Yes. The active electronics work well with EMG pickups.
The pickups feed the preamp input buffer stages rather than feeding the controls directly, so the preamp can work with both passive high-impedance pickups and active lower-impedance pickups.
The passive tone value differs from the usual EMG pot value, so the tone effect may occur more toward the backed-off end of the control rotation, but the overall tone roll-off remains usable.
East UK uses custom Japanese ALPS potentiometers because they are reliable, compact and consistent.
These parts are made to the required size and specification for the preamp assemblies. Larger alternatives may feel different, but often will not fit into the compact J-Retro style layouts.
Many East UK units have been in use for well over fifteen years with their original pots still working correctly.
The BTB-01 is a compact bass and treble module based on the bass/treble section of the J-Retro 01.
It uses a single stacked control with Bass, Treble and Pull for Bright.
It is intended for installations where a simple high-quality two-band EQ is required.
There are two versions of the J-Retro:
The Pre-Shape model offers a slightly fuller low end and a touch of brightness in the highs. This gives the sound more presence and warmth, making it particularly popular with players who prefer a rich, fat tone.
In contrast, the Flat Response version delivers an uncoloured sound when set flat, allowing for a seamless switch between active and passive modes without noticeable tonal change. This version buffers the pickups, which eliminates the effect of cable capacitance — often resulting in a slightly brighter tone despite the otherwise neutral design.
Players who favour a midrange-focused tone — such as those who lean heavily on the bridge pickup — often prefer the Flat Response version as a more transparent starting point. Others who want a fuller, more enhanced tone from the outset tend to favour the Pre-Shape version. It’s important to note that the Pre-Shape boost is subtle — just a few dB of gentle lift at the low and high ends — so either version can ultimately be dialled in to suit a wide range of styles.
In practice, our experience over more than 15 years shows that the Pre-Shape version is by far the most popular, especially among players using Jazz-style basses. As a result, Flat Response units are produced in smaller quantities and may have limited availability.
(We’ve had players who owned several J-Retros try the Flat Response version for variety — but many ultimately return to the Pre-Shape for its familiar and versatile character.)
The differences between the DJ and J-Retro are just about the fitting the plates. The holes in a J bass are in a straight line, those on the DJ are in a slight radius. Electronics is the same for both.Â
Yes. Just follow this procedure:
+ Remove the Passive Tone (single knob). Then fit the jack in that hole.Â
* Electrically the Passive Tone has 3 push-on plugs so easily disconnected.
* Remove the 3 plugs which are connected to the Passive Tone from the Vol/Blend end.
* Remove tone knob and carefully, using a spanner, loosen the nut taking care not to scratch the plate.
* The wiring for the jack stays the same.
* Fit the Jack in place of the Passive Tone, serrated washer should be on the underside, flat washer on the top.
* Take care to tighten the jack nut nice and tight using a spanner.
* The wires will need to be tied neatly out of the way of where the battery sits.
+ The jack wires are a lot longer than the J-Retro wires so ideally it would be best to shorten them.
* Make a note of where the Orange and Green wires are connected to the jack.
* Unsolder the Orange and 2 Green wires at the jack, leave the battery Black wire.
* Retain the length of the Green Ground wire (one on its own) which has a screw terminal on the latest units.
* Crop the pair of Orange and Green wires twisted together – ~40mm for Green, 45mm for the Orange.
* Re-solder the Orange and 2 Green wires as noted, Green wires to middle tag on the jack, Orange to the tag left, opposite the Black battery wire.
Some luthiers have rear mounted in the wood with Jazz layout very successfully, but it’s not a trivial install !!
The knobs/pots are mounted in a straight line, directly attached to the circuit board so the layout has to be exactly that of a Jazz with fixed knob spacing, plus there are 2 tiny toggles with fixed locations too.Â
The threads are short too, designed for a metal plate thickness.
TOGGLE REMOVAL
+ The 3P cap is not attached to the toggle, it’s very close.
* Bend it back a little to get access to the toggle pins.
+ It’s not necessary to trim the epoxy, the PCB will get damaged.
TO GET THE TOGGLE OUT
+ Remove the circuit board from the plate and hold firmly in a vice.
* Without the plate you’ll have access to the 5 pins.
+ Add more solder to all the pins, maybe so that there’s a complete web between the 3 pins backing on to the cap.
+ With some pointed pliers ready to ease the toggle out by gripping within the hole where it broke off, do as follows:
+ Heat all the pins up in turn until they are all molten whilst holding the pliers gripping the toggle.
* If it seems there’s not enough solder, add some more.
+ As the toggle begins to free up, ease it out without force, any force would likely destroy the through-hole plating.
+ As it begins to free up, heat the 3 pins and then the 2, and use a gentle rocking motion with the pliers to ease out the toggle.
* It may be you can you use a gently ‘circular motion’ to heat all the pins in turn, ot the 2 larger retaining pins and then the 3 webbed by the cap.
+ A slight gentle pull is fine, the PCB is thin and springy, but no yanking.
+ The heat will help to loosen the toggle from the epoxy.
* There will be a little moulded shape left within the epoxy, where new toggle will can be pushed into place.
+ Hopefully the toggle can be eased out while the hot solder is molten.
+ Once out suck out an solder in the holes ready for a new toggle.
Distortion in active mode, especially at higher volumes, can occur due to the limited headroom provided by a 9V battery. The J-Retro, with its extensive EQ options, can generate high signal levels that exceed the battery’s capacity, leading to clipping.
To address this:
