2. analog
  3. 129244-13747

Distortion mystery -- MC cart mistracking? / transformer / head amp input saturation??

Could use some input from the experienced high end record spinners here....

Context: VPI Classic 3/JMW 10.5 metal arm (damped w oil)/ZYX R100H --> Audio Note ANS2 xformer (low gain setting) --> Jasmine/Mockingbird modded LP2.5 DU active phono stage on MM 47kohms setting... anti skate off.

Recently switched cartridge over from my Audio Technica ART 9 cart to this ZYX R100H to check it out (bought ’low hours’ from a well reputed A-gonner). On some records, am hearing an occasional distortion in the vocals and mid-upper piano range... usually on transients of increasing volume. I first thought it is mostly at the 1st half of the record... but it seems like it happens throughout the sides of records where it happens (...I know the VPI jig sets minimum tracking error at end of sides). Seems to happen on records that play a little ’louder’... as opposed to audiophile records where volume levels are lower.

Checked ZYX alignment using the VPI jig couple times... am right on. Tracking at 1.9 grams, VTA level. Azimuth good via the balance beam pole on headshell. Tried different tracking forces - up to 2.1 grams, raised and lowered VTA - still distorts. Using Zerostat/CF brush on record, and Zerodust on the cart tip. Record washed with Okki Nokki. Very good hygiene I think.

As an experiment, I removed the AN transformer, and ran the Jasmine in MC mode at 100 ohms loading, and the distortion seems to have lessened greatly. Could the AN transformer be overloading the MM input at the phono stage? But then why just distortion on transients?? Many other loud passages do not distort.

By the way, I have no such trouble in 200-300 hrs with the ART 9 cartridge... just pure musi, clean and gorgeous... just hearing this with the ZYX.

Thoughts/comments/ideas??

Thanks in advance...








jjss49
jjss49's avatar
jjss49 OP
6,612 posts
 
Further on this... I have discovered the Zyx cartridges' output is measured at 3.54 cm and the ART 9 output is measured at 5 cm... so measurement standards are in fact quite different.  

So taken at face value, the R100H output is 41% higher than the ART 9, or measured at the higher standard, R100H output is at least 0.68 mv (vs the ART 9 spec'd at 0.5 mv)!

That would explain some input overload at the head amp!!
almarg's avatar
almarg
9,670 posts
 
Jjss49, yes, that could very well be a contributing factor to the issue, as 5 cm/sec and 3.54 cm/sec differ by 3 db, **if** the two numbers are defined on a consistent basis.

However that discrepancy, which is commonly seen when comparing cartridge specs, is somewhat ambiguous. In part because the amplitude of a sine wave can be defined on either a peak basis (the maximum amplitude it reaches during any part of each cycle) or on an RMS basis (its amplitude as computed on a root-mean-square basis, which may be thought of as a kind of average value). And for a sine wave 5 cm/sec peak equals 3.54 cm/sec RMS.

For further discussion of this see the posts in the second half of this thread, beginning with the posts dated 7-4-2012.

Regards,
-- Al

glennewdick's avatar
glennewdick
1,788 posts
 
I didn’t read every post here so if I’m repeating sorry. But I has a similar situation and like you when I added more load on the cart is seemed to go away after some talk with my audiophile club friends they recommend more loading. I think you are not loading your new cart enough so you get some issues especially at higher frequencies. If like you mentioned it’s better at a 100ohm load there is your evidence that more load is what you need. The audionote SUTs do not have much load I was looking at the same SUT you have and it was just not enough load for my VAn Den hul cart I'm sure your looking at a similar situation 
glennewdick's avatar
glennewdick
1,788 posts
 
Ok just re read the entiler post and the other guys could be on the right track with the over loading. but also look at Load of the cart as well.
jjss49's avatar
jjss49 OP
6,612 posts
 
no i am now determining that it isn’t electrically overloading

the cartridge distorts at the same points on the same records using all step-up and amplification methods

the zyx is definitely not tracking properly or is somehow damaged

i have used the same vpi arm jig set up procedure for ART 9, Koetsu and Zu Denon 103 - the other carts don’t distort

Zyx being sent to Soundsmith for evaluation...
More to discover