Running LOMC with MM (47K) loading


This is the way I run my Zyx 4D and my Benz Ebony L before it. I have a JLTi phono preamp which allows me to do this. I have been satisfied with this pre since buying it new. Yet I may be in the market for a new (Different) one. However some I have seen may not offer this ability. One that has great reviews also  has the loading and gain all tied together. Not sure about Herron but it may be out of production. Not sure about others. 
 
The question comes  with @Atma-sphere comments on loading and circuit stability. He contends that the loading  damps (stops) the cartridge cantilever from moving as freely as it was designed (my words) And it is better IF you can run with no loading. But that requires a stable circuit which not all have. Apparently my JLTi has a stable circuit because I have been running LOMC's this way for a 10-15 yrs. 

That said, should I require this attribute to my next phono preamp? And might I be better off to send the JLTi to Joe Rasmussen  (Allen Wright's partner) for upgrade to Pre and new Power supply?. That will be the cheapest and that is likely to be the step I take. However the question still exists. If the damping is as per Ralph's assessment, it would seem that the stability of the  circuit is of greater importance than the ability to have a lot of loading options with unstable circuitry. Another question, Is loading a band aid for a  circuit which is not at an optimum? I am not an electronic tech so I am not  looking to stir the pot but  for my own  understanding  Thanks
artemus_5
I have a Herron VTPH-2A and I run several lomc cartridges.  I leave the mc input unloaded.  There's something on the Herron site that explains this.  That being said, mine came with several pairs of loading plugs including a pair of 47k plugs.
Which version of the JLTi do you have? My version is mk4 with manufacturer mod (optional loading for MM up to 100k if needed). Now mk5B available.

I wouldn’t even look for a tube phono stages. In my opinion phono stage must be Solid State and JLTi is excellent, if you have a very old one you’d better look for the latest JLTi.

Next to the JLTi on my rack I have Gold Note PH10 with PSU10 (MM/MC, WLM Phonata Reference (MM/MC), 47Labs Phono Cube (MC only).

I think very few people on audiogon are familiar with JLTi, but it's a great bargain and very interesting design, it's not a conventional phono stage! 
@

I have the 4th version. I have loading plugs but don't use them anymore. I talked to Joe about sending it to him for updates. Very reasonable to get that done. That will probably be the path I take.
I remember the shootout with the JLTi and other high price preamps. It was preferred by most and Jay Kaufman became the US distributor. I bought mine right after that. Yes it does sound good. I'm just looking for now. I'm trying to fight off the urge to buy something. LoL. You understand, dontcha? (-:
Thanks @vinylzone. I appreciate the info on the Herron
 I'm trying to fight off the urge to buy something. LoL. You understand, dontcha? (-:


For sure, I have the same disease. 
Try Gold Note PH-10, I bought it after JLTi mk4 
I also have the  Herron VTPH-2A and don't use the loading plugs with my Zu Denon DL-103.  They are out of production, so your only option now is to find a used one.
They are out of production, so your only option now is to find a used one.


Thanks @ big_greg

I have heard nothing but good about the Herron. BTW, is a new one on the drawing board for Keith? I emailed that ? to him but have no reply.
47 kohms is for moving magnets. I would use what is recommended by the cartridge manufacturer. My hana el calls for >400 ohms, I use 430. Not certain why you would exceed the value by 10's of thousands. 
@artemus_5 I just talked to him the other day.  He said he had wound down production and made no mention of a new one on the horizon.  Try calling.  If you can find one of his phono stages, they are excellent.
Keith sold his last VTPH-2A a couple weeks ago. There will be no new design.
Quite a number of experts say that loading does NOT supply physical damping of the movement of the cantilever but it supplies electrical damping that reduces ringing of high frequencies.  Atmasphere and J. Carr of Lyra say that such damping is not required for most MC cartridges (because their resonant peaks are now well outside of the audible range) except if those peaks result in overloading of the phono stage.  

