High output moving magnet cartridges.

G'day all, my latest cartridge adventures inspired by my recent Shure V15III acquisition has led (as usual) to other interesting phono cartridge observations, on this occasion that of phono cartridge output level.

One of my frequently used DIY phono stages is the little one opamp design. It works well, but having only one op amp in the signal path the output level, although perfectly adequate, is a little on the low side. Well it is with my M97xE and AT95E.

However I trotted out my Ortofon 2M Red this afternoon and plugged it in. From past experience I knew that cartridge was pretty high output level and teaming it with the simple one op amp DIY phono stage confirmed it. The output level was nearly as high as my M97xE with my ESP P06 DIY phono stage with two op amp stages producing much higher voltage 'gain' and output.

Are there any advantages or disadvantages to high phono cartridge output? Possibly yes and no. Improved signal to noise ratio is one possible benefit and perhaps phono preamp overload might be a possibility with some phono stages lacking a good input overload margin. Any comments or observations on this? Regards, Felix aka catman.

Well, as high(er) output often goes together with high(er) generator inductance, I rather prefer moderate output... I.e., I'd rather not trade in treble extension for higher output.

Greetings from Munich!

Manfred / lini

G'day mate, interesting point, although with my 2M Red there is no lacking treble, if that's what you mean. I've always found that high phono cartridge inductance tends to result in increased phono preamp 'hiss'. Have you ever noticed this Lini? Regards, Felix aka catman.

Felix, did you use the Very Simple Phono Stage design? If so, then R2 is the resistor to set the gain.

(I've used this with the M97xE as-is and I recall the gain was fine.)

I've found with the 20 or so cartridges I have, that high output cartridges typically have lower compliance, higher tracking forces, more moving mass of the stylus-cantilever-magnet ass'y, more sibilance distortion with less tracking ability, likely more record wear since it is working harder to generate a higher voltage.

The frequency response at higher frequencies with a high inductance cart. is done by using the mechanical resonance to fill in, usually.

To me it´s much better with a low inductance cart. and a low eff. mass needle.

gusten

Yeah, we can go back to ceramic cartridges that have really high outputs, although they require heavy tracking forces (by our standards). I've always thought that high output cartridges make the gain stages easier and simpler to build. That saves the MFG money. It also allows the phono signal to "overwrite" noise in the system so that down stream components can be of somewhat lower quality and still get the job done.

With better equipment, a true high end cartridge with high output will still help bury the downstream deficiencies, so it may have an advantage? I like pairing HO cartridges with modest TTs to get a good overall sonic presentation. If you can afford or acquire true high-end gear, you can play with LO cartridges including MCs, as the system bits will allow that little signal to shine. But not everyone can do that

catman said:

G'day mate, interesting point, although with my 2M Red there is no lacking treble, if that's what you mean. I've always found that high phono cartridge inductance tends to result in increased phono preamp 'hiss'. Have you ever noticed this Lini? Regards, Felix aka catman.

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Well, Felix, it's not so problematic for stereo anyway (compared to CD4 quadro) - but even for stereo a wider treble extension often is nice for "a better portrayal of the ambience"/"improved spaciousness" (I put it like that for lack of a better description - hope you can guess what I mean...). And interestingly enough that even seems to work pretty well, if one already can't really hear that far up anymore - so that it rather becomes a somewhat undefined sensing instead of normal hearing...

And yup, that can happen, 'cause those higher impedance & inductance generator coils basically are the more sensitive sensors, which at the same time makes 'em more susceptible to parasitically induced noise. That's also one of the main reasons, why nudifying MCs is possible and indeed being done - while removing the generator shell from a conventional MM or MI wouldn't be such a great idea, unless one want's to build an EMI detector...

Greetings from Munich!

Manfred / lini

GradoLabs make an entire range of EMI detectors....

Ed in Tx said:

I've found with the 20 or so cartridges I have, that high output cartridges typically have lower compliance, higher tracking forces, more moving mass of the stylus-cantilever-magnet ass'y, more sibilance distortion with less tracking ability, likely more record wear since it is working harder to generate a higher voltage.

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The Shure M91ED must be an exception to the rule then.

dlaloum said:

GradoLabs make an entire range of EMI detectors....

Click to expand...

:yes:

Best description of GradoLabs I have heard. Laughing away.

beatcomber said:

The Shure M91ED must be an exception to the rule then.

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No "rule" just my observation with what I've got. The specs of an M91ED compared to a stock V15 III show the difference too, especially at 10 kHz, giving up some tracking ability for higher output, probably a bit higher moving mass to generate a higher voltage.

The recent threads by the way I'm sure would foster the price rise for V15III

davidro said:

The recent threads by the way I'm sure would foster the price rise for V15III

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Let me see if I can put a contrarian perspective on this....

The V15III/IV and M97/M95/M91/M75 designs all date from a period and philosophy of (when) phase was of no particular concern.

The main struggle at the time (60's) was to achieve something approaching amplitude frequency linearity (flat frequency response in the amplitude domain).

Later and further research work in the 70's started to point towards a need for phase frequency linearity as well...

These designs grounded in the 60's efforts focusing on trackability, frequency amplitude linearity and low VTF (aiming at low wear) - resulted in cartridges where the electrical response has a resonance, and an early frequency amplitude "shoulder" drop off.

The way the whole thing is balanced is by taking the basic response common to almost all cartridges - amplitude frequency response tapers off from a peak of around 250/300Hz gradually downwards at a variable slope (depending on design) of between 0.5 and 1db/octave.
Until it reaches the LCR drop off shoulder, when electrical parameters cause it to drop off much more steeply.

