When things are not understood people generally adopt one of two positions:Mikelandjelo said:
1. this is too complicated (for me to understand)
2. this is so simple (because I don't grasp the complications)
Most speakers are designed for voltage drive. The only reliable way to provide low distortion voltage drive is to use feedback. If that does not answer your question then you may be asking the wrong question.
When something is pulled out of the concept that can be commented like this.Let me save you time and energy..... i will not go this way and discuss further what you said no matter will you or what you will say further.Every speaker can be voltage and curent driven and you are wrong.I will not comment further becouse you show how simple you understand what you said.
I asked simple question and i got my answer.There is feedback in vinyl cutting.What i didnt find is how that feedback is implemented and used in cutting.If you cut something and have feedback
no matter what that feedback is you cant correct whats cut already.So feedback can be only reproduced signal or some info of how deep the cut is......but it cant correct the cut.Right?
I asked simple question and i got my answer.There is feedback in vinyl cutting.What i didnt find is how that feedback is implemented and used in cutting.If you cut something and have feedback
no matter what that feedback is you cant correct whats cut already.So feedback can be only reproduced signal or some info of how deep the cut is......but it cant correct the cut.Right?
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Yes, but it includes also the cutting head within the loop -- lots of resonances to overcome.
Handbook of Recording Engineering - John Eargle - Google Books
Point is one thing.....cut in vinyl is made from information that comes to coil that controls cutter....and no feedback is possible.Whats cut its cut.Thats why sound is always more natural from vinyl....and thats why i had a miracle when i compared what i designed with A Class Technics amplifier i have.......when source is anything but turntable i had always warmer and more natural sound....BUT when i used turntable nobody in room couldnt beleive how big difference is,Techincs sounded like a toy.....I simply matched nature of how is sound recorded to be reproduced same way.Yet,making feedback less d class to give this is not even close to be said hard but its super hard.It took me now 6 years to get there.I opened this discussion to see is there something i missed .... like new feedback concept or new kind of design with all whats known about feedback that sounds "free" and i see that there is nothing new.If there is i will be glad to discuss that.During next year i will publish my website about all i did.Design will be for sale becouse i have no ambitions to manufacture it here in this fuc*ing state i live now.Thank you all for inputs in this topic.
I think what he means is that the feedback can control the voltage/current to the cutter coil but not the cutter tip. The mechanical part of the cutting tip is outside of the feedback loop.
So, while the voltage/current of the coil can very accurately follow the source signal, the actual cutting path may have errors from that.
Then he says that therefor the resulting cuts in the vinyl are more natural - that is a strange way of putting it because it is clear that the actual cuts have errors from the source signal because the cutting point is uncontrolled, with all its vibrations and resonances and whatnot.
Jan
So, while the voltage/current of the coil can very accurately follow the source signal, the actual cutting path may have errors from that.
Then he says that therefor the resulting cuts in the vinyl are more natural - that is a strange way of putting it because it is clear that the actual cuts have errors from the source signal because the cutting point is uncontrolled, with all its vibrations and resonances and whatnot.
Jan
Yes, it is the piece of metal that leaves the coil and cuts the vinyl that is outside the feedback loop. And being mechanical in nature, it must have resonances and vibrations that detract from the fidelity of the process.
In fact it is totally analogous to an amp driving a speaker. You can feedback-control up to the wires of the voice coil, but after that it is open loop. Which is why speaker distortion is often orders of magnitude larger than of the feedback-controlled amplifier output signal.
Jan
In fact it is totally analogous to an amp driving a speaker. You can feedback-control up to the wires of the voice coil, but after that it is open loop. Which is why speaker distortion is often orders of magnitude larger than of the feedback-controlled amplifier output signal.
Jan
Designing a class D amplifier without feedback.
The music is not "free" when feedback is used.
Feedback is not used at the cutting head for vinyl and that's why it sounds better than a Technics CD player.
I suppose Mikelandjelo wants to make a class D that plays music well and is reasoning that it is the NFB that is the problem.
The music is not "free" when feedback is used.
Feedback is not used at the cutting head for vinyl and that's why it sounds better than a Technics CD player.
I suppose Mikelandjelo wants to make a class D that plays music well and is reasoning that it is the NFB that is the problem.
