Matching the cartridge to the phono stage

The basis for my reasoning is as follows:

First, we can group LOMC cartridges as having similar very low inductance in the 1 to 50 microHenry range. Typically more like about 10 uH for a very low output MC. So I would imagine that differences in inductance factor out, and no one is talking about using a less than 47K ohm load with an MM or MI type (and parenthetically, I agree with you and Ralph; I use 47K with LOMCs.)

Second, the effect to which I refer would have to do with parallel capacitance not inductance. Your quoted data re the DL103R (off by 0.5db at 20kHz) shows that the effect I cited is small, but do we know what were the capacitance values in that test? The idea is that impedance due to parallel capacitance will change from a high value to a lower value as frequency increases from 20Hz to 20kHz but even at 20kHz paralllel capacitance is not the dominant source of impedance (typically in the pF range). As impedance due to capacitance goes down with increasing f, then proportionate to impedance at 20Hz, net impedance goes down at 20kHz, shunting slightly more of the signal voltage to ground. Thus, compared to signal voltage at 20Hz, signal voltage at 20kHz would be reduced. Hence the potential for HF roll-off if cartridge internal R and phono stage input Z are mismatched to begin with.

I was meaning to speak in general terms of matching impedances between any two components but thanks for correcting me as regards an LOMC cartridge. I am very aware of the vast differences in inductance among the 3 major types of cartridge but didn’t figure that in. However, many do report that the sound got dull or closed in when they reduced the load drastically below the 10X rule of thumb, say down to 2 or 3X, and I’ve always attributed that observation to an effect of the impedance match. Not meaning to argue the point as your expertise far exceeds mine.

dhite71, Do you see that there is more to it than just whether the phono stage has adequate gain for the cartridge?  Cartridges and phono stages are often blamed for match up failures when really the blame ought to lie with the audiophile who tried to mate unmatchable or poorly matched components.

The SL is an outlier because of its high internal impedance relative to other LOMC cartridges. Plain and simple. The rule of thumb in matching audio components is you want the input impedance of the driven or downstream device to be at least 10 times higher than the output impedance of the driving or upstream device. Where cartridges and phono stages are concerned, that rule is often bent a little but as the ratio of the two impedances falls below 10, more and progressively more of the signal voltage output is lost to ground. That’s often tolerable but also there is a gradual high frequency roll off. So, the SL has internal Z of 33 ohms and Hana recommends phono input Z of >400. Makes sense.

You might also read Atmasphere’s posts where he points out that resistance loading is for the phono stage and that for a well designed phono, the standard 47K load ought to work fine.

It’s the tonearm, not the TT, that determines VTA adjustment. Nearly all tonearms apparently other than Rega tonearms, permit VTA adjustment one way or another without resorting to shims. Preferably you might want to seek a tonearm that affords easy VTA adjustment via a threaded tower, sometimes built into the vertical pillar, or sometimes along side of that pillar, that raises or lowers the pivot and which can be fixed in position once proper VTA is achieved. 

I wouldn't deal with spacers even after 45 years in the hobby, or rather ESPECIALLY after 45 years, because it is a "problem" so easily avoided.

You mentioned Benz and Soundsmith.  Many Benz LOMC cartridges have high-ish internal resistance, like the Hana SL (33 ohms).  So those are just as difficult to match with your phono stage as is the SL.  Soundsmith make some "Low Output Moving Iron" cartridges.  Those also would not be an ideal match for your phono stage, even though their internal resistance is typically only 10 ohms (see below).  If you must have a LOMC cartridge, stick with those that have a low-ish internal resistance.  Like less than 12 ohms, for example, AND a low inductance (that's why the Soundsmith LOMI cartridges need an input impedance of greater than 100 ohms; their inductance is much much higher than that of a typical LOMC.)

To be fair, don't you think that a load resistance switch is sometimes a response to the marketplace which tends to place a high value on fiddling with load resistance, because most audiophiles, who are also potential buyers, do not understand the problem as you state it?  Whew! That was a long question.  Thanks.

Define "pinched".

My guess is that the high gain inputs feed a SUT with a choice of two levels of voltage gain. That would account for the two different load resistance parameters at the two different levels of gain. You can’t fix that unless you change the 47K ohm resistor that serves as a load for the MM inputs. That certainly can be done but first you’d want to know the turns ratios of the SUT. I’m guessing the 0.3 mV input sees a 1:20 turns ratio. That would give an input resistance of about 100 ohms with the standard 47K ohm load on the secondaries. About a 1:30 turns ratio on the highest gain inputs would yield about a 40 ohm net load into that same 47K resistance. I agree that the maker has done a poor job of explaining the circuit. Change the fixed 47K load resistance to 100K ohms, and you could double the respective loads via the MC inputs Most MM and high output MI cartridges work fine into 100K, but the resulting MC input loads are still not quite optimal for the Hana. Pick an LOMC  cartridge with a much lower internal resistance than the Hana, for better matching to this unit.