Spotted this one on Amazona.de.
The following is Google translated from the article:
"The ACME XP60 has set itself an extremely ambitious goal: the polyphonic synthesizer is to be nothing less than a 'faithful replica' of one of the greatest vintage classics: the Oberheim Xpander. The project by developer Markus Malik, who has so far offered modifications, replacement boards and repairs, is actually already in an advanced phase.
ACME XP60 - a compact Xpander
Admittedly, given the name ACME, you might think that the whole project is just another hoax report that comes around every year. But the XP60 is real and the electronics of the prototype are ready, although according to Malik there is still some need for optimization in the layout of the circuit board and the power supply.
Like its role model, the XP60 is also a six-voice analog synthesizer. However, the design is smaller, because the device, which actually has a desktop format, also fits in a 19" rack.
Not only the structure of the sound generation was adopted, but also the operating concept with the three displays. One improvement, however, are the controls with LED rings, whose colors can be customized.
For the sound generation, modern counterparts (clone chips) of the CEM3374 (Dual VCO) and CEM3372 (VC Mix-VCF-VCA) circuits used at the time are used. As a reference, developer Markus Malik was able to build the voice cards for the prototype with original oscillator ICs. In blind tests with mixed operation, no differences could be found between the original and clone chips.
There were also attempts to discretely recreate the circuit of the IC with transistors, but despite adjusted values, there were no satisfactory results in terms of temperature stability and FM, so this approach was not pursued further.
Doepfer, among others, has shown that the implementation of the complex multimode filter with its 15 different filter types can be successful with the A-106-6 XP VCF module.
Initially, no new firmware was written, but the original OS was used during development. The firmware is very complex, as envelopes, LFOs and other modulation options are also implemented using software. Tom Oberheim's consent was requested for the use of the firmware.
If the original firmware is retained, this will also entail certain restrictions, as it does not include parameter control with MIDI CCs, for example, but only Sysex. The developer may not be able to avoid creating his own OS sooner or later.
A small series of 50 units is planned initially, but a continuation is not ruled out. Information on the release, distribution and, above all, the price of the ACME XP60 cannot be given at this time, as there are too many factors that could still influence this.
So there is still a lot to do and we will report on the further progress of development."
