Difficult to answer. Many interdependent variables are involved. First rule, zero gnfb is often insufficient, so we apply gnfb. When gnfb is applied, there is may be 20% inherent drawback and 80% possibility to make mistake.
Yes there is optimum gnfb if it is the last variable to be changed. The optimum is changing from setup to setup, from cct to cct. 'No gnfb or lots of gnfb' is thus wrong.
Sound characteristics will depend on what parameter is critically affected by the gnfb setting. Can be distortion, damping, timing/timbre, transparency, oscillation, etc.
Here we go again. Ever cared to read https://www.edn.com/design/consumer...fiers--Why-there-is-no-such-thing-as-too-much and Part 2 of the same?
Really
? Ok, I give up, don't take me too seriously, you have a bigger fish to fry .The title is "Why..." but he didn't logically answer the question, only loose explanation about control theory (something that we have read many times).
He claimed: "you will find no such extreme claim in this article" when the article's title is "... no such thing as too much (NFB)". Too much nfb will lead to incurable instability. Assume it is still stable, you say? But where is the finite position of being stable? Like i said, 80% problem is due to mistake. You want to stabilize using Miller, but how do you know that you don't sacrifice slew rate? This is an extreme/basic example, in reality there are many other details that has never been explained.
Let's see:
Only for somebody that doesn't know what he's doing.
Exactly where a competent engineer designs to be. It's called "phase margin" and "gain margin".
Set aside Miller is not the only way to compensate an amplifier, there is only a loose relationship between the compensation method and the slew rate. You probably have in mind the Lin topology, but even there the Miller compensation, if done correctly, is not an issue for enough slew rate.
My turn for a question:
Who is "we" above?
Only for somebody that doesn't know what he's doing.
Exactly where a competent engineer designs to be. It's called "phase margin" and "gain margin".
Set aside Miller is not the only way to compensate an amplifier, there is only a loose relationship between the compensation method and the slew rate. You probably have in mind the Lin topology, but even there the Miller compensation, if done correctly, is not an issue for enough slew rate.
My turn for a question:
Who is "we" above?
Really
I rest my case.
I got a very nice cct diagram and user manual with the layout off the web. Only the driver in the PA is germanium - the rest are silicon.
Hopefully I’ll get it going and it will sit quietly on the hi-fi rack - I’ll use it to listen to FM
You, I and most of us here.
No need to repeat the books. What is not explained in the books is how these numbers affect our perception. I don't even calculate PM/GM. Amps with the same PM/GM do not have equal stability. I answered RNMarsh not because I thought he didn't understand control theory but because I knew he knew what he didn't know (because it's not in any electronic books).
I was looking for one on the net and saw a pic, it was the Japanese FM band frequencies, 76-90MHz. I assume you have the model made for EU & N/A?
Pioneer sx 100Ta - Pioneer Gallery - 2011-08-20 19:49 - HiFi Engine
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I’ll stop here, since obviously your expertise goes far beyond mine. I do calculate PM/GM and I have no idea how these numbers are affecting our perception. And the last time I’ve checked, nuclear plants and spacecraft guidance control loops have equal stability for the same PM/GM, it’s a theorem you know, but for audio must be of course different.
My understanding is that for a reasonably linear circuit lower order harmonics mostly are produced without global nfb and the degree is dependent on this intrinsic linearity.
As GNFB is applied these lower order distortion harmonics are reduced in amplitude as is the goal.
As GNFB is further increased lower order harmonics are further decreased but higher order harmonics increase/emerge from the noise floor and can become the subjectively dominant harmonics according to nfb level.
At high nfb levels the 'spray' of higher order harmonics can be programme dependent and the ear is very sensitive to/protests these unnatural dynamic changes in the system noise floor.
Lower levels of nfb allow operation without this dynamic generation of higher order harmonics and can be 'monotonic' and lower order only which is more 'natural' sounding.
Yes I have heard amps with switchable feedback and the sonic result is OL sounds 'big' and 'open' and 'natural' but slightly distorted, and the NFB versions sounded 'cleaner' but 'closed in' and unnaturally 'damped' in comparison.
There will be a 'sweetspot' where these two conflicting behaviours intersect with subjectively minimal static and dynamic 'damages' to the output sound, ie minimal musical sounding lower order harmonics and with minimal production of music level/music density dependent production of upper harmonics.
