I have recently acquired a phono pre amp recommended by Michael Fremer. It is “THE VINYL”, from QHW audio, Spain. It got a great review. I have a Benz Micro Glider rated at 1.1MV. I have no idea how to set the dip switches for MC Load impedance for this cartridge. The options I have are as follows: 47K, 1K, 560R, 470R, 100R, and 47R. I have a solid state amp and pre-amp, and also have a sub that I use, rarely.
His contention is that loading has no effect on the compliance of the cartridge. I showed that it does.
Since the amount of energy directly affects how much force it takes to move any generator by the direct proportion of energy asked of it (for example if you ask 1 Amp of a generator and it takes X amount of energy to spin it, asking 10 Amps of the generator will make it 10X harder to spin).
I provided a link to this effect earlier.
Since a cartridge is also a generator, asking it to make 400X more energy will affect it in a similar way. The only variable is that the cantilever has a springiness that affects the outcome of the equation. But its a simple fact that the coil itself will be 400X harder to move (this being between 47K load vs 100 Ohm load per Raul's example).
Again, this principle is easy to demonstrate. Loudspeakers are moving coil, as they are mechanical transducers just as is a cartridge. If you try to move the woofer with your hand you'll notice it takes a small amount of effort. Now put a short across the speaker terminals and see how easy it is to move the woofer- you'll see its a lot stiffer. The same thing happens with a cartridge.
Raul is arguing for some sort of 'free energy' as best I can make out, since that has to be how it would work if loading did not affect the cartridge in this manner.
Since a cartridge is also a generator, asking it to make 400X more energy will affect it in a similar way. The only variable is that the cantilever has a springiness that affects the outcome of the equation. But its a simple fact that the coil itself will be 400X harder to move (this being between 47K load vs 100 Ohm load per Raul’s example).
If the voltage drops as the loading is applied i won’t be linear power.
And the output current also is likely non linear.
(I think)
Again, this principle is easy to demonstrate. Loudspeakers are moving coil, as they are mechanical transducers just as is a cartridge. If you try to move the woofer with your hand you’ll notice it takes a small amount of effort. Now put a short across the speaker terminals and see how easy it is to move the woofer- you’ll see its a lot stiffer. The same thing happens with a cartridge.
How does this concept affect the transimpedance phono amps?
I guess if they pretty much have 0 ohms input impedance then they would have the stiffest effect upon the cartridge? Rather than the softest?
(Compared to a traditional phono stage.)
How does this concept affect the transimpedance phono amps?
The input impedance is also known as 'virtual ground'. This is a point in any opamp circuit where the feedback is applied back to the input of the opamp. There is a resistor that also connects to that point, which is the input resistor, in series with the signal. The ratio of input resistor vs the feedback resistor sets the gain of the circuit; if the feedback is 10K and the input resistor is 1K the circuit has a gain of 10.
In a transimpedance amplifier, the cartridge itself is that series input resistor. Part of the reason for doing this is to reduce noise, since the Johnson noise of the resistor itself contributes to the noise floor. You can see that the gain of the circuit varies according to the impedance of the cartridge winding; as the impedance of that is decreased, the gain of the circuit goes up. Even with modern opamps care should be taken to keep this initial gain less than 20dB else you can get into distortion issues.
What is important to understand here is that the cartridge isn't actually driving ground, which is what zero Ohms would normally be! Its driving the relatively high input impedance of the amp amp, and is also interacting with the feedback signal. However the cartridge is remote- it is likely feeding a tonearm cable a meter long or so, so the RFI generation will still be present. So loading might still be required.
If the voltage drops as the loading is applied i won’t be linear power.
Since the minimum load specified is 10X the source impedance, we're not talking about a big issue here.
Sorry for the late reply, I’ve been busy with my accountant try to file tax return by next Monday.
I did the Hi-Fi News resonance test on a Denon DL-103 and set the loading at 100Ω and 47kΩ, seems like both loadings unsusceptible to the resonant frequency.
Although theoretically loading will affect the compliance of the cartridge, and 100Ω loading made the cartridge work 470 times harder than 47kΩ loading. But since the coil resistance is much lower than the loading resistance, I think the effect on the cantilever stiffness is insignificant. Therefore the test result show no difference, IMO.
Since RFI is not the music contents, so apply a correct amount of resistive load to damp the unwanted RFI is not an bad idea after all. Again, IMO.
@holmz : As @imhififan I did my tests in specific for resonance and tracking against load changes. Btw, thank's for your answer .
Differences in sound with load changes depends of the active high gain phono stage characteristics and your brain perception about. LOMC cartridges are " non " sensitive to load impedance changes.
Dear @imhififan: " Although theoretically loading..... and 100Ω loading made the cartridge work 470 times harder than 47kΩ loading. ..............., I think the effect on the cantilever stiffness is insignificant. Therefore the test result show no difference. "
Rigth and was proved in other thread:
" certainly not on tracking which is demonstrably false based on IM tests on tracking performance that I have incidentally performed as a function of load. While mechanical impact does occur as a result of electrical load- there is some back emf necessarily generated by the signal current that affects the mechanical motion, but a quick back of the envelope calculation using Lenz’s law and the 10uH cartridge suggests a 2 orders of magnitude difference between the generated signal and the back EMF for a 100 ohm load at 20kHz- certainly not enough to cause tracking issues . By the way, I constructed a model for the cartridge back EMF using Lenz’s law and incorporated it into my simulations.
For those who are interested, the simplest version of the law is V(t)= -LdI/dt.
In this case the parameters can be measured (the LC100A meter from Ebay is a great way to do it) and the back EMF acts to oppose the voltage developed in the coil. The fractional change (attenuation) in the signal voltage is easy to calculate as it approx. equal to -L*2*pi*frequency of interest/Rload. So, it’s inversely proportional to the load R and proportional to the frequency. "
While mechanical impact does occur as a result of electrical load- there is some back emf necessarily generated by the signal current that affects the mechanical motion, but a quick back of the envelope calculation using Lenz’s law and the 10uH cartridge suggests a 2 orders of magnitude difference between the generated signal and the back EMF for a 100 ohm load at 20kHz- certainly not enough to cause tracking issues .
This statement does not support Raul's assertion: it says something quite different!
Dear @imhififan : Thank's again for your advise. The answer to the main subjects in this and other threads ( elsewhere ) where just in front of me and never seen it,. Go figure ! Nothing like those first hand tests
Sorry for the late reply, finally get the tax return filed! 😌
For the Denon DL-103, I chose 1kΩ, because I don’t want to use a too low resistive load to load down the cartridge and at the same time don’t want to use a higher resistance to eliminate those unwanted RFI get into the phono input.
IMO, since RFI is not the music contents, why not apply a correct amount of resistive load to damp the unwanted RFI even though the phono stage can handle it.
On the subject of the tracking… the RIAA sort of works in our favour as the stylus does not have to move as far with the curve sloping down… maybe that lessens the cart getting stiffer for the high freqs? (It is but it hardly wriggles)
I found this thread searching for answers about load impedance on my new turntable and Parasound JC3+ preamp… and while 99% of the conversation/debate here is beyond my interest and understanding I can say that it was helpful in trying a few different things that have resulted in better sound to me.
I have a Pure Fidelity Stratos cart which has an impedance of 45 ohm and recommended loading of 400-500 ohm. I had experiemented with the variable loading on the JC3+ for the past several weeks but always felt like I was missing something. The lower settings (around 100 ohm) seemed smoother yet less dynamic, the higher settings (around 450-500 ohm) seemed more dynamic but harsher overall.
After reading this thread and others linked within I tried the 47K ohm MC setting last night just to see what would happen and lo and behold, it sounds arrestingly better than the recommended loading on my system. A much more wide, expansive soundstage and smoother presentation. Since it was late I didn’t give the bass a workout but I’ll be listening more this evening.
My JC3+ is connected to a Backert Labs Rhythm 1.3 preamp.
Just thought I’d put my .02 in the thread in case there are others like me searching for knowledge in this area. In that it’s not always necessary to follow the manufacturer’s recommendation to get the best sound for your specific system.
@rauliruegasWhat he is referring to is the constant velocity aspect of the cartridge, which is part of the RIAA curve. The faster the stylus moves, the more voltage it puts out. So the RIAA curve rolls off against this characteristic. In fact its often referred to as a 'characteristic curve'.
Holmz, now I seen the ? in your statement. So, you are guessing again due that you do not make the tests yet. Nothing wrong with that because it's the way you are, like to " guess " as in your tonearm thread.
I hope that the test LP you bougth will receive soon. The tests on tracking and resonances will stop your " guessing ". Again, nothing wrong with that.
@atmasphereI read this thread with great interest. This is the first time I've heard what you said. Magazines, manufacturers etc. have not mentioned this. So I change the loading to the 47kohms on my Musical Fidelity NuVista Vinyl stage and lo and beholds it sounds significantly better. I'm not a tech guy so I follow along as well as possible but I certainly notice a positive difference. Thank you!
The preamp sounded terrible, no matter what load or resistance setting. There was an element of distortion or "haze" that hung over every instrument or vocal passage. It sounded awful. And I went down the path of every single dip switch position and I could not discern any noticable audible difference. Stanley Clark bass slam, Pavorati opera with chorus accompaniment, all sounded hazy and distorted. I had to shut the unit down it sounded so bad. I did 2 listening sessions; the second after cleaning all interconnects and making sure all contacts were snug and tight, same results. The unit has been shipped back to Spain for "review". I am always quick to grab something affordable that Stereophile recommends that is a bargain. In this case Mikey Fremer spoke highly of this unit, The Vinyl phono preamp. I'll let you know what they find when they "review" my unit.
I was the one who wrote previously about Faraday's Law and Lenz's law in support of Carr's assertion.
For your information, I have designed DIY phono stages that embody the characteristics that he espouses- very high supersonic overload characteristics for example- and are extremely compliant to the RIAA characteristic, very low noise, and essentially unmeasurably low distortion. There are several hundred of them out there...
In any case, there are no conservation of energy issues here. The mechanical energy of the groove wall reaction to the gravity induced downforce (i.e. the forced motion of the stylus) "uses" Faraday's law to produce an output EMF (voltage). That voltage produces a current that complies with Lenz's law- which essentially defines the inductance of the coil and occurs as an energy conservation consequence- and that current is defined by the total impedance of the coil- the inductance, the capacitance and resistance- the equivalent load impedance in fact.
The back emf is just due to the inductance, and is proportional to the frequency.
For a 10uH inductance at 20kHz, the impedance is about 1.6ohms, so relative to a 100 ohm R the back emf generated that opposes the input voltage is about 1.6/100 of the input voltage, and 90degrees out of phase, so it's about 0.1dB of the signal amplitude.
Yes, the back emf opposes the motion of the cartridge, but it's very small compared to the generated voltage- which is due to the conversion of mechanical energy to electrical energy as described above- and essentially can be ignored in calculating the dynamics of the cartridge arm system.
Say that the effect of back emf is in fact a change (increase) in the effective stiffness of the cantilever assembly. Does that matter? Is a higher stiffness a good or a bad thing?
In the above you can read that it's really just a "thing" not necessarily good or bad, and small changes are of minimal consequences.
You will also discover that many of the things that you thought you knew about cantilever design (i.e. Boron or ruby is better than Al) is not necessarily correct.
For reference, my favorite cartridge is the Miyjama Madake and it has a composite cantilever consisting of a tapered, hollow Al tube with the mounted diamond tip attached to a bamboo section. It actually lends itself well to the splitting of the compliance regions that the above analysis uses.
Dear @wynpalmer4 : Thank's to came to post here because y pasted what you posted several years ago in the subject that the " stifness in cantrilever " could have effects on HF tracking in the cartridge due to loading.
Here imhifiman and me made direct tests in our own systems with the same cartridges and after made changes in cartridge loading we detected no single difference exactly as you posted years ago about your Madake.
By coincidence and after all your evidence after all those years the same person, as in this thread, followed posting what he can't prove in any way.
Dear friends : For some of you that read for the first time the Wyn posts here next I paste what he posted several years ago in other cartridge loading thread:
"" No, I did not design the AD797. That was Scott Wurcer- a colleague at ADI and, incidentally, for whatever it’s worth, also an ADI design fellow. However, I know the design quite well.
He and I were colleagues in the opamp group in the 80s. He focused on high performance relatively low frequency opamps such as the AD712 and then the AD797, amongst others.
I focused on high performance high speed amps like the AD843, 845 (at one point an audio darling), 846 (also a transimpedance design with some very interesting design aspects that I gave an ISSCC paper on) etc. etc. mostly using a complementary bipolar process that I helped develop that I believe was also used in the AD797. I also did things like designing the FET based AD736/737 RMS-DC converter and others.
I moved on to more RF, disk drive read/write, GSM, CDMA etc. transceivers, signal processing, PLL and DSP designs. ""
and here somerthing that he forgot to mention and that comes in that " old " thread that shows that that " myth " of tracking problems due to cartridge loading changes is a lie and nothing more:
""" heavy resistive loading you state could be definitively true- certainly not on tracking which is demonstrably false based on IM tests on tracking performance that I have incidentally performed as a function of load. While mechanical impact does occur as a result of electrical load- there is some back emf necessarily generated by the signal current that affects the mechanical motion, but a quick back of the envelope calculation using Lenz’s law and the 10uH cartridge suggests a 2 orders of magnitude difference between the generated signal and the back EMF for a 100 ohm load at 20kHz- certainly not enough to cause tracking issues. """
Thanks to all you know-it-alls for hijacking my original post. You were all too busy with your science and your theories and your opinions and your nasty behavior. I had not posted anything on the forums for many years. And I came back on with a simple cartridge/preamp loading question and this thread turned into a flamming pile.
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