A question of loading...

I have just replaced my aging tube preamp with a new model. When I was using my older model with tube phono stage, I would run my Lyra Kleos and other MC cartridges with a load of 750 ohms. So, I assumed that with my new tube phono stage, which also utilizes a transformer in the phono stage and is also built into my new preamp, that the same cartridge loading would apply. I listened to the Kleos for about a week with this loading, and frankly, while it was fine, I wasn’t bowled over. Tonight I decided to experiment, so the first thing I did was to run the cartridge straight in, with no loading plugs. WOW, the increase in overall musicality and soundstage width was eye opening! Lesson learned is that not all gear is going to react the same when it comes to cartridge loading, particularly if there is a transformer involved and even if you are using the same cartridge from one phono stage to the next! An eye opener, anyone else experience something like this?
749cdfb3 0814 490e b189 a364ad773263daveyf

Showing 9 responses by atmasphere

"" To claim that the loading affects the measurable frequency response of the cartridge is bogus. However, if inappropriate loading bathes the phono stage in copius amounts of high-frequency noise, it may start to distort (unless the designer implemented various techniques to make sure that this won't happen), and the result will likely be intermodulation distortion. ""

"" If the phono stage does not have high overload margin at ultrasonic frequencies, or not-so-favorable linearity at ultrasonic frequencies, the ultrasonic spike resulting from high-value resistive loads (the spike can be in excess of 30dB at 5-7MHz if the phono stage input termination is 10kohm or higher) can easily result in ringing and intermodulation distortion which will obscure real information.

But if the designer does give his phono stage high overload margin and good linearity at ultrasonic frequencies, the phono stage will treat the ultrasonic spike as simply another signal, and no intermodulation distortion products will be generated that could otherwise be low enough in frequency for the ear to hear.  ""
These statements are exactly in lockstep with what I've been saying and I agree with them 100%.
In the other side JC never said he had white papers of that cantilever stifness as a consequence of the cartridge loading, not even gave any single example with any of his cartridges or other ones where he measured that issue, so no measures about by him and certainly not for any one in this thread.
No-one has ever made a claim that there were any white papers. But FWIW they aren't needed; anyone versed in electronic theory (or anyone who has worked with generators or alternaters) understands how this works.
[FONT=&amp]Playing with the input impedance means also playing with the sound character. The influence of the load impedance on the differences in sound is caused by the change of the crosstalk levels and the amplitude raise at the resonance frequency. The lower the load impedance, the higher the current and the more dynamic the sound.[/FONT]  """

And here we see again (with exception of the last sentence) that Ortofon agrees with Jonathon Carr and myself, although their English is a bit clumsey. The 'more dynamic the sound' bit is false though. It likely has no effect with regard to dynamics as that is a function of the groove modulation. Add this portion to what Jonathan states above and you have nearly the complete picture.

My first hand experiences says that with my phonolinepreamp and in the past with the Classé Audio DR-7 loading at 100 ohms and never happens a mistracking because that kind of loading maybe just the SPL goes a little lower and nothing more.
That's good- but this sort of anecdotal comment isn't evidence or proof of anything in particular.

Raul, its painfully obvious that electronics isn't your field. There is something called Kirchoff's Law (google is your friend), which is taught in engineering and technical classes on the very first day of class, so this is engineering 101. It essentially says that if you put a certain amount of energy in a system, there will not be any more or any less energy in that system at any other point. So if you're going to make a cartridge (which makes energy, we all know that) do more work by making it drive a lower resistance, it would be a violation of Kirchoff's Law for the cantilever to not get stiffer. The cantilever motion is what makes the cartridge generate energy.

Quite literally this isn't rocket science. Its basic technical and engineering science :) taught on the very first day of school. You can prove what I'm saying very easily if you have a bicycle with a wheel equipped with an alternator for lighting. When the lights are not on (simulating no or a light load for the cartridge) the wheel spins easily and for a long time. When you turn the lights of the bike on (simulating a low resistance load of a cartridge), the wheel is harder to spin. There are millions (literally) of other examples.

Now I can put this another way: If what you say (that loading the cartridge has no effect on the stiffness of the cantilever), is true, then you have just solved the world's energy issues! All the world would need to do is build millions of cartridges and load them at low impedances and just collectively move the cantilevers. Since they don't get any harder to move, we get **free energy**!! Yay! a new branch of physics is born, brought to us by YOU! You'll be a famous world hero!

The Greek philosopher Aristophanes once said “Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness sobered, but stupid lasts forever.”

Frank Zappa once said “There is more stupidity than hydrogen in the universe, and it has a longer shelf life.” This was probably a comment about how people will stubbornly hang on to their mistaken ideas, even in the face of reality....

You have a choice: you can have your ignorance cured, or you can choose willfully to be ignorant. The former is smart, the latter stupid. Which is it going to be??

