Phono cartridge matching please help

Discussion in 'Turntables' started by vinylfind, Jan 10, 2019.

  1. vinylfind

    vinylfind New Member

    Messages:
    37
    I have a Audio Research SP9 MK III. These are the gain and loading specifications:

    Gain
    Phono to main output 67dB
    Phono to tape output. 46dB

    Loading
    47K


    It seems to me the gain on the phono is only suited for a low output cartridge. I am using a Denon 103 on the phono/main output and have more than enough gain. However the preferred loading is not 47K. Am I missing out on anything by it not being a perfect match?
    The second specification of gain on the tape output - how would that work? Could I use a high output moving coil or moving magnet on this output? Not sure how that works. I've read that there may not be a way to control volume in that case. Looking for a sub $500 cartridge that would work well in this system without adding a separate phono stage. The cartridge will be mounted on a Rega 300 arm. Looking for a step up in sound from the Denon 103.
     

     

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  2. vinylfind

    vinylfind New Member

    Messages:
    37
    Thanks for replying. I should have mentioned I'm not sure I'm handy enough to do internal soldering. I happen to be considering both of those cartridges. Will I have a good result without making internal changes? I'm afraid the Denon 110 would overload the phono stage the way it's set (factory).
    Can you comment about the gain on the tape output?
     
  3. Bob

    Bob AK Subscriber Subscriber

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    Location:
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    on the facts above, and general practice, the phono gain is 46db which is within the
    accepted range for MM phono cartridge amplification.

    tape output is generally before line stage amplification so the line stage amplification
    is 21db (more than enough to drive power amps).

    any high-output MC will be OK for use here. Most are designed for 47K inputs but
    check. low-output MC will need an additional ~20db gain using a pre-pre-amp.
     
  4. HypnoToad

    HypnoToad Ms Puss Puss Subscriber

    Messages:
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    Location:
    Melbourne, Australia
    If you wish to adjust the impedance to say 100 ohms which is the recommended impedance loading for the DL103r, you can simply put a 100 ohm resistor from the center of the RCA inputs of the phono stage to ground, as it's already 47k this will give you exactly 99.79 ohms which is near enough, it's the same for other values, because the impedance is at a high of 47k it makes little difference to the resulting values when using low value resistors.
     
  5. rothwellaudio

    rothwellaudio Forums Sponsor Sponsor

    Messages:
    1,696
    Are you intending to use the SP9 as normal, ie a preamp, or as an outboard phonostage? As a regular preamp the SP9 is really only suitable for MM and HOMC cartridges.
    As Bob says in post #4, the tape outputs are taken from before the line stage and therefore from before the volume control, ie the output is at a fixed level. If you use the SP9 as an outboard phonostage to feed into another amplifier you could take the output from the tape outputs. Again, really only suitable for MM and HOMC cartridges.
    Again as an outboard phonostage it would be possible to feed a LOMC cartridge into the SP9, max-out the volume control and use the main outputs to get 67dB gain. That's about the right amount of gain for a LOMC cartridge but you would find the signal-to-noise ratio to be rather poor - too much hiss.
     
  6. vinylfind

    vinylfind New Member

    Messages:
    37
    Thanks for your reply. I'd like to use it as the main preamp, normal as is.
    That may explain why I wasn't completely satisfied with the Denon 103. I get plenty of volume, 12 on the dial is pretty loud, but it's no meant for a 47K input (or the Rega arm for that matter)
    I'm going to look at the Hana EH and the Denon 110. I'd also consider a moving magnet. Anything under 500 that might work well in s Rega RB300 arm?
     

     

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  7. Balifly

    Balifly Listening Subscriber

    Messages:
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    Location:
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    The Hana EH has the

    • Stylus: Elliptical
    • Cantilever: Aluminum
    • Output: 2mV

    You may want to look into the the Hana with the Shibata stylus if you like the Denon DL-110.

    It is a lot more expensive though. :)

    For the mm, have a look at the AT VM540 ML

    Stylus Construction - Nude square shank
    Output 4.0 mV (at 1 kHz, 5 cm/sec)
    Stylus Shape - 2.2 x 0.12 mil MicroLine®
    Cantilever - Aluminum tapered pipe

    https://www.audio-technica.com/cms/cartridges/e7a3d4bc8b248b64/index.html
     
  8. vinylfind

    vinylfind New Member

    Messages:
    37
    I think the main issue here is the gain of my phono stage is 68dB. I'm not sure why it's so high as stock - it seems it will only work well with low output moving coils. I just tried an 2M Red just to see if this stage could work with it and it's so loud I have very little range of volume, plus excess hiss. When I use the KAB calculator, it seems I'm stuck with cartridges that have 0.15 - 0.3mv
    https://www.kabusa.com/pregain.htm
     
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  9. heyraz

    heyraz AK Subscriber Subscriber

    Messages:
    2,074
    Location:
    Long Branch, NJ
    That preamp appears to have 2 stages, a phono stage and a line stage.

    My interpretation:
    Phono stage gain 46dB
    Line stage gain (67-46)=21dB
    Total gain from phono input to line stage output=67dB
    Gain from other inputs (CDP, Tuner) to output=21dB

    My guess is using that phono stage (46dB gain) with a cartridge having an output of 1.5mv (+/-0.5mv) is probably optimal for that preamp, depending on the sensitivity of your power amp.
    I think the 2M Red (5.5mv) has way too much output for that preamp.
     
