My LinkedIn professional profile tells I work as IT and enterprise consultant:
Senior Consultant
picoMEGA consulting s.r.l.s.
Information Technology, Project Management, ERP, Netsuite Specialist, Management & Control, Costing, Business Process, Banking software, AS400, Visual Studio .net, Delphi
This is my job.
Then, since I have arranged a few GB on diyaudio for crystals and oscillator boards (the crystals manufacturer asks for MOQ of at least 10/15 pcs for each type and frequency) and I own a company (although in a different market), by the italian fiscal law I cannot operate as a private person.
So I had to incorporate these GBs into my main business, that's the reason why I have added "Audio Hi-Fi Design" to my linkedin profile.
Usually I have lost money with these GBs rather than get a profit.
If I had a commercial interest I certainly wouldn't sell a better oscillator than the NDK DuCuLon (around USD 2000), in the region of the BVA 8607 and the BT ULN (several thousands of USD), and in class with the MSB Tech Galaxy Femto Clock (USD 19000) for EUR 228 (149 for the board + 79 for the crystal).
Bill, understood. There were two different interviews. This one: Purifi Audio - A Straight Wire to the Soul of Music | audioXpress
I found a couple of sections quoted below:
"Sporadic reports of a sort of “granularity” in the sound reproduction also prompted an investigation into whether this indeed happens, and if so, what would be the cause. After a long and winding road, Putzeys finally found a culprit: hysteresis in the ferromagnetic material of the amplifier output filter coil."
"(In case you were wondering about the unusual team up of a speaker designer with an amp designer: the magnetic hysteresis distortion — the memory and crackling noise problem described by Putzeys — is also a big issue for speaker drivers!)"
Don't know where I got that Lars was one of the people who noticed sound in the amp. Might be they talked about it in an audio interview (Darko?). Might be I misremembered slightly. I would have to listen to the audio interview again if it really matters.
I found a couple of sections quoted below:
"Sporadic reports of a sort of “granularity” in the sound reproduction also prompted an investigation into whether this indeed happens, and if so, what would be the cause. After a long and winding road, Putzeys finally found a culprit: hysteresis in the ferromagnetic material of the amplifier output filter coil."
"(In case you were wondering about the unusual team up of a speaker designer with an amp designer: the magnetic hysteresis distortion — the memory and crackling noise problem described by Putzeys — is also a big issue for speaker drivers!)"
Don't know where I got that Lars was one of the people who noticed sound in the amp. Might be they talked about it in an audio interview (Darko?). Might be I misremembered slightly. I would have to listen to the audio interview again if it really matters.
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So if jitter/phase noise on the data conversion process is clearly measurable, please publish your measurements.
I have published mine.
Very true, yet hypothetically if you had to choose (or someone had came to these 2 amps and you had to pick one).
Well there's the issue.
"Today's typical solid state amps on the mainstream market meet such demand audibly" and they play a Steinway grand piano as if it were a Yamaha.
Maybe the measurements available nowadays are not sufficient to clearly explain what we perceive when listening.
"Sound quality vs measurements" the dilemma is still open.
This is besides the point, I don't argue these things.
It sure should be. That's the point I was making: it can't be just measurements alone. Even more so when there's not enough of them. Phase noise effects still seem to belong to that category.
Sorry if my point didn't come across, though I think I made some effort to do so.
Yeah that is what I remember seeing. Interesting that Bruno would investigate anecdotal reports in this depth. The cynic in me might consider that he was looking for a differentiator from the hypex designs, but he does rather appear to be a perfectionist as well as very well grounded in the realities of the audio business.
Glad we are on the same page on this.
Actually those curves looked quite evenly spaced to me.
This may be clearer. The transfer curve of a Vmosfet is very linear as you can see with lots of current. Nelson Pass was taking advantage of this in some of his interesting designs. I used it as well also because it's gain doesn't fade with frequency unto you get very high, way beyond audio.
