Cartridge Loading for a phono pre amp

@rauliruegas  Apparently you've yet to sort out that I've never stated that loading affects frequency response of LOMC cartridges. Please cease and desist from claiming otherwise.

47K is the standard loading value for all cartridges, which is why phono preamps have a 47K input impedance. The reason many LOMC cartridge manufacturers might state a lower value (like 100 Ohms) is that they have no idea how competent the phono section will be to which their cartridge will be connected. Obviously it won't sound right if its sensitive to RFI from the cartridge and the loading detunes that resonant peak to which JCarr, Jim Hagerman and I have referred. So a nominal value of 100 Ohms is specified since there are so many phono sections that do have problems in this regard.

holmz the compliance issue developed by changes in load impedance already was answered in this thread. Obviously not important for a normal audiophile because does not affects neither the LOMC cartridge frequency response

Yeah… Ralph fed me a while ago.

Hence I have no idea why you are still on me about being fed.
I am sated,

Dear friends and @judsauce : " You provided frequency response as a function of loading. "

Well , those charts that I posted ( and I deleted latter. ) was the main part of the J.Carr white papers and the foundation for his statement:

 

" To claim that the loading affects the measurable frequency response of the cartridge is bogus. "

 

With LOMC cartridges the changes in the sound " color " that happens when we change impedance loading comes and is developed by the phono stage it self not by the LOMC cartridge . As I said any one of us can change the loading impedance according what we like or is near our targets on each one room/system.

Hagermann made a calculator to know the frequency resonance of the cartridge coming from the MM cartridges and in his white papers when he speaks of LOMC cartridges he said: " that’s why normally 100 ohms is the manufacturer advise " ( something like that. ).

 

In the other side the main issue for we audiophiles is if impedance loading in a LOMC cartridge affects frequency cartridge response and the answer is: NO, it does not affects the cartridge frequency response.

 

The " golden boy " said everywhere/all audio forums to load LOMC cartridges at 47k and in one thread he posted that’s because is the standard value not in specific to MM/MI cartridges but for LOMC too ! ! ? ? ? Go figure !

 

In that thread an audiophile posted " 47K is the standard for MM. Not for MC. " and the " golden boy " gave and posted this answer:

" Actually 47K is the standard input impedance for all ....., MM or LOMC. "

 

Obviously is wrong.

 

When LOMC cartridges appeared at the same time the LOMC manufacturers designed/manufacture too SUT because there was not active high gain phono stages. So, all phono stages came with 47k where the SUT must be connected.

Latter on appeared the active high gain phono stages to drive LOMC in exclusive way with no facilities to handle MM/MI cartridges, even those LOMC phono stages cames ( even some today ) with impedance load different values choices coming from 100 ohms to 1k ( more or less. ) where no one came with the option to choose 47k. All these are facts not imagination as the " golden " boy ".

Problem with what he posted about is that the normal audiophile has low knowledge levels and tend to believe all those lies.

 

holmz the compliance issue developed by changes in load impedance already was answered in this thread. Obviously not important for a normal audiophile because does not affects neither the LOMC cartridge frequency response

 

R.

You let it go, to lazzy to read.

@whistleraudio  aka @holmz  : I already made the " food " but you want that I " eat it " for you., no way.

You need to make your job.

I asked about compliance as a function of loading.
You provided frequency response as a function of loading.

It is like wanting an omelet, and receiving a half boiled egg, and claiming that the/a meal has been prepared.

We should probably just let it go.

@whistleraudio  aka @holmz  : I already made the " food " but you want that I " eat it " for you., no way.

You need to make your job.

 

R.

JC: " Tonearm cable inductance is typically dwarfed by the inductance of the cartridge signal coils (Lyra PhonoPipe cable inductance 0.75uH, Lyra Kleos coil inductance 9uH), so it makes no sense to reduce the cable inductance if the price to be paid is greater capacitance (which is usually what happens).

When authoring the documentation for our post-2009 cartridges, I went up as high as 600pF cable capacitance (to cover audiophiles who may keep their turntable in a separate room / closet). The official loading recommendations for the Delos, Kleos, Atlas, and Etna reflect this wide range of cable capacitances, and the inclusion of highly capacitive cables for special circumstances is why you may see loading values as low as 95 ohms suggested in our literature.

R.

@noromance : " 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 issue. "

Can you show the envelope and the equations?

