Yes I'd seen it thanks @Quatschmacher (I subscribe to their newsletter 😂). I'm not in any rush to buy the IV, other than their new in house opto-couplers and a standard CV input (but I don't really use the Mu-Tron with expression pedals) I can't see there's a significant amount of difference from the III.
I personally would have been more interested if they'd put in additional controls for attack and decay speed, and putting the Mu-Tron III/Tru-Tron 3x jumper switch on the outside of the casing.
Here's the blurb from their newsletter and some news on other future pedal plans...
The new Micro-Tron IV is based upon the award winning Micro-Tron III and improves it with our very own MU Opto-Mod technology. These are some new parts which we have developed to be direct replacements for the original Musitronics Mu-Tron which are no longer made. We are very pleased with the amazing sound and the consistency of these devices. In the near future we will offer swappable options for even more curve control of your Microtron. Another feature is standard CV input to accept an expression pedal such as the Dunlop DVP4 without modification! Furthermore, you can send envelope control voltage to other units such as the Phasor III and Bi-Phase pedals. The Microtron IV will be available on 11/25 at 11am PST.
Also on this new platform we have been developing the new Bi-Phase II, the modern, streamlined version of the historic BiPhase. About a quarter of the size of the original units, the BP2 will also employ the MU Opto-Mod, technology for better calibration, tighter tolerance and swappable character control. New features like 4/6 stage and CV OUT will open up even more possibilities. The unit is more pedalboard friendly as it routes the signal from right to left and can run off 9V DC power. We are pretty excited for this one and we know you guys are too.
Next up is the Boostron II. This amazingly transparent gain box just makes the world a better place. Based upon the same power section as the Microtron and Octavider, the Boostron II will have a choice of 3 classic preamp boost circuits. The Blaster is a JFET-based boost circuit from the legendary Stratoblaster. The Ranger is the Transistor-based boost circuit of the Dan Armstrong Red Ranger manufactured by Musitronics MU-TRON. Finally, the MU is something that kind of existed before: The sound of your guitar running through a Vintage Mu-Tron in bypass mode. Since they were not true bypass, the gain stage would bleed through the effect and do magical things to your subsequent pedals and amplifier. On the other footswitch there is a dedicated Dan Armstrong Orange Squeezer compressor with squeeze and level controls. Running at the higher voltage, this compressor is so amazingly quiet that you may just leave it on.
Last in line is the Octavider+. Octave and Fuzz make such a fine pair and since a lot of folks may not use the bass-only feature of the Octavider, we figured “what the heck.” There are so many different fuzz circuits, but for historical purposes and general usability, we decide to marry the MXR Distortion+ and the Dan Armstrong Blue Clipper. After some tinkering, we came up with a hybrid diode/LED circuit running at the same high voltage as the Octavider. With a single fuzz knob and a dedicated footswitch, the effect may be controlled by the volume knob on the guitar and may be used independently of the Octave effect. Turn on the octave, blend in some Green Ringer, engage the fuzz……... KILLER analog fun.
Thank you for your continued support of MU-TRON!