MM vs MI vs MC

[Digital1955]

Thanks @JP for the python script. Note that when he says to trim the "silence", he means everything but the sweep itself. I assumed it meant "digital zero" silence and I left the runout of the track after the sweep (like 3 seconds worth), but that no worky.

@levimax FYI, same cart. What load does your SUT present to the cart? I have a Jensen JT-44K-DX on order. Curious to see how much impact it might have. My phono stage input loading for this plot is 100 Ohms, 320 pF total. This cartridge has about 10 hours total on it. -Scott

 

[Tom C]

Interesting that the harmonic distortion products of AT150MLX are lower than ART9XA @ 1K (and 3rd is higher than 2nd). See page 15.

 

[USER]

Thanks @JP for the python script. Note that when he says to trim the "silence", he means everything but the sweep itself. I assumed it meant "digital zero" silence and I left the runout of the track after the sweep (like 3 seconds worth), but that no worky.

@levimax FYI, same cart. What load does your SUT present to the cart? I have a Jensen JT-44K-DX on order. Curious to see how much impact it might have. My phono stage input loading for this plot is 100 Ohms, 320 pF total. This cartridge has about 10 hours total on it. -Scott

View attachment 191444

That's really nice. Good to know of a solid MC option. I am using a Denon DL-103R with a PS-X50 I am trying to restore and this is much better distortion-wise.

Interesting that the harmonic distortion products of AT150MLX are lower than ART9XA @ 1K (and 3rd is higher than 2nd). See page 15.

Don't make 'em like they used to, lol.

 

[levimax]

@levimax FYI, same cart. What load does your SUT present to the cart? I have a Jensen JT-44K-DX on order. Curious to see how much impact it might have. My phono stage input loading for this plot is 100 Ohms, 320 pF total. This cartridge has about 10 hours total on it. -Scott

View attachment 191452

My SUT is DIY and I used the JT-44k-dx transformer and used the Zobel network as described in the attached Jensen paper. From the SUT I go to this "balanced transmitter" https://sound-au.com/project87.htm with the input resistors changed to 47K and from there to the balanced input of an ADC so no RIAA and no phono pre-amp in the chain and it presents a load the cart is looking for. The FR looks very similar to what I got but the distortion levels and pattern is different. My cart is also low hours.

 

[Digital1955]

My SUT is DIY and I used the JT-44k-dx transformer and used the Zobel network as described in the attached Jensen paper. From the SUT I go to this "balanced transmitter" https://sound-au.com/project87.htm with the input resistors changed to 47K and from there to the balanced input of an ADC so no RIAA and no phono pre-amp in the chain and it presents a load the cart is looking for. The FR looks very similar to what I got but the distortion levels and pattern is different. My cart is also low hours.

Ok so if you only have a Zobel on the secondary, then the cart should be seeing 430 Ohms. I was considering trying some resistors in parallel on the primary to lower the load impedance from 430 Ohms, but AT isn't really forthcoming on ideal loads ("> 100 Ohms"). If you look really closely on their sample plot in the owners manual (attached), the have 47K Ohms listed as the load. I've read theories that they always use a SUT and they are referring to the phono preamp load, ignoring the SUT load.

I can't really explain the difference in the 2nd and 3rd harmonics. I've got everything dialed pretty well for alignment, both VTA and Azimuth. I doubt the phono preamp is adding anything additional.

-Scott

 

[JP]

but AT isn't really forthcoming on ideal loads ("> 100 Ohms")

Because all you're really going to see is a change in signal level.

 

[levimax]

I can't really explain the difference in the 2nd and 3rd harmonics. I've got everything dialed pretty well for alignment, both VTA and Azimuth. I doubt the phono preamp is adding anything additional.

-Scott

View attachment 191462

Did you capture the output of your phono pre-amp and if so how did you "remove" the RIAA ? While I can't think of a reason why it would be so I wonder if adding RIAA and then filtering it out could effect distortion? (seems like it would effect FR if there was an issue). My TT is an SL-1310 Mk1 (pretty much an automatic version of an SL-1200 Mk1) with no VTA adjustment and set up using the Technics overhang gauge so nothing special. It does seem to work pretty well with this cart though as the tone arm mass and cart compliance are a good match. I will be interested to see your results with your new SUT. I try not believe in folklore/ magic but I have had very good luck with MC carts and SUTS over the years for both measured results and subjective listening.

 

[dlaloum]

Food for thought.

View attachment 191411

...

