John Curl's Blowtorch preamplifier part III

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#1,221
Tournesol said:
Run for shelter: A serious attack of the commando of the objectivists is happening at the moment. Supported by the usual shelling of disrespect and immutable certainties.
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Have anything to usefully contribute or do you just prefer your own brand of snide rudeness and absolute confidence of your own philosophy?

Because your posts in this vein are consistently disrespectful and insulting. Seems rich irony, no?
 
#1,222
Tournesol said:
Run for shelter: A serious attack of the commando of the objectivists is happening at the moment. Supported by the usual shelling of disrespect and immutable certainties.
Click to expand...
Thanks for your most helpful contribution to a technical discussion.

Some things in life are certain: finite bandwidth, Fourier analysis etc. You can beleive them or disbelieve them; reality doesn't care what you think.
 
#1,223
jan.didden said:
The audio is cut at 15kHz with a very steep filter (100 dB/oct roll-off and 1000's of degree phase shifts) to avoid interference with the 19kHz pilot.
I once did DB listening tests on such a filter with a few guys; 3 out of 4 could reliably identify whether it was in the chain, and they preferred it with the filter in ... 😱
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Content: Group: "Julia goes Mercutio". Musical piece: "Kafune Hanim" aired from a good FM station (Trito Programma, ΤΡΙΤΟ ΠΡΟΓΡΑΜΜΑ | ΕΡΤ WebRadio) at 14-3-2018 ~10:30 AM
All recordings are 16bit/44.1kHz

1. Direct digital recording from an SDR FM dongle (internal HP filtering at 15kHz)
Dropbox - 1.wav

2. Digital recording through a soundcard from an Analog FM tuner with no HP or 19kHz notch filtering
Dropbox - 2.wav

3. Same digital recording through the soundcard from the Analog tuner but with a 19kHz Q20 notch filter plus a LP 16kHz 48d/oct applied through Audacity.
Dropbox - 3.wav

George
 
#1,230
RNMarsh said:
Hahaha Lots of fun. The usual deflections and decoys.

So far haven't seen/heard anyone else try it yet. because there is no need to?

and its so simple to implement and do.


THx-RNMarsh
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However its still a "stationary" signal in the usual time window. Something like Diffmaker using either noise or music should be able to tease out differences over real listening time. Those who discount digital should consider Michael Fremer can share the sonic difference in phono reproduction via digital recordings. And there are some who share acoustic recordings of audio equipment on youtube to illustrate audio properties.

There may well be aspects of time constants in coupling caps that can influence the sonic perceptions. Unfortunately human listening is so evolved it can "error correct" a lot of degradation and still hear the content and a lot more even on ancient acoustic or early electric recordings. For that matter even on early, really poor, lossy digital recordings. A really accomplished listener could probably hear more essential musical detail through a really compromised system than an inexperienced listener on a good system.
 
#1,231
john curl said:
I think that it is appropriate to put in one of the Hirata papers also, so people can see different waveforms that are hard to produce with just sine waves, and are asymmetrical in character. The Hirata test is one of the most interesting that I have ever found that is usually unknown to typical engineers. I have tried it, and it works!
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Resembles the effect of thermal distortion, doesn't it?

https://pearl-hifi.com/06_Lit_Archi...unction-Memory/Junction-Memory_Distortion.pdf
 
#1,233
1audio said:
Something like Diffmaker using either noise or music should be able to tease out differences over real listening time.
...A really accomplished listener could probably hear more essential musical detail through a really compromised system than an inexperienced listener on a good system.
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That is exactly what I wanted to answer to J.S.
...
Adding that an accomplished listener could probably discern and recognize the more essential distortions of an audio system.
 
#1,234
Tryphon, we do need a definitive subtraction test between the original musical source (as best that we can find) and what it 'changes' to after going through an audio gain block. It would be perhaps possible with the BEST DIGITAL like 24-768K or so. Maybe not. In any case, we would probably learn more than we do now.
 
#1,236
I put these papers up, because they show what Richard and I are trying to convey to the public about audio circuit design and amplifier development, based on what we have learned over the decades actually designing both prototypes and commercial audio equipment.
This separates us from those who normally repair audio equipment or have advanced degrees (even in engineering) but mainly have design experience in a different field from audio amplifier design. If you fit in this group, you are amateurs, not professional amp audio designers.
IF any of you can try to understand what Dr. Hirata is trying to convey, even if you can't really understand all the math, you will see that there is more to amp measurement than Thd or related test measurements, and that is WHY loudspeakers can have much more harmonic distortion than the amp driving it, yet the amp can be detected in the signal path! Richard and I have known this from design experience with REAL PRODUCTS for decades. We are just trying to help others that might be interested in better audio design and products.
 
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