The Technics SL-1200 GAE/G/GR general questions thread

Discussion in 'Audio Hardware' started by Halloween_Jack, Aug 1, 2018.

  1. JP

    JP Forum Resident

    Location:
    Brookfield, CT
    For next week, current noise, and why phono stage noise measurements taken with inputs shorted, particularly MM, can often be of pixies. But not here.

    :biglaugh:
     
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  2. Ingenieur

    Ingenieur Going with the flow...

    Location:
    PA
    On my old setup total noise was >10 mV
    7-8 from cartridge alone

    my new one
    Total~7.5 when hot, 6 from cartridge
     
  3. Oelewapper

    Oelewapper Plays vinyl instead of installing it on the floor.

    How did you measure it without measuring anything else?
     
  4. Ingenieur

    Ingenieur Going with the flow...

    Location:
    PA
    here is good :agree:

    You showed me total loop WITH cartridge is what matters.
    My Solo was rated at 0.09 uV equivalent input noise.
    The cartridge is 0.62 uV alone!

    PLEASE do not stop sharing your knowledge here. In my warped mind it is some of the most interesting stuff.
     
  5. Ingenieur

    Ingenieur Going with the flow...

    Location:
    PA
    @JP posted an excel sheet calculator.
    I verified it by measuring noise on a line input
    <0.2 mV (amp and preamp only)
    Then with TT unplugged and shorted, 2-3 mV

    all at 100% volume at speaker terminals
     
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  6. JP

    JP Forum Resident

    Location:
    Brookfield, CT
    Random uncorrelated noise generators in series add as noise power (square root of the sum of the squared noise voltages). This means the largest voltage noise source will be overwhelmingly dominant. If everything else is playing nice, the cartridge should be the dominant source by a sizable margin. On the other hand...

    IF the phono stage is well engineered. A number aren't, sadly. This paints the picture sufficiently: Phono stage noise when cartridge connected - diyAudio
     
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  7. JP

    JP Forum Resident

    Location:
    Brookfield, CT
    I'll probably be a bit scarce here for a bit; a relief to some I'm sure. I finally found arm cables for my Kenwood, so I think I'll throw it on the bench for a refurb and give it some play time. No redrawing of the lines makes that project on-topic for this thread.
     
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  8. thenice22

    thenice22 Member

    Location:
    UK
    No please don't leave leave l like having you round
    the silent majority guess l am
     
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  9. Ingenieur

    Ingenieur Going with the flow...

    Location:
    PA
    He's got a good project in front of him.
    My guess, he'll share :)
     
  10. Ingenieur

    Ingenieur Going with the flow...

    Location:
    PA
    Without being crude, those who find it a relief should just skip over it. Please.

    For those of us who find it 'good stuff', share when you can.

    Technics = MIJ = Kenwood
    :)

    but regardless, share the result any way you choose...but please share
     
  11. JP

    JP Forum Resident

    Location:
    Brookfield, CT
    Not leaving, just occupied.

    It's an L-07D, so I'm pretty sure I'll document it somewhere. Was actually thinking maybe doing the PS-X9 first just to get it out of the way. Just need to figure out more workbenches. Seems the ideal number of workbenches for any given project is always n+1.
     
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  12. Madison Mike

    Madison Mike Forum Resident

    Location:
    Madison
    Lots of people seem to be in this town for one thing or another :righton:
     
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  13. elvisizer

    elvisizer Forum Resident

    Location:
    San Jose
    Madison’s the best, I’m an alum…met my wife there :righton:
    Sad when o’kayz burned down but at least Cathy was able to open another venue- used to date her sister lol
    And then there’s the time my gf punched Shirley Manson at the Paradise. . . . .
     
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  14. Madison Mike

    Madison Mike Forum Resident

    Location:
    Madison
    :laugh:
     
  15. intoaudio

    intoaudio Member

    Location:
    Las Vegas
    Hi group,
    1200GR owner here; got a question about tonearm effective mass. The GR's is 12g, including the Technics headshell, which is 7.67g.

    I need to use a heavier headshell to properly match a cart to the tonearm, in order to get acceptable resonance.

