Technical Cartridge Question

[Boyse6748]

Please don’t confuse me further by confusing replies.

Is there an aficionado on the forum that can explain Cartridge loading?

My current installed cartridge is the Benz Wood SL. I have had this cartridge for a while and always run it via the Whest PS 30 RTD at 100 Ohms 65db gain, which appears to be fine as the spec sheet says ... 0.4v >100 Ohms.

Does >100 Ohms mean this is the minimum loading. I only ask ask, as for the sake of curiosity, I increased the loading to 220 Ohms and it sounds much better but still doesn’t define the upper limit. Confused to say the least.

There are many other settings, I.e. 470k, 1k, 15k (47k I guess is for MM Cartridges)

I am but a poor mechanical engineer and do not understand why this should be so...

Can anybody explain?

Thanks in advance

Peter



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[Jazid]

The general take is that as long as the loading is at least 10x the cartridges internal impedance you will be loading it correctly, and if the spec. sheet says 100 ohm is adequate then it well be. This does not necessarily mean that the cartridge is loaded optimally though, so if you find 220 ohms sounds better then it is. And it's fine for the cartridge as well, as are higher impedances.
There are arguments about loading affecting high frequency resonances, but I'd say if it sounds better it is better ☺


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[Boyse6748]

Thanks for that. The spec sheet says >100 Ohm. ( doesn’t that mean “Greater than 100 Ohm.?) or have I got my <> round the wrong way.


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[Barry]

The SL has a coil resistance of 12 Ohm, so ideally the loading should be not less than 10x that figure, that is >120 Ohm. 220 Ohm ought to be fine.

[Jazid]

Yup, you're both spot on

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[RothwellAudio]

Yes, > 100 ohms means greater than 100 ohms, so it only sets a lower limit. Most LOMC cartridges are specified that way with only a lower limit. In theory anything above the quoted figure should be fine and make no difference to the sound but in practice some people find a subtle improvement with a higher figure than the minimum. Some people claim that one particular load value makes the cartridge sing and everything else sounds terrible but I suspect they're exaggerating.

The usual explanation is that the inductance of the cartridge's coils produces a peak in the frequency response and the load impedance tames the peak. However, doing the maths with some typical cartridge specs makes this explanation less than convincing.
Another possibility is that lower load impedances draw more current from the cartridge and that current flowing through the coils produces a back EMF which damps the motion of the coils. It's the same principle as a power amp with a low output impedance damping the coils of a loudspeaker. However, once again the maths doesn't prove this theory entirely convincingly because the damping effect of the stylus suspension swamps the effect of the current in the coils.
So who knows? :scratch:

[bosa]

My Zyx cartridge states the same (>100) and it sounds a lot better at 220 ohms both with an Edwards Audio MC3 and Whest PS 30 RDT SE. There must be a reason the manufacturer sets a minimum so I have never tried it at a lower setting.

[Boyse6748]

Yes, > 100 ohms means greater than 100 ohms, so it only sets a lower limit. Most LOMC cartridges are specified that way with only a lower limit. In theory anything above the quoted figure should be fine and make no difference to the sound but in practice some people find a subtle improvement with a higher figure than the minimum. Some people claim that one particular load value makes the cartridge sing and everything else sounds terrible but I suspect they're exaggerating.

The usual explanation is that the inductance of the cartridge's coils produces a peak in the frequency response and the load impedance tames the peak. However, doing the maths with some typical cartridge specs makes this explanation less than convincing.
Another possibility is that lower load impedances draw more current from the cartridge and that current flowing through the coils produces a back EMF which damps the motion of the coils. It's the same principle as a power amp with a low output impedance damping the coils of a loudspeaker. However, once again the maths doesn't prove this theory entirely convincingly because the damping effect of the stylus suspension swamps the effect of the current in the coils.
Sp who knows? :scratch:

So......

I think I’m still missing the point (Sorry I’m in dumb mode) but I do sort of understand you reply.

Can I give you two examples.

1. My main cartridge (Benz Wood SL) output impedance of 12 Ohms, this times ten = 120 Ohms. I don’t have a 120 Ohm setting on the Whest, so it’s either 100 or 220 Ohms. (Gain is not an issue, I understand that bit). So why does it sound better at 220 Ohms when on paper, that’s more than is required.!!!

2. My Second cartridge is the (Denon 103 Pro) output impedance of 38 Ohms. This times 10 = 380 Ohms. Again there is no setting for 380 ohms, so it’s either 220 Ohms or 470 Ohms. But to my ears, sounds better at 220 Ohms, Which it exactly the opposite scenario of the Benz. Again, on paper, this is Less than required.

Perhaps the numbers are all meaningless and it’s a Use Your Ears thing !!

