Cartridge Impedance

Ok, FINE! Jeeesh!

Let's see, I split the infinitive "to annoy".  But most people don't know what an infinitive is, these days.  And the rule on that has loosened by convention. What else?

Seriously, my message is that if you learn something more than merely the answer to your simple question, perhaps next time you won't have to ask.  Also, I personally cannot stand knowing the answer (to almost any factual question) without at least trying to discover the why of it.

Poor English is something up with which I shall not put! Ha! 
Your pedantry is beyond my annoyance. But I thought your post was cute.

Just to be more pedantic so as to possibly annoy the OP, "impedance" is DUE to the inductance and capacitance coupled with the resistances.  If there were no reactive components, i.e., capacitance and inductance, then one would only have to deal with "resistance" which is by definition a constant at all frequencies (although in real life, resistors, some types more than other types, have minor properties of capacitance and inductance, at extreme frequencies).

Dear @lewm  @terry9   :   """  Impedance (which depends on frequency), capacitance (from the phono cable to the preamp), and inductance from the MC coils.  The combination effectively forms a broad band-pass filter. """

that's was posted anthonymaw and this is what I posted on the regards:

"""  What normally happens is that in some phono stages when load impedance is changed exist/developed an electrical circuit between the phono stage: inductance, impedance and cartridge inductance and even capacitance and whom react to load impedance in reality is not the LOMC but the phono stage performance. ""

that's " a broad band-pass filter ".


R.




   

Dear friends. If what atmasphere posted: """  the cantilever to do more work and makes it stiffer, less able to track higher frequencies.  """

if that theory is a proved reality then it's welcomed because what a cartridge designer is looking ( between other characteristics. ) is that for cantilevers build materials on choice  its Young Modulus value be the higher  one and that's why the first/main choices are diamond and Boron over any other cantilever build materials that have the higher YM values.


""" Young's Modulus alt. Modulus of Elasticity - is a measure of stiffness of an elastic material. It is used to describe the elastic properties of objects like wires, rods or ...... """

So it's not wrong as he always says but at the end I never seen a white paper that proved that theory and again if already proved then welcomed !.

R. 

You've got three electrical parameters going on here to consider: Impedance (which depends on frequency), capacitance (from the phono cable to the preamp), and inductance from the MC coils. 

The combination effectively forms a broad band-pass filter. 

You indicate you can adjust the impedance that's basically like a slider on an graphic equalizer with a very wide band.

You can probably just tweak it so that it sounds "good".

To be more precise you would need a calibration record and adjust the impedance setting until you get a more-or-less flat frequency response sweep but that requires more equipment and time and effort that you're likely to want to do. 

Keep in mind that your phono preamp stage also applies RIAA equalization.

Hey guys, as the original poster I just want to say, "calm down"! In my original post, I made the error of saying I wanted to change the impedance of the cartridge. I meant I wanted to change the impedance setting on my phono stage, knowing that the response of the cartridge would change. Some of you understood that. And yes, I just want to know how to set up my system. I don’t give a rat’s tush about all the other stuff! It was a simple question and the first 3 responses told me exactly what I needed to know.
I’m not a regular poster here, but I do read a lot of things with interest. But one of the things I’ve found is that when someone asks a pretty straightforward question, the discussion quickly degenerates into a lot of things that are irrelevant. I’ve seen someone ask, "Am thinking of buying only either cartridge X or Y. Any recommendations?" Then someone will say, "I’ve not owned either, but you should try cartridge Z." I mean, WTF! All he wanted was a straight answer. Ok, end of rant and thanks to those of you who answered my question directly and maybe threw in some USEFUL information.
Yes, testing is the name of the OP game!

Dear @terry9 : "" and whom react to load impedance in reality is not the LOMC but the phono stage performance. """

That’s what I posted.