 

Btw, @whistleraudio  posted: " we need a real physicist here. " and is rigth: he need it.

R

Who is whistler?

 

 

Dear friends: Stupidity exist over the world and certainly in this thread too.

 

" We use a Grado Gold " :

That’s a high compliance MI cartridge with a high frequency limit at around 55khz. Here a professional review pasted highligths of the Grado Gold:

 

""

The Grado Gold sits at the top of the Grado ‘colour’ cartridges. In this sense, the Grado Gold cartridge epitomises the sound that Grado is renowned for: a warm, full sound that tends to match especially well with vocal, jazz, classical and other forms of music that have rich arrangements. The Grado Gold is a ‘pick of the bunch’ version of the Grado Silver – one that is judged to be made with excellent quality and care.

The Grado Gold cartrige has a very warm, dark sounding midrange that results in your vinyl sounding like vinyl .....................................................This cartridge can be a little susceptible to hum. The Grado Gold cartridge review suggests that this is due to the design of the cantilever. When playing music the hum is not audible, but it will detract from some of the frequencies and result in less detail throughout those frequencies. ........................................................................................................................................... The Grado Gold is not the most spectacular tracker. Especially sudden changes such as sudden loud chords or grand detailed crescendos might result in some tracking errors. ..................""""

 

The sample reviewed was loaded at 47k as usually with this kind of Grado designs.

 

So, that election of cartridge trying to prove the HF mistraking can be no more poor or stupid for that load changes purpose:

 

" Its got no worries playing a 30KHz tone, but if we start loading the cartridge we can see the output level drop (with some distortion/noise apparently added),..........

Empirically speaking its easy to deduce that the load is affecting the ability of the stylus to trace the groove, which is why we see distortion as essentially the stylus is mistracking. ""

Really? the whole statements posted are false because the Grado Gold, with out loading changes, shows mistraking ! ! ! Go figure ! ? ! ?

 

Laughing for say the least, you make my day. Go a head ! !, be my guest. Tremendous post for every one can learns but you.

 

R.

In this context, is there any relationship between cartridge bandwidth and cantilever stiffness?

The stiffness is a function of the load impedance. Obviously it will be more supple if loaded at 47KOhms as opposed to 100Ohms!

This says nothing about the bandwidth of the cartridge itself, which would be unaffected by the load. However, the stylus has mass and to trace high frequencies must be low enough that its mass is easily moved by the modulations in the groove. Adding stiffness to the stylus support isn't going to help- at some high frequency (which may well be outside the audio band) the stylus will no longer be able to keep up. This does not take much to sort out.

Any modern cutter has bandwidth well outside the audio band. We use a Westerex 3D cutterhead, which was designed in the 1960s and it has bandwidth to 42KHz, at which point its bandwidth is intentionally limited by the electronics.

We can cut a 30KHz tone on a lacquer and play it back on some pretty conventional LP equipment- for that we use a Grado Gold mounted to an older Technics SL1200, the idea being that any cut we make should be playable on that machine. Its got no worries playing a 30KHz tone, but if we start loading the cartridge we can see the output level drop (with some distortion/noise apparently added), whereas at lower frequencies its still perfectly flat (once equalized).

Empirically speaking its easy to deduce that the load is affecting the ability of the stylus to trace the groove, which is why we see distortion as essentially the stylus is mistracking. 

Even though there is no microphone that has bandwidth that high, it seems a good idea to keep the stylus as planted in the groove as it possibly can be. So IMO its important that the phono section be immune to the RFI generated by a LOMC cartridge so a 47KOhm load be used to allow the cartridge to track to the best of its ability.

BTW, if an SUT is employed, you can side step this issue a bit as most SUTs lack the bandwidth to pass a 1MHz or even 200KHz noise source which can be really helpful to many phono sections! IMO this might be why SUTs have a certain following.

 

@noromance : " 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 issue. "

With no tracking issues, that Wayne measured and JC wihte papers shows, bandwindth/frequency response is not affected.

The OP, you or any one else can load their cartridges witrh the impedance that in each one system " sounds " the best with out worried on that electrical/mechanical load issue that no knows system can " detect " and even direct measures can’t. So why distress about? makes no sense .

 

Btw, @whistleraudio  posted: " we need a real physicist here. " and is rigth: he need it.

R.

 

Thanks Ralph.

 

In this context, is there any relationship between cartridge bandwidth and cantilever stiffness? It seems that as the load-induced stiffening increases, the more reduced the bandwidth becomes.