With the cartridges I have used with my phono stage (Viva Fono) I prefer no additional loading or very modest loading (meaning high value resistor) on the primary side of the step up transformer.  With the cartridge modestly loaded, the top end seems more open and airy and the decay of notes sound more natural.  
audioguy, There is nothing sacred about 47K ohms; it's become the standard for MM cartridges by default.  In fact, many have found that at least some MM and MI cartridges sound best with even less of a load, like 100K ohms.  ("Less of a load" means higher load resistance, and vice-versa.) Likewise, there is no rule that says you cannot try loading an MC cartridge very lightly, with the 47K option if your preamplifier provides for it. (In many cases, the needed gain for LOMC in a phono stage is achieved by using a SUT.  With a SUT, it may not be possible to achieve a load resistance as high as 47K, if the SUT is connected to an MM input with a 47K resistance load a priori, because of the effect of the transformer on the load seen by the cartridge.)  You noted that the manufacturer of your Hana recommends "greater than 400 ohms".  That certainly allows for ANY load R above 400 ohms. Which means there is no penalty associated with much lighter loading.  What Artemis refers to is the concept that loads much below 47K on an MC, like 400 ohms on the Hana, are mostly for the benefit of the phono stage circuit. I will let Atma-sphere or anyone else explain that in better detail. 


Wow, that's big news, to learn that the VTPH2A is out of production and not to be replaced.
larryi
Quite a number of experts say that loading does NOT supply physical damping of the movement of the cantilever but it supplies electrical damping that reduces ringing of high frequencies ...
That's interesting. Can you please identify some of these experts?
Rothwell, a company that supplies step up transformers said this somewhere, perhaps in their "white paper" on their site.  Vandenhul says that in their FAQ section of their site.  I think Jonathan Carr (Lyra) has also said this, but, I cannot recall where.

I don't see any mechanism for the electrical loading somehow affecting the mechanical movement of the cantilever.  The loading acts as a voltage divider with some fraction of the signal diverted through  the resistor to be dissipated as heat.  I don't see any kind of feedback mechanism for an induced current in the coils causing a magnetic field that interacts with the magnets in the cartridge.
I have used a LMOC on a Valve Input/Output MM Phonostage.
From a Audible Perspective, the marriage of the Two Devices delivers a prentation that is Rich and Voluminous.

As for a Presentation it suits 'IMV' non complex music combined with female volcals.
It also worked quite nicely with a Male Harmony with Harmonica and Acoustic Guitar.
With ECC81 Valves as a Input, it was Volume Control Hungry to achieve the Listening Levels I prefer, and on a few tracks, the Volume was not enough and the replay was a little wanting for extra Volume.

Put the SUT in place and the same Cartridge becomes a very airy detailed device, that lends itself to all Music Types.
The Volume Control is happiest when set at at approximately half rotation and this leaves ample more for when required.

I have not got a Problem with the MM Stage minus SUT.
I have got a Cartridge that can wear two costumes.
One version is a MM only Cob Horse with a Cart in Tow, and the other version a SUT enhanced performance Flat Race Horse released from the Stalls.     
Pindac, What are you saying?  Seems you are saying that if gain is insufficient, then your cartridge doesn't sound its best.  Which is almost certainly true. Clearly, the ECC81 (also known as 12AT7) substitution produced overall phono gain that was not adequate, but it would help to know what was the tube type for which the phono stage was designed. Just because it is so commonly used in phono stages, I am going to guess it was the ECC83 (also known as 12AX7).  If you did sub a ECC81 for a ECC83, it is no wonder that didn't work well.  The ECC83 has over twice the gain of an ECC81, and also the latter tube requires more plate current than an ECC83 to sound its best.  So you loaded the dice against the ECC81.  If you then added a SUT to the input of the ECC81, perhaps that worked better, because you restored the missing gain.  (I think you are also saying you run an LOMC cartridge into an MM phono stage, implying a stage with not more than 50db of gain and probably less, even when the input tube is the one for which the circuit was designed, plus or minus a SUT.) Other things, like phono input load impedance also change when you add or subtract a SUT, and that too affects SQ.
I don't see any mechanism for the electrical loading somehow affecting the mechanical movement of the cantilever.
It is common knowledge that when you ship a speaker, you should short the terminals because it provides a "dynamic brake" which limits cone excursion from sudden impacts.  A cartridge is simply a speaker in reverse and loading a MC can have a dynamic impact on the compliance.
A speaker voice coil moving in the magnetic field induces a current (if the speaker terminal is shorted) that creates a magnetic field that resists the movement (back EMF).  In the case of the cartridge, where is the back emf or back emf increase by adding a loading resistor to the circuit?  If there is any sort of back emf induced in the moving coil, it would be so negligible compared to the forces acting on the cantilever.  The cantilever is being moved by the tremendous force of the stylus tracking the groove, which in turn is being resisted by the cartridge suspension and the inertial mass of the tonearm and the cartridge.  Any theoretical counterforce from back emf would hardly matter.
@chakster 