""" and makes it stiffer, less able to track higher frequencies. """

that’s not proved, it’s theory. In a normal designed phono stage you can test the MC 2000 LOMC cartridge by Ortofon that has really good tracking abilities and changing load impedances you just can’t detect " less able to track higher frequencies ". For this could happens you need that a cartridge with over 30cu goes down to 6cu ( stiffer. ) and that just can´t be happened because a normal load impedance changes. Just common sense.

Btw, the OP says: """ I just bought a phono pre-amp that allows me to adjust the impedance of a MC cartridge. I was using 100ohms. Now I want to experiment. """

what he need is to experiment with because you or me or any one else here know exactly that phono stage circuit design.

Against that reality, all our posts are irrelevant because all of us own different phono stages and room/systems. Useless, he needs to has first hand experiences and that’s all:  he has in the OP the response. My bad explanation and other only can makes that this Agon new comer can have a mix up: maybe not, who knows?.

Testing is the name of the OP game.

R.

@rauliruegas

The OP is talking about loading his cartridge at his phono stage. When you post, "LOMC cartridges are not sensitive to load impedance, are sensitive to inductance changes," you imply that impedance does not affect the sound. That is incorrect.

Perhaps you meant to say, "It is the preamp, not the cartridge which is sensitive to impedance." That statement would be true, but irrelevant, as the OP wants to know how to set up his system. Compare your statements to those of Lewm and Atmasphere, who contribute to the discussion by explaining the technical details as well as addressing the OP’s point.

The loading is strictly for the preamp’s benefit and does nothing for the cartridge.

The reason it is there is because the inductance of the cartridge and the capacitance of the tone arm cable form a resonant circuit known as a tank circuit, which can be driven into excitation by the energy of the cartridge, creating ultra sonic or (more commonly with LOMC cartridges) RF noise.

If the preamp is unhappy with RFI injected into its inputs it might sound bright. The resistor detunes the tank circuit thus eliminating the RFI and calming things down. The downside as others have pointed out is that the loading forces the cantilever to do more work and makes it stiffer, less able to track higher frequencies.

If the preamp does not care about RFI then there is no need for the cartridge loading. But if its provided with a switch, its a pretty good bet that RFI is an issue. IME use the highest setting that sounds right.


You can find more at this link:http://www.hagtech.com/loading.html

IOW- I’m not making this up (I build phono sections for a living).


Now a side benefit of not having to load the cartridge is often that you also get less ticks and pops, since many of those are created by the phono section itself. Referring to the link above, we see that the peak I mentioned is a good 30 dB (1000x) higher than the signal itself! Yikes! If your phono section has poor overload margin, you tend to get ticks and pops on this account.

@lewm  : ""  The inductance combined with capacitance introduced by the IC and by the input gain stage can cause a high frequency resonance. With LOMCs, this occurs at very high frequencies, well beyond audibility or the capacity of any speaker to reproduce, because of the low inductance and given any reasonable amount of capacitance.   ""

yes, that's what I mean with a very bad explanation and is something that's not totally proved: it's what in theory could happens. Now, we can hear nothing at the frequency that was affected or its frequency range.

As I said, LOMC are sensitive ( very ) to inductance and very tolerant to load capacitance changes.

R.

Dear @terry9  : First than all I said that LOMC cartridges are not sensitive to load impedance changes in the phono stage and that's the phono stage whom is sensitive to those load impedance changes thatform a circuit internally and that " there " even capacitance has something to say.

I never told capacitance affects the LOMC items, it's obvious it did not. You, me and every one else knew about.

R.

Lewm is entirely correct. For LOMC cartridges the input impedance should be set at 10 times the internal impedance of the cartridge or a little above anywhere between 50 and 100 ohms covers most modern cartridges. It is not one of those areas where tweaking makes much difference. Play with different cartridges, move your speakers around, play with different room EQs if you can but messing around here is not productive use of your time. In this regard I always follow the manufacturers recommendation especially if you are dealing with companies like Ortofon and Clear Audio. They know a lot more than I do. 
Input capacitance does make a difference with MM cartridges because it changes frequency response in the audio part of the spectrum. Again the manufacturer will tell you what gives you the flattest response. 