You might want to try that at 100pf... the Technics spec chart for these was quoted at 100pf - individual measurement for each cart/stylus ... and spec was +/- 0.3db 20-20k... (and 15-80k +/- 3db)

What arm and setup is it running in? The 2D makes me suspect something is not right.... (that something could be the suspension rubber on the stylus.... both Technics and ADC had their own special formulations some of which did not do well over time!)

 

[dlaloum]

...Regarding low cap load, I thought so too until recently, but reading and reflecting some articles about carts let me believe that the MM coil winding capacitance becomes dominant in such a setup. Some article, I quoted before some months ago suggested reasonable 120 or 180pF as equivalent circuit parameter (if I remember correct, depending on the cart model). This would add to the a. m. 60pF.
The only electrical way to reduce that total cap influence even more would require a low impedance current preamp, keeping the cart output voltage at almost 0mV...but this would also require a cart-specific equalization...anyway, could be interesting to design and try such a thing in the future...

I agree - the real solution is Cart specific EQ, just get the loading "roughly in the ball park" then use digital eq.

I have experimented with this - and results are excellent - but it is fiddly, and really not suitable for everyday domestic use.... (unless you have the New Technics TOTL Integrated... which has it built in I believe, and makes it easy, with its own dedicated test record)

 

[Digital1955]

Did you capture the output of your phono pre-amp and if so how did you "remove" the RIAA ? While I can't think of a reason why it would be so I wonder if adding RIAA and then filtering it out could effect distortion? (seems like it would effect FR if there was an issue). My TT is an SL-1310 Mk1 (pretty much an automatic version of an SL-1200 Mk1) with no VTA adjustment and set up using the Technics overhang gauge so nothing special. It does seem to work pretty well with this cart though as the tone arm mass and cart compliance are a good match. I will be interested to see your results with your new SUT. I try not believe in folklore/ magic but I have had very good luck with MC carts and SUTS over the years for both measured results and subjective listening.

Audacity has a RIAA filter curve EQ. I did have to extend it above 20Khz. But I probably do need to measure the actual response up to 96 Khz and build a custom filter for my phono preamp as it probably gets wonky above 20Khz. So the more I type I think, you are probably correct about the difference and I need to refine that. The would mean the harmonics are probably only accurate up to 10Khz.

I'm new to MC cartridges and I wanted to give a SUT a try. The raw Jensen transformers are reasonable to buy, so I was looking forward to comparing active vs passive gain. Downside is eta from Jensen right now is on the order of 16 weeks, so it is going to be awhile.

-Scott

 

[levimax]

Audacity has a RIAA filter curve EQ. I did have to extend it above 20Khz. But I probably do need to measure the actual response up to 96 Khz and build a custom filter for my phono preamp as it probably gets wonky above 20Khz. So the more I type I think, you are probably correct about the difference and I need to refine that. The would mean the harmonics are probably only accurate up to 10Khz.

I'm new to MC cartridges and I wanted to give a SUT a try. The raw Jensen transformers are reasonable to buy, so I was looking forward to comparing active vs passive gain. Downside is eta from Jensen right now is on the order of 16 weeks, so it is going to be awhile.

-Scott

Wow 16 weeks, when I ordered mine several years ago they were in stock.

If you really want to get fancy a member here @SIY wrote an article on building a tube phono pre and in the article he explains a method to "tune" the Zobel network of the SUT for your individual cart. https://www.diyaudio.com/community/...a-thoroughly-modern-tube-phono-preamp.163570/ I had issues getting it to work (I don't have a good enough scope) so went with the stock Jensen recommendations but this might be something you are interested in trying.

 

[SIY]

Wow 16 weeks, when I ordered mine several years ago they were in stock.

If you really want to get fancy a member here @SIY wrote an article on building a tube phono pre and in the article he explains a method to "tune" the Zobel network of the SUT for your individual cart. https://www.diyaudio.com/community/...a-thoroughly-modern-tube-phono-preamp.163570/ I had issues getting it to work (I don't have a good enough scope) so went with the stock Jensen recommendations but this might be something you are interested in trying.

Caveat, which I think I mentioned: 10x probe is mandatory.

 

[EJ3]

So you're the competition...

I am also stocked up for both the ULTRA 300/400 (T4P) for my Technics SL-M3 & the V15 V-MR for my DUAL 1229.

 

[USER]

I am also stocked up for both the ULTRA 300/400 (T4P) for my Technics SL-M3 & the V15 V-MR for my DUAL 1229.

Would love to see a proper measurement of the Ultra 300 posted. If you ever consider getting the $19 CBS Test Record and have the means of recording at a 96kHz sample rate, let me know and I can run the script for you. (Ideally you also have a basic multimeter and can do a quick cable capacitance measurement as well.)

