Ortofon 2M Black - frequency response charts

Here’s the second in an occasional series of frequency response charts, this time for the Ortofon 2M Black. (The first was for the AT150MLX.) Test equipment is: Dr Feickert Adjust + Pro software and test record, Michell Orbe turntable, SME V arm, EAR324 phono stage with adjustable loading and Creative Soundblaster sound card recommended by Dr Feickert. I have calibrated the setup with very good results – I think you can assume that accuracy is within 1dB.

Ortofon recommends capacitance of 150-300pF for this cartridge, without saying whether that includes cables or not. Recommended resistance is 47K Ohms.

Let’s start with a “standard” loading of the kind found on most phono stages; capacitance of 220pF and resistance of 47K. I reckon my interconnects and tonearm wiring are good for another 100pF so in reality, the total capacitance is around 320pF, but as I say, the setting on the phono stage is 220pF.

I’ve used a pink noise test throughout. Here are the results shown with the conventional log scale:



And here’s the same data but with a linear scale:




What we seem to have here is a cartridge with a flat response through most of the frequency range, a 2½ dB hump at 10kHz and then, perhaps most surprising, a quite large fall-off of 5dB at the very top end. However, if you look at the linear scale, that drop-off doesn’t really begin to bite until 16kHz which is beyond most people’s hearing range anyway. So I think in practice you’re looking at a fairly neutral cartridge, apart from that 2½dB blip at 10kHz which probably wouldn’t be very noticeable.

 

Now let’s see what happens if you drop the capacitance. This is with 100pF set on the phono stage (plus another 100pF in the cables, for a total of 200pF) and the same, 47K, resistance:



Not much difference, really. You can see why they say anything from 100pF to 300pF will do.

 

So let’s try altering the resistance instead. This time we go back to “standard” capacitance – 220pF on the phono stage (making a total of 320pF with cables) but we’ve dropped the impedence from the standard 47K to 33K. Here’s what happens:



Well, what do you know! We’ve kissed goodbye to the 10kHz hump. Still got that drop-off at the very end of the spectrum, though.

 

Now we’ve got rid of the hump, I wonder what happens if you drop the capacitance again?

Here’s with the 100pF setting on the phono stage (still 33K):



And here’s with the 20pF setting on the phono stage (still 33K):

 

Well, well. Anyone like neutral? Just to finish off, let’s do a whole series of tests at 20pF on the phono stage and 33K.

This is pink noise, log scale:



This is pink noise, linear scale:

Oh darn, I've lost this one. Have to skip it for now.

This is sine sweep, log scale:



This is sine sweep, linear scale:



As you can see, the sine sweep seems to indicate slightly more of a lift to the lower bass than the the pink noise test. Otherwise, it's remarkably flat.

 

Just for the record, here's what happens in you drop the resistance even lower. This is 20pF and 22K:



I think the message is, "Don't go there."

Any special requests for loadings? You can choose from any combination of:

20pF, 100pF, 220pF, 330pF or 470pF

with

100K, 47K, 33K 22K or 15K.

I'll keep the cartridge on for a few days in case anyone asks.

 

Any guess as to why the chart rises on the amplitude scale as the loading goes down? (As always, thanks for taking the time.)

 

I might guess that low loading is under damped and some ringing starts. Cap loading will tip the front end as well. Very interesting measurements.

 

Interesting. I can’t get away with loading my AT lower because it kills the sound, and ringing could be a good descriptor. I listen for the horns, which get kind of buzzy. Even at 41K or so, it makes a mess of the sound. 62K and low capacitance is clear sailing.

 

This is great. Does anyone know if someone has done this with a Dynavector 20XH? These are the 2 carts I'm considering for upgrades and a neutral response would be nice for my planned archival project.

 

MC cart is going to be a little less fussy, oddly.

 

The thing is, the charts don't show actual amplitude, obviously - the average (mean) amplitude is re-based to zero and you then have a chart that shows you the degree to which the amplitude of each individual frequency deviates from the mean. The idea is to make it easier to compare one chart with another.

