Does anyone get silence using the mono button w out-of-phase test track?

Discussion in 'Audio Hardware' started by Mugrug12, Oct 16, 2018.

Thread Status:
Not open for further replies.
  1. Mugrug12

    Mugrug12 The Jungle Is a Skyscraper Thread Starter

    Location:
    Massachusetts
    Hi I was wondering if anyone uses a test record like hifi news etc, and can produce silence by using the mono button on the out of phase test track. On my player (ortofon om40 + black widow mkI) it becomes very quiet w the mono button but you can still hear it.

    Is that a symptom of crosstalk? I can also hear the single Chanel test in the other headphone if I turn it up and listen real closely. Do you think this is normal?
    Is there a way to measure this crosstalk without a computer? I don't think my tonearm has azimuth adjustment so maybe no point in worrying.

    Also while you're here- should I use the weight plate in the ortofon cart or do you think I should remove it since I have a very low mass tonearm?

    Thanks!
     
  2. Mugrug12

    Mugrug12 The Jungle Is a Skyscraper Thread Starter

    Location:
    Massachusetts
  3. Thomas_A

    Thomas_A Forum Resident

    Location:
    Uppsala, Sweden
    Well the test should cause considerably lower output but is difficult to interpret in terms of fine adjusting azimuth.

    The weight is there to compensate for a light arm. Remove it if you use a heavier arm. OM=Optimum Match. Meaning that the cartrigde weight can be adjusted to the arm effective mass.
     
  4. missan

    missan Forum Resident

    Location:
    Stockholm
    No it´s not possible to have total silence. The weight should of course be used on a light arm, not on a heavy arm.
     
    snorker likes this.
  5. Mugrug12

    Mugrug12 The Jungle Is a Skyscraper Thread Starter

    Location:
    Massachusetts

    It seems like ortofon is saying the opposite but I'm not sure why. From the om cartridge page on ortofon.com

    "Ortofon's answer to perfect tonearm matching. Ingeniously tucked into the top of the mounting bracket is a tiny, removable weight-plate.
    • If your tonearm is an standard tonearm, just leave the weight-plate.
    • If your tonearm is one of the low mass types, then simply remove the weight. The mass of your OM cartridge is now a mere 2.5g."

    Ortofon OM Series

    I'm confused...
     
  6. Catcher10

    Catcher10 I like records, and Prog...duh

    I don't know anything about the weight thingy......but I doubt you will get total silence, but it should be less. Measuring crosstalk can be done with a DVM, fairly involved process as you are measuring the output from your speakers. Fremer details out how to do it here That Crazy Little Thing Called "Azimuth" Part 2
     
    Mugrug12 likes this.
  7. missan

    missan Forum Resident

    Location:
    Stockholm
    Well don´t be, how can both me and Thomas A be wrong at the same time. :)
     
  8. Thomas_A

    Thomas_A Forum Resident

    Location:
    Uppsala, Sweden
    I think it may only be removed or added if the tonearm cannot be balanced in Ortofons recommendation (or it is a typo). But with respect to the resultant resonance frequency it is good to keep it between 9-11 Hz. For example:

    If you have a 4 g arm, a 2.5 g cartridge at 25 cu gives 12.5 Hz (a bit too high). Adding the weight reduces this to 10.6 Hz (better).
    If you have a 11 g arm, 5 g cartridge at 25 cu gives 7.95 Hz (a bit too low). Removing the weight increases this to 8.7 Hz (better).
     
  9. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    One thing interesting about an out-of-phase test signal on vinyl - it moves the stylus up and down. The groove gets deeper and shallower. For it to cancel when summed to mono (mono being only horizontal movement of the groove), we see that the cartridge would have to be perfectly aligned, and would need to be built perfectly symmetrical. Even small skating forces may cause the "perfect" cantilever to deflect and tilt to one side, and there are only two points on the disc where alignment can be correct with a traditional tonearm.

    But the larger effect that would cause incomplete cancellation would be allowed manufacturing tolerances of the cartridge. Most cartridges have channel balance specifications matching sides to only +/- 1.5dB to 2.0dB. Phono stages and their RIAA EQ components, or any amp or other component in the signal chain before the mono switch, also will have some difference in tolerance side-to-side.

    Crosstalk specifications should not cause incomplete cancellation - think about it this way: crosstalk does a little bit of "summing to mono" right in the cartridge.
     
    missan and The FRiNgE like this.
  10. The FRiNgE

    The FRiNgE Forum Resident

    Theoretically, two identical out of phase tracks will cancel each other. A digital waveform does exactly that, complete silence. In the analog world, complete silence from an analog source is impossible. The out of phase test is a strict test, even the slightest difference in the L+R channel will produce sound. The lower the sound level, the better the cartridge performance. I have never run this test, but the out of phase band can be utilized to adjust the azimuth, provided the response of the L and R channels are nearly identical.

    Don't feel disconcerted by hearing just a little audio, in fact your cartridge is performing admirably.
     
    Last edited: Oct 18, 2018
Thread Status:
Not open for further replies.

Share This Page

molar-endocrine