Raul, I beg to differ.  Most hi-gain phono stages are "stressed" by using a high input resistance, e.g., 47K ohms, rather than using a conservative 100R with a typical LOMC.  Well designed high gain phono stages tolerate anything up to 47K without problems.  (Here and in my above post, I was referring only to MC phono stages that do NOT incorporate an SUT in order to achieve the gain needed for an LOMC.)  Probably Raul is doing the same.

The reason LOMC cartridges are relatively tolerant to capacitance (vs MM cartridges) is their very very low inductance, in the 50-100 micro-henry range, as compared to MM cartridges which exhibit inductance in the ~500 milli-henry range.  The inductance combined with capacitance introduced by the IC and by the input gain stage can cause a high frequency resonance.  With LOMCs, this occurs at very high frequencies, well beyond audibility or the capacity of any speaker to reproduce, because of the low inductance and given any reasonable amount of capacitance.  With MMs, you have to be careful about added capacitance, because the resonant peak is moved downward near to the audio frequency range due to inductance, but some benefit from just the right amount  of added capacitance which boosts treble in a desirable way.  This is the way I understand it, and I welcome any corrections.

@lewm   Nice summary.

@rauliruegas   Not true. My Koetsu (LOMC) responds to load resistance, but not load capacitance. I usually run it at 1K or more, with internal resistance at 5R.

Dear @jmh128 :  LOMC cartridges are not sensitive to load inpedance, are sensitive to inductance changes.

What normally happens is that in some phono stages when load impedance is changed exist/developed an electrical circuit between the phono stage: inductance, impedance and cartridge inductance and even capacitance and whom react to load impedance in reality is not the LOMC but the phono stage performance.

If the phono stage has a good circuits design then 100 ohms normally is the " rigth " value to go and forget to make changes.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

As a rule of thumb, the input resistance of the phono stage should be about 10X the internal resistance of the phono cartridge, to assure a flat response from 20Hz to 20kHz, all other things being equal. So, first you have to know the internal resistance of the phono cartridge. For a moving coil, this will be the resistance across each of the two coils of wire that produce L and R channel signals. The manufacturer will or should publish such data. Measuring it yourself can be dangerous to the coils, because meters put a current across the coil that can burn it up if the wires are delicate, which they usually are. Technically, "impedance" is different from resistance, but for purposes of the match between MC cartridge and MC phono input, the two terms can be used interchangeably, although it’s true that the phono cable and the gain device at the phono input (whether tube or transistor) will have an input capacitance that also adds to the capacitance seen by the cartridge. (Impedance is defined as resistance dependent upon frequency. Capacitance adds to resistance at any frequency, to affect impedance at that frequency.) MC cartridges are relatively insensitive to low levels of capacitance (e.g., anything at or below 150pF, but this is not a hard number), because their inductance is very very low compared to MM cartridges (more than 1000X lower, in fact).

So, for a LOMC cartridge, the internal resistance will typically be in the range of 10 ohms, unless you’re dealing with a Denon 103 or others like it that have a relatively high internal resistance of 40 ohms (as I recall). If your LOMC has internal resistance of 10 ohms, then obviously your phono stage can be loaded with a 100 ohm resistor or any higher value, and you can expect this match will not roll off frequency response, much, below 20kHz. Still, some of us have found that loading an LOMC at 1000 ohms or even 47K ohms, for two examples, can yield a more open sound. A salient point is that the load resistor actually is loading the phono stage, so if your phono stage is very stable, 47K ohms works fine. If you are using a high resistance LOMC, like the Denon 103, then obviously you are going to experience some high frequency roll-off if you run it into 100 ohms. Some guys like this effect. As Chakster and others have said, you also lose some signal voltage when you get down below a 10X ratio between input (phono) R and output (cartridge) R. 

