Rethinking Phono Preamp Gain Settings

Discussion in 'Audio Hardware' started by avanti1960, Jul 8, 2017.

  1. psulioninks

    psulioninks Forum Resident

    Location:
    Midwest USA
    Ha - I was just thinking this same thing!
     
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  2. Ontheone

    Ontheone Drifting Towards the Dead Wax

    Location:
    Indianapolis
    I'd sell the DV cart and build an analog front end that create sonic synergies within the budget the OP can afford. Feels like forcing a square peg into a round hole. A nice few hundred dollar ~0.5mV cart with a $600 phono stage will probably sound much better at this budget than forcing the DV to perform with poorly matched gear. Again, my 2 cents.
     
    patient_ot likes this.
  3. FalseMetal666

    FalseMetal666 Forum Resident

    Location:
    San Francisco, CA
    I think the way to go, still, is to get the best MM-only phonostage you can and supplement with the Piccolo. For example, a Graham Slee 2SE for $400, plus the Piccolo, would put you right around your budget.

    Test out the Karat to see if it's doing what you want. If not, return the Piccolo, sell the Karat, and get the best MM you can afford to match with your new Slee piece.
     
  4. Ontheone

    Ontheone Drifting Towards the Dead Wax

    Location:
    Indianapolis
    I agree with that too.
     
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  5. nvilletele

    nvilletele Active Member

    Location:
    New City
    I get what you are saying, but there are certain emotional reasons I wish to use the DV/Karat Ruby cart, that go beyond even (non-) cost of the cart for me. At this point, it becomes an issue of money vs. performance solely on the preamp side.

    Right, exactly.

    Not sure about any need to rebuild it, it seems ok, but admittedly, what do I know?

    Yes, good advice. I may just need to do that.
     
  6. FalseMetal666

    FalseMetal666 Forum Resident

    Location:
    San Francisco, CA
    If you're willing to go as high as $600 on the used market, the world is your oyster. Take a close look at Sutherland stuff.
     
  7. Ontheone

    Ontheone Drifting Towards the Dead Wax

    Location:
    Indianapolis
    This unit might work within budget. I think gain may be enough depending on line stage gain. I realize I don't have all details of OP's system.

    Daynavector P75 mkIII

    [​IMG]
     
  8. psulioninks

    psulioninks Forum Resident

    Location:
    Midwest USA
    In thinking about product options available...if I were trying to maximize my buy for dollars spent and get something that would pretty much work with any cartridge I tossed its way...I think I would post a want add on US Audio Mart for a Rogue Audio Triton or Triton II phone stage:

    Rogue Audio

    Specs:
    • Moving coil (MC) or Moving magnet (MM) operation
    • Three stages of amplification for ultra low noise
    • Precise RIAA equalization +/- 0.1 dB 20-20KHz
    • Massive, fully-regulated multi-stage power supply
    • Rumble filter (user selectable on/off)
    • 20, 30, 100, 300, 1K, 47k, 75K, 100K Ohm loading options
    • 0, 47, 150, 470,1K Picofared loading options
    • Mono switch
    • Hatch cover for easy loading access
    • Four gain settings: 43dB, 55dB, 60dB, 70dB
    • Ultra heavy-duty gold RCA inputs
    • Precision components throughout
    • Heavy machined aluminum faceplate
    • Two heavy (2 ounce) copper circuit boards
    • Detachable IEC power cord
    • Entirely designed and hand built in the USA
    • 3-year manufacturer's limited warrant
    These units have sold between $600-$700 used.

    Just my two cents...
     
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  9. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    Possibly, that was a few years ago. I don't think the lab report there goes into extreme detail either. Sometimes MAR will show a detailed chart on how overload varies, if at all, across the range of frequency.
     
  10. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    The A-Weighted S/N ration for that high MC gain setting isn't great. Unweighted it's probably ~50dB. I'd probably look into a different option, if it were me.

    That could mean a used MC preamp that's really nice, a dealer demo/open box unit, or the previously dicussed MM + headamp option.

    Your money, your call.
     
  11. Phil Thien

    Phil Thien Forum Resident

    Location:
    Milwaukee, WI
    The Sutherland 20/20's S/N measurements (Source: Sutherland Engineering 20/20 phono preamplifier Measurements ):

    The Sutherland's construction is completely dual-mono; crosstalk between the channels was unmeasurable. With the input shorted and the gain set to 40dB for MM cartridges, the 20/20's unweighted, wideband S/N ratio (ref.1kHz at 5mV input) was excellent, at 79.4dB. This improved to 87.9dB when A-weighted. In the worst case, with 64dB of gain, the unweighted, wideband S/N ratio was a still-good 64dB left and 68.2dB right, both figures referred to 1kHz at 500µV. Again, A-weighting the measurement gave the expected improvement, to 73dB left and 74dB right.

    Certainly better than the MoFi, but still pretty noisy IMHO.

    I'd bet dollars to donuts that I could pickup 10db by powering the MoFi via batteries. It comes with a pretty decent wall wart, but a good quality linear supply would undoubtedly be better, and batteries even better.
     
  12. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    Numbers for the Sutherland seem respectable to me when in high gain mode. I'd be more worried about general record noise a sensitive Mc cart would pick up off a record.