In the later charts the upward hump at 10kHz has disappeared and that has the effect of lowering the mean. The knock-on effect from that is that other frequencies that were previously at the mean are now above it and it look as if the whole curve has shifted upwards. It would be much clearer what was happening if we were looking at linear scale charts but that's not the convention so I reluctantly avoid them most of the time.

Not a very good explanation, I know, but I hope it's something to go on.

 

The interactions we are seeing occur because of the relatively high inductance of MM cartridges (and IM).
With MCs, even the high output types the inductance is way lower, usually of a factor of ten and so they aren't troubled by loading to anything like the same degree.
Extremes of resistive loading can influence them - especially driving them into loads of just a few Ohms.

These are just tuned circuits - nothing more or less.

If I might offer one bit of advice re loading.
Don't get too fixated on flat lines. This is vinyl - the land of character and imperfection and you'll drive yourselves mad chasing the holy grail of the perfectly flat response.
IME it's good to tweak loading such that strong peaks are controlled, usually by varying the capacitance (downward in most case) but eliminating them completely often requires too much resistive loading and this can skew the overall balance and completely change the character of your cartridge. As can been seen, once you increase resistive loading by going below the upper 30s you very noticeably start tilting the response. Broadband amplitude changes of even fractions of a dB are very audible, often far more so than saving a dB of two from a narrow peak.

 

Interesting thread. The only problem is that pink noise by definition has a 3db/octave drop and I'm not seeing that in your graphs. I'm also not getting the kind of drop off in the high end you're getting. As I mentioned in a couple of other threads, I finally got a nice result by actually adding capacitance to my rig. For my old AT150MLX I'd removed the capacitors from my Cambridge Audio 640P and tamed the highs, but for the 2M Black, that didn't work. After lots of experimentation, I found that adding 300pF capacitors in plugs (much like folks solder resistors in RCA plugs to create loading plugs) and trying those in combination with various loading plugs I've tried over the years), I was able to match pink noise curves, both those generated in Adobe Audition, and also the built-in one from izoTope's Ozone 5 equalizer, which I used below. That Analog Productions Test LP you didn't like in the other thread actually has a nice set of pink noise tracks on side 2.

Here's my match of a 2M Black playback of the lateral pink noise track 2 (green line) with the pink noise line in the Ozone EQ. No drop above 10k, pretty flat right up to nearly 20k, where the cutting engineer has to roll off anyway to avoid overheating the cutting head.





However, out of curiosity I also recorded track three, the vertical pink noise, inverted one channel then summed to mono. This results in a drop. In the following graphic, the pink noise line is still there along with the lateral (green). Notice how the vertical (blue) matches and overwrites the green line until about 6k, where there's a gentle roll-off.


Since lateral corresponds to Mid and vertical to Side, I experimented with the Ozone EQ in Mid/Side mode, applying a gentle Baxandall EQ curve (+1.4dB at 20k, high shelf, 5.6Q) to the Side (vertical) recording. It matched pretty well as you can see in the following (the EQed vertical is the white line):


Note that these are all done with the horizontal axis set to Log view.

More important than matching the lines, I find that simple little boost to the vertical highs is really doing a nice job in opening up the top end in my needledrops without harshness. Details seem more focused in space. I don't know if this is an issue with the 2M Black, my 2M Black (which was a 2M Bronze with upgraded stylus), my old mutilated 640P, my Xpression II turntable wiring, or what, but it sounds good now (except for the darned Pro-Ject resonating motor hum).

 

I wish JA at Stereophile would start looking at cart reviews like this. I loved the old Stereo Review graphs, back when lps gear rules. Oh, wait, that is happening again. Too many great phono stages are offering loading options now not to know we are using the right ones. It may be time for the TT manufactures to start listing their cable capacitance to help.