  10. sqlsavior

    sqlsavior AK Subscriber Subscriber

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    No, your phono stage gain is 46 dB, which is suitable for MM carts, not LOMC, which the Denon is. The Rega arm is too light for the Denon, unless you tack a couple of nickels to the headshell. Seriously. :confused: The Denon has marvelous tone when in the right arm, but its conical stylus limits detail, which is still just fine for many devotees. You have a preamp with lots of line-stage gain, so you are able to get usable volume from the Denon, but it is hardly at its best. If you want to stick with the Denon, you could get a step-up transformer, which will solve the loading issue as a side effect, but probably result in a small usable range on your volume control - i.e. 9 o'clock may be quite loud. Inline attenuators between your preamp and power amp would solve that problem, but it seems like a stretch. Alternately, if you have input-level controls on your power amp, you could turn those down. But you would still need more tonearm weight to get good bass and proper tone out of the Denon.

    Basically you have good components, but poor synergy between them.
     
  11. rothwellaudio

    rothwellaudio Forums Sponsor Sponsor

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    This is correct.
    This is also correct.

    The "problem" is the 21dB gain in the linestage. CD players have a 2V output and 21dB gain will raise that to 20V. That's fine if your power amp has an input sensitivity of 20V, but how many do? 750mV is more like typical.

    Really, the phonostage is a moving magnet phonostage - simple as that.
     

     

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  12. vinylfind

    vinylfind New Member

    Messages:
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    Yes the Red is absolutely too much.
    Thanks for your reply. I'm not locked into the Denon, I know it's not the best match for either the arm or preamp. As I said I tried a 2M red which at 5mv was way too high. So I'd love to try a moving magnet but it seems you are all saying it would have to have somewhat low output to get a usable volume range. Most I've looked at are 4mv and I'm wondering if there are any that are more in the 2mv range.
    I'm sending a picture to AR of the loading posts that are located on the bottom of the unit. If I'm understanding the manual right the unit comes with 560pf capacitors installed, but I see the previous owner installed load resistors in parallel, but Im not able to identify them. The color bands don't correspond to the resistors that AR supplies in the kit that are listed in the manual. Finding out if and how the unit was modified is my first step.
     
  13. vinylfind

    vinylfind New Member

    Messages:
    37
    So when using the KAB calculator, I'm looking for something that results in 46 rather than 67dB, assuming the gain in the AR hasn't been altered?
     
  14. vinylfind

    vinylfind New Member

    Messages:
    37
    90ECF1F8-B5B9-40DA-B689-D965B307E3D7.png
    Here are the specs for the Perreaux 3150 amp. Can we detemine the input sensitivity from this?
     
  15. vinylfind

    vinylfind New Member

    Messages:
    37
    I know this is a moving coil, but would the Hana EH at 2mv be an option? That would require 44dB gain from the phono stage according to the KAB
     
  16. rothwellaudio

    rothwellaudio Forums Sponsor Sponsor

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    The picture is very small and difficult to read but it looks like the sensitivity isn't quoted. What's the preamp like with another source - a CD player for example? I would expect the volume control to be very sensitive, so much that you're restricted to just the bottom end of its travel. If so, a pair of attenuators at the power amp's input sockets would solve the problem and solve the cartridge problem at the same time. I would recommend 20dB attenuators, which I sell.
    http://www.rothwellaudioproducts.co.uk/html/attenuators.html
     

     

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  17. heyraz

    heyraz AK Subscriber Subscriber

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    Location:
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    Look closer at your preamp's specs.
    The CD section is attenuated by 12dB.

    Grado's Statement Series 2 cartridges are MI and have a rated output of 1.0mv.
    Plug and play.
     
  18. vinylfind

    vinylfind New Member

    Messages:
    37
    [​IMG]I just opened the bottom panel to see the turret terminals. It appears something was done. According to the manual there are two 560 picofarrad capacitors on the impedance loading pegs. It states these should not be removed when using moving coil cartridges. What has been wired in parallel with the capacitors? What does this mean as far as cartridge selection?

    Update: I was thinking the blue resistors were wired to the terminal posts. But upon closer examination I think just the two at the top marked 560 are connected to the posts, nothing else is. So this means at least this part is still factory spec, right?
     

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    Last edited: Jan 17, 2019
  19. vinylfind

    vinylfind New Member

    Messages:
    37
    I might pick up a Schitt Mani just to see how having four gain choices could open the field of possible cartridges up. I'm also considering the Rothwell attenuators. And the DL110.
     
  20. rothwellaudio

    rothwellaudio Forums Sponsor Sponsor

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    No, 5mV is ok with a 46dB phonostage. It will be too loud because your SP9 has 21dB gain in its linestage, not because the phonostage has too much gain.
    Say you have the Shiit Mani set to 42dB gain - about right for the 2M Red - and you feed that into a line input on your SP9, you will still be sending the signal through the SP9's linestage with its 21dB gain giving you 63dB in total.

    Here's the SP9 mkIII manual:
    http://www.audioresearch.com/ContentsFiles/SP9MKIII Manual.pdf
    On page six it tells you how to reduce the gain of the linestage by 6dB. Unfortunately, that still gives you 15dB gain. However, as heyraz rightly says, the gain of the CD input is 12dB lower than the other line inputs, so you could use that and the volume control would be a bit more user-friendly.

    Still, the SP9 is (was?) a pretty expensive preamp with an onboard phonostage. It seems a shame to abandon the onboard phonostage and use a pretty cheap external phonostage instead. A pair of 20dB attenuators at the power amp's input sockets would be my preferred option.
     
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