Sorry but just trying to get my head round this !!!! as I’m planning in the future to get a decent Cartridge, “ Perhaps the Dynavector DTR XV-1s” or is the 4K asking price wasted if I don’t know or understand the optimal loading point.

Thanks in advance.




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[RothwellAudio]

Sorry but just trying to get my head round this !!!! as I’m planning in the future to get a decent Cartridge, “ Perhaps the Dynavector DTR XV-1s” or is the 4K asking price wasted if I don’t know or understand the optimal loading point.

Show me somebody does know or understand the optimal loading point. If there was one, it would be logical for the manufacturer to know what it is and specify it - but they don't. If I was being cynical I might say that Brand X know their top-flight cartridge sounds best with a load of 137.9 ohms but won't say so because they know there are no phonostages which offer that load, so it's safer to say ">100 ohms" instead and that way they won't lose any sales.
More likely, it doesn't matter all that much and anything above a certain figure will be fine.

Anyway, don't get too hung-up on the x10 thing - it's only a rough guide. I guess it originates from the need to define a minimum load impedance for an acceptable signal loss. Take 1dB of signal loss as an arbitrary figure and you end up with the x10 "rule".

I have no explanation for your empirical findings, sorry. With the Denon, how much of a difference is there between the 220 and 470 ohm settings? How sure are you that you have the same listening levels when making comparisons? Is the difference enough to worry about?

[Boyse6748]

Thank you Andrew, wise words indeed.

You have convinced me....... just Sit, listen and enjoy. The different loadings are so minute to the overall sound..... Perhaps it’s just not worth losing sleep about!

Peter .


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[Jazid]

Possibly another thing the manufacturer factors in when stipulating minimum impedance is whether this might be for a head amp like you are using or an SUT. I have nothing to back up what follows being solely an SUT guy but I would be quite surprised if that choice mightn't affect the performance of the cartridge in quite subtle ways across the frequency spectrum and thereby adjust optimal impedance (which is itself a fudge of a figure)? Perhaps the figure given by particular manufacturers is aimed more at one type of setup than another, or maybe its just an average given as a general, hopefully helpful, indicator?

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[Barry]

Another possibility is that lower load impedances draw more current from the cartridge and that current flowing through the coils produces a back EMF which damps the motion of the coils. It's the same principle as a power amp with a low output impedance damping the coils of a loudspeaker. However, once again the maths doesn't prove this theory entirely convincingly because the damping effect of the stylus suspension swamps the effect of the current in the coils.
So who knows? :scratch:

Slightly off topic, but when experimenting with the electrical loading of Decca moving iron cartridges, I found that heavily loading the cartridge (i.e. low values of load resistance) affected the tracking ability. I put this down to increased electro-dynamic damping of the cartridge.



Back on topic, I agree that the x10 rule is only a rough guide, but I have found that using values greater than 10 times the coil resistance can sometimes offer sonic improvement, whereas using values less than 10 times causes the cartridge to sound "closed in" (for want of a better description). For example, this is what I have found for the cartridges in my collection:

Denon 103 (coil resistance 40R) - load impedance 470R

Ortofon SPUs (coil resistance usually < 10R) - load impedance 100R

EMTs (coil resistance 24R) - load impedance 600 - 800R

Van den Hul MC-1 (based on a Benz generator, coil resistance 13R) - load impedance 220R.

Just as it is worthwhile experimenting with VTF and VTA and bias settings, I believe it can also be fruitful to experiment with values of load impedance. Sometimes it is best to just enjoy the results of optimisation by ear, rather than worry about any technical explanation.

[Boyse6748]

I’m sort of getting this concept..... forgive me, but just listened to Tubular Bells (once at 220 Ohms) base heavy...mids a bit muddled, high frequencies truncated.

Then back to 100 Ohms ... all is back to normal. Perfect.!!!

More Ohms (higher than recommended) diminishes the top end... I.e more bass but less top end.

I guess a lower loading would cause high frequency distortion, you will know soon enough.

It’s a weird world this hi-fi stuff....... you would think I would know better at my age, after some 50 years with this kit.

I’m convinced now, that to take the manufacturers guide, and then adjust either side to see what suits.

I think when a loading says >100 Ohms, try that first, then maybe 220 Ohms (use your ears) Bass or top end.... your choice.

Thank you all, we live and learn,!,!,!

Especially “Andrew” - Rothwell Audio” (another learning curve)

Peter


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[Mike Reed]

So....



1. My main cartridge (Benz Wood SL) output impedance of 12 Ohms, this times ten = 120 Ohms. I don’t have a 120 Ohm setting on the Whest, so it’s either 100 or 220 Ohms. (Gain is not an issue, I understand that bit). So why does it sound better at 220 Ohms when on paper, that’s more than is required.!!!

