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Fender Deluxe Reverb Reissues: 65 vs. 68 Custom

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  • Fender Deluxe Reverb Reissues: 65 vs. 68 Custom

    Differences between two Fender Deluxe Reverb Reissues: 1965 Blackface vs. 68 Custom Silverface

    This thread may not strictly belong in the "Vintage Amps" area, as it discusses modern reissues. But I can't think of a better place to post this information, so here goes:

    In another thread I was looking for compatibility information about faceplate hole size and spacing between the current Fender DRRI boards and various aftermarket chassis options. A side topic came up about putting the 68 Custom boards into a 65 DRRI chassis:

    Originally posted by Steve A. View Post
    Are you thinking of getting a $75 board set from Allesandro? I might get the '68 reissue boards to put in my '65 DRRI...

    https://www.ebay.com/itm/Fender-65-D...t/282699850543

    https://www.ebay.com/itm/Fender-68-D...t/272892974919
    If you already have a complete amp then you won't need the complete set of boards, you could also effect the change by just doing a few component swaps.

    This is the difference in parts between the BF 65 DRRI and the SF 68 Custom:

    Code:
    Descriptor    Part #          65 BF DRRI      68 Custom SF DRRI
    Tonestack     C23             0.047           0.022
    Reverb Mixer  R30             1M              470k
    NFB Shunt     R10             2k7             5k6
    Coupling      C10,C16         0.1             0.022

    Summary of the changes:


    1. Changing the "mid" cap in the tonestack from 47nF to 22nF will result in a bit of bass boost in the 68 Custom. This is because the smaller cap changes the cutoff frequency for the RC lowpass filter formed by the slope resistor and the mid cap, in addition to changing the CR high pass filter frequency formed by the mid cap and the 6k8 fixed mid resistor.

    Here are two plots from TSC that show the effect of the cap change with the bass control max'd out:

    Click image for larger version

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ID:	873459Click image for larger version

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    2. Changing the Reverb Mixing Resistor from 1M to 470k results in stronger wet signal available for mixing with the dry signal.

    3. Increasing the ratio of the NFB series resistor R10 to the cathode resistor will result reduction of the feedback factor (H). Less NFB results in earlier breakup for the power amp. (You might want to make this mod switchable.)

    4. Reducing the value of the coupling caps will reduce the frequency response for bass signals in the output stage. This is the classic fix for "Fender farting." Decreasing the size of the coupling caps from 100nF to 22nF decreases the time constant of the AC coupling circuit, thereby allowing faster cap discharge and decreasing the "Crowhurst" variety of "blocking" distortion.

    Have fun!
    "Stand back, I'm holding a calculator." - chinrest

    "I happen to have an original 1955 Stratocaster! The neck and body have been replaced with top quality Warmoth parts, I upgraded the hardware and put in custom, hand wound pickups. It's fabulous. There's nothing like that vintage tone or owning an original." - Chuck H
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