Ortofon 2M Black - frequency response charts

Agreed - no capacitance at all can lead to RF issues in some circuits, but often there is no issue.
Often the input wiring and pcb layout of the phono stage is adding around 20-30pf stray capacitance without any loading caps.

I've never looked at the spec for Incognito. I don't 'do' wire as a rule so will have dismissed it as overpriced audiophillia, but perhaps that was premature if it really can offer 50pf + decent screening and flexibility in a decent length.

 

No, there’s absolutely nothing wrong with my test results or setup and I can easily prove it to you using the Hagerman loading page you referred me to earlier in this thread. If you look at the loading page

http://www.hagtech.com/loading.html

you'll see that, just above the first chart, there’s a calculator that enables you to calculate the resonant peak for any cartridge by entering a) its inductance and b) the capacitative loading you’re using.

As you said earlier this thread, the inductance of the Ortofon 2M Black is 630mH.

A standard loading would be 220pF of capacitance on the phono stage plus (in my case, using stock wiring and interconnects) another 155pF in the wiring, making a total of 375pF.

If you enter those figures and hit the “calculate” button, you find the resonant peak for this cartridge is…10.3kHz! Which is exactly the figure my chart produced for the “standard” setup at the beginning of this thread.

You say you’ve found a lab test on the internet that shows this cartridge has a resonant peak of 18kHz. I wish you’d provide a link but in any event, that’s fine – it’s entirely consistent with my charts. All it means is that the people in the lab used a different capacitative loading and if you check out the Hagerman loading calculator, you find the loading they actually used to obtain this figure was 125pF. (If it wasn't, then their chart is just plain wrong.)

The reality is that you can move the resonant peak around at will by simply altering the capacitative loading and it’s meaningless to talk of the resonant peak of any particular cartridge without simultaneously giving the figure for capacitance. As we’ve seen time and time again, raising capacitance pushes the hump to the left and lowering it pushes the hump to the right. If you can change your capacitance, you can put that hump almost anywhere you like.

Having said that, the fact remains that the vast majority of people who purchase the Ortofon 2M Black don’t have the option of changing capacitative loading. They will have a phono stage with a fixed capacitance of around 220pF and they will also have another 155pF or so of capacitance in their arm wiring and interconnects, making a total of about 375pF. I’ve tried to be kind to the Ortofon 2M Black in this thread but unfortunately it does have an unusually high inductance and the result of that, and the inevitability of the Hagerman formula, is that these purchasers are stuck with a resonant peak of 10.3kHz (as confirmed by my charts) which is not at all ideal. As Hagerman’s mathematics show all too clearly, high inductance + high capacitance = low resonant peak, the result of which is an unattractive hump in the easily audible range and a heavily rolled-off top – again, as clearly shown in these charts.

As a postscript, I think you said you were running your Ortofon 2M Black with a capacitative loading of 420pF. I tried entering this figure into the Hagerman calculator and the result was horrific – a resonant peak of 9.8kHz! From memory you’ve killed that peak by selecting an unusually low impedence. Fair enough, if you like the result, but I’m puzzled as to why you’d call into question charts showing a resonant peak for this cartridge at 10kHz or 11kHz when you yourself are getting an even lower figure?! If your charts, or anyone else’s, are showing a resonant peak of 18kHz with a capacitative loading of 420pF, or even just 375pF, then I can say with absolute, total, mathematical certainty that it’s those charts that are wrong, not mine. Just ask Hagerman!

 

...which is why, when my AT carts were too bright for me, some helpful person here recommended Hagerman's phono pre, which has a miniscule capacitance of only 14pf. I didn't want to mess with resistors, and this helped considerably with the resonant peak.

 

Agree. I can get my capacitance as low as 118pF total, and it sounds pretty good. Looks pretty good on a chart as well.

