Aurak preamps are pertinent to this thread because they both depend upon independence of inductance with level, and apply different current load to cartridges. Also very handy for showing mech resonances etc.
Personally I don't mind a separate Aurak thread so long as it doesn't trash the sense of threads involving discussion and evolution of it like this one or the mech resonance thread. Just lately I have lost the sense of meaningful discussion in several such threads after they were split, which is a shame IMO.
To an extent, discussion just goes where it will.
This particular thread explores some interesting axioms upon which Aurak depends and I don't mind it - it's the lesser of 2 evils versus perpetual splits IMO.
LD
Personally I don't mind a separate Aurak thread so long as it doesn't trash the sense of threads involving discussion and evolution of it like this one or the mech resonance thread. Just lately I have lost the sense of meaningful discussion in several such threads after they were split, which is a shame IMO.
To an extent, discussion just goes where it will.
This particular thread explores some interesting axioms upon which Aurak depends and I don't mind it - it's the lesser of 2 evils versus perpetual splits IMO.
LD
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Pleased to tip the hat to your fine op-amp. BTW GBW is fine at 4.5Mz or so, don't know what I was remembering so steady as she goes.
Yes, triangle wave shapes are correct. Angle=velocity, and peak curvature=acceleration. The 'flats' and 'edges' of square waves map on to angles and curvatures of the triangles.
LD
I share your opinion that splitting threads isn’t always helpfull.
In the end you have no idea where to find things back.
So let’s keep it the way it is now, unless some group buy may start somewhere in future.
That would automatically land somewhere else.
Hans
My personal vote is for discussion of transimpedance loading as a concept where it makes sense and another thread to link together all the bits on the practicals of how to build one. As I found going through the mechanical resonance thread to find all the useful bits can take a while.
We possibly also need an idiots guide for those who can't just look at a circuit and go 'ah' . I would put myself up to write that as I am that idiot 🙂.
We possibly also need an idiots guide for those who can't just look at a circuit and go 'ah' . I would put myself up to write that as I am that idiot 🙂.
I would vote for less splitting, I'm already confused as to where to put comments and end up monitoring all the threads at the same time.
On the inductance vs level issue, what is the expected magnitude of the effect and at what level does it sort of become six of one or half dozen of the other? The data showing inductance vanishing at extremely low levels can't be rationalized with my measurements of the L/C resonance still being there in the noise floor (no signal).
That would than have the form of a “sticky” to keep things together and less of a place to discuss.
Is that would you mean ?
Basically yes. One thread that pulls everything together from the last few years. If people also want to discuss things there I am ok with that as it's like herding cats to keep people on topic 😀.
Given that all the key discussions on the Aurak concept are in a thread on cartridge mechanical resonances we are already totally confusing to ourselves let alone anyone new who comes along. I'm just happy the discussion is being had personally.
Given that all the key discussions on the Aurak concept are in a thread on cartridge mechanical resonances we are already totally confusing to ourselves let alone anyone new who comes along. I'm just happy the discussion is being had personally.
My own measurements show inductance unchanged at 10s of uV, which is 50dB down on 5cm/s @1kHz 0dB
There is no magnetisation curve mechanism that can give 60 dB dynamic range constant and then suddenly plunge at lower levels
I think that we can conclude that the low level falling inductance is a measurement artifact.
The fault is mine, mea maxima culpa. I am reworking the jig used to estimate "L", vis a vis excitation level.
Not gonna expend a lot of shekels but it wasn't difficult to make -20 and -40dB attenuators with 1206 resistors which will work from DC to just under 10MHz for the HP3577 or Bode100.
Not gonna expend a lot of shekels but it wasn't difficult to make -20 and -40dB attenuators with 1206 resistors which will work from DC to just under 10MHz for the HP3577 or Bode100.
I agree.
I am surprised though. I expected work done to take the B-H curve through reversal of direction to show up as a constant loss, and so an increasing percentage of a small signal. In other words B-H loop relatively wider at small signals - ie hysteresis loss. Where does that show up then, or if not why not, I wonder?
LD
Then we would need an administrator who takes care of this special “Aurak” archive thread as a gatekeeper to decide what comes in or should be rejected, having administrator softwaretools at his or her disposal to perform this task.
If not, it will simply become split off thread number next, being exactly what we would like to prevent.
Are you the person willing to taking this position ?
Hans
Firstly, I can only say for sure that the Goldring G10x2 body is linear with level, other brands I cannot say.
I would expect any hysteresis loop effect to be gradual with level, not something abruptly starting at some level and going off a cliff
Most low end measurements so far showed the impedance but to accurately calculate the inductance one also needs an exact noiseless phase.
I’m still puzzled why Jack’s measurements where showing something of a decay at low levels, differing for different cartridges.
Cartridge dynamic behaviour
Was this really erroneous ? Maybe someone having increased the sensitivity of his gear could show what other Carts are doing.
For sure. But no sign, and I wonder why?
In spherical cow land, applied change to field has to do work on a high permeable material before it produces associated 'linear' change of flux. It could be my understanding error, but B-H loops are a family of curves that progressively 'sit inside each other' as signals get smaller, and gradually get broader ie more lossy as signals get smaller. I didn't think a B-H curve for a a high permeability material is ever truly reversible. And becomes less so at small signals? That's why I was expecting to see an effect...…..
LD
Hans you think of a complicated scenario.
The dedicated thread would serve the purpose of a depository for the schematics of the SE and balanced Aurak and the explanation of how they work by their designers.
Open it, you and lucky feed it with the schematics and the explanation. You may state up front if you are about to encourage discussion there.
Otherwise, leave the situation as it is now, where looking for the schematics in long threads makes it difficult or prohibitive
George
Hans, I don't think this would require George powers. Just one place where the latest info is and links to discussions. As the meanders of discussion seem to always come back to one place I don't think a gatekeeper is needed, just a librarian.
Jackini, where would we have been without making mistakes and learning from them? 🙂
Sitting in an armchair is a safe place, criticizing work of others is a safe (non) activity.
Please keep up the good work
(I see you often site Latin expressions. A good book to read between experiments, hm... Memoirs of Hadrian )
Lucky, see second attachment in this post
Cartridge dynamic behaviour
This is for a single frequency excitation (120Hz).
With higher frequency, the opening of the curve along the horizontal axis increases , reflecting the increase in losses (for a given core, hysteresis loss is a function of f, eddy current losses is a function of f^2)
George
Most low end measurements so far were mainly showing the impedance and not the inductance.
For an accurate inductance calculation one needs to measure the phase to within a few degrees and that was difficult to achieve so far. Maybe someones improved test gear can give new insight.
I’m still puzzled as to why Jack’s measurements were showing a decay in inductance, was this really erroneous ?
Bill I don’t have administration powers and there is no need to invoke an administrator for that.
If Lucky and Hans understand the need of a technical forum to have some easily to find and reliable in content location for schematics and explanation of evolving of a certain design, they will self administer it. They are the designers.
I leave it here 🙂
George
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