Cartridge loading

Most of my MC cartridges are better with loading much higher than 100 Ohm, normally 1000 Ohm, 10 000 Ohm or even 47 000 Ohm is better. But do not expect that you will stay forever with a chosen loading, it depends on the mood. 

This arm is not optimal for your low compliance Denon cartridge, simply learn about tonearm/cartridge resonance. Your cartridge must be used with super heavy tonearm as the compliance of Denon is extremely low! 

Make sure to use the heaviest possible headshell and add subweight on the back of your tonearm to increase the mass of the arm as much as possible.  

Dynamic compliance of your DENON DL-103 cartridge is 5cu @ 100Hz , convert it to 10Hz and it will be 8.5 cu - this is extremely low compliance if you don’t know. Look at the specs of your Denon to check it if you don’t believe me. To convert 100Hz to 10Hz you need to multiply on 1.7, so this is why the compliance is 8.5 cu @10Hz.

The do yourself a favor and measure tonearm/cartridge resonance with a Test Record to make sure about resonance frequency.

Any cartridge with such a low compliance require tonearm with over 30g effective mass, Technics tonearm effective mass is about 11-13g as far as i know.

If your aluminum body made by Zu does not require a sub weight then it’s not heavy enough to increase tonearm mass twice as much!

Actually using an SPU on Technics tonearm is a perversion just like using Denon 103 on this arm. It’s like making a truck out of sport car. But the SPU models at least have an Elliptical or Replicant-100 stylus tip while your Denon 103 is a CONICAL (worst profile ever in the history, dirt cheap and full of distortion while playing).

Technics tonearm is a killer with high or mid compliance MM/MI or MC, but with the low compliance cartridges you’re close to the extreme.

I love Zu Audio speakers, but i don’t understand why you bought their Zu Denon for your tonearm ? Better cartridges with the most advanced stylus profiles and cantilevers are even cheaper than Zu Denon which is $750 as far as i know ? Maybe with harsh horn speakers a rolled-off Denon sound will help, but in a normal system it doesn’t (imo).

You can experiment with different loading for sure to find what you like, but you can change your cartridge to something perfectly match for your arm, it must be a mid compliance cartridge (not extremely low compliance like your Denon 103 / 8.5cu at 10Hz or 5cu at 100Hz).

I bought the cartridge from Audiofeil ( sold via Audiogon) and was assured it was a good match for the VPI Scout that I bought it for. It was still pretty much brand new when I had it mounted on the Technics. In 2020, I plan to get the Dynavector DV 2X L cartridge as I owned the older model before and loved the sound. Do you think Audiofiel gave me a bum steer?

Since they gave you recommendations for VPI i am not sure what it correct or not, because i never owned a VPI with hteir tonearm. But i still own Technics tonearms and Technics turntables and for this arm Denon DL-103 is not optimal at all (like any low compliance cartridges). For example Dynavector KARAT23rs or KARAT17D2 are perfect for Technics tonearm because the compliance is much higher! 

In my experience dealers not always understand everything regarding tonearm/cartridge resonance and even about cartridge compliance. I remember how difficult for me was to get any valid information from ZYX dealers, they could not answer my questions regarding tonearm/cartridge matching, so i learned some stuff myself over the years. 

My advice for you is to try some of the very best MM cartridges on Technics turntable, you will be surprised how good an MM cartridge can be in comparison with more expensive and practically inconvenient (because of the retip) LOMC. if you need help with MM just ask me. 

A MC cartridge is inherently a current generator and the best way to get the ultimate performance out of it is to treat it as such and feed it into a current amplifier.

By definition a true current amplifier would load a cartridge with a dead short which is about as far away from 47K as you can get.

The current injection phono amp is 47 Labs Phonocube (input impedance is ZERO aka "0" )

The current source power amp is First Watt F2J and probably the one and only current source amp on the market, only 100 units made by First Watt. 

I have both in my system

As I have mentioned many times, the input impedance cannot be zero.

@lewm So the designer Junji Kimura is lieing everywhere about 0Ω inpedance of his own 47 Labs 4712 Phonocube and slightly cheaper 4718 phonostage too, and every reviewer repeating it ? I just don’t understand why then everywhere the input impedance in his special circuit stated as ZERO if it’s 2-4 Ω ? What’s the goal to tell it’s 0 Ω if it’s higher, will it help to sell more units ?

Saying that a (working) phono stage has zero input impedance is similar to claiming to travel at the speed of light

but this is exactly what i do when i travel back in time to find some rare cartridges 

@lewm 

I don't accuse anyone of lying, except a certain President of the USA on some occasions.