 

I think you're taking this all a bit too personally. I wasn't attacking your work here, just trying to point out that there may be something wrong with your setup because the big fall off you're showing isn't showing up elsewhere. Check the various reviews around the net for the 2M Black when it first came out (Google them). Several of them provide frequency response charts that pretty much match Ortofon's own stated specifications of 20Hz-20kHz, +2dB, -0dB. surely you're not saying that professional audio publications and a company with a 60 year track record in phonograph playback are wrong and you're right.

Again, I'm not attacking you, just trying to nudge us all along to some better understanding of this all. Yes, as you mentioned, I recommended the Hagerman loading site (I also recommended the vinylengine.com tools as they are equally good and more extensive). This handles the electrical resonance, but there's also mechanical stylus tip mass resonance to consider. There are in fact many factors affecting the eventual sound of vinyl playback. I don't think we can isolate just loading and try to draw conclusions.

As with most things in life, if there were a simple answer, we'd have all settled on it and moved on to other stuff.

 

Indeed. My old AT150MLX sounded great after I got my capacitance down to the level. With stock loading/capactiance it sounded like someone had cranked the treble control up to maximum!

 

Now come on, Stefan, I’ve had enough of this. Why wouldn’t I take it personally when you go on and on trying to discredit my findings by saying there’s something wrong with my setup? You’ve provided no basis whatsoever for this very damaging claim other than to say that other charts don’t support my findings. Well, like I said, I’ve had enough and I’m finally calling you out on this. I say you’re talking nonsense and you know it. You haven’t provided links to any such charts because these charts don’t exist – you’re making it up. I know this because I’ve searched long and hard and have found evidence of only two charts, both of which support my findings, as follows:

First, there’s this very poor quality chart that apparently appeared in Hi Fi World in November 2007:



Here’s the link:

http://www.hi-fiworld.co.uk/index.p...174-ortofon-2m-bronze-2m-black.html?showall=1

This chart is completely meaningless because it states nowhere on the chart itself or in the accompanying text what capacitance or what impedence was used. However, looking at the red line, there appears to be a peak at around 18kHz – maybe this is the so-called “lab test” you were talking about earlier? – so we can deduce from Hagerman that the capacitance used was somewhere in the region 125pF. I can’t get as low as 125pF on my setup but I can get down to 175pF and I showed the chart for this loading (with standard resistance of 47K) in post #48 above. Here it is again:



Taking into account the 50pF difference, which would push their “hump” a little further to the right than mine – the charts are remarkably close. Both are pretty much flat until you get to the high frequencies, then there’s a modest hump of around 2dB, then the beginnings of a fall-off which is never completed because on their chart, as on mine, it disappears off the right-hand edge. As I said when I did my test for this loading, “I think that's a very nice looking chart indeed” and Hi Fi World seems to agree with that verdict, giving the cartridge a favourable review. So where’s the inconsistency? The Hi Fi World chart may be badly labelled and hard to decipher but apart from that I have no problem with it at all and it’s completely in line with my findings here.

Second, there’s apparently a test report on the Ortofon 2M Black, dated March 2011, on Paul Miller’s Miller Audio Research website. (Paul Miller, I believe, is the editor of Hi Fi News). I can’t get past the website registration in order to read this report, which is immensely frustrating, but there is reference to the frequency response chart on the Audio Asylum forum where a forum member posts as follows:

Here is the link to the thread:

http://www.audioasylum.com/cgi/vt.mpl?f=vinyl&m=989410&VT=T

As you can see, the Miller Audio Research tests apparently reveal that the Ortofon 2M Black has a huge (10dB!) fall-off at 20kHz. Again, we don’t know what loading they used – I would hope that we would know if we could only see the report – but in this case we can deduce that they used a much higher capacitance (and 47k resistance), probably consistent with the capacitance you’d get from using a normal phono stage with stock arm wiring and interconnects. Again, this is entirely consistent with my charts for higher capacitative loadings and very clearly contradicts your assertion that other tests don’t show a big fall-off after the “hump”.

