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Headshell advice

Discussion in 'audio' started by yespsb, May 24, 2022.

  1. yespsb

    yespsb pfm Member

    This week I am starting to overhaul my recently acquired Kenwood KD 8030. I have purchased a new AT OC9 XSH and I am now looking for a new headshell as I am planning on fitting my other cartridge to the original Kenwood headshell. I believe the AT-LH range of headshells were designed for the OC9 range but that's about as far as my headshell knowledge goes.

    From scanning various forums I notice there is reasonable body of opinion that says different headshells produce different sonic characteristics but as this my first experience of a tonearm with a detachable headshell I have absolutely no point of reference and that is where I would appreciate your help and advice.

    In your experience do they make a difference and which do you prefer ? Thanks in advance Paul B
     
  2. Tony L

    Tony L Administrator

    I’d attempt to optimise mass/compliance, i.e. find out what the effective mass of the arm is with the standard headshell, what the compliance of the cart is, do the math, and go heavier/lighter from there to get it right in the zone.
     
    Amber Audio likes this.
  3. yespsb

    yespsb pfm Member

    Cheers Tony, I appreciate your reply, according to the Vinyl Engine info the effective mass is 17 - 19 grams.

    My OC9 XSH weighs 7.6 grams and the AT site states Static Compliance is 20 x 10 – 6 cm / dyne & Dynamic Compliance is 16 x 10 – 6 cm / dyne (100 Hz).

    Being candid I have not got a clue re compliance data or what to do with the info from the AT site - this a big learning exercise for me
     
  4. Tony L

    Tony L Administrator

    [​IMG]

    Here’s a little graph that @Robert made many years ago. Add the cartridge weight to the arm mass plus say 0.5-1g for bolts, and try and end up in the blue zone, ideally the middle of it.
     
    paulfromcamden likes this.
  5. Amber Audio

    Amber Audio This is the Day

    Dynamic Compliance at 100Hz needs converting to 10Hz to work with the Vinyl Engine calculator (green is what you are aiming at - not set in stone cos some carts work fine even when the maths says no), rough rule of thumb is multiply by 1.5 to 2 times, some use the average of 1.75 times. Decent write up here https://audiokarma.org/forums/index...ge-compliance-specs-what-do-they-mean.923703/

    Quick look online it seems your arm Eff Mass is at least 17g and Headshell 11g. The OC9 cart plus bolts is say 8g (24g total mass) and compliance is 16 so that is 24 to 32 - go with 28. I think you might want to go with a much lighter headshell.

    https://www.vinylengine.com/cartridge_resonance_evaluator.php
     
  6. yespsb

    yespsb pfm Member

    Big thanks to both of you, there's plenty there to get my head around, hopefully it will click, either way around I will keep you updated. ATB Paul B

    Ps AA roughly how light a headshell are you talking about ?
     
  7. Amber Audio

    Amber Audio This is the Day

    Something like the Technics/OEM copies around 8g or ADC LMG1 about 6g.
     
  8. poco a poco

    poco a poco I'm Jim

    You can just put your figures total mass and compliance in this calculator here to get the frequency figure and the graph is below for the theoretical best region:
    http://www.resfreq.com/resonancecalculator.html

    You can also calculate for the compliance or total mass, so a quick way to workout the best headshell weight.
     
    Amber Audio likes this.
  9. Amber Audio

    Amber Audio This is the Day

    Alternative approach
    http://korfaudio.com/calculator

    [​IMG]
     
    andrewd and poco a poco like this.
  10. yespsb

    yespsb pfm Member

    Fascinating info. According to Korf chaps a head shell in the 8-13 gram range should work well which should I think give me plenty of choice
     
  11. poco a poco

    poco a poco I'm Jim

    The calculators are all fairly good and usually good enough, but they to depend on the accuracy of input figures. Really the compliance figure given by the cartridge manufacturer. Not always entirely accurate and nearly always a little sample to sample variation.

    The HiFi News Test Record has a track that tells indicates what the resonance frequency is ( you watch how the headshell vibrates as the frequency changes). I have one and do see some small variations from the theoretical calculated figure. Not essential, but useful confirmation you got it right.

    https://www.juno.co.uk/products/len-gregory-hi-fi-news-analogue-test/554220-01/
     
    andrewd likes this.
  12. yespsb

    yespsb pfm Member

    Thank you Jim
     
  13. yespsb

    yespsb pfm Member

    By a happy coincidence I have just got myself a bit of a deal on a AT-LH11H. This feels the right choice as 11g is the weight of the original Kenwood headshell and the 11g AT version seem to be in short supply - without forum advice I would have probably gone for the cheaper AT version with threaded holes which is apparently difficult to set up so it shows the benefit of asking people with hands on experience and the benefit of audio forums

    PS bit by bit my own knowledge base is growing and the links and advice above have been a great help
     
  14. Vinny

    Vinny pfm Member

    Headshells add considerably to the effective mass of a tonearm, simply because they are a long way from the pivot.
    Presumably an effective mass for a tonearm minus headshell would be exactly that. In which case, adding a headshell will add effective mass twice - once due to the headshell itself and once (far less) due to the increased distance from the pivot, of the CBW.

    Calculating the added effective mass due to the headshell is simple enough - mass times the square of the distance of the centre of mass of the headshell from the pivot - you just need to get the unit correct to be able to just add it to the figure given for just the tonearm.

    I would guess that it will be a gramme or two.

    Measuring Tonearm Effective Mass- Vinyl Engine

    The Korf calculation must asume some particular effective length.
     
    Last edited: May 25, 2022
  15. Tony L

    Tony L Administrator

    That Korf calc is really neat. I won’t post mine as it’s almost identical to Amber Audio’s (12.5g mass, 8g cart, 1g bolts, and a converted 16cu for the MP-500). It comes out looking much the same, nicely in the green with any overshoot below 10Hz.
     
  16. Amber Audio

    Amber Audio This is the Day

    They used a Jelco 750 9” and DL-103 plus SL-15E. They theorise that modern carts are so different to the ones used 60 years ago to come up with the compliance charts that a new method was needed along with a new formula.

    https://www.dropbox.com/s/jrcossnd4919t7n/DrivenHarmonicOscillation_enV2.pdf
     
  17. yespsb

    yespsb pfm Member

    On this subject, every day is a school day for me ~ thanks one & all
     

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