Well. On my side, I think the most interesting things we can discuss is, at the contrary, this kind of (non audiophoolery) stuff. Specially in this thread where a lot of us do not need any help when we are at a design in progress, unless asking for (with no answer, most of the time.).
Discussing original or new ideas, sharing experiences, talking about the quality of gears and components on the shelves etc. that is what interest-me. Where are the works on this double coils feedback idea ?
Most of us are clever enough to make the difference between snake oil and real medicine. It is very easy to ask the good questions when something looks technically incorrect and to enlighten-it in a friendly and polite atmosphere.
The reader is intelligent enough to make the difference, to accept and understand with indulgence the little strangeness of one or the other, and to sort out between the good and the chaff. Who, here, need the sermons and the excommunions of pseudo priests of the politically correct ?
I wonder why some valuable (?) people here look unable to think with nuances and that, when you share an experience like I did with my CD lead trick, or Simon with his double tape one (that i take with a pince of salt), they classify you immediately in the drawer where they rank the members of some sect practicing black magic. With all the prejudices, lack of respect and kindness that goes with it.
This endless crusade against snake oil produces collateral damages and there is nothing positive, constructive about it. And it is BORING.
Cool, men, cool !
If someone is naive enough to love buying cables at $ 10,000 an inch, no animal has been abused. If he is convinced that his system is better after that, he will have bought pleasure and satisfaction and helped the family of the snake oil vendor to live.
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Sometimes. Textbooks and technical journal articles are hardly worthless. Anything that actually does work should be consistent with the standard model of physics. Unfortunately, sometimes things get dismissed too quickly due to assumptions about the limits of what could be involved.
With power cords, it was their possible effects as filters. With lost reverb tails, it was a lack of understanding about of how complex some of the DSP is in a modern dac. Sometimes the problem has been with over reliance on old hearing research that is impossible to replicate or critique because the exact details of how it was performed are unknown (and, yes, I know there have been consistent results over many studies. But, same problem with all of them, as described above). And so on.
Phases of the moon, however, are unlikely to have much effect on equipment although they could affect perception in some humans.
AC filters: I don't know if it's been discussed before, but that's a good topic. I simulated a few dedicated filters recently, and they all ring like hell. Is it audible? I don't know. Is it bad? Surely. Anyway, it's an easy fix with a RC damper at the ouput.
Attached is a Schaffner filter that has some following in the French audio circle; the green curve is stock, the blue has a somewhat optimized damper.
Attachments
It's a simulation.
I'm a long way off from the finished item. Actually, I'm currently preparing a drilling template for the chassis, so I'll be happy to have something to repoprt on before the summer
If you're talking about the parasitics of the components of the filter itself, I wouldn't loose too much sleep over them: you can double or half the damper values before anything significant shows up (see the .STEP command)
I'm a long way off from the finished item. Actually, I'm currently preparing a drilling template for the chassis, so I'll be happy to have something to repoprt on before the summer
If you're talking about the parasitics of the components of the filter itself, I wouldn't loose too much sleep over them: you can double or half the damper values before anything significant shows up (see the .STEP command)
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Zung, the RLC circuit that's exhibiting oscillatory ringing is (L6 series L7) parallel C10. (Ignoring C4 series C7 since they are so much smaller than C10).
This explains why the resonant frequency is ~ 1 kHz.
Good old linear systems theory, applied to this second order system, says you'll get critical damping (zeta=1.0) when the load resistance (R8 parallel R6) = 0.5 * SQRT(3.6E-2 / 6.8E-7) ... namely, 115 ohms. Be sure to choose C8 large enough so that its capacitive reactance at the mains frequency, is waaaaaaay lower than R8.
This explains why the resonant frequency is ~ 1 kHz.
Good old linear systems theory, applied to this second order system, says you'll get critical damping (zeta=1.0) when the load resistance (R8 parallel R6) = 0.5 * SQRT(3.6E-2 / 6.8E-7) ... namely, 115 ohms. Be sure to choose C8 large enough so that its capacitive reactance at the mains frequency, is waaaaaaay lower than R8.
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Hard to simulate, taking into account the various noises carried by AC mains, the load of transformers+ rectifiers etc...
Don't you think ?
The crucial part is the "...are not supposed to be ..." , because usually we don´t know if it is ensured in reality for a specific device or a class of devices.
Hitting these devices with a hammer (literally) would be, compared with normal situations in listening rooms, a test with a generous margin and would -unfortunately- result in measurable reactions of the devices in quite a lot of cases.
Usually it needs much less than this brute force approach (ok,ok.. there are very tiny hammers out there that could additionally be used without much force) something like tapping a pcb with a screwdriver will already trigger some reaction if for example a potentiometer is directly soldered to it.