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[Holmz]

Are all MI and MM made to drive into 47k ohms?
Just got a new phonostage as I have been wanting to upgrade cartridge, but have been limited to 42dB gain into 47k ohms.
(I could have loaded it, but did not have enough gain for any low output cart.)

I’ll install the Garrott bros MI, but looking ahead to try a lower output cart.

 

[dlaloum]

Are all MI and MM made to drive into 47k ohms?
Just got a new phonostage as I have been wanting to upgrade cartridge, but have been limited to 42dB gain into 47k ohms.
(I could have loaded it, but did not have enough gain for any low output cart.)

I’ll install the Garrott bros MI, but looking ahead to try a lower output cart.

Sort of - it became an informal industry standard a long long time ago...

But if you read the fine print on some of the manuals that came with cartridges back in the day... you will see words such as "recomended load up to 70k"...

What they were trying to say (without actually saying it, as most MM stages were already 47k at that point) - was that optimal performance was achieved with a load other than 47K !!

So yeah - all MM's and MI's are basically specced for a 47K resistive load. - but often, the optimum load can only be determined by measurement and adjustment.... I have the bits & bobs to adjust R load from around 27k to over 100k I mostly find 35k to 70k covers things.... the combination of C and R loading provides a wide range of "voicing" options.

Also worth keeping in mind that whatever the original manufacturers specs were for a MM/MI... all bets are off when you replace the stylus with a non-original one.... and at that point you are on your own for determining what the best loading is.

Typically when someone says "this new needle is allowing me to hear so much more detail" (or other similar...) - it often indicates some peaks and troughs in the frequency response that weren't there before.... and the potential need for load adjustment to get the cartridge back to neutral. On the other hand, many people prefer the new "voicing"...

But if I am going to mess with Voicing, I prefer to do it at the Room/Speaker EQ level, and to know exactly what is happening, rather than roll the dice and take a random EQ, and hope it suits me!

 

[levimax]

I have been wanting to upgrade cartridge, but have been limited to 42dB gain into 47k ohms.

If you want to try a low output MC cart with your phono stage you can get a SUT (step up transformer) which will add voltage gain with no noise and just a little additional distortion. It is a relatively expensive solution but a good SUT can work very well.

 

[Tom C]

For cartridge loading, I believe it is a widely accepted rule of thumb for the cartridge to face a load at least ten times its internal impedance. Any less than that, and too much of the output signal will be dropped across the cartridge itself. Internal impedance of the cartridge is always given by the manufacturer, because it’s necessary information. It’s OK if the input impedance of the phono stage is far beyond that. You just don’t want it to be too low. It’s usually more of a concern with MC cartridges, because of the effect of an SUT on the reflected impedance.

 

[Holmz]

If you want to try a low output MC cart with your phono stage you can get a SUT (step up transformer) which will add voltage gain with no noise and just a little additional distortion. It is a relatively expensive solution but a good SUT can work very well.

My new phone stage has a SUT built in if I want to use it.
There is a dip switch so it is up to me to decide when I want it in… or not.


My question, I suppose, is; “I see all sorts of flowery words about cartridges, but how do I choose one?”
- I would like to know how output voltage affects sound. Like is a low output better than a high pout always/sometimes/or-depends?
- I can understand the stylus shape and the cantilever materials and stiffness.
- And I can understand wanting the resonance to be high.


I was looking at a Hana ML months ago.
And I was looking at a variety of SoundSmith (MI) carts.
The Audio Technica ART-9 is also on my list.

Now that I have more gain available, as well as SUT(s)… I have a larger space to select from.
(I was already having a problem with less choice )

 

[Tom C]

I don’t think low output is particularly better than higher output. The idea is that you want the lowest moving mass possible, and if you use just a few turns of wire in your MC design, a consequence of that will be low voltage out.
To my thinking, it’s best to try to match the output of the system to the input sensitivity of the phono stage (aka gain staging). No sense overdriving the input of the phono stage, distortion will rise that way. If the output is too low, you won’t be able to get the benefit of driving your amp to full output. Sometimes when analyzing the combination of cartridge and SUT, you have to decide if you want to impedance match the cartridge to the phonostage, vs matching the output of the SUT to the input sensitivity of the phono stage. I prefer to match the output of the cartridge + SUT to the input sensitivity of the phono stage. You will end up with a lower turns ratio for the transformer, which has benefits. I also don’t think super high precision is all that important. A 1:10 transformer and a 1:20 would probably adequately cover just about any scenario.