MindPrint T-Comp Tube Compressor — Recapped, New Tung-Sol 12AX7 Pair, MUSES8820 Op-Amps (100V)

The MindPrint T-Comp is a two-channel tube compressor designed and built in St. Wendel, Germany. Compression is handled by THAT Corporation 4301 "Analog Engine" ICs (VCA with true-RMS level detection), while a 12AX7 dual triode in each channel forms a variable saturation stage. The tubes run from a dedicated +300V high-voltage supply with DC heaters — real plate voltage, not a low-voltage "starved plate" design. The Tube Sat control takes the sound from clean, transparent compression to subtle tube warmth and on to clearly audible saturation, with a tri-colour Sat LED showing how hard the tubes are being driven. Program-dependent Adaptive attack/release and a 300 Hz sidechain filter (which reduces the compressor's response to low frequencies) make it easy to get natural-sounding results, and Link mode turns it into a stereo bus compressor. Equally at home on a mix bus, drums, vocals, or bass. This unit has been recapped, fitted with a new matched pair of tubes and socketed MUSES8820 op-amps (disclosed in full below), and fully function-tested by the seller, a professional electronic musical instrument technician. Working Condition Japanese domestic 100V version. Fully tested and confirmed working at 100V. See "Power Supply — Please Read Before Buying" below. All functions verified on both channels: Threshold, Ratio, Attack, Release, Adaptive, Filter, Link, Tube Sat, Input Gain, Output Level, Comp On, the input/output level meters with display switching, the gain reduction meters, and the Sat LEDs. All pots and switches operate smoothly — no scratchiness, no crackle, no intermittent contacts. Serial number: 286305 Recap — Power Supply and Audio Circuitry Given the age of the unit, every electrolytic and tantalum capacitor in the power supply and in the audio and control circuitry on the main board has been replaced with new parts. Except for the tube high-voltage supply noted below, capacitance values follow the original design, and voltage ratings were kept the same or raised: Power supply section: power-supply-grade low-ESR capacitors. Tube high-voltage (+300V) supply: the three filter capacitors replaced with 22µF 450V tubular electrolytics. Power supply rail decoupling: tantalum capacitors (2.2µF ×8) replaced with new tantalums of the same rating. Audio and control circuitry: audio-grade capacitors — 100µF ×5, 22µF ×12, 10µF ×14, 2.2µF ×4, 1.5µF ×2, 1µF ×2. Bipolar (non-polarised) electrolytics: 2.2µF ×6, replaced with new bipolar types. Please note: the capacitors on the LED meter / switch board have NOT been replaced. They serve only the level and gain-reduction displays, not the audio path, and both meters work correctly. New Tubes Both tubes have been replaced with a new matched pair of Tung-Sol 12AX7 (current Russian-made reissue). Modification: Socketed Op-Amps — MUSES8820 The six MC33078 dual op-amps in the audio path — input stages, tube-stage output buffers, output level stages, and balanced output drivers — have been replaced with Nisshinbo (formerly New Japan Radio) MUSES8820 audio-grade op-amps, mounted in sockets. Because they are socketed, the op-amps can be changed back to the original MC33078 type (a widely available part) at any time without soldering. Apart from the op-amp change and the capacitor replacement described above, there are no circuit modifications. Additional Servicing All switch, pot, and connector contacts have been cleaned. The unit has been cleaned inside and out. Power Supply This is the 100V Japanese domestic version, fitted with a dedicated 100V mains transformer. The T-Comp was built in separate 230V, 117V, and 100V versions — there is no external voltage selector. This unit has been tested at 100V only. In the US and Canada (120V), a 120V-to-100V step-down transformer is required. In Europe, the UK, Australia, and other 220–240V regions, a 230V-to-100V step-down transformer is required. Please do not connect it directly to 120V or 230V mains. The unit draws very little power (31 VA maximum, per the manufacturer's specifications), so a small step-down transformer is sufficient. Rear Panel / Connections Inputs: balanced XLR / 1/4" combo jacks (unbalanced sources also accepted). Outputs: separate balanced XLR and 1/4" outputs on each channel, usable at the same time. Insert: 1/4" TRS insert jack per channel (unbalanced; placed after the input gain and before the compressor). Ground lift switch. Detachable IEC power inlet. With the power switched off, relays connect the inputs directly to the outputs (hard-wired bypass). The optional DI-Mod S/PDIF digital I/O module is not installed. The original slot cover is in place. Cosmetic Condition Scratches and general signs of use on the top cover, the bottom panel, and the rack ears — see photos for the full picture. The right rack ear is slightly bent. The unit racks and mounts normally. The front panel is clean, with slight wear to the printed legends in a few places. No unusual…