    So, doing some math, 12g minus 7.67 gives you 4.33g. I am using an Ortofon LH-4000, with a weight of 14.3g. Simply adding the 14.3 with the 4.33 gives me an effective mass of 18.63g.

    Am I correct here, or am I missing something?

    Thanks in advance for your responses....
     
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  16. Davey

    Davey NP: koleżanka ~ place is

    Location:
    SF Bay Area, USA
    It's a little more complicated than that since the headshell mass is not directly over the stylus, it is spread out between there and the connector, and some headshells have a higher percentage of their mass near the connector. So a better approximation would be to take the difference in the headshell weights, in this case around 6.7g, and multiply that by 70%, so around 4.7g added to effective mass. But the counterweight will need to be moved further from the pivot too, so that adds more effective mass, so maybe make it around 7g. So as you can see, in the end, your method probably is close enough.

    Another thing to keep in mind, if the tonearm is specified at 12g effective mass, that is usually measured with no cartridge installed. When a cartridge is installed, the counterweight gets moved further from pivot to balance, so effective mass increases (disregarding the further increase due to cartridge mass). If set up for an 8 gram cartridge, your 12g tonearm becomes 15g, so then add the 8g cartridge and it is 23g. Some of the old Technics specs included the cartridge weight that was used for measurement, often 6g. There's an Excel calculator you can play with at Effective Mass Calculator.

    What cartridge are you planning to use?
     
    Last edited: Oct 9, 2021
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  17. C.Ludwig

    C.Ludwig Well-Known Member

    Location:
    Kentucky
    You are not missing anything. You might want to check out the AT-LH18H headshell too. It has features to easily adjust azimuth, and stylus to headshell tail distance while it’s non slotted screw holes assure compliance to the Technics tracking error scheme.
     
  18. Ingenieur

    Ingenieur Going with the flow...

    Location:
    PA
    The 12 increases due to CW offset increase
    say 15
    Then add cartridge and head shell delta?

    so in my case for example:
    Head shell is 2.4 heavier, I'll use 2
    Cartridge with hardware 6.8
    Total ~ 15 + 2 + 6.2 = 23.8

    correct?

    the calculator
    23.8


    [​IMG]
     
  19. intoaudio

    intoaudio Member

    Location:
    Las Vegas
    Hi there,
    Thanks for your insights.
    I'm using a Goldring Eroica H cartridge, 6.6g with hardware, estimating 9mm dynamic compliance. Vinyl Engine's calculator would put that, at my calculation, at the top of the acceptable resonance range.
     
  20. Davey

    Davey NP: koleżanka ~ place is

    Location:
    SF Bay Area, USA
    Yes, probably close. I don't know how accurate your 8g measurement is for the tonearm, I'd expect a little less, maybe around 6-7 g would get you in the 12g range for effective mass, but it's all kind of guesswork to a certain extent :)
     
  21. Davey

    Davey NP: koleżanka ~ place is

    Location:
    SF Bay Area, USA
    You're just estimating dynamic compliance at 10Hz by taking 50% of the specified 18 mm/N (cu) static compliance? May be closer to 12cu based on the Paul Miller Lab report for the Eroica LX. In any case, it is a relatively low compliance cartridge so you should be fine, probably the more weight the better.
     
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  22. Ingenieur

    Ingenieur Going with the flow...

    Location:
    PA
    I measured it 3 times at platter level
    Fluctuated between 7-8, settled on 8
    Even if 7, small overall difference
    Thanks
     
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  23. intoaudio

    intoaudio Member

    Location:
    Las Vegas
    Good to know; thanks for that.
     
  24. Davey

    Davey NP: koleżanka ~ place is

    Location:
    SF Bay Area, USA
    Is your pivot to stylus distance set to 23.3cm because you are using Baerwald alignment? Is this the type of discussion that gets your buddies here in this thread mad at you? :)
     
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  25. Ingenieur

    Ingenieur Going with the flow...

    Location:
    PA
    Yes

    I also verified tracking force and CW distance.
    The CW is sort of an estimate to center of mass, used a metal rule.
    I weighed it, exactly 100 g with the dial

    :biglaugh:

    they'll get over it
     

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