It seems that way slightly, but there is an electrical component as well as mechanical.
And the stiffness may be more like a phase shift than an amplitude decrease??

we need a real physicist here.

In this context, is there any relationship between cartridge bandwidth and cantilever stiffness? It seems that as the load-induced stiffening increases, the more reduced the bandwidth becomes.

You follow with your tale at Munich but in at least 3 different threads in different internet forums where you, JC and I participated about and where you posted your same " tale " he never confirmed that agree in that " less able to track HF ".

You were not in Munich, plain and simple.

JCarr did not address the topic of high frequency traceability one way or the other. I recommend you set up an LP mastering lathe as I have and you can sort all this out easily enough.

If you are saying that by making the cantilever stiffer that its ability to trace a smaller and smaller waveform in the groove, requiring the stylus to move faster and faster against that increased stiffness, and somehow its ability to move that fast is unaffected, be my guest. But on a very basic level, the idea has no merit.

 

Again: " To claim that the loading affects the measurable frequency response of the cartridge is bogus. "

He not named " bandwindht ".

 

You said: " less able to trace high frequencies. " any cartridge that's " less able " to trace HF change the frequencies where is less able to pick up the grooves information. But the issue is that you can't prove it with true facts/measures.

 You follow with your tale at Munich but in at least 3 different threads in different internet forums where you, JC and I participated about and where you posted your same " tale " he never confirmed that agree in that " less able to track HF ".

 

With out facts and confirmation for me all that is a lie and false as Wayne proved.

 

R.

@holmz  : Be straight and tell me what exactly you want to tell me with:

 

" a spell check on Raul I think. "

 

R.

 

Raul's handwaving aside, I agree 100% with what JCarr has stated, quoted by Raul during his handwaving nonsense above.

Loading does not affect the bandwidth of the cartridge, nor is that something I stated. Raul is employing a strawman argument (a logical fallacy, by definition false) by attempting to put words in my mouth. 

If you ask JCarr directly, he will agree to the fact that loading the cartridge at a lower resistance will stiffen the cartridge cantilever (something quite different from changing bandwidth...). He and I met and spoke about this topic at a Munich audio show 6 years ago; he looked me up at our room, this was after an active thread on cartridge loading on the What's Best forum. 

What I have maintained is that the additional stiffness may decrease the ability of the cartridge to trace high frequencies, not that it would reduce the bandwidth of the cartridge!

If loading had no effect on the cantilever stiffness, then free energy would be the result. At least so far, free energy has not been recognized by the world at large- it remains the stuff of conspiracy theories. It would be quite odd that phono cartridges would somehow be exempt from the laws of physics 😂 Put another way you can safely ignore Raul's rant.

 

 

@holmz : " He never posted that loading to hard a cartridge will cause stiffness to the cartridge cantilever enough to mistracking. "

It was I that wondered whether the loading affects the compliance in theory

I was who posted that only to clarify that J.Carr never support those false statements by atmasphere. Tha’s all.

" to which answered " with false statements. Good for you if that is what you was looking for.

It was not about mis tracking tests, it was about the motor affecting the stiffness in theory, whether or not it had impact on the sound was not my primary focus,

 

I paste all those information coming for true experts for we audiophiles can learn and don’t believe in what " some one " is spreading every where with out facts.

 

Unfortunatelly we are part of these corrupted AHEE. Such is life but people have the rigth to learn out of that AHEE.

what is AHEE?

 

Btw, who is: whistleraudio that you show in your last post.

a spell check on Raul I think.

 

 

Anyway in your last statement seems to me that in some way we are in agreement on that issue. Good.

R.

Maybe in agreement in that it doesn’t matter.

But maybe not in agreement as to whether the load being high or low would affect the compliance and which way it would do so if it did.

@holmz : " He never posted that loading to hard a cartridge will cause stiffness to the cartridge cantilever enough to mistracking. "

I was who posted that only to clarify that J.Carr never support those false statements by atmasphere. Tha’s all.

 

" to which answered " with false statements. Good for you if that is what you was looking for.

 

I paste all those information coming for true experts for we audiophiles can learn and don’t believe in what " some one " is spreading every where with out facts.

 

Unfortunatelly we are part of these corrupted AHEE. Such is life but people have the rigth to learn out of that AHEE.

 

Btw, who is: whistleraudio that you show in your last post.