You are showing your ignorance Dover. 47K is not standard for a MC and not standard with the Etna Lambda, which I am listening to as I type this. 47K is the standard for MM. Not for MC.
Actually 47K is the standard input impedance for all phono sections, MM or LOMC.

LOMC cartridges often seem to need lower impedances, but this is really for the benefit of the phono preamp, not the cartridge, due to the reasons Jonathan Carr has talked about, mentioned earlier on this thread.

I've been telling people this for years. If your phono section does not have troubles with the RFI caused by most LOMC cartridges (and the capacitance of the tonearm cable) then 47K will sound just fine.

An additional side benefit will be less ticks and pops, since the phono preamp will generate ticks and pops if the input section is overloaded by the RFI at its input. It is for this reason that tubes have a distinct advantage over solid state, as its easier to designed a phono section using tubes that is hard to overload.
OTOH, do tubes have a distinct advantage?? I would say that they do when it comes to overall SQ, plus the decreased likelihood of overload, BUT they are never 100% quiet...at least IME. There is always some minimal hiss..and this leads me to believe that their noise floor has to be higher than ss.
Yes, they are noisier but they can be quiet enough that 0.2mV is no worries.
Jonathan Carr never says anything remotely similar about optimum loading for his cartridges. I am looking at Jonathan Carr's loading chart that came with my Etna as I type this and depending upon the gain setting and the total capacitance of the tonearm wire in interaction with the phono stage and the recommended loading ranges between 104 and 340 ohms for 0dB gain and between 284 and 887 in the highest gain column of +6dB.
But that is Jonathan Carr who sees things (rightly so) from the perspective of the cartridge manufacturer. Now lets talk about phono stage producers. They don't espouse charts, they talk about listening. Each phono stage manufacturer knows the attributes of their designs. My Manley Steelhead with built in step-up transformers is not going to behave the way a Sutherland 20-20 (just for example) will.
To say that 47K is the standard or de facto or even starting-point loading for a LOMC is ludicrous. 

You might think it ludicrous, but 47K is the industry standard for phonograph inputs nonetheless. Because many phono sections have problems with the RFI generated by LOMC cartridges (keeping in mind how much gain they employ to work with cartridges of output this low) its common to see loading options on such preamps. Think about it this way: Since all cartridges are different, and you need an input resistance with any circuit that can amplify, what would be the correct value for that resistance?? You might ask your self why most phono sections have a 47K input impedance... the answer is that is the industry standard; it was not something that is a random coincidence that so many phono sections are built this way.

Jonathon has his recommendations for a very simple reason: He cannot be sure that the phono section to which you are connecting his product is going to be alright with the RFI generated by the cartridge/tonearm cable combination. Further, he's also go not idea what cable you're using! So he has loading recommendations on that account, and they cover a range rather than being a specific value. He also knows that most phono sections don't deal with the RFI issue very well. But if you talk to him, which I have done in person, you find out that he thinks 'no loading' (IOW the stock 47K input of the phono section) is better if you can pull it off.

Its true as you say that not all phono sections act the same :)  That is a bit of an understatement! For example, a phono section employing an SUT will not have RFI issues, since the RFI is blocked by the SUT. Instead, you have to be careful to load the output of the SUT correctly so that the transformer does not 'ring' (distort) on account of the specific impedance of the cartridge (if you want to know more about how the ringing phenomena works please ask). So you'll find that depending on the cartridge, different resistor/capacitor values are used to accomplish that loading. So yeah, that's quite a bit different from a solid state phono section using opamps or an all-tube phono section that can run the LOMC cartridge straight in!

There is no single advantage, today SS phono stages just can't be overloaded in normal condition: comes with very good headroom. That " problem " was a " problem " of the past/several years ago.
With a solid state phono section using either opamps or discreet transistors, its the part that is outside the feedback loop that is open to overload. This is the input circuit of the preamp, which might be no more than the base of the input transistor.  We're talking about an electrical peak of 20-30dB that occurs with all LOMC cartridges in tandem with the tonearm cable (the former having a high-Q inductance, the latter having a capacitance; the two in parallel form the resonant circuit, whose resonance might be at several MHz). While there are SS phono sections that deal with this properly (Pass Labs for example) its a falsehood to say that all of them do!

Its a simple fact that if the designer has not made provision for this resonant peak, it can overload the input circuit, resulting in a tick or pop when it does so. To get around this problem, you have two options: design the phono section to take quite a bit more input voltage than LOMC cartridges are known to produce (and do as much as you can to prevent RFI from coming in through the input connectors), or come up with a loading provision (the 'loading resistor'), so the resonant peak can be detuned.

