Cartridge Loading for a phono pre amp

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.  

Everybody have a nice day.  NOT.

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. """

R.

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.

Regards and enjoy the MUSIC NOT DISTORTIONS,

R.

Just another bit of food for thought.

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?

Equivalent circuit of a phono cartridge (pspatialaudio.com)

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.

@wynpalmer4

👍 Thanks! It's always a pleasure to read your posting in here, AK and diyaudio!🙏

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.

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.

@atmasphere I 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!

Hello, I am the poor guy that started this post with a simple question of pre-amp load settings.

Is anyone interested in my results when testing all of the settings on the pre-amp that you all recommended?

Si.

Please.

Hello, I am the poor guy that started this post with a simple question of pre-amp load settings.

Is anyone interested in my results when testing all of the settings on the pre-amp that you all recommended?

For acting like a psychic, may i ask where the LP is in the postal system?
And I should be picking up the ADC this weekend of next week.

I think I have the RIAA curve backwards though, so it would not help us at higher freqs with loading… exactly opposite.

atmasp, thank's but no.

🤣

atmasp, thank's but no.

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.

R.

@rauliruegas What 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  : Sorry my ignorance. Could you explain in specific what do you mean with:

" the RIAA sort of works in our favour as the stylus does not have to move as far with the curve.."

Thank's in advance,

R.

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. 

@imhififan thanks mate!

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)

And did you choose 100 ohms, 47 kph, or something in between?

@holmz

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.

http://www.hagtech.com/loading.html

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 

Good ! !

R.

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!

JC.
,,,get a life.

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. "

R.

@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.

R.

@holmz 

I always prefer phono stage featured user select-able loading option, so the user can choose their preference.

And did you choose 100 ohms, 47 kph, or something in between?

As previously asked…:

So sonically was the difference between 100 ohms and 47k readily apparent?

@holmz 

I always prefer phono stage featured user select-able loading option, so the user can choose their preference.

@imhififan So sonically was the difference between 100 ohms and 47k readily apparent?

I put in a new stage a couple of weeks ago, and it arrived with a 1260 ohm loading and a SUT in-line. It was not a great sound... but I was excited.

So I pull it off the shelf, and opened it up to go to 47k for a MM cart with dip switched for no SUT.

And the sound came good.

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.

@rauliruegas

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.

Dear @holmz  : Did you follow the @imhififan  advise? , this is his advise:

 

" Perform a simple test with Hi-Fi News test record will give us the answer.."

Tests for resonance and tracking changing load impedance

I need to wait for it to arrive before I can use it..

Dear @holmz  : Did you follow the @imhififan  advise? , this is his advise:

" Perform a simple test with Hi-Fi News test record will give us the answer.."

Tests for resonance and tracking changing load impedance.

R.

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.

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.)

Dear @imhififan  : Due that was your advise: " Perform a simple test with Hi-Fi News test record will give us the answer.."

Did you the resonance and tracking tests?

Thank's in advance.

R.

Raul is obfuscating.

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.

Occam's Razor sorts this out easily enough.

@holmz : That's a highligth of the Swiss CH 95K+ phono stage.

R.

 

Again, you readed it in a wrong way because you or me can’t find out any " wizard " in my whole system.

 

What’s happening with you and with what you read here and every where?

 

R.

OK @rauliruegas what is this:

 

 

The P1 "Wizard"

 

As with all voltage amplification circuits, proper impedance loading is crucial to the resultant frequency response of the audio signal. The P1 provides a selection of five hundred resistance values from 20Ω all the way to 100kΩ in logarithmic increments; you’ll have steps of 1 ohm in the 20 Ohms range and the gaps between the values are increasing as you go upwards. The steps around 24k Ohms or above, are at 500 ohm increments. While most manufacturers will tell you to "go with your ear" while choosing the right loading, CH has developed an approach based on scientific measurements. The P1 is built in with an ingenious two part "Wizard" which will determine the optimal settings for GAIN and MC loading resistance automatically.

 

The P1 comes with a test LP designed to work with the P1’s internal distortion analyzer.

 

How reliable is the Wizard? I compared the results generated by the P1 versus the results from my own proprietary test LP and analog setup software currently under development. We arrived at the exact loading choice with a difference of only 10-20 ohms. Assuming we are relying on each other as the reliable benchmark, the results are close enough to be called scientifically verifiable! "

 

Swiss made too and expensive Dartzeel 18NS. MC load impedance up to 300ohms:

What's happening with you and with what you read here and every where?

I don’t know, I admit that I am having a hard time following along.

@holmz  : " I happy you have a wizard,...."

Again, you readed it  in a wrong way because you or me can't find out any " wizard " in my whole system.

What's happening with you and with what you read here and every where?

R.

Dear @imhififan  : I followed your advise and my curiosity and made some tests with 4 different cartridges mounted in two identical tonearms in the same whole room/system. Cartridges were: Denon 103, Sumiko Talisman ( B ), vdH Colibri and Ortofon A95 and I used 3 different of my test recording LPs where I runned for resonance and tracking . All cartridge/tonearm alignment set up as accurate as I can and take care of recording/stylus tip clean. I used too the after market AT vacuum hold down item as Discwasher gun demagnetizer. I did it with and with out using the damping silicon tray in the tonearms:

results in all cases were with out differences because thwe load impedance changes.

I used too 5-6  LP demanding tracks of nor mal MUSIC recordings one a Sheffield direct to two track recording where by a fault in my sample ( I think is a fault but not totally sure. ) in one track several of cartridges have a mistraking in that high frequency grooves. Here the mistracking in the 103 was what normally is no matters of load impedance and the others where the mistracking is really near to non-perceptible stays that way.