 

Anyway in your last statement seems to me that in some way we are in agreement on that issue. Good.

R.

@whistleraudio 

 

He never posted that loading to hard a cartridge will cause stiffness to the cartridge cantilever enough to mistracking.

It was my question of whether the cartridge was a current device, and whether the ease of pushing the current through the load affected the stiffness… to which @atmasphere answered.

I was not commenting on sound, just I was confused about back EMF type of affect upon the cartridge’s motor by having a high, versus low, ohm load.

Any change would be like the tail wagging the dog, and small compared to the masses ands mechanical compliance… and resonant frequency… of the arm/cart “system”.

Dear @judsauce  : Start with Benz advise at the end is the cartridge manufacturer and knows all around cartridge/tonearm/phono stage to achieve the best of each cartridge. So you can  start with 470 ohms and test it with LP tracks that you know very well what should be its quality performance levels.

MF loaded his Cadenza Black in your phono stage review at 100 ohms and even at 47 ohm and he did not mentioned any single quality level bad performance because that cartridge loading.

 

Btw, @holmz , next  I pasted what J.Carr ( Lyra cartridge designer ) posted about cartridge loading:

"" 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.   ""


He never posted that loading to hard a cartridge will cause stiffness to the cartridge cantilever enough to mistracking.

What I pasted is a JC conclusion with foundation in his white papers coming from 2018 where  made a in deep analysis, modeling/simulations, with white papers including charts of the behavior of loading an LOMC cartridges with different impedance values along different capacitance values too.

 

Other gentleman that in the past works for Analog Devices been group leader there and where he made/designed  several AD items proved in real time what JC said and that does not exist cartridge frequency response anomalies in any way:

 

""  may not be a renowned Audio Designer, but I am a somewhat renowned IC designer with credits that include cell phone transceivers and high performance opamps.

 I did not design the AD797. That was Scott Wurcer- a colleague at ADI ( Analog Devices competitor to TX/B&B ). 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. Then he continue:

 




""  is why any of the purported effects of 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.

  ( He measured and is the only gentleman I know he did it. )

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 issue.

 As for the rest, well, take the Madake for instance- the resistive load that people (reviewers) claim is best literally varies by nearly four orders of magnitude! I load mine with 60 ohms (as do many users) and I find that the resolution and dynamics is excellent while maintaining a natural timbre, tonal balance and micro/macro dynamics while not creating the unnatural etched image that many "high resolution" MC cartridges produce.

By the way, I constructed a model for the cartridge back EMF using Lenz's law and incorporated it into my simulations.

One of the "joys" of being an IC designer is the compulsion to measure/model everything! However, once the skills are developed it's relatively easy to do as long as someone else has done the hard work of producing suitable models to use.  "

 

All those by this gentleman and J.Carr are facts, something proved not coming from theory or a book.

 

So, the next statements are totally false and a falacy:

 

"  it will make the cantilever stiffer and less able to trace high frequencies. It can and does affect the interaction between the arm and cartridge (effective mass and mechanical resonance).  "

 

@holmz  , not only were proved the statements are totally false but who posted the statements never posted anywhere where he is sharing that false information any tests/measurements/facts to prove it and always only dead silence and not only that but it's just a little of common sense to know that information is false:

 

first effective mass is not affected and the existence of  mechanical resonance for that false " stiffer " cantilever just can't happens at a level where can has a measured effects. Look, if we take a tonearm with 12gr. on EM and a cartridge with say 18cu on compliance and 10 grs. of weigth the tonearm resonance frequency is: 8hz..  Now, you have to change the cartridge compliance from 18cu to 15-14cu ( stiffer ) to change the resonance frequency to 9hz but that does not affects high frequencies.

 

It will be an stupidity by my self to follow post arguments against something false when exist real test/measurements that already proved are false..

 

Regards and enjoy the MUSIC NOT DISTORTIONS,

R.

Always start with 47K to see if the preamp works with RFI at its input. If yes (the preamp is unperturbed by RFI), this will get you the best sonic performance. If it sounds better with lower resistance loads, then the preamp does not handle RFI well.

Also ... with an output of 1.1 you might start at 52 db of gain.

The options I have are as follows: 47K, 1K, 560R, 470R, 100R, and 47R.

There are three more options worth experiments:

257R (560R+470R)

322R (1K+470R)

362R (1K+560R)

 

Thanks @atmasphere .