Of course if you use the loading resistor option, you are asking the cartridge to do more work. If you're using 100 ohms as a loading resistor, that's a couple of orders of magnitude more work than if the cartridge is driving 47K. This results in the cantilever being stiffer- the same as what happens with a raw woofer if you short it out (they are both based on the same principle of operation).  This is not a matter of debate, if you feel the desire to do so, take it up with Mr. Ohm. Ohm's Law cannot be defeated and isn't open to interpretation. If there is more current flowing, it has to come from somewhere and that somewhere is the motion of the stylus in the groove. So the fact that the cantilever gets stiffer is not controversial. Anyone versed in the art knows this- Jonathan Carr and I discussed this issue at the Munich Show a few years ago. 

Raul's stipulation that this overload issue is something of the past is correct as most phono sections were only designed to have 'enough gain, low enough noise and proper EQ' and the electrical resonance was ignored. But he is incorrect in his assertion that this has been put to bed; this is why loading provisions exist on current equipment and are identified as 'loading' when they are really there for the benefit of the phono section, and the phono section will sound different if the RFI isn't suppressed. Its likely that the cartridge will sound different too, not because you are preventing it from ringing, but because the cantilever becomes stiffer as the 'load' resistance is decreased. This measurably affects its mechanical resonance in the tonearm. 

Ralph-thank you for your very polite and informative response. I apologize for my strong words directed at you.
No worries- and no offense taken. But I appreciate your words.
What is odd, and I am not quite understanding this part, is why with my older CAT phono stage, which did not use a SUT at all, that a load of 750 ohms was better sounding than straight in at 47Kohms, yet with my new model, this is definitely not the case. Presumably due to the SUT in my new CAT??
A lot to unpack here....

Its a lot easier to build a tube input circuit that has much higher overload characteristics! In a tube circuit meant for LOMC, if you overload it with too much input voltage, the overload isn't occurring in the input stage- it happens further downstream. With solid state, the overload often occurs at or very near the input, often because the circuit uses feedback, and the input section might be outside the feedback loop- even if its only the base of a transistor. But semiconductors are far more likely to rectify RF energy too, since they are diodes at some point or another. Its this latter characteristic that makes them more pesky in this regard.

SUTs are another matter altogether! I suspect Ken got tired of people calling about noisy tubes and SUTs are a way to get around that. For tubes to be really quiet in the front end of a phono section, they have to be at the top of their game. As they lose transconductance with age, the noise goes up. You have to keep the tubes active even when the preamp is being used playing CDs, so the tubes are going downhill all the time. By installing an SUT, you can easily quadruple the usable life of the input tubes.

But that comes at a price! SUTs have to be properly loaded to prevent ringing (distortion) and the proper load varies from cartridge to cartridge, since transformers **transform** impedance. So if you have a 10 ohm cartridge, the output of the SUT will be an impedance much higher than if you have a 5 ohm cartridge. So the load it needs will be different too. If the load is insufficient (too high impedance) the transformer will ring, which is to say some very high amplitude harmonics will appear at its output. This makes them very tricky to use! I find that even with them set up right, you lose a bit of detail (bandwidth at this signal level shouldn't be an issue)- that's why I've really stayed away from transformers in the audio path.

It does make sense-once one understands the higher resistor value being to ground-that the lower resistor value approaches a short circuit and that the cantilever becomes stiffer and less damped, not less stiff and more damped. Damping is the absorption/dissipation of energy.
Just to be clear- if you load the cartridge more, the cantilever will be more damped in addition to being stiffer. This can affect tracking if you get the resulting mechanical resonance outside of the 7-12Hz window.

I still maintain-righty or wrongly-that two things are at play with loading. One can argue that they are interrelated. One is preventing ringing/overload and another is changing the magnetically induced behavior of the cantilever.

We need to be really specific about what is happening here. Many years ago I had this idea about building a little box that would sort out what the ideal loading value was for a LOMC cartridge. This might have been about 30-35 years ago... At any rate, what I found was that **the cartridge itself does not ring at audio frequencies**. You can pass a 10KHz square wave through it and it will look exactly like a 10KHz square wave at either end of the cartridge. Quite simply the inductance is so low that its inconsequential at audio frequencies. It can't ring (and on this point, MM cartridge most definitely **can**, so loading with them as affecting things at or very near audio frequencies). BUT- it can have effects at much higher frequencies as I described earlier. (The result of my research in this regard was that I would not be able to make such a box, since ringing wasn't the issue.)

BTW, if there is some question about what the load should be, @lewm 's rule of thumb of being 10X higher than that of the cartridge itself is a pretty good one. Such a value will detune the radio frequency issues and won't affect the output level of the cartridge.

There are more than just two things going on with loading- and they are very much interrelated as you say. Two are caused by the cantilever getting stiffer- it can affect how the cartridge tracks and its arguable that being less supple, is less able to trace higher frequencies. So that's two things. But the loading affects the preamp too; by eliminating the RFI at the phono input, it can make the preamp less bright (a common result of RFI in audio circuits) and possibly less ticks and pops if the phono section has poor high frequency overload margins.