I talked to Joe Rasmussen about a month ago about having the upgrade done. He says that the Mark 5 is a Big improvement over the 4. Quoting Joe,

 " JLTi Phono was never meant to compete
with our more expensive VSE FVP and SVP full Phono/Line Pre-amps, but to be a much cheaper stand-alone phono stage and great value.
That has changed...  For a fraction of the cost, this is on a different level entirely ...In a way our JLTi Phono is also a "current mode"
phono stage, also known as transconductance circuit, but again, we do it in a different way."

I just got an estimate from USPS for shipping to Aus. which was quite a bit  cheaper than the others. Since its small, It should be OK.
Now the problem will be not having a phono preamp for 3-4 weeks. Guess I'd better look for a temp replacement. Alnic 1202 looks interesting but loading is preset with the gain you choose. Interesting concept I wonder how they came to those figures.
The question for me is still this. 

@lewm  I'm hoping Ralph (Atma_Sphere) will chime in.

@larryi  I believe Ralph indicated that the electrical signal is what actually stiffened the suspension. But I am not elec tech minded. So my descriptions may be off as far as terminology. Hopefully he will chime in
47 kohms is for moving magnets. I would use what is recommended by the cartridge manufacturer. My hana el calls for >400 ohms, I use 430. Not certain why you would exceed the value by 10's of thousands.
47K is the industry standard for all cartridges, MM or LOMC.
damping is not required for most MC cartridges (because their resonant peaks are now well outside of the audible range) except if those peaks result in overloading of the phono stage. 
^^ This. Overload of the input section of the phono stage can result in ticks and pops. That is a very real argument for looking for that phono section that does not require a load!
I don't see any mechanism for the electrical loading somehow affecting the mechanical movement of the cantilever. The loading acts as a voltage divider with some fraction of the signal diverted through the resistor to be dissipated as heat. 
Its not a feedback mechanism. You are working with a misconception. The loading is not a voltage divider; its directly across the output of the cartridge and in the input of the phono section.

When a magnetic motor or transducer is loaded, it has to do more work. That work comes at a price: its harder to make the transducer move. You can prove this easily to yourself because a loudspeaker is a moving coil device not unlike a cartridge (and can be used as a microphone in a pinch). Remove the speaker cable from the speaker and remove the grill cloth. Push on the woofer and see how easy it is to move. Now put a quarter across the speaker terminals so as to short them out. Try to move the woofer again. You'll see its less compliant. The same thing happens when you load a cartridge. Its simple physics. This was put more succinctly:
It is common knowledge that when you ship a speaker, you should short the terminals because it provides a "dynamic brake" which limits cone excursion from sudden impacts. A cartridge is simply a speaker in reverse and loading a MC can have a dynamic impact on the compliance.
In the case of the cartridge, where is the back emf or back emf increase by adding a loading resistor to the circuit? If there is any sort of back emf induced in the moving coil, it would be so negligible compared to the forces acting on the cantilever.
Because the cartridge is a transducer producing voltage from physical movement, there is no back EMF like there is in a speaker which is doing the exact opposite! The 'EMF' in this case isn't 'back', its 'forward' which is to say it **IS** the signal :)

When a cartridge manufacturer specifies a load less than 47K, its because they either don't realize that the load is really affecting how their reference preamp works, or more commonly, they know they can't predict which tonearm cable and phono preamp you are using. Because most phono preamps have stability problems, its wise for them to make some recommendation. They are probably assuming that the tonearm cable is only a meter in length, which in turn tells them that the capacitance of the cable probably does not exceed 100pF, since getting over 30pF/foot is unwise in a phono cable.