You go on to say Ortofon’s own stated specifications for this cartridge are “20Hz-20kHz, +2dB, -0dB” as if that somehow contradicts my findings. It doesn’t. Look again at my chart immediately above, with capacitance of 175pF and impedence of 47K. The whole point of doing that chart was to replicate the manufacturer’s recommended loading for this cartridge, however unrealistic it might be in real-life conditions. And sure enough, we found that the manufacturer’s recommended loading, difficult as it is to achieve, does indeed produce the manufacturer’s stated performance. So there’s no inconsistency there at all – everything fits.

Finally, in another attempt to undermine my credibility (which I’m not to take personally), you ask: “Surely you're not saying that professional audio publications and a company with a 60 year track record in phonograph playback are wrong and you're right?” My answer to that is: “Not at all. I’m saying that professional audio publications and a company with a 60 year track record in phonograph playback are right, and I agree with them. It’s you that’s wrong.”

If it seems I’m making a lot of this, it’s because if anyone ever took your unsupported claims seriously, it would be hugely damaging – it would discredit all the tests I’ve ever done in the past and all the ones I might ever do in the future. So again, I’m calling you out - either show us the charts that contradict my findings or please, stop these baseless attacks on my setup.

 

Good news, I've now been able to register with the Miller Audio Research site and can reproduce the frequency response charts that appear there.



Frequency Response, 500Hz-20kHz (Lateral, -8dB)







Frequency Response, 500Hz-20kHz (Vertical, -8dB)




So there we are - a resonant peak below 10kHz and then the big fall-off, confirming the results I obtained when applying high levels of capacitative loading and refuting Stefan's claim that "the big fall off you're showing isn't showing up elsewhere."

Some notes:

1. Anyone can see this research for themselves. All you do is email your name and email address to


avtech at milleraudioresearch.com (replacing the word "at" with the usual sign)

and you will get a login by return. The report is filed under March 2011.

2. The frequency charts for frequencies below 500Hz are shown separately.

3. The frequency charts shown here are tested into a resistive loading of 47k.

4. Annoyingly, the capacitative loading is not given. But we can deduce from Hagerman that in this case the loading is high because the hump has been pushed well to the left, revealing the full extent of the fall-off that lies to the right.

 

Worth noting that nearly all MM class cartridges fall away quickly after 20khz. The only exceptions are the low inductance types such as Grado and the old Technics models.

I recall many years ago, when in depth cartridge reviews were the norm, wondering why some pretty inexpensive MMs were producing cleaner looking square waves than expensive MCs. Only later once I'd developed my understanding did I realise that the MCs were able to reproduce the original cutter head ringing and so the square waves looked worse. They had a response extending out to 30-50khz in most cases.

Given the inductance of most MM class cartridges, combined with the typical loading conditions, and the mechanical resonances within the stylus/cantilever assembly the best we can achieve is reasonable flatness to a little past 20khz - but no more.
We can use radically unorthodox loading to extend this in some conditions, but we end up with a very odd frequency response so this isn't the answer.

 

In my case, I suspect I am shifting the peak far enough to the right that my tubes are rolling off the highs before the cart does, which in my particular situation is more pleasing to my ears.

 

Wow. I don't see the point in all the drama and hyperbole. We're talking about a phono cartridge's frequency response here, not world peace!

I was going to go digging around for links but clearly you seem to take anything that contradicts your findings as some sort of deliberate personal attacks that you fear will be, as you put it "hugely damaging" to 'all the tests you’ve ever done in the past and all the ones you might ever do in the future' (By the way, there are some who feel using a Soundblaster X-fi Surround and a laptop to conduct such tests does more damage to their crediblity than someone's comments on an internet forum! They're not exactly laboratory grade, in spite of what Dr. F might recommend.).

So I'm not going to bother playing the game. If you want to sit back and think I'm was just making this up, go for it. I wasn't, but I don't feel the pressing need to prove myself (and besides, when I get into technical discussions, you simply say you don't understand it all anyway). So Ill bow out of this thread and put you on my ignore list so there's no danger of my ever hugely damaging your tests until the end of time, and all that stuff.

