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Thread: Jelco effective mass

  1. #1
    Join Date: Nov 2011

    Location: Suffolk,UK

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    I'm arecurringnightmare.

    Default Jelco effective mass

    Anyone here know what the Effective mass of the Jelco SA -750db is? I can't seem to find a reliable source.

    Also am i right in thinking the Headshell mass is 12Gr?

    Thanks in advance.
    Charles

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  2. #2
    Join Date: Nov 2009

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    I'm Juha.

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    I have this info, cannot remember where I got it:

    Effective mass 20gr for SA-750D 9"

    Effective mass 26gr for SA-750L 12"

    Effective mass 18gr for SA-250ST 9"
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  3. #3
    Join Date: Jan 2008

    Location: Mid Lincs

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    I'm Buffet-blower.

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    Quote Originally Posted by selfaddict View Post
    I have this info, cannot remember where I got it:

    Effective mass 20gr for SA-750D 9"

    Effective mass 26gr for SA-750L 12"

    Effective mass 18gr for SA-250ST 9"
    I see there was an answer from the Head of Sales at Jelco (in Japan I think) to a letter written by someone on VE - he stated it was 20g but didn't say if it was with or without headshell. I'd presume without, seeing as the SA250T is would be very close at its own 18g eff mass (which is fixed shell).

    The info does seem somewhat elusive though - been searching for a while myself.
    Richard.

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  4. #4
    Join Date: Nov 2011

    Location: Suffolk,UK

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    I'm arecurringnightmare.

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    Thank you. I had Emailed Jelco direct for the answer, if i get a reply i'll post here, just for future reference.

    Does seem strange them not showing the Effective mass in their Spec sheet tho. Surely its one of the most important aspects for Cartridge matching.
    Charles

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  5. #5
    Join Date: Jan 2008

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    Quote Originally Posted by Artifolk View Post
    Does seem strange them not showing the Effective mass in their Spec sheet tho. Surely its one of the most important aspects for Cartridge matching.
    Those were exactly my thoughts too.
    Richard.

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  6. #6
    Join Date: Apr 2011

    Location: Kingston, Surrey, UK

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    I'm Alex.

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    Quote Originally Posted by Artifolk View Post
    Anyone here know what the Effective mass of the Jelco SA -750db is? I can't seem to find a reliable source.

    Also am i right in thinking the Headshell mass is 12Gr?

    Thanks in advance.
    Charles,

    The standard headshell is a tiny bit under 12g.

    The arm's effective mass is 20g, as shown in this email from Jelco below (posted to Vinyl Engine). I can't imagine that the effective mass is quoted without the headshell - that would be 32g, and most modern medium/low-ish compliance cartridges would be rendered incompatible.

    Posted Mon, 01/25/2010 - 20:45 by Alfredo56

    I asked the news of the effective mass Jelco arm SA 750-D, the answer:

    Dear Bisogno,

    Thank you for your inquiry for SA-750D tonearm.
    Effective mass is 20gr.
    Damping oil is 500cps silicone oil.

    Best regards.

    Haruo Uchida/sales manager.


    Kind regards,
    Alex
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  7. #7
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  8. #8
    Join Date: Jan 2008

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    Hi Andrew,

    The answer is that the Jelco SA-750D (the most commonly sold model) has an effective mass of just under 14g, which of course can be tailored (mass decreased or increased) by fitting a lighter or heavier headshell to the tonearm.

    Ignore other info in that respect, given earlier on the thread, as it is bogus.

    The SA-750D is thus best suited for use with low to medium compliance MC cartridges. The Denon DL-103, for example, is a really good match.

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  9. #9
    Join Date: Jul 2014

    Location: Ukraine

    Posts: 60
    I'm Andrew.

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    Hi Marco! Thanks for reply.
    I've also contacted with Jelco Ichikawa support and asked them to confirm this information.
    They confirmed it:
    Thank you for your inquiry for SA-750L(12") effective mass.
    Details as follows.
    Effective mass is 10.96gr without cartridge.
    Effective mass is 18.56gr with 6.5gr cartridge.
    Best regards,

    Haruo Uchida/sales manager
    Therefore, previous info about the 26 grams of Jelco SA-750L is absolutely incorrect.
    Regards, Andrew.
    Michell Orbe with Moerch DP-6 Gold Precision > Shure Ultra 500 / London Jubilee / Miyajima Kansui > Croft RIAA R / Miyajima ETR-800P / Audion The Converter DAC > Audion Premier 2.0 > Audion Golden Night 300B/PX25 & Audio Black Shadow 845 > Audio Nirvana 15" Classic Alnico with Tannoy ST200.

  10. #10
    Join Date: Feb 2008

    Location: Down South

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    I'm Neal.

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    There is an effective mass calculator over on VE, you need the resonance frequency given by a test record, the cartridge compliance, cartridge and fastener mass. The resonance frequency needs to be quite accurate though, I ended up recording the resonance track whilst timing it from the start to the point at which the arm went unstable then analyzing the track in Audacity and noting the frequency at the timing point.
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