    Not sure about battery power for the Mofi. I don't believe I've seen anyone try that. Could be an interesting experiment.
     
  13. Phil Thien

    Phil Thien Forum Resident

    Location:
    Milwaukee, WI
    Well if someone wants to send me a LOMC cartridge, I can work-out the details.
     
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  14. nvilletele

    nvilletele Active Member

    Location:
    New City
    Someone had mentioned the Graham Slee preamps.

    I see the Gram Amp 2 SE at $410 for MM, which could be paired with Piccolo2 for MC, or just used with MM Cart.
    And there is also the Era Gold V legacy product, $999 new, but available used for450, for MM

    What are your thoughts on these two models generally, alone for MM or with headamp for MC use?

    There is also the Gram Amp 3 at $399 for MC, .2 to 1.0mV input sensitivity.
    How might this be with the Karat cart at .2 mV? Risky, or not?
     
  15. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    Graham Slee makes great stuff but I do recommend signing up for their forum and asking your questions there.

    Graham Slee Audio Forum | HiFi System Components

    You can borrow anything they make for the cost of shipping for a 2 week minimum loan. Testing in your own home is probably the best way to evaluate whether or not it's going to work well with your cartridge.

    US Loaner Program - Graham Slee Audio Forum | HiFi System Components

    Now, with G.S. you typically get an MC only phono preamp for an MC cartridge, or you run one of their MM stages with Elevator, which is an active step up device. The GS MC stages usually have around 61-62dB of gain. With the Elevator you end up with around 64dB of gain.

    According to the KAB calculator, 64dB would be the approximate amount of gain for your cartridge. This calculator usually errs on the conservative side for gain recommendations.

    Note that the GA3 MC model that Music Direct sells is different from the current model.
     
    Last edited: Jul 1, 2020
  16. Phil Thien

    Phil Thien Forum Resident

    Location:
    Milwaukee, WI
    Interesting catch. I recently got one of these even though @patient_ot and MoFi themselves suggested no more than 4-5mv cartridges.

    I noticed on mine that they had changed the subsonic button. Previously the button had to be out to engage the subsonic, now it has to be in.

    Obviously changing the button used is pretty simple stuff, but they did change it, so they could have changed other stuff.
     
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  17. Davey

    Davey I carry the moon inside a silver bag

    Location:
    SF Bay Area, USA
    Yea, it actually measures quite a bit better than his Graham Slee for input overload, but nothing really to compare, don't know of any previous tests. As mentioned above though, the overload is just listed at the 1KHz reference.
     
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  18. patient_ot

    patient_ot Forum Resident

    Location:
    USA
    Yep. If anyone can find a test that shows the overload throughout the frequency spectrum that would be interesting to look at. I also think the designs of the Studio and Ultra may be different, i.e. the Ultra is not just the Studio with a headphone amp. IIRC the S/N and THD numbers per factory spec were different to start with between the two Mofi units.

    At any rate, The Goldring 1042 cartridge was audibly distorting with the Mofi SP, and it didn't do that with the G.S. Reflex M. Why? I can't say for sure - more testing would be needed. Mofi doesn't really provide guidance on suggested cartridge output whereas G.S. suggests 1.6mV to 9.2mV for the Reflex. The only info on that score I was given was during my email exchanges with Mofi's people (not just sales folks).

    At this point I no longer have the Mofi or the 1042.
     
  19. nvilletele

    nvilletele Active Member

    Location:
    New City
    I finally got my Technics system set up with the turntable and MF V90 LPS in my music room. The Kenwood is going into the closet and the bedroom will get the Denon receiver I had mentioned. The DV/Karat sounds pretty damn good to me, to be honest through the SU-V96 amp and my Bose 901 pair. I get good volume and to my non-expert ears, no significant hiss or distortion, etc.

    I have also set up my Bose active equalizer a little differently this time. Instead of using the tape 2 connections, I used it with the alternate connection method, connecting it to the Pre-Out, Main-In terminals on the amp (after removing the shorting pins). Then I also connected my Technics SH-8028 graphic equalizer to the amp via the tape 2 connections as it normally calls for. So the Bose active equalizer is always engaged, but instead of using its treble and other controls (or if desired, I guess, in addition to them), I can also engage the Technics equalizer to fine tune the sound further. I like it, it really brings out both ends nicely, adds some punch while retaining clarity.

    There is a little hum at very high volume, noticeable between tracks but not really otherwise and not much if any at mid to lower volumes.

    I have already decided to return the MF and get the MoFi StudioPhono. If I want to change to a higher end preamp, or add a headamp, someday, that option is always available. The extra $130 net is well within my budget, and I can use the savings to buy more records.

    But for now it is sounding pretty damn good to me. Next, I’ll see how ell my AT15Sa works on the MM with the new stylus I just bought from turntableneedles.com.

    It’s all good now, and can only get better. What I have learned from you all is definitely going to aid me as I proceed. For now, baby steps. Maybe someday I’ll have a Sutherland or the like. But so far, so good. In fact, pretty excellent.

    Thanks everyone for all the help and advice on preamps and dealing with low output MC carts.
     
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