Audio Technica AT150MLX - frequency response charts

I’m opening this thread to post some frequency response charts for the Audio Technica AT150MLX. Accuracy is not guaranteed because the charts pick up everything in the entire test chain, from the test record itself, the turntable, the arm, the cabling and the phono stage to the soundcard and the software in the PC. Plus, I’m no expert. So they’re really just for entertainment and discussion.

Equipment is: Dr Feickert Adjust + Pro software and test record; Michell Orbe turntable; SME V arm; original SME interconnect; EAR 324 phono stage and Creative Soundblaster X-Fi Surround 5.1 external USB soundcard (as recommended by Dr Feickert). Measurement is taken from the EAR 324 outputs via the soundcard into a Dell laptop. The cartridge is brand new.

Just before starting I thought I’d post a couple of things from the Japanese leaflet accompanying the AT150MLX. In the official US specification, the frequency response for this cartridge is given as 10-30,000Hz but oddly, the Japanese leaflet gives it as 10-23,000Hz:

You can also see that the suggested loading is 100-200pF at a standard 47K ohms.
Second, there’s a tiny chart that looks like a frequency response chart - the x-scale is certainly Hz though I can’t make out what the y-scale is. It’s also just possible to see that the test was done at 100pF, which seems very low – my interconnects alone give me 75pF and I reckon the tonearm wiring is good for another 25pF so there’s 100pF before even reaching the phono stage.

 

Anyway, moving on, here’s my first frequency response chart for this cartridge - a pink noise test. This is with capacitance set at 100pF on the phono stage, so if you add in another 100pF for the interconnects, you’re looking at a total of 200pF. Resistance is – I was almost going to say futile, but in fact it’s 47K.

 

I thought it might be fun to try and flatten out that bump at the end a little so here's the same again but with resistance down to 33K.

 

And now... of course, you know what's coming next. Yes, it's 22K.



Hmm, that looks a bit odd to me - and what happened to the start of the chart?

 

I would love to see graphed results with this cart @ 62K and 120pF. Thanks for posting!

 

I almost forgot - VTF is 1.25g.

I'll keep this cartridge on for a while and post some more charts soon. Meanwhile, if there are any special requests for loading, let me know and I'll try to accommodate them.

I've only had time to play a couple of records with it so far but it sounded lovely at my initial setting which was 100pF (+100pF in the interconnects) and 33K. Tracking was awesome and I'm even beginning to wonder if it could out-track the Shure V15VxMR, which I'd previously thought of as unassailable.

 

Yes, sorry, we cross-posted there. I should have said that the loading possibilities are any combination of

pF: 20, 100, 220, 330 or 470

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

 

The Y-axis in that AT diagram will be a dB scale. Top graph is the frequency response, bottom is crosstalk (I think).

Thanks for sharing, back2vinyl.

 

Well if you get industrious or bored, there’s always loading plugs. I can start from 100K or 62K, and I have worked down in different combinations as low as 25K, but I lack the testing gear you have. So thanks for posting!

I can get a 118pF from cart to phone pre, but no lower.

 

Glad you're enjoying the new cartridge. That 33k setting looks a lot like your (up to) now preferred Shure/Jico response (with a bit of a wave-shaped curve). You have to keep it practical of course, but I thought the linear graphs were also very useful for showing the effects of loading (as with MM cartridges the resonance peak is situated in the 10kHz-20kHz band).

If we may suggest additional tests, I think the most useful would be with the 20pF and 220pF settings (at 47kOhm). The first would be the closest you can get to the AT spec. and the second is what quite a few non-adjustable phono-pre's come equipped with as standard (other than the ones with 100pF/47kOhm, which you have already shown).

I can be mentioned that load-tuning of MM cartridges is primarily done with capacitance, shifting that treble peak up or down in the spectrum. Many adjustable phono stages offer only capacitance switching at a fixed 47k impedance in their MM mode.

 

Thanks for posting this! I just installed this cart this weekend. I don't have enough technical knowledge to intepret these charts correctly--can someone tell me what they mean in non-tech terms? To me, it looks like the wave looses its mojo around 1000Hz (?). For a cart with a frequency response of 10-30 (or 23) kHz, that doesn't make sense, but like I said, I'm sure I'm not reading it right.

My phono pre-amp--Rega Fono MM-- has a stated pF of 100, and my Rb303 tonearm wiring, I'm estimating, has another 100, so my system's chart would probably look most similar to the top chart. Anyone want to educate me as to what that means?

By the way, I'm very happy with the AT 150mlx so far--I think it sounds great!

Thanks in advance for your patience with this non-techie.

 

Frequency axis on many charts leaves something to be desired. Basically, there is a frequency rise at the top, which is the AT “house sound”. The instability of the signal as you move to the right is (my guess) attributable to the decreasing wavelength at higher frequencies.

Capacitance pushes the peak higher and back into the range where it is audible, so in pure theory, less is more. I have the intent of keeping this cart in my table a long time, so I found a good deal on the Incognito rewire for the RB300 (50pF) and worked with the designer of my phono stage to alter its stock settings, which are now 68pF and 136pF (plus 50pF for tonearm cable).

 

Ah! It never occurred to me that the TOP graph could be frequency response but I think you're absolutely right. I'm not sure I even know what crosstalk is but I think frequency response is enough for one thread!

We should get together. With your loading plugs and my testing gear, we could rule the world!

Meanwhile, however, I'm afraid we're stuck with the EAR 324 settings.