Other track was the last third part of the Telarc 1812 where not only has a toruose low bass grooves for any cartridge but at the same time tortuose high frequency with the Carrillon/tambourin/triangle. Here the load changes shows no difference on tracking/resonance and in all the LPs " clicks/pops " were non-existents due to load changes.

R.

@holmz  : " So we are on two different targets..."

Again, for whatever reasons you just don't read in the rigth way the posts in thios and other threads because I was not who posted:

"" Your target for mechanical resonance is between 7-12Hz. The mechanical resonance is a product of the mass of the cartridge in the arm vs the compliance of the cantilever of the cartridge. Changing the load from 47K to 100 Ohms can easily get you outside of this target window- and that can cause tracking problems.. " " 

R.

Dear @fundsgon @holmz : " also been an exercise in personal credibility..." , Really? because again   your " trusti man " is way wrong, not the calculator that’s similar to the one in VE.

The Lyra Kleos is a great match for the SME V as I posted with a true resonance frequency at 9hz. Better than that impossible.

The other calculation is wrong because the Lyra compliance spec is at 100hz not at 10hz that’s what all calculators run. Japanese cartridge compliance specs normally comes measured at 100hz instead 10hz and at 10hz the Kleos has a compliance around 17-18cu not 12cu.

Any rookie knows that, even me. Obviously both of you have to follow learning, as today.

R.

 

atmasphere @holmz : " " Your target for mechanical resonance is between 7-12Hz. The mechanical resonance is a product of the mass of the cartridge in the arm vs the compliance of the cantilever of the cartridge. Changing the load from 47K to 100 Ohms can easily get you outside of this target window- and that can cause tracking problems.. " "

 

Where out side in specific: 5hz? 15hz? 6hz? . All you have to do is show it.

 

 

R.

Ah you are talking about cartridge stiffness with respect to the arm/cart resonant frequency.
I was only wondering about the stillness changing.
And not wedding that to overly affecting the arm per se, but more as to whether the loading is affecting the cartridge stiffness, and maybe affecting the tracking of the cartridge.

So we are on two different targets, which are not intersecting.

I happy you have a wizard, I am not even sure what it is, but I like to at least have an intuitive feel for physics, if I cannot have a grasp on the equations.

I would want that grasp, irrespective of whether I had a machine that told me the answer.

This has been a fabulous technical lesson provided by one of the industries best. This has also been an exercise in personal credibility. Desperation vs confidence. Compliance vs torque. What a discussion; one for the ages

I am usually always confident 😎, so I have a start on it.

This has been a fabulous technical lesson provided by one of the industries best. This has also been an exercise in personal credibility. Desperation vs confidence. Compliance vs torque. What a discussion; one for the ages.

@holmz Oh man, you're doing Raul's homework for him😄

If I cannot get fed, then at least I can do the cooking or the dishes ;)

So you're not going to answer my question? That leads me to think you are simply trolling. Because there are internal losses, the cantilever will not be quite 470 times harder to move; we'll call it 400, assuming that its also designed to operate at 47K. 

This is based simply on this fact:

https://physics.stackexchange.com/questions/120005/why-do-electricity-generators-have-to-work-harder-for-higher-loads

Since the generator only converts mechanical power to electric power, the motor driving the generator shaft must supply at least 10 times more power in order for the generator to supply 10 times more power.

This is fundamental and inescapable.

You are correct on one thing, it was pretty easy.

The arm has an 11 gr effective mass, the cartridge is 9 grams; the compliance is rated 'Approx. 12x10-6cm/dyne at 100Hz' note the word 'Approx' (that is variable based on load). Now plug those values into the calculator:

http://korfaudio.com/calculator

You'll see for starters this cartridge is not a good choice for this arm. Now let's assume that the cartridge is loaded at 800 Ohms. By decreasing the load to 100 Ohms we ask slightly less than 8x the current out of the cartridge. This will increase the stiffness a bit, how much is difficult to know without more specific information about the cartridge, but as you see from the first link of this post it has to be significant. Let's assume that the load is a fractional bit of the compliance instead of dominating it. You can see what happens if the compliance is decreased by decrementing from 12 to 11, which is conservative; this puts the results outside of the green zone on both charts.

Do it with this example:

tonearms SME 5   Cartridge: Lyra Kleos    resonance frequency: 9hz.

So you can go from 47k to 100 oms  and 70 pf of capacitance

Now, show that that load change puts  out of the ideal range. Easy for you, just show it.

@rauliruegas I see you are refusing to answer my prior question to you. I've handed all the information you need to you on a silver platter. But the way you are reacting suggests you are not here for any other reason than to troll. If that is not the case, go ahead and answer my prior question. Here again for your convenience, are both of my prior questions.   If you are disinclined, I can only assume its because trolling is your goal rather than anything else:

Anyone with an elementary school education can work out the math here. Perhaps, knowing that, you can tell me where that current is coming from??  If you can answer that, a bonus question: what is the consequence of that current flow?

atmasphere @holmz : " " Your target for mechanical resonance is between 7-12Hz. The mechanical resonance is a product of the mass of the cartridge in the arm vs the compliance of the cantilever of the cartridge. Changing the load from 47K to 100 Ohms can easily get you outside of this target window- and that can cause tracking problems.. " "

Where out side in specific: 5hz? 15hz? 6hz? . All you have to do is show it.

R.