Micro Booster MK3 Onboard Guitar Preamp with Push-Push switch-pot [Retired]

SKU: uBST3 Category:
⚠️ The uBST MK3 is retired. Check out the new uBST MK4.

From buffer level up to +20dB of flat & clean FET boost with Push-Push True Bypass! BECOS Micro Booster on-board guitar preamp takes magnetic pickups signal and delivers a controllable, low noise signal boost, that pushes guitar amplifier into solo mode on-the-fly.

 Wiring Diagrams & FAQ
 Demo Video | More
 9V battery not included

From buffer level up to +20dB of flat & clean FET boost with Push-Push True Bypass.

BECOS Micro Booster Onboard Guitar Preamp can be installed in any guitar or bass to boost the signal from passive magnetic guitar pickups. It is powered by one or two 9V batteries, connected in series.

Based on a FET implementation derived from original vacuum tube audio amplifier circuits, it was carefully calibrated for a best sounding clean boost. It features a variable gain control which starts from Unity Gain and goes up to +20dB of pickup’s signal amplification. On the lowest gain setting it can be used as a FET buffer. A further trimming control allows for either attenuation or setting the lowest gain starting point.

It is engaged by a PUSH-PUSH switch-pot (switch up). When not engaged (switch down), the pickup signal is True By-passed and goes straight to the output. Potentiometer side of the switch-pot is not part of the booster’s circuit – it only replaces the potentiometer in your instrument (volume or tone).

More info

 Wiring Diagrams & FAQ
 Demo Video | More
 Due to transportation safety restrictions, this product ships without a 9V battery.

Build Option

500K Switch-Pot (push-push), 250K Switch-Pot (push-push), No Switch-Pot (board only)

Note! The product name, design, circuit, components, description, pictures, technical specifications, functionality, etc. may change anytime and without prior notice (Terms and Conditions). We advise you to check the manual (only available as a downloadable PDF above in this page) for details on the product's current features and functionality. If you spot errors, inconsistencies, or if you need more information or assistance, please contact us.


Watch video demos of Micro Booster installed in different guitars.


Electronics knowledge and hand working are required. Woodwork may be necessary.


  • Pot side of the switch-pot is NOT part of booster's circuit

    Booster comes latest in the guitar signal path. The circuit is attached to a Push-Push Switch-Pot. Switch side routes signal through booster or True By-pass. Pot side replaces volume or tone pot in your instrument.

  • Micro Booster in guitar's signal path

    Besides rewiring the potentiometer, there are only two solder points to make, Input and Ground. Existing mono instrument output is replaced with a stereo connector wired to booster's board. The booster is powered as long as instrument cable (mono) jack is plugged in. Battery should last for months.

Installation Videos


Read FAQ's and consult published Wiring Diagrams and use them as starting point for your installation.
If you still have questions, send us an e-mail.

Frequently Asked Questions

Adding a booster circuit into guitar signal chain gives you more options for gain control. They are more effective with tube amps which are highly dynamic, and a booster changes that dynamics. However, having it in the guitar, gives the advantage of pushing the amp in an instant, which is great especially on live playing. BECOS Micro Booster was designed to push up pickup's signal, while retaining all its sound characteristic. We call it a "flat boost".

In higher gain setting the boost results in increased saturation and sustain. Because of the natural compression on high gain, you won't hear the difference right away or if the boost is not wildly increased - which we advise against -, but having the guitar in your hand and playing, you will definitely FEEL the difference. It all depends on taste and objective. A booster is a tool that may be used to shape the gain structure, or to push the amp into clipping, or... whatever you chose to use it for. "Where you can really tell the difference on higher gain channels, is to back the guitar volume down to 5 or so, somewhere medium for a nice rhythm distortion. Then, when you hit the boost, there's a huge difference! It's like going back up past 10 on the guitar volume to about 15." - as one of our users suggests.

Yes. The booster comes latest in the signal path, regardless where the signal comes from - bridge or neck or both. It does not matter where the switch-potentiometer is installed - it is not part of the booster's circuit. It just replaces a pot in your guitar (volume or tone), so that the booster electronics can be attached neatly to the new pot. And, yes, the new switch-pot also has the routing signal switch function: through booster or by-pass direct to output. Please download and read the manual, for relevant information and consult published wiring diagrams.

The potentiometer side of the switch-pot is NOT part of booster's circuit, and is meant to replace volume or tone potentiometer in your instrument for the convenience of having a switch and a potentiometer into one single physical device. So the potentiometer has to be rewired just as it used to be - passive. If it is the tone control that is put in place of, the tone capacitor has to be moved to the new pot as well. If it is the volume control that is to be replaced, you just have to rewire the new pot as it used to be. Booster's PCB is just attached to the switch-pot to pack everything in place. The switch side of the component routes signal through booster or true by-pass.

BECOS Micro Booster Preamp is designed with FET transistors which are very tube-like sounding. The circuit is configured for clean boost in its default setting and is a clean boost that is provided. The sound is transparent and it can only be likable, for any pickup, for any amp. When not used, the switch-pot puts the signal in true bypass and the sound is pristine and unaffected in any way. You can check our demo videos on our YouTube channel as they will become available.

Some noise may be heard especially with single coils, which amplified by the booster is more audible. Single coils are notorious for being a bit more noisy than humbuckers which have signal phase canceling from the second coil. If you want to check the noise of the pickup, just put the booster in bypass and raise the amp input gain to the point of booster's amplification, and compare. However, you will hear less noise from the amp because it is better shielded anyway, but you will understand what the booster amplifies in place.

