One of the reasons I left this forum 10 years ago was EnABLed. Meantime, I found out that quod licet Iovi, non licet bovi.
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My own preference is mostly to listen to a standard music recording that I know very well. There are particular things that I listen for. Sometimes look at a 1kHz FFT too, but my diy setup at home is all I have and it is rather sparse in the way of measuring equipment. Never thought I would be doing what I am doing now when I retired, made no effort to keep things that might have turned out to be useful.
Jam has his own methods, but he did say Pass HPA-1 was designed by listening and he only used an AP at the very end to check a few things. Said he mostly used Audeze LCD-X headphones for the listening.
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Hehe, it's the cryo treated single pair Cat 5 speaker wire I can't get my head round.
That's it right there, we can choose not to be a****** at whatever the cost.
The DC Servo we all know and love
THx-RNMarsh
WRT DC servos, Jungs book refers to this 'high speed' current feedback
amplifer with DC servo, Bell Labs, 1965, see P28
Op Amp Applications Handbook - Walt Jung - Google Books
Jensen (Transformers) brouight out the 'Twin Servo' mic pre in 1988 and I'm
pretty sure there was earlier use in pro audio.
SSL 9000 series consoles used servos (AFAIK)
FWIW, the traditional style of DC servo design as per Jung etc etc is audible in a very HQ replay system compared to no servo.
We (myself and former associate) spent some time to design one that matched true DC coupled circuit, IOW completely inaudible, which we did
eventually achieve. It is quite a bit more complex than the typical opamp LPF approach.
TCD
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CMA is a naming convention occasionally associated with the current conveyors of the 3 types CCI, CCII, CCIII.
The most known current conveyor topology is the current mirror. Here's a simple description of current conveyors and their applications.
http://www.jmdet.com/wp-content/uploads/2016/05/Paper-02.pdf
There are a few things I tend to listen for. Usually, I listen first for IMD on group vocals and or groups of instruments verses the sounds of individual vocals or instruments. The distortion has a sound that one can learn to recognize pretty easily. I also listen for audibility of reverb tails, and a few other things.
I'm trying to add some of the things Jam has mentioned listening for, but not much experience with those yet.
Having been doing it for the time that I have been working on dacs here, I have learned to associate certain artifacts with issues in certain areas of circuitry. Sort of, doesn't always point me in the right direction at first
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Hello Terry.
JC IIRC has commented that different opamps in DC servo circuit cause amps to sound different.
What artifacts did you find audible in the Jung DC servo ?.
What did you come up with as inaudible DC servo solution ?.
Dan.
As I understand it, CMA is signal controlled Constant Current Source as opposed to standard Voltage Mode Amplifier which is audio signal controlled Constant Voltage Source.
Usual implementation of CMA is by means of feedback voltage generated by sensing resistor between load and ground return.
This means that CMA will supply audio signal controlled output current regardless of load impedance......iow the output voltage is the undefined variable.
In case of VMA the output voltage is defined by audio input signal and the output current is the undefined variable and according to the load impedance.
VFA and CFA are different subject, however VMA and CMA operation can be implemented by means of VFB or CFB topology.
Hope that clears things.
Dan.
Stinius aka Reodor Felgen aka Waly aka ...
In my book, it's called defamation.
I'm happy to read it is only an opinion. What says RNM is only his opinion too. How do you intend to impose yours ? By sympathy? It missed . Because the difference between you is while he is not insulting nobody, you do-it. Don't you re-read what you type ?
At the same time that I was learning to read in primary school, I was told that:
1- It is a proof of a dirty soul that to speak badly of *someone* in public and behind his back. There, it looks like harassment.
2- It is a lack of intelligence and a childish attitude to contradict the assertions of anyone without providing valid arguments to demonstrate otherwise. Opinion is not an argument. Insults neither.
The burden of proof is on the prosecution.
3- It is a total lack of righteousness and honesty to attack a person rather than his arguments.
4- Only cowards attacks in packs and participate in lynchings.
... When I even see people for whom I felt respect participating in the kill, seeking the applause of their little court, oh Lord, we hit the bottom !
And all those behaviors, that violates the rules of life in society and those of the forum for a "naming convention" about CFA amplifiers, are-you all serious ?
Because of a handful of frustrated, jealous and badly behaved individual that are left free to let off steam, (encouraged ?) this thread has lost all interest. At least, for me. Such behaviors, with a nauseating atmosphere, asinus asinum fricat, always precedes the death of a forum. No need to explain why.
i'm not arguing about any technical point of view, here. neither I take a party or another. Just comportments that, in my book, have no excuses.
Now you can go wild, as usual, it will only illustrate what I said.
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That's right and they shouldn't.
All the servos we tried and they are all pretty similar in function, seemed to mess with the bottom end to some small degree.
I designed an optically coupled circuit with HQ opamps and a very low corner frequency. An LDR did the offset adjustment. There was a LPF on both opamp
integrator driving LED and also the LDR. It took quite a bit of tweaking to get everything well within 'adjustment' range so there was adequate 'headroom'
on the adjustment but it worked really well and was as close to no servo as we could get.
These days I would probably just use a really HQ, new gen audio fet IP
opamp and a very low CF. But if the application is super critical then I'll dig
into the opto toolbox.
TCD
But once you consider what kind of business he is in, it's no longer strange.
Good question.
Who do you mean "we", you and your business associate?
Would one of those some things be Bybee?
You appear very unhappy on this forum. There are many other forums online that are different, in case you didn't know.
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