 

I had a big problem with the 2M Black into a stock Quad 34 phono stage (22opf) due to the peak. It made everything sound horribly thin and tizzy around cymbals etc, just nasty, even though my ears are only good for a bit above that (I can hear to about 13khz). Getting the phono board altered to 47pf made all the difference: from very bad to very good. I've about 180-200pf in tone arm cable, so was well over the Ortofon loading recommendation. I've also got a EAR834P, and one can obviously tube-roll that to get the balance you want to some degree. I've no idea what it's loading is. As a result of this thread I plan to alter the Quad 34's phono to 33k or so next to flatten that peak out even further. The 2M is a superb cart, it's a shame it's loading is a little atypical as I guess many folk will never get to hear what it can actually do. This thread is bang on IMO, the measurements match both what I hear and the expected outcome indicated on the Hagerman site.

 

To be clear, I have an AT 150MLX loaded at 62K with about 118pF capacitance including the cable. I have not had good results with the lower loading.

 

Same with many of the better ATs Tony.

Can be too zingy and shinny into most standard loading, but back the capacitance right off and nudge the load impedance down a little and they sound very nice.
Like you I've run some expensive MCs but I'm quite happy using a £200 AT the moment with some care over loading. Big transformation. I'm going to do some needledrops later in the needledrops thread so have a listen.

I can understand why jupiterboy might prefer the 62k. The low capacitance is key to shifting the peak away from the area where its really audible.
Once you've moved it to the very top of the audio band or beyond, the flatness is far less important IME. Lift at the very top (>15khz) just adds a little sparkle and air IMO, and a droop just makes things perceptibly sweeter. The core tonality of the cart remains.

 

I'm sure you are right, and I now suspect that when I borrowed your 150MLX and didn't like it I was actually going the wrong way with capacitance - IIRC I added it, so was probably just ramping-up the very brightness and thinness I didn't like. It's taken me a long time to really understand this stuff, e.g. to realise one is altering a resonant peak (both frequency and amplitude), plus a roll-off.... if anyone had explained it had similarities to say a Moog synth filter I'd have got it instantly!

 

My working theory is that I am pushing the natural rise in the cartridge response beyond where my amp naturally rolls off. This is fine tuning the sound of the overall system. 54K is also not bad, and is actually better on noisy records.

The bottom part of this graph shows how my amp performs at the 4ohm outs.

 

Ah, the wonderful world of valve amplifier output impedance

 

So, tell me if I've got this right. All MM cartridges are going to have a natural hump in the frequency response chart between 10kHz and 20kHz. Exactly where that hump lies will depend on the inductance of the cartridge and the capacitance of the loading and can be calculated mathematically (although there'll probably be some slight variation depending on real world conditions).

Now, after that hump - meaning, to the right of it - there'll be a fall-off. If the hump is far enough to the right anyway, we'll never actually see the whole of this fall-off - and maybe even none of it - because most or all of it will be off the chart. But if the hump is far enough to the left, we'll see this fall-off in all its glory.

My question is, where does the fall-off stop, or does it never stop? In all the charts we've seen for the Ortofon 2M Black, for example - not just mine - we always see the beginning of the fall-off but we never see its end. It's as if it's going to go on for ever and the only thing that ever stops the remorseless decline is the right-hand edge of the chart!

I guess with most MM cartridges this question doesn't arise because the hump is so far to the right that the fall-off doesn't even begin. But plainly it's more of an issue with the Ortofon unless you can get the capacitance down far enough to shove that hump from the 10kHz mark to the right-hand edge.

My second question is, we know you can kill the hump by lowering the resistance. But does that kill the fall-off, too? It seems to, thinking back over the charts we've seen here, but it's not something I've tested for.