Post removed 
Thanks @atmasphere 

Much appreciated
Atmasphere,

Thank you for your explanation.  I understand that in the case of the speaker movement, that movement induces a current, which in turn, if you complete the circuit, creates a magnetic field that resists the movement of the speaker.  Could you expand further on the mechanism for resisting the motion of the cantilever?  Is it also the magnetic field generated by the coils in the cartridge?  As for conservation laws of simple physics, I can see the price being paid for the loading being paid by the electrical signal, but I don't quite understand why it has to be paid by resistance to the physical movement of the cantilever.

Jonathan Carr of Lyra, said, in a very long post in the What's Best Forum that when we load a cartridge;

"we don't affect what the cartridge does at all (unless the value of the load approaches or drops below the internal impedance of the cartridge).  What adding resistive loading at the phono stage input accomplishes is to dampen the resonant energy of the ultrasonic spike, and give the phono stage an operating environment that isn't so likely to trigger any latent non-linearity tendencies that the phono stage circuitry may have.  

For the reasons given, the phrase "cartridge load" is misleading.  "Phono stage input terminator" is a better description of what really happens."

I am wondering what aspects of his comments you agree with or disagree with.  I regard you both as experts in this field.

Thanks.

The reference was made to ECC81 to help explain why there may have been a need to use the VC at a full rotation.
The arrangement of Tubes and Brand Selection of Tubes used with the Phonostage are a result of it being Bespoke Produced for me with trials on other Tube Configurations and Brands having been undertaken.
ECC83's were rejected by myself as a Input Valve.
The design allows for the usage 83's, and I knew that the 83 would allow for more Gain with the LMOC.  
As said, the outcome of using the Cart Direct to Phonostge or via a SUT
has not created anything unwanted, when it comes to Sound Quality.
There are Two Presentations available from one Cartridge. 
 
Pindac,

I find it interesting that you experimented with lower gain tubes and use of a SUT and like that combination.  I think that there are many ways to achieve the sound one personally favors, and it is your own taste and matching to your particular system that matters (I tend to like SUT in phono setups myself).  I also agree that one can have quite different sound from two arrangements and one is not necessarily inferior to the other.  

I am curious as to why the ECC83 in the input stage did not work out sonically for you.  I've tried a few different ECC83/12AX7 tubes in my phono stage and they can sound dramatically different, so, perhaps it was the particular brand/vintage that did not work out for you.  I was lucky to have a friend who had a wide array of these tubes so I got to hear a number of vintage tubes.  I ended up getting Telefunken ECC 803S tubes (real vintage tubes, not fakes).  These tubes are certainly not for everyone's taste as they are leaner and brighter than many other vintage alternatives.
@larryi 
             I have a long experience with Valve Equipment.
For a person like myself, with sesitivities to certain perceived sounds that are catergorised as detractors as a result of a Sonic Trait.
I am very careful not to produce a Sound that draws my attention to a Sonic Trait that is noticeably present and not an attractor to the Sound Quality.
The Phonostage I was having produced was a ECC83 Input/Output as a Prototype.
It had a lot to offer and I heard it evolve with a couple of design changes to the Power Supply and exchanges of the Internal Components to Matched Boutique Parts.
I heard the model,that in the words of the designer / builder was a finished model, without much more to be done.

I informed the designer that it was possibly one of the best all Valve Phonostages I had heard.
I made it known that the ECC83 was causing me a concern.
There was something overbearing as a Sonic Trait and the Perceived Weight Underpinning the Music and Vocals are too much for my liking.
The Weight was quite noticeable, and the projection of the Mid's and Highs were subdued as a result.

There was a friction between myself and the designer, that had a very constructive conclusion.
Shortly after the last audition, I was offered a audition of the same Device with ECC81 Valves at the input stage.
I accepted this offer and the rest is history, with a couple of twweaks to the components and the ECC81's the Phonostage was now where I wished for it to be.

As a follow up to my receiving the Phonostage, another friend kindly offered to extend the fledgling experience, by making available a very attractive collection of Vintage Matched ECC81/ECC83 Configurations.