He prefers 'natural' sound i.e. linear and nonlinear distortion, noise etc. Feedback gets rid of most of this 'naturalness'; digital systems mostly never had it to start with. So he prefers vinyl, tape etc. (AM radio too?) as they are more 'natural'. He wishes to share with us his ignorance of how feedback works.jan.didden said:
Hi Mikelandjelo (correctly: Michelangelo),
You need to check MFB (motional feedback), a method to integrate amplifier and loudspeaker into a single feedback system. Also worth checking the principle of ACE Bass invented by the Swedish company Audio Pro. These are working in the bass region, not around the crossover, though. One thing is sure: No matter how much current is the loudspeaker drawing from the amplifier at the crossover: if it is measured flat, it is flat.
You need to check MFB (motional feedback), a method to integrate amplifier and loudspeaker into a single feedback system. Also worth checking the principle of ACE Bass invented by the Swedish company Audio Pro. These are working in the bass region, not around the crossover, though. One thing is sure: No matter how much current is the loudspeaker drawing from the amplifier at the crossover: if it is measured flat, it is flat.
The wrong conclusion because of wrong reference.
Comparison should be done with live audition and not with other playback system.
Only then can you say that the sound is "more natural", otherwise it is just a trickle of the ear.
It is known that tube amplifiers sound much more enjoyable to the ear (compared to those transistorized ) just because it distorts but this distorts the natural sound and does not improve it.
Well. Misattribution errors abound. Nevertheless, a class D will switch at what frequency...300kHz or 400kHz? Pretty slow and the reason for Putzeys needing to use a 7th order (I don't recall) Butterworth filter in the feedback forward path. It's a bit of a dog's breakfast. So I understand why our Sistine painter is trying to avoid it. Personally i would avoid a switcher but each to their own.
Well, in these days of intense ABX testing we learned that almost anything even up to pretty high crossover distortion numbers sounds the same. The "no feedback" concept gets up high in ranking then.
Hi Jan
-Cutting vinyl with cutterhead powered from GNFB-free amp is possible , our DIY member Atmasphere already is doing that for many years,
`` Those of you who have been watching the blog on our website may have noticed that we mentioned using a set of M-60s for LP mastering with our mastering lathe.
I thought I would post this for those interested. We chose a Westerx cutterhead, as it has a nominal 10 ohm impedance and the stock transistor cutteramps for it only make 125 watts. So it seemed like we would have no worries with a set of MA-1s to drive it.
However saying that the cutterhead is 10 ohms really glosses over the subject. It starts on the low end at about 8 ohms, has a peak of impedance due to mechanical resonance in the midrange, then continues up from about 9 ohms to about 25 ohms at 25KHz. Now in an LP mastering situation you have to apply the RIAA pre-emphasis; this means that you have to make a fair amount of power at high frequencies because so much emphasis is added.
That is why the transistor amps are rated for so much power (the cutterhead itself cannot handle anything near that power level) because the transistor amps lose power as frequency increases due to the load, being capable of only about 40 watts into this load at 20KHz.
So as a result our M-60 works out to be an ideal amplifier, as it actually is capable of more power/less distortion into the higher impedances.
The cutter system employs a feedback module that adds about 30 db of feedback around the head and amplifier. This is required; without it there would be no channel seperation due to the mechanical suspenions in the head itself. It also controls head resonance.
So we set up a set of M-60s without feedback, and a speaker protection fuse, since you can toast the head pretty good with only 20 watts or maybe a little less.
So far the results have been excellent and the operation is keeping quite busy!
The cutting system is capable of cutting grooves without distortion that no cartridge or arm combination could ever track! In addition, the lathe cuts are considerably quieter than the best vinyl, rivaling digital in terms of dead silence. The bandwith is amazing, good from about 5 Hz to well over 40KHz without effort; with some mods to the electronics and a different needle installed on the cutterhead we could cut a 50KHz subcarrier in the groove with FM stereo modulated on the carrier!
I can't say how well an OTL would work on other cutterheads like the Neumann, but for the Westerex its ideal. ``
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``In fact it is totally analogous to an amp driving a speaker. You can feedback-control up to the wires of the voice coil, but after that it is open loop. Which is why speaker distortion is often orders of magnitude larger than of the feedback-controlled amplifier output signal.``
-I think that on the other side of recording chain recording microphones capsules basically is out of any GNFB loops to .
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