2. My Second cartridge is the (Denon 103 Pro) output impedance of 38 Ohms. This times 10 = 380 Ohms. Again there is no setting for 380 ohms, so it’s either 220 Ohms or 470 Ohms. But to my ears, sounds better at 220 Ohms, Which it exactly the opposite scenario of the Benz. Again, on paper, this is Less than required.



The impedances you state above are the cartridges' INTERNAL impedance. My Transfig is a very low 1 ohm, my Koetsu 5 and previous Benz 12; one or two other highish end cart's are 30 to 40 ohmsbut generally they run between 4 and 15 ohms.

As I had a Benz Ebony with my Superline, I can tell you that it sang at 220R but sounded lacklustre on the 100R plug. My Urushi, conversely, does the exact reverse. You tune by ear, making 100R your starting point and go up. Lyras, and I think DVs, prefer 400 to 500 ohms exterior loading on s/s stages.

I think you'll find, at 220R, dynamics improving, with a fine balance of bass and mid/treble. There's absolutely no harm in experimentation. If you use capacitance plugs/switches, these are far, far less important with m/coil cart's (but useful if you have RFI), but again, if you stray too far above 1 nanofarad, the s.q. may exhibit a 'sat upon' sound, losing dynamics.

I'd be interested to know what you have in mind for a step up the cart. ladder. After Benz, I'd imagine that a DV might be a bit neutral, despite having a lot more detail etc. The cart. which followed my Ebony was and is the Transfiguration Proteus, but any Transfig would give a similar presentation of effortless lack of boundaries, difficult to call 'warmish (as Benz) but certainly not crossing the Rubicon into coolish /neutral (as per Lyra). Pls. excuse dodgy adjectives used as a necessary adjunct to describing the wonderful/frustrating world of cartridge transducers.

Be careful, when choosing a cart., to try to match the effective mass of the arm to the cart's compliance (flexibility of cantilever, effectively) requirements. E.g., Myajimas are at their best on heavy arms, Koetsus prefer heavier (upper medium mass territory ). Lyra are okay on medium mass (11 + g) and Benz a little heavier.

[Boyse6748]

Mike, at 70+ I’m still on a learning curve.... I’ve been the happiest ever with the Benz (some say, a pipe and slippers cart) but not for me.

I’ve always hankered for something that might knock me out... like ...... Lara, Koestu, Dynavector .... etc etc.

But hell, are they some money.....and you can listen first (I mean with your own kit). I’m afraid not!!

A Vinyl junky.... but getting into Roon with the Mytek Brooklyn Dac.... no settings... just listen.?!!!

MQA Steaming is just the dogs......... it’s getting better and better.

Sorry"...............from a vinyl die hard.

I thank you for your comments.... most instructive [emoji106]

Peter




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[Mike Reed]

Peter, i'm in my late seventies, but unlike you, have no interest in or intention to pursue intangible music. Vinyl, CD and radio are my turn-ons. Re. your next cart. (and this occurred to me just after posting the above), why don't you go for the Benz LPS? Absolutely top-notch yet 'affordable' compared to Japanese alternatives. It's quite a heavy cart., so requires a heavier tonearm counterbalance. I disagree about Benz being 'pipe and slippers', though; they're not ! Koetsus are far richer and darker than Benz, e.g. (and generally unaffordable to boot).

[Boyse6748]

Mike, I’m not trying to pursue intangible music. Like you you, vinyl, cd and radio (via my beloved Dynalab Fm) give me the most joy. I am very lucky to have the best TT/ Arm ever made “in my opinion” ... the fabulous Denon DP80/Dynavector 507 MKII ARM. Just trying to get the best cart I can afford. I might well go for the Benz LPS..... A fab cartridge.

As you must already know, the Dynavector arm can handle any cartridge ever made, regardless of mass. Just trying to take advantage of this wonderful price of kit.

Roon came to me by a bit of a mistake...but to be able to listen to the “ any” music currently available is quite novel.

Sorry, not a techie, but love this form of music also.


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[RothwellAudio]

Slightly off topic, but when experimenting with the electrical loading of Decca moving iron cartridges, I found that heavily loading the cartridge (i.e. low values of load resistance) affected the tracking ability. I put this down to increased electro-dynamic damping of the cartridge.
Thanks for that feedback. I've been aware of the theoretical possibility of low load impedances damping the cartridge's motion for a long time but never experienced the effect in practice. Now at least I know someone who has.
The coil-damping effect of the load impedance is something that's hardly ever mentioned in technical papers, manufacturer's specs or on forums. I think Graham Slee is the only other person I've heard mention it.