MPC-100A Mic Preamp / Compressor-Limiter FAQ

Q: Where can I get a light bulb for my MPC-100A?

A: Contact us! We'll get you what you need

Q: When should I change my vacuum tubes?

A: We have seen 10,000 hours and more out of our vacuum tubes without signal degradation. We accomplish this by regulating the heater voltage to the tubes, greatly increasing their life, something of a rarity if this industry. So, time is not as much of an issue as is sound. If you hear a ringing sound in your audio or when you rap your knuckles on the front, the tube is going microphonic. If you hear an increase in the noise floor, the tube may need to be replaced. Contact us if you need new tubes, we can help.

Q: How do I align my meter?

A: In Level mode, you'll need to contact us for the alignment procedure. In GR (gain reduction) mode, take off the top of the unit and warm up completely. BE VERY CAREFUL AND TOUCH NOTHING ON THE INSIDE OF THE UNIT; POTENTIALLY LETHAL VOLTAGES INSIDE. EVEN WITHOUT POWER CONNECTED CAPACITORS WILL STORE A CHARGE THAT CAN SHOCK AND POTENTIALLY KILL. If you are unfamiliar with doing this, please have a qualified service technician do this for you. Set the meter select switch to GR. With a small, flathead screwdriver, adjust VR4 near the middle, left side of the main board until the meter rests at 0. VR4 is located in the middle of a line of 3 trim pots next to a large, black square (U5) and to the back right of the vacuum tubes. It is helpful to switch back and forth from Level to GR to make sure the meter sits in the proper position.

Q: What are the actual attack and release times on the compressor?

A: The nomenclature on the MPC-100A is a little vague because the settings are a little vague. The way we design our compressor circuits make them react in a very musical manner so the timing circuits can vary. For example, when the compressor is put in medium release and a very quick signal, like a snare drum, comes through, the release time is quite a lot faster than if a slower, more legato signal like a voice comes through. So you can see why we don't have specific markings.