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What we perceive happens between our ears. There are brain wave measuring devices to show that. You wouldn't use such device to measure sound waves, would you?
Audio electronics measurements and listening to form correlation between the two have been done nth times throughout its history. Adequate amount of sound characteristics can be predicted based on measurements now, especially DACs and amps.
Different dac structures have different responses to jitter. So, e.g. for multi bit dacs the proven way of achieving low jitter might be by multiplication of a lower frequency, lower phase noise clock. Certain dacs respond differently to that. The data only aplies to a certain dac type or topology and not necessarily to others (as much).
So to take proven jitter figures of a clock as a black and white in it's meaning for the SQ of a dac is a hard thing to do.
When measuring an amp, and comparing damping factor, do differences of that tell you how it will play out sonically when hooked up to a real life load, or are its measurements, double blind verified, only aplicable to sq when output impedance is equivalent?
Feedback changes the frequency response, in onteraction with the load. Only in isolation should one claim one amp being more transparent, more HiFi, over the other, as you claim, yet we hook them up with real loads and frequency response might change enough to claim otherwise.
Just a few examples of why opinions might differ from "scientifically proven" data.
In other words, we know less than we think we do, mainly because we measure data that are a result of very strict rules and by that are of high resolution, but only within a small boundary that resolution, that meaning applies: once you hook up your clock or amp to a different dac or load, it's extracted data might be less or even no use at all anymore.
So no, it ain't all proven to the N-th times. Many things are, but not nearly all.
So to take proven jitter figures of a clock as a black and white in it's meaning for the SQ of a dac is a hard thing to do.
When measuring an amp, and comparing damping factor, do differences of that tell you how it will play out sonically when hooked up to a real life load, or are its measurements, double blind verified, only aplicable to sq when output impedance is equivalent?
Feedback changes the frequency response, in onteraction with the load. Only in isolation should one claim one amp being more transparent, more HiFi, over the other, as you claim, yet we hook them up with real loads and frequency response might change enough to claim otherwise.
Just a few examples of why opinions might differ from "scientifically proven" data.
In other words, we know less than we think we do, mainly because we measure data that are a result of very strict rules and by that are of high resolution, but only within a small boundary that resolution, that meaning applies: once you hook up your clock or amp to a different dac or load, it's extracted data might be less or even no use at all anymore.
So no, it ain't all proven to the N-th times. Many things are, but not nearly all.
When you use them without feedback loop you get high distortion.
The F1 amp (IRFP240) has around 3% distortion at 8W power output (1kHz 8ohm), while a GM70 or 845 amp at the same power output has a distortion around 0.8%.
And moreover we should compare the harmonic spectrum of the distortion, the tube amp is mainly 2nd harmonic, 5th harmonic is -90db and 7th harmonic is practically zero.
Good to know, since I'm not able to predict anything based on the measurements I'm very curious about your predictions.
Please, predict the sound characteristics of the following DACs:
- Naim Audio CD3 (TDA1541A/SAA7220)
- Audio Note DAC5 (AD1865)
- Soekris DAM1021 (discrete R2R)
- Buffalo-IIIsePro38 async mode (ES9038Pro)
- Buffalo-IIIsePro38 pure sync mode (ES9038Pro)
And the following amps:
- First Watt F1 (IRFP240)
- Audio Note Ongaku (211)
- Hypex NCore NC500 (Class-D)
Since both have no feedback loop the IMD should be similar and low enough.
You can simulate the IMD or you can ask syn08 to measure it for you.
This is a simulation of a zero feedback solid state power amp I have to build as soon as I find the time.
At 14W power output (1kHz 8 ohm) the THD is around 0.1%, but there is no voltage gain from the active devices.
As soon as the circuit is modified to get voltage gain from the active devices the distortion increases significantly.
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Sorry but I don't know.
You should do a listening comparison between different amps (with and without feedback loop) and then measure them to understand if you can find a relationship.
It is more audible than HD. You might find this interesting Pass LabsAudio distortion and feedback - Pass Labs