Oscillators are also known to be quite sensitive to this kind of mechanical impact .
And if really using a forceful hammer hit we will notice that a lot of cables (not being constructed for low microphonic reaction/triboelectric effects) and components will do something unexpected; at least unexpected if people are working under the "..are not supposed to be...." assumption.
Of course usually these artefacts are quite low in level in relation to the signal levels but nevertheless real.
The more difficult part is to find out if these reactions lead to different perceptions when listening in a normal/casual way to reproduced music.
At that point no generalization - neither based on anecdotal (incredible difference heard) nor on theoretical considerations (can´t be because...., which often seem to mean "i don´t want it to be" ) - helps.
Of course and as an isolated effect quite easy to measure (mechanical reaction of the horn to mechanical impulse stimulus), but can be difficult to detect if measuring the acoustical output of the system.
It's a simulation.
I'm a long way off from the finished item. Actually, I'm currently preparing a drilling template for the chassis, so I'll be happy to have something to repoprt on before the summer
If you're talking about the parasitics of the components of the filter itself, I wouldn't loose too much sleep over them: you can double or half the damper values before anything significant shows up (see the .STEP command)
If using such modifications in real world applications we must keep in mind possible code violations, if - under any thinkable conditions - touchable parts will be exposed.
I applied double sided sticky tape around a tone arm tube once... to dampen any resonances and vibration pickup. And on top of the cartridge shell. And, then to hold the cartridge to the shell without screws. Yes, it audibly affects the sound.
-RNM
Sorry, it was late, and I was in not such good form. By the way, I am not taking sides with Scott or against you. I would simply like to see a lessening of the tensions between all sides. We all can get out of sorts at times, me included, but I hope we can recover quickly and return to more cordial interaction.
Thanks.
Attached is the filter I think I'll use; it's based on a 4th order kit from eBay. Original on the left and green curve, modified with dampers on the right and purple curve; C4 is 2x6.8n because that's what I have in my junkbox. Your comments are very welcome.
Attachments
Of course, at line levels ... preamps of phono moving coils or microphones are an other story... That request special attention.
If, with no signal across, a potentiomètre is microphonic, I would think it is ...time to service it ;-)
Osclillators ? Good point. Cristal is microphonic, indeed. It should be interesting to shield and damp them ? Any jitter improvement expected ?
Coils are too. Same remark. If it is in a FM tuner, I really do not care, so far from any Hifi anyway...
And about the level of vibrating effect and what kind of audible impact when listening music? As long it is quiet in the silence with the hammer, i do not ask myself any question ;-)
The differences between the two horns were readable both on the frequency response curves (High writing speed with bruel & Kjaer at this time) and impedance curve.
On the walls of an acoustic enclosure, fine sand allows to see where are the vibratory nodes and the "loops" (?) at various frequencies. Useful if you want to optimize their damping, placing reinforcements where it matters. Typical example where a DIYer can do better than an industrial manufacturer.
Everyone had, has and will have the right to share listening impressions or experiences, on this forum.
There is an objection raised and evidence is asked to be provided when from the listening impression a conclusion or a generalization over a technical issue is drawn
“the law that is violated” is the slip into a classical logical fallacy.
Have you counted how many are (were?) the regular contributors in this thread?
George
Don't worry, Mark.
It is touching to see one of the most delicate gentlemen of this forum feel guilty. I have never felt the slightest aggression from you, on the contrary.
As for me, I have the greatest admiration for Scott and the astonishing depth and breadth of his ... technical knowledge. Too bad i feel him sometimes a little, say tough and suspicious. The opposite of John, which is sometimes a bit ... poetic.
Two people I would like to see reconciled and would love to meet iRL As I believe the truth is in the middle and both are obviously passionate as i am.
If I sometimes take John's defense, it's because he's often attacked in an indelicate way, and I'd take Scott's as well if he was hurt by a horde of audiophile zombies hypnotized by Baron Bybee.
Lot of very interesting and valuable people, here, more than everywhere else I know, on my humble opinion.
Including you ;-)
But maybe I'm stupid to dream of a bit of tenderness in a world of bullies?
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ABORT! Those are CMCs, not inductors. You do not know the actual series inductance, but it is likely 1/100th to 1/300th the common mode inductance. You need to add a K statement to the simulation to show they are coupled inductors.
Can you list some of those collateral damages? Let me start with one, thinning wallet of sellers.
What about him posting claims on internet forums?
This thread is mainly about clever large egos stroking themselves by attempts to belittle others, but I think you know that already, if you didn't you must be stupid, and I can now feel superior...so thanks for that.
Yes, they were around $900 from KEF direct as a refurbished pair.
These do need about a month of playing to break in adequately.
Using Sound Organisation lead filled stands with custom wood tops
and a cork interface to the speaker bottoms.
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