Here's what can help containing the noise:

  1. A proper shielding, not one made with "conductive paint". If you ask a proper trained technician with electronic engineering background, you will find that an effective shielding of the electronic circuits can be done only with iron cage, of a certain thickness. The next practical option for guitar is cooper foil (if it is sticky type, be sure the sticky tape is also conductive!). Shield also pickup's cavity and be sure to shield the plastic pickguard as well. Paint shielding is "effective" up to a point and is "most effective" with humbuckers, which are already quiet due to hum canceling coils. As a last option, use aluminium foil.
  2. Connect all ground wires in a single point which makes contact with the shielding.
  3. Reduce the length of every wire in the electronic cavity before the booster, because every wire is an antena. Anyway, try to push them away from the small electronic parts on the circuit board of the booster.
  4. To investigate aditional noise sources that are amplified, temporarely stay away from the guitar amplifier and other electromagnetic sources such fluorescent lights or tv or power lines - they all radiate noise which is picked up by the pickups and the wires in the guitar, which amplified, will start to be heard. Also change the position of the guitar in relation to these sources, to hear the influence on noise; there might be positions with less noise, so you will understande the source and how the pickups and the wires inside guitar picks it up. Some more noise will be heard if you don't touch the strings with guitar volume open or in a certain position. Amplified, this noise is more obvious.
  5. Play with booster's gain from the minimal level; raise it up in small increments and test the effect of it, when compared to bypass levels. Use only the amount of amplification needed to push the amp or effects in front of the amp, if you have any. Most likely, after a certain point, you won't hear much difference in amp's response, especially on higher gain channels, because of their natural compression. Speaking of pedals after booster and in front of the amp, especially if you have distortion pedals, they will also add their noise and they will amplify even more of what is in front of them. Bypass them temporarely to check the added noise.

That is pretty much what can be done to contain an existing noise which is there from the start anyway, but then, amplified, will become more obvious.

At playing levels, say in a band, these noises are usually covered and could be ignored during rehearsal or live performance. In between... there is the noise gate pedal.

Also, keep in mind that not all single coils behave the same, due to their construction materials and frequency response. With different pickups you will hear different noise/things. Try the guitar and the booster with a different amplifier as well, just to compare and draw a conclusion.

The booster is powered only when the instrument cable is inserted. Power consumption is very low and it can last for months. Most likely, the battery will have enough power for at least 300 hours of continuous usage, even more. The optimum battery voltage is above 9V. It can be powered with up to 18VDC using two 9V batteries in series. This higher voltage is recommended expecially for bass guitars which have higher output amplitude. When battery voltage drops bellow 7V, the booster is likely to overdrive the sound a bit, especially if the pickups are humbuckers with high output, but you will find this very likable because of a tube-like overdrive, with nice smooth recovery. This clipping will be less obvious if the pickups have a low output. Most single coils in Fender guitars will not overdrive the booster even if the battery drops bellow 6.5V.

YES. Installing it in a Gibson original or a Gibson-like guitar is the easiest installation because there is plenty of room in the electronic compartment. The Push-Push switch pot's shaft precise dimensions (9.8mm) allow for the easiest installation in place of bridge pickup controls (tone or volume), because they are placed on the edge side of the guitar, where the top wood is thinner. We did install it in place of neck pickup tone control though, where the body wood is a bit thicker (around 8 mm), and we still did it. Of course, every guitar is a bit different and the wood may be thicker or thinner from one instrument to another. Sometimes Gibson use "long shaft" pots for their controls, but they are in fact EXTRA long and the length is not always needed nor used, but they use long shafts because it is easier to install. For our case, with a minimal skillful hand and only if it is necessary, a bit of wood trimming with a small cutter around the hole on the inside electronics compartment, can provide up to 2 mm more. This is enough for an installation of our Push-Push pot even in the thicker part of the wood. In fact, our pots are exactly the same as those used by Gibson and other manufacturers for providing such feature, and it is the only one available in the market. So, if they installed it you can do it as well. If you have to trim the wood a bit and/or if you have shielding which add to the wood thickness, you will have to stick a small piece of isolation tape to avoid potentiometer's lugs to touch the shielding. We have a video installation of the Micro Booster in an original Gibson Standard Traditional guitar on our You Tube channel which you can check it up.

YES. Telecaster electronics compartment is very narrow and the bottom between the potentiometer and pickup switch may have to be routed in some Telecaster bodies, so that the 9V battery can be fit inside. Some trimming might be needed as well just near the tone or volume control to make room for booster's circuit. If needed, the booster volume knob can be taken out through the metal plate of the controls, simply by drilling a 6 mm diameter hole in the plate, at around 11-14 mm from the center of the existing control hole. The installation difficulty is medium for a skilled person which can handle sharp tools. We did it from the first time, so you can do it as well. We have a video installation of the Micro Booster in an original Gibson Standard Traditional guitar on our You Tube channel which you can check it up.

YES. There is plenty of room underneath the pickguard for the battery and booster's circuit. If needed, the booster volume knob can be taken out, simply by drilling a 6 mm diameter hole in the plastic pickguard, at around 11-14 mm from the center of the existing control hole. Some wood trimming may be needed in some bodies if booster is to be installed on the bridge/center tone pot. Please watch a Fender installation video on our You Tube channel.

BECOS Micro Booster Onboard Preamp for Guitar & Bass is designed and fabricated in Romania / European Union in our own micro lab. One by one, it is assembled, tested and packed by a guitar lover. Highest quality components are sourced from top suppliers. PCB's are produced at the highest standards possible. Batteries are high quality alkaline, for long lasting operation. We care about quality, reliability and customer satisfaction and we are proud to say that this product is Made in Europe/Romania.

Join Waitlist Please leave your valid email address below to be informed when this product becomes available for purchase.
Written communication is subject to Privacy Policy.