It was agreed the Phonostage would receive approx' 200 Hours of use, which was done through a Reverse RIAA and CDP on repeat.
 
The Designer /  Builder,  myself and a selection of members of my local HiFi Group were present on the day, to take part in the Vintage Tube Rolling experience on the Phonostage. 

The Tubes in use today by myself were unaminously agreed by the attendees, that from the permutations produced, the combination of the Valves I have in use were a stand out over the other arrangements.
The options on permutations on this day were quite vast, so not all were achievable. 
One thing that is recollected quite strongly, is that particular valves that were thought to be quite capable, did not Pop into the Limelight with a
 X Factor during this Tube Rolling session. 

As said I can use ECC83's at the Input without any concern for the Phonostage.
I have not felt the need to return to a configuration I struggled with at an earlier date.    
we don't affect what the cartridge does at all (unless the value of the load approaches or drops below the internal impedance of the cartridge). What adding resistive loading at the phono stage input accomplishes is to dampen the resonant energy of the ultrasonic spike, and give the phono stage an operating environment that isn't so likely to trigger any latent non-linearity tendencies that the phono stage circuitry may have.  

For the reasons given, the phrase "cartridge load" is misleading. "Phono stage input terminator" is a better description of what really happens."

I am wondering what aspects of his comments you agree with or disagree with. I regard you both as experts in this field.
I agree with Jonathan. He commented to me when we met at Munich a few years ago about how loading can affect the compliance of the cartridge and I have to admit I'd given it no thought until he brought it up. My main concern since the early 1990s about using loading as a solution is that its a bandaid for a phono section that has problems with RFI injected at its input. He is probably correct that the loading won't affect the cartridge very much until the load is near that of the impedance of the cartridge itself (at that point the output of the cartridge falls off). The winding in a cartridge

But it *does* affect the mechanical resonance of the cartridge in the tonearm and this in turn can affect how the cartridge tracks, as you want that resonance to be between 7 and 12Hz.  But for the most part you can certainly get the cartridge to track in many arms while driving a lower resistance load. Its simple physics that the cantilever will be stiffer. How that affects things will vary depending on the cartridge, arm and load resistance used. 


Pindac,  I apologize if my earlier post seemed overbearing.  I do respect that each of us has a slightly different "taste" in SQ, for want of a better phrase.  What I assumed is that your phono stage was designed to provide what we commonly think of as MM levels of gain (anywhere from 39db to less than 50db), when using an ECC83, i.e., your phono stage was designed around the ECC83 input.  I assumed or guessed that into that ECC83 input tube socket, you are now using an ECC81.  This substitution would "work", but it would not be optimal for operation of the ECC81 (too little current, mainly), and as you know, there would be a significant penalty to overall gain of the phono stage.  With such a phono stage using the ECC81, it is not at all surprising that you found it worked best with a SUT.  In fact, if my conception of your phono is correct, I am surprised it works at all with an ECC81, when you use any typical LOMC cartridge, unless there is a second gain stage following the RIAA filter section.  (I guess I also misunderstood you to say originally that you far preferred the ECC81/SUT configuration to no SUT; I now understand you to say that you like the sound both ways but that the character is different, not surprisingly.)  Anyway, unless you are using a linestage with inordinate amounts of gain, into an amplifier with very high input sensitivity for full output, driving very efficent speakers, or some combination of these, it is no wonder you need to twist the VC fully over to achieve satisfactory sound pressure levels.  So, first question, was your phono stage designed FOR the ECC81 as input tube, once you inter-acted with the designer, or for the ECC83?  For slightly less gain in an MM stage, compared to the ECC83, many people use the 5751, which pops right in to an ECC83 design and is in between the ECC83 and ECC81 in terms of gain.
I am not a EE minded person.
My Trust was with the Engineer for the design / prototype builds.
As is, with all my other Amplification.

