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John East J Retro Preamps



The J Retro 01 Bass Preamp is designed to fit directly into standard "Jazz" style basses without modification, including a 9v battery.

$299.00 - $325.00
$299.00 - $325.00

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Control Configuration

  1. Volume/Blend Stack
  2. Treble/Bass Stack
  3. Mid/Mid Stack
  4. Blend & Pickups Switch
  5. Active/Passive Switch
  6. Available in Black, Chrome, or Gold Finish


The J Retro 01 Bass Preamp is designed to fit directly into standard "Jazz" style basses without modification, including a 9v battery. Its high quality circuit uses three stacked knobs and includes an active blend circuit plus a 3 band equalizer with bass, variable frequency mid, treble and bright function.

A very gentle built in contour gives immediate colour without detracting from the basic sound of any bass. The active blend circuit prevents the loss associated with many passive basses where, when both pickups are up full, the signal from one pickup feeds into the other and vice versa.

However, a switch is included to allow a passive equal mix of both pickups. A second switch - basic "get-you-out-of-trouble" passive mode is included in case the battery dies in crucial circumstances, but this mode allows lots of useful settings too.

Easy to fit, no routing or modification on most basses.

A standard PP3 battery fits under the plate in the standard cavity in most J-style basses.

Technical Specifications

Volume/Blend Stack

  • Volume

  • The upper knob is the Volume which has two sections under the same knob. A high impedance for the passive path and a low impedance section is used for the active circuitry. When used active, this knob has active circuitry after it'so that the feed to your amplifier is a low impedance drive.

  • Blend & Pickups Switch

  • The lower outer knob is the Blend balance for the pickups. Turn it fully clockwise for the neck pickup alone and fully anti-clockwise for the bridge pickup. The midway position, which has an indent, gives an equal mix of both pickups. The balance between the pickups is continuously variable with progressive level compensation towards the single pickup settings. Important:- The Pickups switch (by the blend) must be set pointing towards the jack for the Blend to function.

    Treble/Bass Stack

  • Treble: (+12dB @ 3 kHz, -12dB @ 1kHz)

  • The upper knob is the Treble control with boost and cut. The central 'flat' position is indented. The cut settings work on lower frequencies compared to boost to give a deeper sound when the top is rolled off.

  • Bright: (+8dB @ 7kHz)

  • Pull the Treble knob for the Bright setting.

  • Bass: (+15dB @ 50Hz)

  • The lower outer knob is the boost only Bass control. The frequency band of boost gets progressively lower as the boost is increased. An indent midway is included to aid the setting of this control.

    Mid/Mid Stack

  • Mid Boost/Cut: (+/- 12dB)

  • The upper knob controls the amount of Mid boost or cut at frequencies according to the setting of the Frequency knob. The midway indent is the 'flat' position.

  • Mid Freq: (150Hz - 3kHz)

  • The lower outer knob is continuously variable and sets the Mid frequencies for boost or cut.

  • Active/Passive Switch

  • Towards the jack for active, the opposite for passive.


    Rate and Review this item
    Verified Buyer
    Great Preamp!
    By from on 10/20/2016
    This is an amazing preamp. It allows many tonal options and I really don't think its capable of producing a bad one.; It dropped right in to a D Lakin Basses Joe Osborn Jazz bass with no problem. I did have to go back and shield all the cavities, but that was not due to the preamp. It is now completely silent even with the treble boosted to the max. I was so impressed, I reached out to John via his website about installing a J Retro Deluxe in my Sadowsky. I know...sacrilege. It sounds that good! John was very helpful. Having the ability to adjust the mids is crucial to achieving a tone that cuts through the mix. Great product!
    Verified Buyer
    Best pre-amp for passive jazz basses
    By James Manuel from on 6/9/2016
    A little expensive but money well spent fit perfectly in the fender jazz modern 77 in about 30:00 mins.
    Verified Buyer
    Bassist & Vocalist
    By David Morris from on 1/15/2014
    This is by far the best sounding pre-amp I have ever owned and in over 40 years of playing bass, I have played thru many! Bravo John East! This thing rocks! It is a little pricy but once you hear it you won't mind! Buy yourself one now! Gonna get one soon for my P-Bass!
    Verified Buyer
    Very nice retrofit!
    By Chris from on 1/15/2014
    Fits nicely and tight in the route. Nice 3-band e.q.Smooth pot rotation, battery life has been very long for me personally, switches are crisp. Passive operation is nice although restricted to only full bridge on or equal blend of both pickups.Very clever design and fitment.I would recommend this as an option to any Jazz bass player with a standard control plate and top route.Great unit!
    Verified Buyer
    By Dale Keown from on 1/15/2014
    Amazing preamp. I can't say enough about it. It's a pretty tight fit in the body cavity but the sound is excellent. The mid sweep alone is worth the price. The treble is not harsh and there is low end to spare. I love it.

    For those who say it diminishes the passive Jazz bass growl, they are wrong. You can dial in even more growl with this pre.
    Verified Buyer
    By Randy from on 1/15/2014
    The J-Retro brought my 96 Jazz Dlx V with TI flats to life...with the original need for new pickups now...from Chamber music to full out does it all.
    Expensive...yes...but well worth the investment.
    I just dropped my 3 gigging basses down to one!!
    Awsome product.