data going into the (same) DAC is bit perfect between the two copies, you can have any differences. I remain confused.
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The thumbdrive data output is bit perfect but possibly timing precision is changed. I have a Gooped 3 inch USB M-F extension cable (Jitterbug sort of equivalent) and connecting this in series with USB thumb drive or portable hard drive causes similar change in sound of played files.......despite the data signal path and processing. I fully agree that theoretically this should not be happening, but in practice I find that it does and on any system and before there are any ABX etc nonsense calls this has been proven without doubt, ie 100%. The subjective improvements are akin to reduction in system jitter and quieter power supplies with more extended highs and more extended lows, greater clarity and finesse in sound and quietness between notes etc and above all much better conveyance of groove/emotion factor. Here's those Test Dept - Two Flames tracks again to give you some idea of the kind of differences I'm talking about.

Dan.
 
#26,240
Max Headroom said:
Chris, multiple pairs of files sounded different on dedicated playback devices such as shelf mini-system and car audio.
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Can you describe the difference in sound between these files?
One explanation might be flash memory less errors on write and less errors on read causing less correction and timing noise of decoded/corrected and operating system level delivered data.
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This is good, you seem to have some kind of hypothesis (or "theory" if you like), As mentioned in another post, the actual data is played back from RAM. Also as mentioned, MS Windows and Linux are not RTOSs, and the common way to make up for that is making a RAM buffer substantially larger than it would need to be in an RTOS, so that the buffer won't run out (causing the sound to stop) if the processor(s) spends an inordinate amount of time on another task.
OTOH somehow it seems that there is something deeper going on and more is recorded than just ones and zeros and that energy storage, energy transfer and energy transduction are more complex than we consider.

Dan.
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That's a fascinating hypothesis. I can only wonder how it can be tested.
 
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