I was under the impression that the current from the motor was the same with and without the load, so 47k would be a higher voltage across the resistance, and lower resistance would be less voltage.

Looks like I got it backwards.

@holmz 

Back EMF?? No. Any cartridge is a generator of power. When the load on any generator is reduced in resistance, more current can flow. This energy has to come from somewhere (otherwise a new branch of physics would be created...) and it comes in this case from the motion of the stylus in the groove- the cantilever becomes harder to move.

You can easily demonstrate this principle for yourself. A loudspeaker operates on the same principle of a moving coil in a magnetic field. If you have a woofer with nothing connected to it you'll find it easy to move the cone with your hand. If you then place a short across the terminals of the speaker you'll find that the cone is a lot harder to move.

What the load resistor does is three things: it detunes the resonant peak I mentioned earlier, thus eliminating the RFI and it causes the cantilever to be stiffer, possibly reducing the ability to trace high frequencies and certainly affecting the mechanical resonance of the cartridge and arm combination.

So you solve a problem for a phono section with a design bug, in exchange for introducing possible tracking issues. Not a good set of options IMO.

@judsauce The industry spec is 47K for all cartridges. When you load the cartridge at a lower resistance you are asking it to do more work (produce more power to drive that load). Even though its a tiny amount of power, it will make the cantilever stiffer and less able to trace high frequencies. It can and does affect the interaction between the arm and cartridge (effective mass and mechanical resonance).

Wouldn’t loading it down to 250 ohms from say 47k make it softer as the back EMF os gone that “would have been” stalling the motor?

Or do I have it backwards?

@judsauce The industry spec is 47K for all cartridges. When you load the cartridge at a lower resistance you are asking it to do more work (produce more power to drive that load). Even though its a tiny amount of power, it will make the cantilever stiffer and less able to trace high frequencies. It can and does affect the interaction between the arm and cartridge (effective mass and mechanical resonance).

The loading is not for the benefit of the cartridge! The cartridge generates Radio Frequency Interference (RFI) because its inductance is in parallel with the capacitance of the tonearm interconnect cable. This forms a resonant peak which can be activated by the energy of the cartridge itself. That activation is called 'excitation' in radio parlance.

That RFI can be 1 or 2MHz and is injected directly into the input of the preamp via the interconnect cable. If the preamp isn't OK with that, it won't sound right.

If the designer was aware of this fact, 47K will sound fine because the preamp will be unperturbed. Otherwise you will have to use the loading and deal with all that comes with that.

So start with 47K. If the designer knows what he's doing, that will be the position that sounds best.

+1 @artemus_5 

I'm the guy decreasing the load at hi-fi shows and watching the reactions. More open, less constricted and damped. 

Thank you all for your responses.  All this info is very helpful in getting started.

BEST TO YOU ALL!!

Why not try 47K? I believe Mr Luschadek (founder of Benz) recommended that. I ran my Ebony L on 47K which sounded more open. I run my Zyx 4D that way also. From my understanding of Ralph’s (Atmasphere) explanation, the loading or not loading is dependent on the phono stage’s stability. Try it on 47K. Then try it on Benz’s recommended loading. See which one you like better

I've always found Benz cartridges are happiest with higher loading.

I would start with the 1k load and work down. Experimentation is needed though.

You won't hurt anything by trying different loads.

 

 

This is something you need to just try and see for yourself—there is no “correct” value.  Given the quite high output of the cartridge, the 24 ohm source impedance of the cartridge reported by imhififan sounds about right.  I would expect anything from 47k to 470 to be the best sounding.  But, if the cartridge still sounds bright, or thin, or in need of more bass, an even lower value might sound better.  I would only be surprised (and mildly so) if 47 ohms is the value thar sounds best.

Think this may be right:
 

If 100 ohms loading is too low and 470 ohms is too high, you can turn on both 470 ohms and 560 ohms to get approximately 250 ohms loading.

Certainly will be the closest.

I have a Benz Micro Glider rated at 1.1MV

I think your Glider is the SM ( medium output level) with 24 ohms resistance and recommended loading is 240 ohms or higher.

If 100 ohms loading is too low and 470 ohms is too high, you can turn on both 470 ohms and 560 ohms to get approximately 250 ohms loading.

https://benzmicro-northamerica.com/benz-micro-glider/

 

In general, you set the load impedance to 10x the internal impedance of the cartridge. So for example, if 30 ohms, 300 ohm loading is a good place to start.