I think that's different configuration. Suppose you have hf partial vibrations from a breaking-up cone, you can't put in a filter 'after the speaker' to take care of that, and have to worry about losing signal with the partials.
Not sure how your post relates to the thing we're discussing?
Edit - sorry forgot to quote - this is reply to SY
jan
Not sure how your post relates to the thing we're discussing?
Edit - sorry forgot to quote - this is reply to SY
jan
A breaking up cone is different in that we're not talking about a single-valued function. The output of a cartridge (or LF output from a speaker) is certainly single valued. So what I'm driving at is that if you get a resonant peak because of the tip-groove mechanics, why would a complementary "dip" electronic network not compensate it, just because one has a mechanical origin and the other an electrical origin?
I agree fully. My worry - maybe unwarranted - is that the complementary dip network would also cause a dip in the wanted signal.
I think the answer would depend also on whether the cantilever resonance is caused by a signal at that resonance frequency or by other causes like the movement and drag of the cartridge across the vinyl surface.
jan
You can compensate it. The problem is, compensation will only work single frequency. IOW, a sweep can show flat, but that's not music which is transient.
I don't like multi-order speakers for that reason. When an energy storage mechanism is used to increase conversion efficiency, transient response suffers.
Give me horns anyday...
jn
John, I'm not following you. If I create an inverse transfer function electronically, it covers more than one frequency- that's the whole point of specifying Q and fo (assuming a simple second order). For something not-so-simple, you can still create an arbitrarily accurate inverse function.
The product of the electronic transfer function and the mechanical one will be unity, so no overall energy storage regardless of forcing function and its frequency. Again, single valued functions...
The product of the electronic transfer function and the mechanical one will be unity, so no overall energy storage regardless of forcing function and its frequency. Again, single valued functions...
Consider a mechanical system which has a q of 100 at a center frequency of 1Khz , and put a filter in front of the electronics such that the overall sine response is flat. You've supressed heavily the frequency of interest to get the overall flat response.
Also, consider an independent system with a totally flat response through the band.
Drive the designed flat one with a gated sine at 1Khz and look at the response.
Drive the massaged system with the same gated sine. The output of the system at resonance will require multiple cycles to build up amplitude.
The "fixed" system has a poor transient response at the resonance frequency now, that is the consequence of using a storage mechanism to achieve efficiency.
jn
Chris, I will help you with the public exposure (I can share the tar)
For a tip with an effective mass of 0.27mg (Denon DL-103)following a theoretical groove with an 20KHz triangular 5cm/sec modulation, the resulting peak acceleration is 10,000m/sec^2 (1020G).
The inertial force due to this acceleration btn tip side and wall land would be 0.0027N.
Increasing by 20db the modulation velocity to 50cm/sec, these numbers are multiplied by 10.
In a more common case (1KHz at 5cm/sec) acceleration drops down to 500m/sec^2 (51G) and force is at 0.0000135N
I am sure that calculations based on tip dynamics will give wild peak temperatures but wouldn’t published images prove any thermal induced evidence at the groove lands, if that high temperatures were really occurring?
http://www.synthgear.com/2010/audio-gear/record-grooves-electron-microscope/
George
I thought we were talking MM, we have discussed virtual ground input MC before. I think John said it makes things sound like "under water". No comment on that but, I have never found a means to measure phono distortion via a test record nor a stylus that didn't have pretty bad distortion at highish level. An easy test that requires no instruments is 10k 1/3 octave noise, the low frequency IM is gross and easily audible (Telarc even had a warning in the liner). We discussed experiments to measure how reciprocal the coupling was. Just try and put REAL NUMBERS on the magnetic force of the current (100uA or so levels) and the mechanical energy in the stylus assembly and guess. This is very different from a ribbon mic where the "motor" is almost massless and the field huge.
Our discussion about spherical stylii and the use of pre-distortion on many LP's was a real eye-opener for me.
SY, I think jneutron says eccentiall the same think but I'll try as well.
Would you be satisfied from the result of applying a pre equalized signal to your speakers to compensate for one room acoustic resonance(assume perfect match of fo and Q)? The two systems are loosely coupled there too.
Is there any technical criterion in such a case by which one can be guided to equalize one resonance but not try to electronically equalize another?
George
That's a beautiful link George ---thanks for that.