 

--------------------
It is clear that this car likes 33K loading and low cap. That is pretty special response to me. Sit back and play some vinyl.

 

Well, I have taken the journey using loading plugs, even using different kinds of high quality resistors. I have given everything from 100K down to 21K a good long listen. 41K with 190pF or so is pretty compelling, but I still get some odd stridency in the upper mids. Some days I think it is all a negotiation with how the high frequencies get rolled off, one option being the loading caps vs. allowing the tubes to do that job. What I see on all the charts is that lower loading also reduces the high-frequecy extension, causing a more rapid drop off at the top. I can’t hear much above 16kH, but I still lose a lot of the room cues and nuances at lower loadings.

 

How about 47K when loaded with it's minimum recommended 150 pf ?

I wonder how the Blue would fair ...

Thanks

 

My phono stage had a native 50K setting, which was not bad at all. Many people are using alternative loading to achieve as close to a flat response curve as possible. The primary complaint is “too bright”. That is not an issue in my system. I have more of an issue with mid-range suck out.

 

Using low-tech terms, can anyone describe how these measurements compare to the AT 150mlx graphs posted previously? With each cart operating at ideal settings, which measures better (I suppose "better" is more neutral)? Are they in the same league? The 2M is more expensive--is it worth it?

Full disclosure; I'm not really interested in the comparison because I care which cart is better, it's more because I have trouble analyzing these types of graphs, so I'm hoping a comparison of the two chart sets will shed some light on what I'm looking at. I appreciate everyone's patience as I learn.

 

Here are some DV graphs:







They are 20xH (this is the high output, old version), 17D3, and I believe the last one is a Te Kaitora Rua. These are all flat within 1 or 2 db, so much smoother than what you are seeing with the MM graphs here.
-Bill

 

IIRC the Red and Blue use a slightly different generator and produce greater output. Very likely use more coil windings to achieve this and so inductance will rise. They'll likely produce different traces and require different correction compared to the Black and Bronze as a result.

 

Thanks for posting Bill.

The DV17 is always astonishingly flat.
We could speculate as to why, but several factors such as very low inductance and very high mechanical resonance pushed way outside of the audio range must be factors. That incredibly short and rigid cantilever has some clear benefits.

I really like the Karat range as they were once known. Probably get closest to making vinyl sound tonally close to good digital. No additional warmth or fuzz of any kind. Not to everyones taste but it's a great cart for those wanting to switch between their digital and vinyl sources with minimal change in character.

 

Actually the 2M Red and 2M Blue are the same except for the stylus, where the Blue is a nude mount. The 2M Bronze and the 2M Black share a common cartridge generator, which has a bit lower output, and these also have different stylus profiles, Fine line and Shibata.
-Bill

 

Just thought I'd update my post above. This morning I decided to tweak my alignment, VTA, etc. It'd been nearly a year since I last did so and I was wondering if maybe I could reduce or eliminate the difference between the lateral and vertical frequency graphs. I went back to an old alignment strategy I'd experimented with before. Instead of going for the Baerward (Lofgren A) DIN approach I was using this past year, I used Conrad Hoffman's excellent arc template generator with custom inner and outer grooves (136mm outer groove, 56mm inner groove). This gives me lower average tracking distortion (0.4% versus 0.5%) and moves most of the tracking distortion to the outer grooves, where the impact is less since the grooves are spaced farther apart. I also decided to set my VTA a bit tail down (thanks to Bill/KT88 for mentioning that somewhere in one of the thread recently).

The results are quite good. The same comparison of recordings from the lateral and vertical pink noise tracks from the Analog Production Test LP shows the lateral curve still flat right up to 20kHz and the vertical curve flat up to about 17kHz where it only falls by about 1.2dB to 20kHz. The resulting sound is very focused and balanced. I also noticed on a needledrop I just did how in izTope RX Advanced spectral view I can more clearly see the points where faders are pulled down between songs so my backgrounds not only sound blacker, they are!

Long live tweaking!