Ohh, same here, but 100%

I never did any research into the 47 Labs product, but I did read as much as I could find about several others, most of which are far more costly than the 47Labs, and some of which have been given rave reviews (e.g., Aqvox, BMC MCCI, etc), and none of those truly provides zero ohms input impedance, if you read the fine print. But that doesn't lead me to believe they aren't excellent in SQ. In fact, I think that when M Fremer reviewed the BMC MMCI, he indicated its input Z is about 4 ohms. 

Maybe Kemura's circuit of the 47 Labs Phonocube is just a different design ? Very expensive unit with that power supply, luckily i bought used sample.  

@lewm

Is THIS what you have?https://audiocubes.com/products/47-laboratory-4712-phonocube

Yes, it doesn’t work without special power supply, so there must be a power humpty (first in the list) and i have it with my phonocube.

If you’re buyin’ a Phonocube without power supply it looks like a good deal, but it doesn’t work. The power supply is 3 times bigger than the cube itself and superheavy. For superb results some people use 2 power supplies for 1 Phonocube (dual mono).

More images of this set with power supply and cube are all HERE (not mine).

And you can study about parts and its unique but very simple circuit HERE.
Let me know what you think now when that guy cracked it and explained why the input impedance is almost ZERO. But that guy is not the designer of the Phonocube, he just made a clone.

P.S. I think i posted all these in another thread long time ago.
The PhonoCube originally designed for Miyabi 47 Lab cartridge. 

Which current injection phono stage do you use ?

The idea is to replace the input resistor with the cartridge itself- so that the virtual ground (present in any opamp circuit) is the output of the cartridge itself. In this circuit the cartridge isn’t doing the sort of work as it would be if the cartridge were presented with an actual 0 ohms impedance!!

Very interesting @atmasphere  
I wish i could understand more, they don't make Phonocube any longer, probably because they do not make Miyabi 47 cartridge anymore.  

Any other phono stages with the same circuit ? 

About 3 days ago i hooked up my current-injection phonostage (47 Labs Phonocube) to my system and i was blown away! We were sitting here with a friend of mine who often comes to my apartment. Even him is quite familiar with the sound coming from my two Luxman PD-444 turntables with various tonearms and cartridges, using different phono stages. Prior to that we already selected our "cartridge of the month" just for fun, it was an MI cartridge (Grado Signature XTZ) connected to WLM Reference phono stage with upgraded load resistors (100k Ohm Vishay). The second best was LOMC Fidelity-Research FR-7fz connected via Luxman toroidal silver SUT to JLTi 47k Phono stage, probably it was too bright.

I want to tell you that same FR-7fz on FR-64fx with W-250 counterweight and N-60 stabilizer never ever sounded as good as with the 47 Labs Phonocube phonostage. The impedance of this cartridge is 5 Ohm, the output is 0.24mV. Prior to that i have tried this cartridge with Gold Note PH-10 phonostage direct, with WLM and JLTi direct, also with ZYXCPP-1 headamp and with two different SUTs too.

With 47 Labs Phonocube the cartridge became so alive and emotional contact with the music is so strong that i can clearly say this is the best phono stage i have ever heard. We did the same next night and again and again... My feeling is like i’m right there with musicians, the sound is so dynamic and open that it’s a kind of psychedelic experience. The rest of the chain is passive Pass Aleph L preamp and First Watt F2J current source power amp, upgraded Zu Audio Druid mk4 speakers with latest Zu Audio drivers (101db) and Radian super tweeters.

What i am gonna say here:
With current-injection phono stages you don’t have to think about loading at all, no optional loading! But it’s completely different experience with relatively low impedance LOMC cartridges. And i did not try my Phonocube with Miyabi cartridge yet, so i can only imagine the result, because it was designed for Miyabi. I decided to check FR-7fz with Phonocube because i am using this cartridge in my system often and i thought i knew its character.

I believe our @lewm experienced something similar with his new current injection device with his MC2000.

My advice to others:
FORGET ABOUT CARTRIDGE LOADING!
Look for current injection phono stages for your low impedance LOMC cartridge, there are quite a few on the market. None of the conventional phono stages with optional loading in my arsenal (like the Gold Note PH-10 with PS-10 or JLTi mk4 for exampe, or my WLM Phonata Reference) are even close to the sound coming from the current injection little phonocube (without optional loading).

I am using original Phonocube, but here is a DIY version with schematic (to read how it works). 

The topic about Cartdige Loading is hot.
But here is something about Speakers Loading from Zu Audio:

https://www.zuaudio.com/low-voltage/2020/1/24/loading-resistors?mc_cid=709c630e33&mc_eid=cdb0d19c49