I used to visit a chatroom on Stickam, associated with the very popular Hank & Jim Radio Network, and at one point another person asserted that vinyl records encoded bits in the grooves --- directly! He mentioned that he was an attorney, and I expressed relief that I was not his client.
I again have to remind us that we're talking about the stylus tip and not the grooves getting to these extreme temperatures. And as far as I know we haven't found a reference yet that backs up the assertions. It may turn out to have been someone's speculation that took on the aspect of a scientifically sophisticated urban legend and propagated.
"The Moving Finger writes; and, having writ,
Moves on: nor all your Piety nor Wit
Shall lure it back to cancel half a Line,
Nor all your Tears wash out a Word of it."
The question of what a patch of vinyl gets to during the traverse is certainly interesting and important, but it's not identical to the tip temperature. Also, a before-and-after would be fascinating, and in the comments in the link an electron microscope is mentioned that does not require the plating operation for viewing the sample. Identifying where one was on the record might be tricky, for the comparison of before and after.
Another nice touch would be to show a scale for the wavelength of red light, or a multiple of same, as an inset in some of the higher-magnification pictures. Many tend to short-sell what a stylus is really doing, and tend to think of light as a finer probe than it is. One micron is pretty big.
Two thumbs up !
[fixing a resonance with another resonance]
Similar problems with acoustic 'traps'.
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Horns
Way off topic, but I have to chime in, that I 100% agree with the multi-order enclosure analysis, (I greatly prefer acoustic suspension myself) but only pure radial horns do not suffer from reflection-induced distortion as proven by Dr. Gene Patronis of GT. I attended his seminars a few years back where each type (tractrix, biradial, exponential, etc.) were demonstrated and the difference is not small, especially as SPL increases and the air becomes non-linear in the throat.
He holds many patents in this field and is worth a read...back to the topic at hand...
Howie
Howard Hoyt - WA4PSC
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
WXYC Chapel Hill, North Carolina - 89.3 FM
1st on the internet
Way off topic, but I have to chime in, that I 100% agree with the multi-order enclosure analysis, (I greatly prefer acoustic suspension myself) but only pure radial horns do not suffer from reflection-induced distortion as proven by Dr. Gene Patronis of GT. I attended his seminars a few years back where each type (tractrix, biradial, exponential, etc.) were demonstrated and the difference is not small, especially as SPL increases and the air becomes non-linear in the throat.
He holds many patents in this field and is worth a read...back to the topic at hand...
Howie
Howard Hoyt - WA4PSC
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
WXYC Chapel Hill, North Carolina - 89.3 FM
1st on the internet
MultiTone tests
The multitone tests most closely simulates a music signal source and produces both Im and harmonics. In checking the available published test data when using such, the 'noise' or grass between the tones grows by 20db when 15 tones are used. Rises another 20db when 30 tones are used (40db rise). I assume this increase in noise/unwanted freqs continues with ever more applied tones. So, we can assume that the level might contribute to the coloration of sound heard if the amplifier (opamp) does not have an extreamly low distortion to begin with. Thx - RNm
The multitone tests most closely simulates a music signal source and produces both Im and harmonics. In checking the available published test data when using such, the 'noise' or grass between the tones grows by 20db when 15 tones are used. Rises another 20db when 30 tones are used (40db rise). I assume this increase in noise/unwanted freqs continues with ever more applied tones. So, we can assume that the level might contribute to the coloration of sound heard if the amplifier (opamp) does not have an extreamly low distortion to begin with. Thx - RNm
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Is 20 khz triangular realistic? I would have expected sine for this derivation. Are the peak G's representing slew max or where the stylus hits the vinyl wall?
jn
I found one more interesting discrete opamp. Looks like an instrumental amp loaded on output transformer. V/I converters drive controlled by current common cathode stages with deep feedback by voltage. However it is power amp, but can be used as line level output stage with smaller tubes. Thanks to transformer output can be balanced, for professional studio usage.
Attachments
Yes. And iirc you can drive a ribbon microphone to low but audible levels, though you wouldn't want to. Reminds me of the time I drove a tuning fork crystal a little too hard and heard it break.
Speaking of bad news for cartridges, one could put d.c. current through one you weren't too fond of
and listen to the changes to the frequency response.