Increasing inductance or capacitance will bring the shoulder in closer (lower frequency) lowering them will push it out further.
Raising the loading R can steepen the drop and also create a resonant peak at the shoulder frequency.

This peak can be used to fill out the amplitude frequency loss in the high midrange/low highrange (where the natural slope is at its worst)... at the cost of a sudden drop of in amplitude afterwards... so to extend the high end, the designers then targeted the mechanical resonance of the cantilever to provide an amplitude boost just after the shoulder - thereby providing extended frequency response.

THE DOWNSIDE:

every resonance causes phase anomalies....
using two resonances to achieve flat frequency amplitude response, puts one phase problem on top of another making it even worse.

These Shure designs are bad news in terms of phase frequency linearity!

To assist in visualising the issues - attached are measured and modelled responses for an M97xE (the measured parts are from a Jico SAS N97xE stylus) - loading used is 375pf 47k total loading.

I cannot provide a plot for cantilever phase response as I have no means of measuring it - but physics dictates that the phase anomalies generated by a resonance whether caused electrically or mechanically are very similar in end result - so you could add a second phase graph shifted to have the peak coincide with the mechanical cantilever resonance.

The graphs are:

M97xe LCR amplitude - basic theoretical electrical response based on the inductance/capacitance/resistance (LCR)
M97xE Group Delay - phase frequency graph of the basic theoretical electrical response based on LCR
M97xE LCR with loss slope - the actual measured "inefficiency" loss slope from the M series cartridge is added to the base LCR slope - this is the base "cartridge" behaviour. (seperate from cantilever)
N97xE cantilever - actual measured cantilever response - note that it is very linear until it hits its mechanical resonance - the peak is a combination of the effect of the pure mechanical resonance along with the suspension and damping of that resonance.
Amplitude F-R M97xE - measure response of the cartridge - effectively the sum of the LCR + Loss Slope + Cantilever


If I had a V15-III or IV I would measure it and provide those plots/models...

But the principle is exactly the same - the electrical response can be modelled and plotted.
The loss slope has to be measured (has to do with physical construction of the cartridge, better cartridges have a lower angle slope...- lower loss), as does the cantilever resonance.

Knowing the inductance of the V15III/IV we know that it cannot provide the quoted amplitude frequency response without havin a substantial cantilever resonance to boost the high end.
It's principle of design is the same as the M97 demonstrated here.

If you have any concern with phase linearity - these are fundamentally flawed designs.

The V15V on the other hand has the cantilever resonance at 35kHz (outside the audio range) - and therefore removes one cause of phase non-linearity.

It does use a smaller LCR resonance to fill out the high end however - so is still not totally phase linear.
Perfection is hard to achieve!

bye for now

David

(now you can donate your flawed V15III to me.... obviously worthless as it is so fundamentally flawed...)

dlaloum said:

Let me see if I can put a contrarian perspective on this....
(now you can donate your flawed V15III to me.... obviously worthless as it is so fundamentally flawed...)

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Sorry I quite lost the track of your teaching. But I think I smell something fishy here :nono:

Some interesting points here

Despite very much appreciating what they do, I did chuckle to myself re. David's little Grado quip. Classic

Hands up - I don't know too much about the potential physics involved and the pros/cons in delivering high output, but (like Felix) my personal findings in this area don't quite align with some of the theories being proposed here.

I make recorded samples of most of the carts that come my way via the use of a CD recorder.
I always set the recording level on the same rig, using the same section of a test track and record this value as a simple comparitive record of Cart output.

By quite some margin the highest output (MM/MI/HOMC) cart I've had is the Ortofon 2M Black.





Not too much in the way of (visible) cantilever mass here, no obvious tracking issues and it delivers plenty up top :scratch2:

Sure but do lower output cartridges end up sounding better?

I was having a listen to a Signet TK9e yesterday (AT25) - one incredibly smooth cartridge - one of the most realistic portrayals of acoustic music I have heard....

2.2mV output - 88mH inductance

It is possible to achieve a "reasonable" output with low inductance (as this example shows) - but it is still less than half the output of "standard" high output cartridges (which tend to be around 4 to 5 mV)

And at 2.2mV the output is still sufficient for most standard budget MM phono stages.

dlaloum said:

Sure but do lower output cartridges end up sounding better?

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Extra low moving mass -> usually smaller magnet --> less output

Mechanical resonance frequency outside audible band --> then magnetic system resonance should also be outside the audible band --> then inductance should be low ---> less coil windings --> less output

Exceptions apply, of course.

dlaloum said:

Let me see if I can put a contrarian perspective on this....

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I really appreciate your detailed explanation David. Very thorough and comprehensive. If this were an exact science, you explanations would have to hold true for all scenarios, and all equipments. However, it is not, and I'd be suprised if 2 in a thousand (or less) scenarios, equipment setups and human ears are even close to identical. Identical equipment setups in different surroundings will sound different to the same ears, etc.

The best that most of us can do is to try to understand the basic principles of the equipment, know something about their characteristics, know what kind of influence our listening area can impart, and recognize the limitations of our own hearing systems.

If it sounds good - Enjoy it.

If it doesn't soung good - Enjoy changing it or tweaking it until it sounds better.

The forums, threads & posts on AK have certainly given me a treasure trove of information to wade thru. I have tried to understand what I can, research what I don't follow, and apply what I learn to my own scenarios and equipments.

And I have really enjoyed it so far!

Thanks guys - - -

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