My contribution to the prototypes was to supply a quantity of Boutique Components from Brands the designer did not usually use, as well as supply ears to help with assessments as the design was developed.
This was done more under the guise of further learning, rather than believing a improvement could be achieved through exchanging components.
The designer had Two Identical schematics for 83Input / 83 Output Prototypes.
The Models only differed, as one model was a Single Input, and the other Model has Three Switchable Inputs. 
A Brand of Copper Cap's I chose are exchanged from the designers selected ones in my Phonostage,  these are allowing a Lighter Airier Presentation more aligned to my preference.
A lesson learned one can say.

As for the Phonostage as a development, I heard it with 83's Input Output, 81 Input/ 83 Output and a ECC82 Version .
The Power Supply has been produced in a couple of versions,
the second version is a very noticable improvement over the first edition.
I have the second version Power Supply.
I also know there was a surprise moment about the measurements, and in Layman Terms, the quietness of the Phonostage was extremely impressive.

Recently I have learned there is now another version Three of the Power Supply.
A friend who has been in the company of this Phonostgae on a few occassions has been impressed by this design, which has resulted in them now purchasing one with the Version Three Power Supply.
I am yet to learn whether it will be the same as mine or a 83/83.
This will be determined when the COVID restrictions are altered to allow non family members into anothers home, and the evaluations can start.

The restrictions with COVID over the past year has prevented the HiFi related 'get together' experiences I enjoy.
Hopefully I can get out and meet very soon and hear some of the
Lock Down developments that took place.     
You load the cartridge to what sounds good to you on your system and every system is different it is not a band aid but a load as you like it type of thing but i have found that you load a mc at about ten times its internal impedance for best results on most systems.
You load the cartridge to what sounds good to you on your system and every system is different it is not a band aid but a load as you like it
Its a band-aid in the sense that if the phono preamp doesn't have a problem with RFI injected at its input, you'll find that loading doesn't affect the sound nearly as much. So you'll be able to run with the stock 47K and it won't be too bright.
Well,@atmasphere, you have answered another question I had about whether loading is actually a band aid. Seems to be a natural progression. However I suppose it could also be an option for the customer who needs to tame their systems tendency towards brightness. At least that wa an early finding I had with some different components. Thanks
However I suppose it could also be an option for the customer who needs to tame their systems tendency towards brightness. At least that was an early finding I had with some different components. Thanks
Its not always an option to seek out a phono section that doesn't have this problem! So loading will probably be a thing for the foreseeable future.


For me the big thing is ticks and pops. I don't like them. A phono section that doesn't require loading at the input is also far less likely to generate ticks and pops on its own, caused by a poor high frequency overload margin at the input of the circuit.
I loaded several carts (from Lyra Delos through 3 different Benzs) at 47K through my Pass XP15.  Sounded clear and extended, and not "bright" at all.  TBH, it sounded almost the same at ~1K vs 47K.  Perhaps the Pass is one of those phono stages that's not that sensitive to loading.  I now have a Andros Deluxe II, which only goes up to 1000 ohms.  I leave it at that.  Sounds lovely and better than the Pass, but that's a different discussion.
It has been about my experience that once you have a value above 200 ohms or so, there is not that much difference; at that point, you are not applying much loading.  That is why some phono stages, like the Linn Linto, had fixed loading at some almost universally acceptable value of something like 125 or 150 ohms.  

If you want to adjust tonal quality, such as increasing the apparent bass response, you can go with more loading (to decrease the treble response) by selecting a LOWER value, but, this comes at the expense of lower gain and a more muffled sound.  If I need a "fix" for something like excess sibilance and shrill top end, I tend to look more at altering VTA/SRA than changing loading.
Larry,  200 ohms would be fine for most LOMC cartridges that have an internal resistance of 20 ohms or less, but there are some exceptional LOMC cartridges that have a higher internal resistance and will be affected by 200 ohms as a standard.  I think you know this, but I thought it ought to be pointed out to those who might not. By the same criterion, I don't think one can say that 125 or 150 ohms is "universal".  Once you go below a critical value, where the load R becomes much less than 10X the internal resistance of the coils, you start to roll off the top end of the frequency response and to lose signal voltage to ground.  Like you say, if the cartridge is too bright, it's best to tame it by some other method, IMO.
Perhaps the Pass is one of those phono stages that's not that sensitive to loading.
Yes. Nelson knows what he's doing.