Chakster mentioned "critical damping".  As I understand it, critical damping occurs at the particular load resistance where you first start to lose signal voltage to ground; the idea is to go down only to the point where that phenomenon just starts to occur.  You would need test instruments to achieve that goal accurately.  I don’t agree with someone who wrote that you can use the load resistor as a sort of tone control by ranging it from say 100 ohms to 47K ohms. In my experience, once you get above the 10X ratio, there is not a great deal of difference to be heard as you approach 47K, except a very subtle sensation (in my system) of greater open-ness to the sound. It’s subjective, but if you were measuring frequency response, you wouldn’t see a great deal of difference.

I have no intention to hijack this thread.

One more question please?

Its has been my understanding, for many years, that adjusting or tuning the impedance (resistance) on a phono stage for a MC cartridge also helped with dampening of the bass speaker cones.  It can reduce the 'springiness' of the cone and help unmuddy the low end.
Is this correct?  
Thanks!

@kingbarbuda

 For MM cartridges, the capacitance of the input of the amplifier should more or less match the value of the MM cartridge. The higher the capacitive value of the input of the phono stage, the duller the sound will be. The lower the capacitance of the phono input, the brighter the sound gets. A mismatch results either in dark dull sound or an overbright, distorted signal. The capacitance of the phono cable should be taken into account when matching a MM cartridge to the phono stage as the capacitance of the cable adds to the capacitance of the phono input.

This is all irrelevant for MC cartridges, it's completely different story. 

I was talking about adjusting the impedance setting on my phono pre-amp.

I suspect that the OP is talking about resistance.

I don’t have a MC cartridge. But I do have an Ortofon 2M Black. I also have a phono Preamp that allows for changing the capacitance. Ortofon recommends a capacitance of 150-300pF. I asked Ortofon, given the above range, what is the best capacitance setting to choose and why? Here is the answer I received:
”For MM cartridges, the capacitance of the input of the amplifier should more or less match the value of the MM cartridge. The higher the capacitive value of the input of the phono stage, the duller the sound will be. The lower the capacitance of the phono input, the brighter the sound gets. A mismatch results either in dark dull sound or an overbright, distorted signal. The capacitance of the phono cable should be taken into account when matching a MM cartridge to the phono stage as the capacitance of the cable adds to the capacitance of the phono input.”

A higher ohm setting will increase the treble and decrease the bass, a lower ohm setting will decrease the treble and increase the bass. There is no correct setting it's a matter of personal taste.

More prominent.

You're welcome @jmh128 :) 

Thanks to all! You've answered my question.

1) With higher load impedance on your phono stage you're actually unload the cartridge, you have to try this if you're looking for more open sound and better high frequency. You can try anything up to 47k Ohm for MC cartridge. Don't be afraid to try 'electromechanical damping' as it too can be tuned and you may like it also, even possibly better.

2) With lower load inpedance on your phono stage, rather than unloading by going high, this in fact causes the coil to produce more current and hence this introduces electromechanical damping - the output will be lower, so keep that in mind, and explore the final value, deciding by listening. Personally i've find a range of 100 Ohm - 2200 Ohm very pleasant for 99% of my LOMC cartridges. However, there are some cartridges that can be just fine with load impdance lower than 100 Ohm. 

Anyway, it depends on the personal preferences and recomendations from the manufacturer. They are normally declare anything higher than 100 Ohm and you can't make harm by going anywhere up to 47 000 Ohm. If your cartridge is not bright then going higher (unloading a cartridge) is better in my experience. Your experience can be different in your system. 

The cartridge impedance is what it is, there’s no such thing as adjusting the impedance of the cartridge. What’s adjusted is the impedance or load the cartridge sees. Top end changes are easily noticeable, but there’s more to it than that. Reading up will help, but you learn a lot more by just doing it. https://www.mysonic.space/phono-cartridge-impedance-loading

Changing the impedance from 100 to 200 ohms with my Denon moving coil increased the clarity and focus and the highs sound better.