JC and NP have built their careers on amplifiers that are not uber clean but have gained listener preference to typical high GNFB designs.
This approach of course depends on circuits that are intrinsically 'subjectively clean' and naturally damped and the application of low level GNFB serves to 'keep a lid on' amplifier errant behaviours triggered by reactive/reflective loads without unduly inducing HF 'noise'.
So ultimately the choice of GNFB level is to cause 'natural sound' damping characteristic and deviation from this causes overly 'loose' or overly 'tight' sound, and both are rejected by the ear when given the choice.
Dan.
My understanding is that the current eval board for the AK4499 is limiting its actual performance. That is both encouraging and frustrating of course. The other important question would be whether the improvements (lower noise and lower distortion) are audible since they are all beyond anything that is a demonstrable, verifiable threshold. How much lower than -120 dB in DAC noise floor be audible, same for distortion? There may be other aspects that aren't as identifiable or quantifiable that could be important but what would they be?
In what occasions do you usually do a 'critical thinking'? I'm confused/surprised by way of your thinking in your posts. But I'm aware that this is a unique thread. I think I will re-read your PGP and YAP projects to understand your thinking and see if I could learn something new there.
Measured how? DSD, PCM, IMD, low order, high order, constantly changing order?
May I ask what you have heard about the first evaluation boards?
Have the Rev.0 eval board data sheet here, but that's all on that at this point. It shows they are using OP1611 for I/V, and discrete power supplies for their version of what ESS calls AVCC. They include AK4137 and AK4118 chips on the boards, but no differential summing stages. Lots of dip switches and WinXP vintage configuration software that won't run on Win 10. Nothing too unusual with the latter, given the software situation these days.
RE AK4499- What I saw was that the current implementation can be improved in terms of AVCC and possibly other aspects of the conversion which can make for improved performance. This is AKM's first current output DAC. There is a lot to learn about how to get its best performance and sometimes the rush to get something gets in the way of getting the most from it. It's a lot more stuff to get the audio out and I/V converters are not trivial.
None of us will have access for a while so we can only look at confidential datasheets and speculate.
None of us will have access for a while so we can only look at confidential datasheets and speculate.
Haven't read the datasheet closely but what's with the I/V feedback net pin (the "I" pins)?
You can probably get the software working on Windows 10 as long as it doesn't use any 16-bit code, which is rare. A lot of old MFC apps still work fine, might require some compatibility options set. Win32 is still the base API.
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There is so often some surrealism in these forum discussions; the _original_ post was the one i´ve cited before and _my_ response to this _original_ post was this one, and of course the mentioned quote is included:
John Curl's Blowtorch preamplifier part III
As you still haven´t contacted me for copies of the cited evidence wrt to the "distraction/stress" evoked by different test protocols (including the ABX) is it safe to conclude, that you have simply no interest in scientific evidence of this field if you don´t like the content?
Further, as you´ve implicitely confirmed, you didn´t do any tests, didn´t try any recommendations, haven´t read any literature about propper sensory.
So, overall, you did nothing yourself,no effort at all, beside criticizing others (more knowledgeable members) for their critic? Isn´t that outright funny?
You had some advice for others:
"....at least not before you and your next of audio kin have a crash course in feedback principles and math and can subsequently have an educated conversation about....."
Wouldn´t it be a good idea to follow your own advice? (means educate yourself on propper sensory testing)
It would most likely prevent you from writing nonsense like "positive controls are BS" or "vanilla Foobar ABX"
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Your claim was about (snake oil that Jakob (x) tried to sell over at hydrogenaud.io) and a couple of weeks ago you asserted that i was lectured on at other forums about good sensory testing.
For these claims you have to bring evidence.
Up to now you were only mentioning someone who wrote about "Meilgaards book" and "the role Zwicker and Fastl played" , so no evidence for your claims at all.
Btw, Meilgaard´s book is one example of a good introduction to sensory testing, i´d recommend, so i strongly encourage you and syn08 to work it through (but please remember it´s just the beginning) 😉
Jakob, as I can see it in each of your posts, the Acute Accent (´) isn't the right character, it should be the Apostrophe (') instead.
isn't, not isn´t
isn't, not isn´t
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