 

In a moment I'm going to post another set of charts but first I just want to pick up on a point raised by Antares. A lot of these charts I'm posting will show quite a sharp hump or spike towards the right which could look quite alarming to people not familiar with such charts. It makes it look as though the cartridge's frequency response suddenly leaps upwards in a highly uneven way, almost to the point where you might think it defective. But this is just an effect of the log scale, which compresses the frequencies closer together as they get higher. I'll show you what I mean.

First, here again is the chart from post #2 above.



If you look at the x-axis, you can see it's a log scale: "0.1" is 100Hz, "1" is 1,000Hz and "10" is 10,000Hz.


Now, here are EXACTLY the same results presented in a different way.



This time the x-axis scale is the more familiar linear scale and you can now see how that "spike" on the right of the log scale chart is in actual fact not a spike at all but a very smooth and gentle rise that's not so alarming after all.

(And yes, Antares, it does bear an interesting resemblance to the Shure V15VxMR/Jico SAS chart on the other thread!)

I hope you find this reassuring.

 

OK, here's the next set of charts. This time I've switched the capacitance on the phono stage to its lowest possible setting, which is 20pF. Allowing for another 100pF in the interconnects etc, we're looking at total capacitance of 120pF. That's very close to the 100pF that Audio Technica appears to have used in its test chart reproduced in post #1, assuming they took into account the capacitance of the wiring.

First of all, here is my 20pF + 100pF with resistance set at 47K - same as AT.



Well, there's a resemblance: their chart does drop off very slightly before rising, but I'd be the first to admit it's not an exact match.

Now, here we go again but with resistance at 33K:




And 22K:



And finally, 15K:

 

I'll just add here a repeat of the same 33K data but this time with linear scale:



I think that looks very nice and I've very much enjoyed listening to it that way this afternoon. I do like this cartridge very much indeed and there's a good chance it could become my cartridge of choice.

 

I'm sure other people could interpret it far better than me but yes, you'd be looking at the chart in post #2 which is now repeated in post #14. It seems to be pretty much a straight line until it reaches 1kHz where, as you say, it falls away very slightly - you can see this better in post #14, second chart - and then gently climbs again to give a very slight lift at the top end. To my mind this is a desirable pattern because it avoids too much emphasis on the most sensitive part of the human hearing range where the vocals lie but gives a very slight extra emphasis on the top end which might help you hear the shimmer of the cymbals and produce a sense of air and space. So if you're enjoying it, I can very well see why and I don't think there's anything their to give you any concern at all.

 

Very nice indeed - I know I'd enjoy that myself. This is what I'd call a present day audiophile response curve . Maybe the Shure one worked for bright 80's releases (or RVG remasters...), but certainly a lot of what is mixed/mastered for iPod buds/phones today can use a little help in this direction as well. Thanks again.

 

Thank you! This is very helpful.
--Rischa

 

Jupiterboy, belatedly, this one's for you. Unfortunately I don't have a 62K setting so instead here's 100K and maybe you can interpolate between that and the 47K chart, already posted.

This is 20pF plus 100pF in the cables, at 100K.



As you might have guessed, it exaggerates that wave at the right. Here it is again in linear.





Maybe just a touch too extreme?

 

Yes indeed! Good point.

 

Here's (possibly) the last batch of charts and the first in the group is in some ways the most important of all. I'm saying that because it's done with the phono stage set at 220pF and 47K which is pretty much how all phono stages come these days, assuming they're not adjustable. As I've said before, there's another 100pF of capacitance in the interconnects and tonearm wiring so really the total is around 320pF but the setting on the phono stage is 220pF.



I think what really stands out about this chart is how very similar it is to the charts for the 100pF setting on the phono stage and the 20pF setting on the phono stage, when resistance is set at the same level. (See earlier charts.) So in other words, even quite large changes in capacitance are making relatively little difference to this cartridge's frequency response. That may be reassuring since the majority of people aren't easily able to adjust the capacitance on their phono stages.

By the way, here are exactly the same results but charted with a linear scale.



I think that's a pretty nice looking curve and as I say it's what you're probably getting with any standard phono stage that has no adjustable settings. No wonder people like this cartridge!

Just for the record here's the same capacitance at 33K.



And 33K linear.



And 22K.

 

And finally 22K linear - I ran out of space on the last post.



That's all the charts I'm planning to post for this cartridge but I will be keeping it on the arm for a while so if anyone has any special requests, let me know and I'll see what I can do. The available loadings were posted in post #7.

 

To my ears, 1ooK is too extreme, and at that loading pops and clicks become the main course. Thanks so much for posting. It gives me some insight into what I am hearing. My amp @ 4 ohms out drops off pretty rapidly after 20kHz. If you compare 100K to 47K you can see, as anticipated, frequency response peaks a bit higher, but is also extended further into the high frequency range.



At lower loadings, frequency response is flatter, but also less extended. When the frequency drops more rapidly, I believe it presents audible unpleasantness in my system. By extending it a bit (62K), the higher frequencies become relaxed sounding. I have made my loading plugs using the best materials (copper Y splitters and a variety of high quality resistors), but the compromises I have to endure to tame that bump are not worth it.

 

Interesting--when you say 100K, I'm assuming this is capacitance? (I'm not correcting you, just making sure I understand what you're saying, as I'm not too technical-minded myself)--my Rega Fono MM has a capacitance of 100, but I've noticed a decrease in pops and clicks.

For anyone who's interested, here's a re-posting of some of the observations I made on the 150mlx over on my RP3 upgrade thread: