The J-RETRO 01 is designed to fit directly into standard “Jazz” style basses without modification, including a PP3 battery, in most cases. Its high quality circuit uses three stacked knobs and includes an active blend circuit plus a 3 band equaliser with bass, variable frequency mid, treble and bright function.
The J-RETRO comprises an Active 3 Band EQ with Sweepable Mid. Its design ncludes limited Passive Control. Designed to fit Standard Jazz Basses – 4s & 5s.
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, and this mode allows some useful settings too.
EASY TO FIT, NO ROUTING OR MODS TO MOST J STYLE BASSES.
A STANDARD PP3 BATTERY FITS UNDER THE PLATE IN THE STANDARD CAVITY IN MOST CASES.
HARDWARE OPTIONS: Chrome, Black or Gold. (Can be mixed by special request)
Specifications
BASS & TREBLE
TREBLE (+12dB @ 3 kHz, -12dB @ 1kHz)
BRIGHT (+8dB @ 7kHz)
BASS (+15dB @ 50Hz)
MID LEVEL & FREQUENCY
BOOST/CUT (+/- 12dB)
FREQUENCY (150Hz – 3kHz)
User Manual
Installation & Operation
Videos
John gives a complete walkthrough on how to install a J-Style preamp.
What they Say
The J Retro preamp arrived yesterday and I was able to install it in about 30 minutes. I did solder up the battery box on my bass (holds 2, so I wired it for 18v) for use with the preamp. My gosh, this tone is what I’ve been searching for with this Mike Lull Jazz bass!
The J-Retro transformed my Geddy Lee Jazz and the pickups were well balanced. They really are great preamps. My home made bass which uses a status graphite jazz neck, seymour duncan p/j and a badass bridge is absolutely perfect and your circuit / bass beats the pants off a few high level instruments I’ve had!
Hello John, The J-Retro already arrived today and I just popped it in my bass within a few minutes. It sounds great.
I’ve purchased one of your J-Retro 01 preamps for my fretless ’98 Mexi Jazz, and installed with no problems.  I’m using Lindy Fralin split-coil pickups, with a 5% overwound bridge pickup. Oh my…I think this just became my favorite bass! Those Fralin pickups have all sorts of growly tones buried in there, and the preamp brings them out VERY nicely.
It arrived about 12 and I installed it after lunch. Thanks for such prompt service. Your retro pre-amp gives an amazing range of tones for me to play with, like having a totally different bass, but still a Jazz.  Can’t wait to see how it sounds in the band mix in a couple of days.
 I wanted to take a brief moment to thank you for creating a high quality product that delivers what it promises. I recently upgraded my Fender American Jazz V with some Nordstrand pickups and one of your J-Retro preamps. I am absolutely blown away at how good it sounds with only very minimal settings.
Are EMG active pickups compatible
We have good number of preamps out there with EMG Actives, and they work well, with happy customers who say they are a good combination.
About Passive Tone Pots
Many of our units have Passive Tones. Our tone pots have the same capacitors as EMG but the tone variation will occur more towards the end of the rotation due to our pots. The maximum effect will be the same as the EMG tone pots. In other words, the passive tone won’t be as smooth as the EMG pots.
Prepare to install: screen pickup cavities
If there’s any interference noise, many aren’t aware that it’s important to screen PU cavities as the highest priority, even with “noiseless” PUs. Noise can be reduced with humbuckers and dual coil designs, but very few pickups are totally noiseless in my experience. Reference Guide here
Using 18V power
All our products, although supplied with a single 9V battery clip, are designed to work 9V or 18V out of the box. Just add the additional battery, or connect to an 18V battery box, no other changes are necessary.
Either add another battery snap, as below pic.
Or snip the single snap and connect to an 18V battery box, Red to Red, Black to Black.
All East products are designed to work on 9V or 18V with no change to the electronics.
Battery life depends on the battery type, quality, and spec. There’s not a one size fits all answer.
The J-Tone requires just over 2mA of current. So a battery with a capacity rating of 500mA should last ~250 hours.
If battery voltage is measured, that should always be done whilst under load, especially if a battery has had some use. Once battery voltage reads below 6V under load, it should be replaced.
Distortion will set in according to the battery voltage and signal level coming through the preamp.
So it’s hard to specify the exact voltage where distortion will set in. It depends on the output of the pickup(s), how high the volume is set, and how much low-end EQ you have dialled in.
If you had low output pickups, the voltage could go lower before distortion set in, for example.
The chips are spec’d to work down to 6V, but they will often work to a much lower voltage. See below about measuring the battery voltage.
DON’T DO THIS: Don’t disconnect and take the battery out of an instrument to measure the battery. It will often be a false reading if the battery has been used to any extent.
IMPORTANT – Measuring The Battery with an East Preamp:
The battery should be connected to the preamp with a jack inserted into the instrument so that the preamp is turned on. In other words, the preamp is loading the battery.
Then probe each terminal with your meter while the battery is powering the preamp.
(The reason for having the battery connected, is that a weak battery can still show what appears to be a decent voltage without the preamp)