Separately, it's interesting to hear the results people are getting from different loadings. At the moment I've got mine on 20pF on the phono stage + 155pF in the cables. When I set the resistance at the standard 47K, there are times when I worry that there's just a little bit too much top edge and sizzle, but it's very LP dependent. I used to think small changes in loading didn't make much difference but even just lowering the resistance to 33K seems to take away the cutting edge and make it a more relaxing listen. You could call the 47K sound "insightful" and enjoy it very much on some days, but if your ears are tired 33K seems more gentle. I'm not sure yet which I prefer.

 

Lowering resistance brings the fall-off more rapidly. Raising it actually extends the frequency response, or keeps it above 0db into a higher frequency range. In my situation, the natural roll-off of the tubes (and I have NOS tubes that probably perform differently than what is shown in the chart I posted) allows a very natural sounding bloom and airy extension that is much more preferable than the roll-off caused by loading plugs. And honestly, I tried many different kinds of resistors, all with slightly different sonic signatures. In the end, I find sending the high end signal through the system rather than trying to beat the signal down produces much more natural sound. I could swap in a nice SS amp and it might be a completely different story.

Check the charts people post and compare the results. The lower the loading, the sooner the signal drops off the cliff.

 

That's very interesting and I'm going to start looking for that. Unfortunately my phono stage only has one setting above the standard 47K and that's 100K. (No 68K!) But I'll test with that more often.

 

I think you will hear it sounds VERY different. Toning 100K down is as simple as taking a Y-splitter, soldering an appropriate resistor into an RCA-plug shell, and adding that to the signal coming off the turntable. Mass and materials are key. Using an all copper solid Y-splitter works pretty well. Amtrans .75 watt resistors worked pretty well. Tantalum is very musical but a bit dull.

Having old, quirky gear, I appreciate being able to do this fine tuning.

 

I know I wasn't going to post any more charts for the Ortofon but jupiterboy got me interested in the idea of HIGHER resistance which I hadn't tested for. Unfortunately I only have one setting above the standard 47k Ohms and that's 100k Ohms so I tested for that. All the charts in this post are with the capacitance set at a "standard" 220pF on the phono stage and with another 155pF in the wiring, making a total of 375pF - well above the manufacturer's recommendation.

Just as a reminder, this is what we got at the very beginning of this thread with the standard 47k:




So, we have a flat line, then a 2 1/2 dB hump at 10kHz, then a 5dB fall off.


OK, so now, here's the 100K:




Ouch - that's a bit disappointing. Now the mid-range has a 2db depression and the hump at 10k has doubled in size! And the 5dB fall-off is still there, unaffected.

The increase in the hump makes sense to me. After all, lowering the resistance squashes the hump flat so if you increase the resistance, you'd intuitively expect it to do the opposite.

But the effect on the midrange came as a surprise, and I don't think this fits with what jupiterboy was saying.

Anyone have any thoughts?

Here's exactly the same chart but with a linear scale, just for curiosity's sake:




Also, just by way of a periodic check, I ran the same test using the sine sweep test track instead of pink noise. Here it is in linear scale:




I'm more than happy with the very close correlation, except for one detail - that little uptick at the very left-hand edge. If I switch back to log scale, you can see it more clearly, but I'll have to start a fresh post because you're only allowed four charts per post!

 

Continued from last post:



See? Right at the very bottom end of the audible spectrum, the sine sweep chart briefly reads 2dB higher than the pink noise chart. I wonder why? It's a tiny discrepancy but I might try asking Dr Feickert if there's an obvious reason for it. Maybe it's just the pilot tone at the start of the sine sweep test! Or rumble on the run-in groove.

 

We have seen some charting where the data was above the zero db line, so there is some variance in that regard. And to be clear, the only Ortofon cart I own is a MC. What we are specifically not seeing is a pushing of the peek into the higher frequency range, which has appeared in previous charts with lower loadings.

I can tell you that 100K on my phono amp sounds like this chart looks—unlistenable.

Thanks again for the work. I don’t know what to conclude, save that I’m an old dude who has been to too many hardcore shows.

Still, on interwebs tests, I have some hearing in the 17Hz range, so I’m not completely deaf.

 

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For my 2 cents, you've done a remarkable job with these posts. Kudos.