47 steps in attenuators seems to be another inexplicable industry standard.
@fsonicsmith That's because if you don't go entirely electronic with the volume control, its insanely expensive to get a custom switch built with the exact number of steps you want. So you get a switch that someone already makes. That part is expensive too- but you don't have to buy 1000 in order get it.
Ken uses a SUT that doesn't really have a lot of boost because I think he believes that as the step up increases, the loss is SQ is too great.
That's been our experience too. The more stepup you use the less bandwidth you get.

We regularly run cartridges that are 0.2mV. If you have an SUT you should be able to get in that same range quite easily. The only thing you would have to work on is the loading of the SUT, with which Ken might be able to help you. We use Jensen Transformers when we use an SUT; they have published a pdf file of all the loading values for a great deal of different cartridges including Lyras.

Keep in mind that 0.25mV is 6dB less than 0.5mV; that means you'll have to run the volume control up a few notches to get the same sound pressure. I don't think you'll have any problems doing that :)
So not going with education huh?

A.Porter place he was running his low impedance MC cartrige around 400-500 and when I listened to it ( I/O phono stage. ) I told him that something was wrong with and I suggested to change the load impedance to 100 ohms and the cartridge quality performance " shines as never before " ( this was the AP words. ) and yes : nigth and day change for the better.
No doubt.
if inappropriate loading bathes the phono stage in copius amounts of high-frequency noise, it may start to distort (unless the designer implemented various techniques to make sure that this won't happen), and the result will likely be intermodulation distortion. ""
Apparently Albert's preamp needs that because
If the phono stage does not have high overload margin at ultrasonic frequencies, or not-so-favorable linearity at ultrasonic frequencies, the ultrasonic spike resulting from high-value resistive loads (the spike can be in excess of 30dB at 5-7MHz if the phono stage input termination is 10kohm or higher) can easily result in ringing and intermodulation distortion which will obscure real information.

The issue that's false is that exist mistracking when more current running through the cartridge.
I don't think anyone has stated that this leads directly to mistracking.
The issue is that mistracking not that cantilever stiffness. It's you who need to prove with measures that can gives the rigth answer to that question I made it two years ago and that you never answer.
That is probably because I never stated anything as you seem to be implying here. I think this is probably because I use English as my main language and you don't; this apparently has resulted on a misunderstanding on your part.

What I *have* stated is that loading affects the stiffness of the cantilever. And further, that this could affect its ability to trace high frequencies. But I can see that this statement can really be misinterpreted. Note the use of the conditional 'could' in the sentence, as well as the rather ambiguous 'high frequencies'.

So let me put this another way. Most cartridges easily go to 40 KHz, I've measured this by cutting signals that high on my lathe and playing them back. Now we know that loading down the cartridge makes the cantilever stiffer. Are you saying that if the cantilever were ***easier*** to move, that it was less stiff, that it would not trace high frequencies as well? If the answer is 'no' then you have to accept that if you make it stiffer, at some point (maybe well out of the audio band) the ability to trace higher frequencies might not be as good.

Now the other aspect of cantilever stiffness is the mechanical resonance that the arm/cartridge compliance system exhibits. Making the cantilever stiffer is another way of saying that you reduced its compliance. Are you saying that by reducing the compliance of the cartridge that such will have no effect on the mechanical resonance? If no, then you accept that the mechanical resonance is affected by the compliance of the cartridge.

In 2018 thread where wyn posted and before the first wyn post you posted not one but twice:

""" When you load at a very low value (like less than 100 ohms) its possible to reduce the cartridge output and also decrease high frequency tracking abilities. ( Btw, wyn runs his mandake at 60 ohms and performs fabolous. Obviously no tracking issues. )

"" the cartridge is asked to perform more work as it has to drive the lower resistance. This makes the cartridge cantilever stiffer and less able to track higher frequencies. This is why the resistor can act as a tone control. ""
Yes, and this is all correct. Note the use of 'is possible' in the first paragraph, and the use of 'can' in the second. These modifiers must be considered in the use of English as a language.
Other curious things that happened with you in those threads in 2018 is that in both threads JC participated and in both threads he not supported with a post the conversation you said took place in Munich when talked about that low load impedance consequences. Weird.
This is innuendo. Come up with a link- and I will talk to JCarr myself if he is denying that conversation took place, but I doubt that is the case- he's been pretty steadfast. What is more likely is you are using a logical fallacy or simply misunderstood due to the language barrier. The latter has happened before on other threads.
MC are almost immune to impedance loading.
Well it took a couple of years but we're finally in agreement- nice to see that you've come around.