Realistic 42-2101/42-2101-a Phono Preamps

Discussion in 'Audio Hardware' started by Robin L, Aug 12, 2015.

  1. scompton

    scompton Forum Resident

    Location:
    Arlington, VA
    The Realistic STA-2200 receiver uses MOSFETs. Sounds nice too.
     
  2. UnmarkedBill

    UnmarkedBill New Member

    I ended up with this Realistic 33-1057a, a little later I suspect, but similar stuff inside? I noticed the schematic of the 42-2101 calls for C1327 transistors, mine has C1815 transistors, are these also a FET? Would you suspect this preamp is comparable to the 2101 or 2101a sonically?

    <blockquote class="imgur-embed-pub" lang="en" data-id="a/uSPIn"><a href="//imgur.com/uSPIn"></a></blockquote><script async src="//s.imgur.com/min/embed.js" charset="utf-8"></script>
     
  3. UnmarkedBill

    UnmarkedBill New Member

  4. WestGrooving

    WestGrooving Forum Resident

    Location:
    California, U.S.A
    I have the 42-2101A and believe it uses a pair of BJT NPN transistors for each channel.
     
  5. Mileater

    Mileater New Member

    Location:
    Wisconsin
    the 42-2101a and 42-2109 upgraded are excellent, they perform way past there value!!
     
    Last edited by a moderator: Jun 3, 2018
  6. Paul Lancaster

    Paul Lancaster Member

    Location:
    Trenton, TN
    Would you mind sharing how it's been upgraded? Re-cap, power supply, etc.
     
  7. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    Here's my attempt at making the schematic diagram for this thing legible

    [​IMG]
     
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  8. Paul Lancaster

    Paul Lancaster Member

    Location:
    Trenton, TN
    Thanks harby, appreciate that.
     
  9. Pwoolar

    Pwoolar Active Member

    Location:
    San Antonio, TX
    Resurrecting once again!

    I have a 1977 Realistic STA-84 and I've been comparing the phono stage to various others from the time period. It's almost a direct clone of the Onkyo TX-2500, and extremely similar to a couple Marantz and Sansui models too.

    Unsurprisingly, it's 99% the same as the pre being discussed in this thread with one notable exception: the 42-2101 uses four 2SC NPN transistors whereas the STA-84 uses two 2SA PNP up front followed by two 2SC NPN transistors (just like the Onkyo mentioned above). Other than that they're wired just about identically so I'd imagine the STA-84 performs on par with the 42-2101. That particular model of receiver hasn't jumped up in price like the more popular Realistics, so if you're looking for a solid, all-discrete BJT amp with essentially a 42-2101 built in you can most likely find one for a good price on the bay etc.

    Oh and hello, I'm new here!
     
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  10. Mileater

    Mileater New Member

    Location:
    Wisconsin
    upgrading the 42-2101a realistic phono preamp. well, the basic electrolytic cap replacment is a start and worth while... then you can get into the signal path resistors/caps, swap ceramics with poly film... removal of the power transformer and replacement with a wall wart... total removal of the power supply with 9 volt battery source. upgrading the trasnsisotors mostly just the power transistor, i've started to cut the board into three sections and mounting them seperate. these little preamps are fun!!
    they far out perform many many other preamps and i would put them against any 'opamp' style unit any day.
    If you can solder and read a schematic go for it!
     
    Last edited by a moderator: Dec 15, 2018 at 10:58 AM

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